PERFORMANCE ANALYSIS OF ABSORPTION HEAT TRANSFORMER ...

PERFORMANCE ANALYSIS OF ABSORPTION HEAT TRANSFORMER

by

JURIZAL JULIAN LUTHAN, B.E.

A THESIS

IN

MECHANICAL ENGINEERING

Submitted to the Graduate Faculty of Texas Tech University in Partial Fulfillment of the Requirements for

the Degree of

MASTER OF SCIENCE

IN

MECHANICAL ENGINEERING

Approved

Accepted

May, 1987

7 J?

/ 9^/^ ^^ ACKNOWLEDGMENT tie. 3^

The author would like to express his sincere appreciation to Dr. Atila Ertas. his

advisor, for his helpful guidance, contiunous encouragement, and tireless

assistance. He always had time and was never too busy to listen. The assistance and

criticisms of Dr. James H. Lawrence are gratefully acknowledged. The appreciation

is also extended to Dr. Herbert J. Carper and Dr. Timothy T. Maxwell for their helpful

suggestions. The financial assistance received from the Department of Mechanical

Engineering which was made available by Dr. Edward £. Anderson, the Chairperson,

is greatly appreciated. At last, the help from Dr. D. M. Pouchack. manager of

Technical Service, of Lithium Corporation of America is gratefully acknowledged.

ji

TABLE OF CONTENT

Page

ACKNOWLEDGMENT U

ABSTRACT v

LISTOFTABLES vi

LISTOFFIGURES vu

NOMENCLATURE ix

1. INTRODUCTION 1

2. LITERATURE SURVEY 4

3. ABSORPTION HEAT PUMP CYCLES 9

Absorption HeatPump Cycle 9

Reversed Absorption Heat Pump (}ycle 16

4. THEORETICAL MODEL 25

System Analysis 25

Mass and Energy Balances for Ammonia-Water 34

Mass and Energy Balances for LiBr-Water 39

Performance Criteria 44

Computer Implementation 47

5. RESULTS AND DISCUSSIONS 52

Calculation Results and Discussions 52

Application Example 71

6. CONaUSIONS AND RECOMMENDATIONS 76

111

Conclusions 76

Recommendations 78

REFERENCES 79

APPENDIX 80

A. Computer Output Sample for LiBr-Water System 81

B. Computer Output Sample for Ammonia-Water System 82

C. Ammonia-Water Data Matrices 83

D. Specific Volume of LiBr-Water Solution 89

IV

ABSTRACT

Many industrial sectors reject heat to the atmosphere in the form of hot water

with temperatures between 40° and 70°C. This rejected heat, owing to its low

temperature, is of little significant to the generating processes unless a means to

boost its temperature is available. However, there is a device with which this low

grade heat can be upgraded; that is. by employing a vapor absorption heat

transformer (AHT). It is anticipated that by using this device the amount of heat

rejected to the atmosphere can be reduced by recycling the upgraded low heat back

to the process. This research will investigate the performance of Ammonia-Water

and Lithium Bromide aqueous solutions in a single stage AHT. Comparison will be

made between the findings of the two proposed aqueous solutions for the same

system and operating parameters to determine the relative merit of each one.

LIST OF TABLES

Table Page

1 Influence of AX Variation for NHs-Water Solution 67

2 Influence of AX Variation for LiBr-Water Solution 68

3 Waste Heat Temperature Variation for NHs-Water Solution 72

4 Waste Heat Temperature Variation for LiBr-Water Solution 73

VI

LIST OF FIGURES

Figure Page

1 Absorption Heat Pump Basic Components (Ammonia-Water System)... 10

2 Absorption Heat Pump Basic Components (LiBr-Water System) 11

3 Single Stage Absorption Heat Pump Cycle (Ammonia-Water System).. 13

4 Single Stage Absorption Heat Pump Cycle (LiBr-Water System) 14

5 Single Stage Vapor Absorption Heat Transformer Cycle (Ammonia-Water System) 17

6 Single Stage Vapor Absorption Heat Transformer Cycle (LiBr-Water System) 18

7 Enthalpy-Concentration Diagram for Aqueous Ammonia System 19

8 Enthalpy-Concentration Diagram for LiBr-Water System 20

9 Pressure-Enthalpy Path Traversed by Pure Refrigerant 22

10 Upgraded Low Temperature Heat Application Example 24

11 Pressure Selection Procedure 27

12 Temperature and Pressure Levels of AHT (Ammonia-Water

System) 28

13 Temperature and Pressure Levels of AHT (LiBr-Water System) 29

14 Counterflow Heat Exchanger System 33

15 Generator System (Ammonia-Water System) 35

16 Evaporator System (Ammonia-Water System) 35

17 Generator System (LiBr-Water System) 40

18 Evaporator System (LiBr-Water System) 40 19 Output Heat Temperature as Functions of Waste Heat and Condenser

Sink Temperature 54

vii

20 Temperature Boost as Functions of Waste Heat and Condenser Sink Temperature 55

21 Performance Characteristics of AHT (Ammonia-Water System) 57

22 Performance Characteristics of AHT (LiBr-Water System) 58

23 Mass Flow Rates and Concentration Difference of AHT (Ammonia-Water System) 61

24 Mass Flow Rates and Concentration Difference of AHT (LiBr-Water System) 62

25 Circulation Ratio and Percentage of Pump Work for Ammonia-Water System 64

26 Circulation Ratio and Percentage of Pump Work for LiBr-Water System 65

via

NOMENCLATURE

AHT : Absorption Heat Transformer

COP : Coefficient of Performance

CR : Circulation Ratio

E : electrical energy. Btu/hr

hjj : enthalpy of point n. Btu/lbg|

J : heat-mechanical work equivalent constant

m . : refrigerant flow rate. Ib^^/hr

m^ : flow rate of strong solution. Ibj^/hr •

m^ : flow rate of weak solution, ih^/hc

P^ : pressure of the condenser, psia

Pg : pressure of the evaporator, psia

P|j : high level pressure, psia

Pj : low level pressure, psia

Pjj : pressure of point n, psia

PWR : Percentage of Pump Work of Output Heat. %

AP : pressure difference, psia

Qjj : volumetric flow rate of point n. ft^/hr

0, : rate of heat flowing out of the absorber. Btu/hr

Q^ : rate of heat flowing out of the condenser. Btu/hr 'C

Q. : rate of heat flowing into the evaporator. Btu/hr *e

Qg : rate of heat flowing into the generator. Btu/hr

IX

QQ : rate of output heat. B tu /hr •

Q^Yi ' ^^^ ^^ ^ waste heat available, Btu /hr

T^ : condenser temperature. ^

Tg : evaporator temperature. °F

T^ : temperature of point n. ^

TQ : temperature of output heat , °F

Tj : condenser sink temperature, ^

T j : temperature of the waste heat available, ^

v^ : specific volume of point n, f t ' / l b ^

Wp { : work of solution pump 1, Btu/hr

Wp 2 : work of refrigerant pump 2, Btu/hr

Xg : concentrat ion of strong solution

X^ : concentrat ion of weak solution

e : heat exchanger effectiveness. %

r[ : exergy efficiency. %.

CHAPTER 1

INTRODUCTION

According to the study conducted by Blue and Arehart [11, the United States

annual energy consumption is roughly 8.44x10^ TJ of which about 60% is supplied

by oil and gas. The U. S. industrial sector consumes 37% of this figure and rejects a

large amount this energy as waste heat. There is also an indication that about 35% of

this figure, or about 2.85x10^ TJ per annum, is rejected in the form of hot water with

temperatures between 40° and 70° C.

Irrespective of the complicated nature in the rise and fall of the price of oil and

gas, the need to further utilize this rejected energy which is currently dispensed to

the surrounding environment is justified owing to the fact that the oil and gas

reserves are ever decreasing. Another point that reinforces the justification is that

by utilizing this rejected heat the severity of heat pollution in the surrounding

environment can be reduced.

But this low temperature heat is of little significant to the process (it is the very

reason for its rejection) unless a means to boost its temperature is available. Several

means that have been considered recently to recover this waste energy [21 may be

classified into three broad categories, they are :

1. heat pump systems

2. heat engines, and

3. direct utilization for space heating or commercial applications.

The focus of this thesis is placed on the heat pump systems.

2

In a broad sense, a heat pump takes energy from a low temperature source and

with the help of work from another source discharges this energy into a high

temperature environment. The work that is needed to accomplish this task may be

in the form of electrical energy, high-grade heat, or low-grade heat which in turn

can be used as a base to claasified the heat pump still further according to the

energy it consumed.

Electrical-energy actuated heat pump, also known as vapor compression heat

pump, is the one in wide commercial use today. But because it still consumes a form

of high-grade energy excludes it from the standpoint of minimizing the

consumption of high-grade energy or fossil fuel.

The high-grade-heat actuated heat pump operates on direct heat provided by

on-site combustion of fossil fuel such as gas. oil. or coal. This alternative is also out

of the consideration based on the standpoint stated above. Thus, the only alternative

left is a low-heat-actuated heat pump which, save for a very small amount of

parasitic high-grade energy, performs its duty based entirely on the available low

temperature heat that is being rejected. It is anticipated that by using

low-heat-actuated heat pump (or also known as absorption heat transformer) the

amount of heat rejected to the atmosphere can be reduced with an added advantage

of minimizing the consumption of high-grade energy or fossil fuel. Since by

employing this device the upgraded low heat can be recycled back to the process.

After being exhaustively utilized in the process, it is finally discharged into the

atmosphere.

The objective of this research is to investigate the performance of

Ammonia-Water and Lithium Bromide-Water solutions in a single-stage vapor

absorption heat transformer (AHT) and compare them for the same system and

operating parameters. The investigation of each solution's performance

3 characteristics will be conducted by developing a computer code suitable for each

solution that contain the governing equations. Comparison will be made between

the findings of the two aqueous solutions to determine the relative merit of each one.

Despite the fact that there are many combinations of working fluids suitable for

the AHT systems, the choice fell upon Ammonia-Water and Lithium Bromide-Water

solutions. The reason for the choice is that since the proposed working fluid

combinations have opposite operating characteristic, that is. while water is the

refrigerant in Lithium Bromide-Water systems, ammonia is the refrigerant in

Ammonia-Water systems.

CHAPTER 2

LITERATURE SURVEY

In 1980, Blue and Arehart [1] published the result of their study that estimate

the United States energy consumption and the associated waste heat per annum.

Based on these figures. Perez-Bianco conducted a study to utilize this waste heat [21.

The objective of the study was twofold, they were : (1) to find out whether heat pump

will find applications in industry and (2) to identify desirable delivery temperatures.

He predicted that energy saving on the order of 1x10^ TJ per annum may be realized

using the temperature-boosying technology. To meet these objectives the following

three residual-heat-actuated heat pumps were analyzed :

1. Turbine-compressor heat pumps

2. Closed-cycle absorption heat pump

3. Open-cycle absorption heat pump.

As working fluid. Lithium Bromide-Water solutions were employed.

The research was continued by Grossman and Perez-Bianco (31 with conceptual

design and performance analysis. Of the three types of the residual-heat-actuated

heat pumps only the second, closed-cycle absorption, was further studied. In this

investigation. Lithium Bromide-Water and Lithium Chloride-Water solutions were

used as the working fluid pairs with the intention not to rule out other fluid pairs

combinations but rather to evaluate the potential of the cycle with what seemed to be

the most suitable fluid pairs at present. As guidelines to working fluid selections for

the system, the paper cited several important points to be taken into consideration in

4

choosing fluid pairs. In order to evaluate the performance of the conceptual design,

a computer code was written for that purpose. They found that Lithium Bromide-

Water solution gave a higher temperature boost than the Lithium Chloride-Water

solution when desorbed under the same conditions. This outcome may make Lithium

Bromide-Water solutions the preferred working fluids to Lithium Chloride-Water

solutions, they concluded. The investigation was intended as a preliminary step

toward the construction of a prototype working system in Oak Ridge National

Laboratory.

Trepp [4] gave a short account of the state of the art of heat transformers up to

that time, 1983- He discussed the possible combinations of heat transformation using

an absorption heat pump with three heat reservoirs for single- and multi-stage

systems. Attention was given to working fluid selections both from theoretical and

practical work standpoints. He discussed inverse absorption heat pums (AHT) as well

where the difference with absorption heat pumps is that now the evaporator and the

absorber are in a higher pressure level in comparison with the condenser and the

generator/desorber.

Grossman and Childs (51 further explained the computer simulation model they

developed to predict the performance of an AHT for temperature boosting of low-

grade heat. The computer code was intended to simulate a single-stage. Lithium

Bromide-Water system that was being constructed. Based on the computer code they

investigated the effect of waste heat temperature, cooling water temperature, and

solution circulation rate.

Huntley [6] reported the performance test results of the single-stage prototype

system that was constructed to study the possibility of upgrading industrial waste

heat to produce process steam. The system used Lithium Bromide and water as the

6

working fluids and was designed to operate with waste heat temperature ranging

from 60° to 100°C (140° to 212°F). He reported that performance data from the 45-kW

(12.5 ton) prototype heat pump have shown good agreement with theoretical

predictions. Most of the energy for operation came from the waste heat with only

low inputs of electrical energy for parasitics; electrical coefficients of performance

ranging from 50 to 85 had been demonstrated. This feature made the heat pump

attractive from the standpoint of energy conservation. The successful operation of

this heat pump prototype had demonstrated that this concept is an easily operated

and practical candidate for energy recovery from waste heat industrial applications

where low-temperature steam is needed. The manufacture of Lithium Bromide

absorption heat pumps could rapidly be transferred to industry because the

materials of construction are common and component of design is very similar to

presently manufactured Lithium Bromide absorption chiller system, he concluded.

Kripalani, etal. [7] conducted a comparative performance study of a single-stage

AHT with Lithium Bromide-Water, R21-DMF, R22-DMF, and R22-DMErEG as working

fluid combinations. The following ranges of operating parameters were considered :

a). Heat source temperature from 50° to 70°C to represent the generating and

evaporating temperatures,

b). Heat sink temperatures from 15° to 40°C to represent the condensing

temperatures.

As the results, the following performance characteristics were presented :

a). The heat delivery temperature (solution temperature at absorber outlet)

which represents the maximum temperature boost that can be achieved at

specified source and sink temperatures,

b). The circulation ratio which is an indicative of the auxiliary pump work.

c). The coefficient of performance (COP) which is an indicative of the system

performance based on the first law of thermodynamics,

d). The exrgy efficiency which represents the system performance based on

the second law of thermodynamics.

They concluded that of the four pairs of working fluids. Lithium Bromide-Water and

R21-DMF combinations operate favorably in AHT systems in comparison with the

other pair.

Stephan and Seher [8] gave a review of the present knowledge on the heat

transformer. After a description of the principles of heat transformations,

different types of single- and two-stage sorption heat transformers were presented

and discussed. Examples of practical realizations and applications were also given.

While the results of a detailed analysis of a real single-stage absorption heat

transformer working with Ammonia-Water were discussed in their second paper [9],

They included irreversibilities due to temperature differences, pressure drops and

efficiencies for the absorber and the liquid pumps in their study, and also the

performance of the retification column was considered. Heat fluxes were delivered

or removed by fluids like water or humid air. The working temperatures of the

process were varied. From the analysis, possible ways of losing exergy were

identified and evaluated.

Grossman [10,11] gave a discussion on his surveys of the possible multi-stage

schemes of absorption heat transformers for industrial applications. A systematic

approach was taken to identify systems with improved coefficient of performance,

greater temperature boost, and combine cooling/heating effects. Operating

diagrams of these systems were described and a comparison between them given,

based on performance criteria and potential cost.

8

Grossman and Michelson [121 presented and discussed a generalized computer

simulation of AHT. The simulation program could be used for various combinations

of AHT components and working fluid pairs.

CHAPTER 3

ABSORPTION HEAT PUMP CYCLES

Absorption Heat Pump Cycle

Similar to an absorption refrigearating machine, the Absorption Heat Pump

follows a closed, continuous absorption thermodynamic cycle (Fig. 1 and 2). Besides

gages and valves: generator, condenser, evaporator, and absorber are the main

components of an absorption system. But unlike vapor compression heat pump in

which there is only one working fluid, the refrigerant, the vapor absorption heat

pump uses a combination of. at least, two working fluids. The volatile one of two

serves as the refrigerant while the non-volatile plays as the absorbent. These two

fluids circulate through the entire system to produce the desired effect.

The absorbent as well as the generator and the absorber play the role as the

compressor in vapor compression heat pumps. There are many combinations of

refrigerant-absorbent fluids available but only two pairs of such combinations will

be considered in this research. They are : Ammonia-Water and Lithium Bromide-

Water solutions. In Ammonia-Water systems, ammonia is the refrigerant while

water is the absorbent. On the other hand, in Lithium Bromide-Water systems, water

is the refrigerant and Lithium Bromide is the absorbent. Thus, the two refrigerant-

absorbent combinations have opposite operating characteristic, (^nsiderable

energy is generated during the absorption of the refrigerant by the absorbent.

After the absorption the resulting solution becomes weak (diluted) for Lithium

Bromide-Water systems, while it becomes strong for Ammonia-Water systems.

9

10

a a

a o a

a a o a o

8

B cu

a>

o o •-

o Xi <

11

1 1

u (U V) c (U

T3 c o CJ ^ .

-o •H U 3 QJ

cr -u •H CO J 2:

k u

Vi

o 4-t n3 u o a to > ^ ^ w

^

a

wo u 3

I

i2 d d o

a o

CQ O i

a 3

04 «_>

a>

d o o,

JD

CT3

X

12

In a basic continuous absorption cycle, the refrigerant follows the complete

cycle which is common for both systems. Ammonia-Water and Lithium

Bromide-Water. While the pure refrigerant is traversing the complete cycle.

Lithium Bromide-Water or Ammonia-Water solutions ciculate only between the

absorber and generator. In case of absorption heat pumps, the generator and

condenser are on a higher pressure level in comparison with the evaporator and

absorber as can be seen in Fig. 3 and 4.

Starting at the generator. Fig. 3 and 4. the heat applied to the aqueous solution

causes water or ammonia vapor (the refrigerants in the two systems) to be boiled off

and circulated to the condenser. While the remaining aqueous solution, strong

solution for Lithium Bromide-Water systems and weak solution for Ammonia-Water

systems, goes to the absorber. By cooling the condenser, heat is removed which

causes the change in the state of the refrigerant from vapor into liquid. This liquid

refrigerant then travels to the evaporator which is at a lower pressure level.

Because of this low pressure, heat from a low temperature source is transferred into

the evaporator that vaporizes the liquid refrigerant. The refrigeranat vapor

generated in the evaporator flows to the absorber driven by the prevailing pressure

difference between the two components. As the aqueous solution inside the absorber

comes into contact with the vapor, absorption process occurs as the result of the

affinity of the aqueous solution towards the incoming refrigerant vapor. This

process of absorption generates a large amount of energy that comprises of the

removal of the refrigerant's sensible heat, the evolving heat of solution, and the

heat released during condensation. At this stage, the aqueous solution's concentra

tion changes : it becomes strong in case of Ammonia-Water systems or weak in case

13

3

75 TD a -H >-i to cu

to •l-l

X

^ ^ cu u 3 en en 01 u

:? o ^

14

o CO

L !-i

a en c o -a c o " <

\

XJ -

eat 0

»-i^

TD

Liqui

Water

u 3 W QJ cn TS (U - H >-i CO

^4

c o

•H cn (—• CO C - ^ X CO ^ >

>

CO 0 1

o ro

0) u CO

00 •H X

3 (U

cn -H CU CO 5-1

PL.

o

a s (/) u

I u

PQ

^? a 3 o*

a>

d o *^ o, o CO

:5 <•) j j '3D d ••

00 . o 4

CO

X

15

of Lithium Bromide-Water systems. The resulting aqueous solution is then pumped

to the generator where the cycle begins again.

In a practical absorption heat pump application, a high temperature heat

source (usually a gas flame) is applied to the generator just like in absorption

refrigeration while a low temperature heat is applied in the evaporator. Heat

energy at a temperature between the heat source in the generator and evaporator is

released by the condenser and the absorber. A solution pump and two expansion

valves create the pressure difference across the high and low pressure sides. Hence,

in using an absorption heat pump for energy recovery, a gas flame would be used to

fire the generator, the waste heat woukld be introduced at the evaporator, and an

intermediate temperature heat would be produced from the condenser and absorber.

The absorption heat pump delivers more heat than it consumes from the high

temperature heat source for the generator and the energy to power the solution

pump. The ratio of delivered energy to the total input energy is known as

coeeficientof performance (COP); for an absorption heat pump, it is greater than

unity. Because the only moving component of an absorption heat pump is the

solution pump, a long operating life of the unit can be expected. The only drawbacks

to the absorption heat pump are the high initial investment and the requirement of

a high temperature flame for the generator. The second drawback makes absorption

heat pump unsuitable for the purpose of minimizing the use of fossil fuel which is

the focus of this research.

16

Reversed Absorption Heat Pump Cycle

By reversing the high and low pressure levels of a conventional absorption

heat pump, a new cycle is obtained. Hence, in this new configuration, the generator

and condenser are at the low pressure side while the evaporator and the absorber

are at the high pressure side. Also, an additional solution pump is appended to the

system between the condenser and evaporator. The cycle is known as Reversed

Absorption Heat Pump or Absorption Heat Transformer (AHT). Fig. 5 and 6. The

advantage gained from reversing the pressure levels is that now the need for a high

temperature heat source is eleminated so that this change enables the generator and

evaporator to absorb the available waste heat which is at lower temperature in

comparison with flame temperature. The path traverses by the aqueous solution can

be seen in Fig. 7 and 8. while the path followed by the refrigerant is shown in Fig. 9

with the points labeled in reference to Fig. 3 and 6.

Referring to the enthalpy-concentration diagrams of Fig 7 and 8, corresponds to

the path traversed by the aqueous solution, an aqueous solution with the prescribed

concentration (weak or strong) leaves the absorber, point 4. at the output heat

temperature and the high pressure. The aqueous solution is cooled as it passes

through the heat exchanger because at the same time a relatively cooler aqueous

solution is flowing countercurrently from the generator. At the heat exchanger

exit, point 5. the aqueous solution has the concentration as of point 4. But its

enthalpy, temperature, and pressure ar intermediate to the conditions that can be

achieved by the low and high pressure sides for the same concentration. The

aqueous soluUon then passes through an isenthalpic expansion valve which reduces

the pressure. As the solution enters the generator, point 6. at the low pressure.

17

c o •H tn c 0) CO > CX . H X (0

w >

u c (0 J-l 0) DO

•H >-i

*M 0)

PS

0) Wl 3

Pu.

1 1

C o

•H

3 rH

o CO

- - H

(1)

3 i-i (0 ^J GJ C c o H

a i j >v

on

I

«e d o a a

<

o

u

a u o

d u

c c

c w

<

o a. «

> a>

3

d ITS

oanssaaj

18

c o •H cn c O- rH X CO w >

4J c CO U 0) 00

•H V4

U-l (U Pi

 s

u

a u CO

d u «^ ti a>

d o •• o, o (A

Xi 

i2 CO

'3) d

<•! op

aanssaaj

\ +

h j X

I—I CO

J3 4-1

c

1 --

Jligh Pressure

5,6 /

19

Output Heat Temperature

Waste Heat Temperature

Low Pressure

weak strong

Concentration

Fig.7. Enthalpy-Concentration Diagram for Aqueous Ammonia System

20

High Pressure

h, . .

rH h . , CO J

1 - -

utput Heat Temperature

Waste Heat Temperature

,ow Pressure

+ strong

weak

Concentrat ion

Fig.8, EftChalpy-Concentration Diagram for LiBr-Water System

21

waste heat is added. This heat addition boils the refrigerant out of the aqueous

solution resulting in a new aqueous solution concentration, weak for Lithium

Bromide-Water or strong for Ammonia-Water, as of 1. The remaining aqueous

solution is now at the waste heat temperature and the low pressure. The solution

pump 1 raises the pressure and the enthalpy of the aqueous solution to point 2. As

the solution passes through the heat exchanger, it absorbs the heat that is realeased

by the solution flowing from point 4 to point 3- Leaving the heat exchanger, the

solution acquires the conditions of point 3- Inside the absorber the solution meets

the refrigerant vapor from the evaporator that again causes the change in the

aqueous solution's concentration by absorption. Energy is released as the absorption

of refrigerant vapor by the soltuion accompanied by the evolving heat of solution

and the heat given off as condensation of the refrigerant occurs. At the end of the

absorption process, the soltuin reaches the conditions of point 4 where the cycle

begins again.

The pressure-enthalpy diagrams of Fig. 9 which together with Fig. 5 and 6

explain the path followed by the refrigerant. Inside the generator the solution is

heated by a source at the waste heat temperature that causes the refrigerant to boil

out of the aqueous solution. The refrigerant vapor generated leaves the generator

exit, point 7. at the low pressure and the temperature of the waste heat. Reaching

the condenser, the vapor is cooled by the sink that causes the vapor to liquefy, point

8. The pressure and the enthalpy of the liquid refrigerant is then raised to point 9

by means of solution pump 2. Inside the evaportor. the liquid refrigerant vaporizes

because of the heat applied which is at the waste heat temperature causing its

enthalpy to increases as of point 10. At last, the refrigerant vapor is absorbed by the

aqueous solution in the absorber accompanied with the production of heat.

22

p , • •

u 3 (/) cn a u

P, . .

10

H »•

^8 ^9 Entha lpy

H — » — « *

^7 ^^10

Fig.9. Pressure-Enthalpy Path Traversed by Pure Refrigerant

23

In using the AHT for energy recovery, the waste heat is applied to both the

generator and the evaporator while a low temperature heat is rejected at the

condenser at the sink temperature. A higher temperature heat in comparison with

the temperatures of the waste heat and the sink is produced in the absorber. Thus

the required high temperature source in the case of absorption heat pump is

elminated with an additional pump is installed as the compensation.

There are many AHT applications possible, one of such applications is shown in

Fig. 10. The realization of this typical arrangement is in food processing plant or

petroleum industry. The process needs high temperature heat which after being

used is rejected at a much lower temperature. Usually this exhausted low heat is

dissipated to the surrounding atmosphere causing heat pollution that destabilizes the

habitat in the vicinity of the point of rejection. But by appending an AHT system

somewhere near the final exhaust point of the process some of this rejected heat can

be converted back to high temperature heat. Depending on how high the required

temperature needed by the process, a single- or multi-stage system may be built to

meet the requirement of the process. While the unconverted remaining is rejected

to the atmosphere. Hence the application of an AHT system is not only reduces the

amount of energy consumption that is desirable from the standpoint of energy

conservation but also reduces the amount of heat rejected to the atmosphere that

mitigates the severity of heat pollution.

High Tenp

Heat

24

Pump Work

Low Temp.

Exhaust Heat

Absorption Heat

Transformer

Low Temp.

Heat to Sink

High Temp

Heat

Fig.10. Upgraded Low Temperature Heat Application Example

CHAPTER 4

THEORETICAL MODEL

System Analysis

As Trepp [41 concluded in his paper, the temperature of the useful heat of AHT

depends upon the temperature of the waste heat available and the condenser sink

temperature. In order to get the desired output temperature; the high and low

pressures required, and the strong and weak concentrations can be varied for a

fixed values of the other two temperature levels. With these two temperatures hold

fixed and by applying mass and energy balances acsross the system, the other

variables of the system can be obtained. While the physical and thermodynamic

properties for both working fluid combinations are determined from published data

113.141.

In analyzing the system, the following assumptions have been employed :

1. There is no heat transfer between components.

2. Pressure drops in the pipings are negligible except in expansion valve.

3. The heat losses and gains to and from the surrounding in the various

components are neglected.

4. The refrigerant leaving the generator is free from water vapor.

5. The effectiveness of the heat exchanger is 85%

25

26

To enable the analysis of the system, the following information should be

known:

1. The amount of the waste heat available (Btu/hr)

2. The temperature of the waste heat available.

3. The output temperature desired.

4. The condenser sink temperature.

By employing the mass and energy balances in addition to the above required

information, the following results of interest about the system can be determined :

1. The amount of the output heat produced at the absorber (Btu/hr).

2. The heat transfer for the generator, condenser, evaporator, and absorber.

3. The mass flow rates of the refrigerant, absorbent, and refrigerant-absorbent

solutions.

4. The concentrations of the weak and strong aqueous soltuions.

5. The work needed by each solution pump.

6. The pump work percentage of the useful heat.

7. Circulation Ratio.

8. Coefficient of Performance.

9. The system's exergy efficiency.

To begin the analysis, the high and low pressures must be determined first.

Referring to Fig. 11.12. and 13. their determinations begin with arbitrary selections

of the high pressure. Using the selected high pressure, the evaporator temperature

which is the saturation temperature of ammonia vapor is then determined. While

the condenser temperature, corresponding to saturation temperature of liquid

ammonia, is determined using the selected low pressure. The temperatures obtained

are then checked against the waste heat and sink temperatures. The evaporator

27

Chose P, and P, a L

T =Saturation c Tcnp. at P,

T =Saturation c Temp, a t P

L

N

X

a t T ,P , a h

© © Fig.U. Pressure Selection Procedure

28

d o •H (fl a (u CO > P-rH X CO w >

c CO u 0) 00

•H U

M-l 0)

OJ

(U u 3

P4

1 1

c o •H 4-1 3

f H O

CO

1 1 1

-- o

>-l

o 4J CO u CU c (U

C D

S

OO CO c y CU

•> pa oc

H CU 4J cn CO 3

CO

OJ Q . 6 0)

H

•cy

CO (U re

O 4-1 CJ (U

•>-) 0) Pi

a C/)

u iJ

I

d o a a

<

o C/)

>

u 3 crt (/) (1> t i a, -o d a> 3 « ^ C<j u 

f -f\i

IZ

p^ 0)

1^

p^

00

ajnssajj

29

CU

u 3 u CO l-t (U B 

a>

u. 3 «0 CO

a>

d

u

I u a

tZ

ajnssajj

30

temperature should be lower than the waste heat temperature to enable the

refrigerant to vaporize inside the evaporator. On the other hand, the condenser

temperature should be higher than the sink temperature so that the refrigerant

inside the condenser can be liquified. If either one or both of these checkpoints

cannot be passed, pressure selections are repeated until they are satisfied. Having

obtained the two pressures, aqueous solution concentration determinations come

into play. The strong concentration is determined from the conditions prevail at the

absorber exit, point 4, in which its temperature corresponds to the output heat

temperature and its pressure equals to the selected high pressure. The weak

concentration is determined from the conditions of point 1. the generator exit,

which is at the waste heat temperature and the low pressure level. As the last

checkpoint before the program can proceed to the main part, the strong and weak

concentrations are compared. If the set up condition cannot be met. new pressures

must be selected. Otherwise the analysis of the system can be started.

The above procedure applies to Lithium Bromide-Water system with the

differences are that now the refrigerant is water and strong and weak

concentrations should be read as weak and strong concentrations respectively.

With reference to Fig. 12 and 13 together with the assumptions, the following

assignments can be made :

Generator exit: point 1 and 7

Ti = temperature of the waste heat available

P) = the selected low pressure

hy = aqueous solution's enthalpy at Ti andP^

Vi = specific volume of the aqueous solution at T and weak concentration

(for Ammonia-Water) or strong concentration (for Lithium

31

Bromide-Water)

T7 »temperature of the waste heat available

P7 = the selected low pressure

hy = aqueous solution's enthalpy at T7 and P7

(^ndenser exit: point 8

T3 = temperature of the waste heat available

PQ = the selected low pressure

ha = liquid refrigerant's enthalpy at Tg andPg

V3 = specific volume of liquid refrigerant at Te and P3

Evaporator exit: point 10

Ti 0 = temperature of the waste heat available

Pi 0 = the selected high pressure

h 10 = refrigerant vapor's enthalpy at Ti Q and Pi Q

Absorber exit: point 4

T4 = temperature of the desired output heat

P4 = the selected high pressure

h4 = aqueous solution's enthalpy at T4 and P4

The isentropic pump work for solution pump PI is

i v v i ( P 2 - P i ) W„ =—^ (1)

P' J

for Ammonia-Water solution, for Lithium Bromide-Water solution it is

•••' J

32

in which P2 =P, and Pi =P, h I* Knowing the pump work, the enthalpy at point 2 is

for Lithium Bromide-Water, while for Ammonia-Water the enthalpy is

h2=hi *(Wp^/ii^)

The isentropic pump work for refrigerant pump P2 is

m vgCPg - Ps) Wp2= (4)

J

in which Pg = P,, and Ps = Pj.

Knowing the pump work, the enthalpy at point 9 is

h9=h8 +(Wp2/mr) • (5)

Since the pump works are isentropic then T2 =Ti andTg =T8.

The liquid counterflow heat exchanger. Fig. 14. has an effectiveness of e, where

actual heat transfer 8 =•

max. possible heat transfer

T4-T5

T4-T2

33

Fig.14. Counterflow Heat Exchanger System

34

Thus: T5 =e(T4-T2)+T4 . (6)

Then the aqueous solution's enthalpy at the heat exchanger exit:

hs = aqueous enthalpy atTs and strong concentration (for Ammonia-Water)

or weak concentration (for LiBr-Water).

For the isenthalpic expansion valve :

Mass and Energy Balances for Ammonia-Water

The flow rates of the ammonia and water can be determined by applying

steady-state mass balance across the generator and absorber. Fig. 15 and 16.

Ammonia balance :

• • •

mg = mi + my

or

fl^s^-°V^-^r = ^ • 7*

Water balance :

m5 =mi

35

Wast Heat '^Tg,Q9

JL.m ;X ;hi ^^ w w 1

m ;X ; h , s s 6

4 1

Fig.15. Generator System (Ammonia-Water System)

{ {

r 9

+

10 • u

Waste Heat

Fig.16. Evaporator System (Ammonia-Water System)

or

Generator energy balance (no work)

• • • •

Qg- m hg »mihi + myhy

or

Evaporator energy balance (no work)

• •

36

(1-Xg)m5-(1-X^)i(i^ = 0 . (8a)

m^hi +m^h7-m5h6 = Qg. (9a)

(hio-h9)mj. = Qg. (10a)

Since the total available waste heat enters the cycle in the evaporator and generator,

then :

• • %t,-%'% (11)

Substituting equations (9a) and (10) into (11) gives

• • • •

(hy-hg +hio)mf •fflw i "^s^6'^wh- ^ ^ ^

37

So far there are three unknowns in the preceding equations, thus to be able to solve

them three equations are needed. They are equations (7a), (8a). and (12a).

Now letting : Xi "flij Ai =1^

X2 =ffl^ A2 =X^

X3 «mj. A3=-l

equation (7a) becomes

A1X1 + A2X2 +A3X3=0 . (7a')

Let: Bi ^ l - X ,

B2=X^-1

then equation (8a) becomes

B1X1 •B2X2 = 0 . (8a')

Let: Ci =-h6 E = Q h

C2=hi

C3 =h7 - hg • hio

transforms equation (12a) into

C1X1 +C2X2 + C3X3=E. (I2a')

38 The three equations with the three unknowns are :

AiXi • A2X2* A3X3=0

BiXi + B2X2 =0

C1X1 •02X2 + 03X3 =0

By employing Cramer's rule, the following will be obtained

Xi X2 X3 xi = ; X2= ; X3 = —

where

A =(AiB2C3 • A3B20i)-(A3B2Ci + A2B1C3)

= - ( l - X s ) h i + ( l - V h 5 + (X^-Xs)(h7-hg + hio)

Xi=-A3B2E = (X^-l)Q^h

X2=A3BiE = (Xs-DQ^h

X3=E(AiB2-A2Bi) = (X -Xs)Q^h

Hence

(X,-X,) (13a)

and the rate of output heat produced in the absorber is

• «

39 (X,- l )

m-, = flL. (14a) (x^-v

m = . (15a) -(l-Xs)hi + (l-X^)h6 + (X^-X5)(h7-hg + hio)

The rate of heat dispensed from the condenser is

Qj.=(h8-h7)mr (16a)

Qj = m^h3 +m5h4-m^hio (17a)

Mass and Energy Balances for LiBr-Water

Similarly, the flow rates of water and the salt can be obtained by applying

steady-state mass balance across the generator and evaporator. Fig. 17 and 18.

Water balance:

• • m5 =mi + m7

or

• • (l-X^)m^-(l-Xs)ms-mr = 0 . (7b)

40

m ;h^ r ' 7

Waste Heat T9.Q9

Gene ra to r

! • • m ; X ; h , s' s' 1

% ' \ ' \

Fig.17, Generator System (LiBr-Water System)

r ' 10

\ ; \

Waste Heat T ,6

e e

Fig. 18. Evaporator System (LiBr-Water System)

Salt balance :

m^ =mi

or

Generator energy balance (no work)

• • • •

Qg + mghg =mihi + m7h7

or

41

X^m^-Xsm5 = 0 . (8b)

m^hi +mj.h7-m^h6 = Qg. (9b)

Substituting equations (9b) and (10) into (11) gives

(h7-hg •hio)m,. +m^hi -mgh5=Q^lj. (12a)

So far there are three unknowns in the preceding equations, thus to be able to solve

them three equations are needed. They are equations (7a). (8a), and (12a).

By letting : Xi =m^ Ai = 1 -X^

X2=m5 A2=Xs-l

X3 =mp A3=-l

42

equation (7b) becomes

AiXi • A2X2 +A3X3 = 0 . (7b')

Let: Bi =X^

B2=X5

then equation (8b) becomes

B1X1 + B 2 X 2 = 0 . (8b')

Let: Ci =-h6 E = 0 ,j

C 2 = h i

C3 =h7 - hg + h i o

transforms equation (12a) into

C1X1 +C2X2 + C3X3=E. (12b')

The three equations with the three unknowns are :

A1X1 + A2X2 • A3X3 =0

B1X1 + B2X2 =0

C1X1 + C2X2 + C3X3 =E

43

By employing Cramer's rule, the following will be obtained

Xi X2 X3 xi = — ; X 2 = — ; X 3 = —

where:

A =C3(AiB2 -A2Bi)-A3(BiC2-B2Ci)

= X^hi ^Xjhe * (X^-X5)(h7 - hg * hio)

Xi=-A3B2E = -X5Q h

X2=A3BiE = -X^Q^„

X3 =(AiB2-A2Bi)E = (X^-Xs)Q^n

Hence

m-, = m (13b) (x^-V

. - \ •

m^ = m,. (x,-v (Ub)

m-= C15b) -X^hi* Xsh6*(X^-Xs)(h7-hg + hio)

The rate of heat dispensed from the condenser is

44

bc=(h8-h7)mr (16b)

and the rate of output heat produced in the absorber is

• • Qj = m5h3 + m^h4-m,.hio . (17b)

Performance Criteria

An important quantity in the analysis of an absorption system is the mass flow

rate of the strong solution (for LiBr-water) system which is needed to absorb a unit

mass flow rate of water vapor from the evaporator. This quantity is called

Circulation Ratio which is given by

CR (18a) Xj-X^

The expression for the circulation ratio for Ammonia-Water system is somewhat

different from the one above owing to the difference in the meaning for strong and

weak solutions. However, the quantity reflects the same physical meaning and is

given by

1-L CR= - ^ (18b)

Xg-X^

45 Conventionally, heat pump performance is defined in trems of (^efficient of

Performance which is given by 121:

COP (19)

Although this definition is suitable for most practical purposes but it has two

drawbacks if directly applied to AHT systems. The first one is that equation (17) does

not differentiate the temperature at which Q and E are delivered and supplied

respectively. This drawback may cause that although two heat pump systems have

the same COP but one of them may outperform the other by delivering Q at a higher

temperature. The second drawback is that, in the case of a residual-heat-actuated

heat pump which is the focus of this research, the COP may attain a very large value

since the system consumes very small power to run the two solution pumps (hence

the name parasitic power). This second drawback will render difficulty in

differentiating two residual-heat-actuated heat pumps if the definition above is used

without modification. However, since the physical meaning of the COP is the ratio of

the desired output to the expense that has to be paid and noting that in case of AHT

(by neglecting the parasitic power) the price to be paid is provided by the available

waste heat, then a slightly different COP is obtained. It is given by

COP = — ^ . (20)

Qe * Oo Qwh

46

By redefining the COP the second drawback has been addressed, that is. there is

no way an infinite COP (if the parasitic power is completely neglected) can be

resulted in evaluating an AHT system. But the first drawback is still untouched. To

overcome this difficulty a means to depict the performance of an AHT based on the

Second Law of Thermodynamics is sought.

With the recent interest in energy conservation the use of availability or exergy

or essergy analysis has become prevalent for steady-state analysis. It is known that

if the temperature at which waste heat delivered is close to sink temperature, the

availability of Q i is small. As the temperature of the Q i increases so does the

availability which is the indicative of maximum amount of mechanical work that

can be produced from that energy.

Thermodynamics availability is released when one unit of fuel is burned. As the

combustion takes place, successive heat transfer and conversion operation (from

reactants into combustion products) occur, the temperature of the energy originally

embodied in the fuel decreases and so does its availability. When the temperature of

the energy reaches equilibrium with the atmosphere at the sink temperature, its

availability reaches zero as well. As the result, the energy remains cannot be used

for any useful purposes and it is usually dissipated to the environment. This

background makes energy conversion processes that conserve availability are

desirable. Since the conservation of availability gives way to energy conservation.

Thus, the following second-law efficiency is defined in evaluating the energy

conservation potential of an AHT system [21:

1 - - ^

47 T.

T (21)

Twh

The numerator in the above expression depicts the availability produces by the

output heat. Because the higher the temperature at which the output heat is

produced in reference to the sink temperature the lower the ratio inside the

brackets will be. The same thing applies to the first term in the denominator. While

the second term appears to be different to the first since the work supplied to the

pumps (usually in form electrical) is independent of the surrounding temperature.

As a whole, the denominator represents the availability supplied to the AHT system

under consideration.

0>mputer Implementation

It is apparent from the discussions above that the procedure in pressure

selections should be repeated until the suitable pair of pressure has been obtained.

Thus it would be advantageous to develop a computer program to handle the routine

in analyzing the system.

In this undertaking, the waste heat temperature is varied between 110^ and 190^

and the condenser sink temperature is between 50^ and 80^. While the useful heat

temperature is varying up to 250^. These temperatures as well as the associated

pressures are used to determine the properties of the two proposed aqueous solutions.

Thus, to enable these operations data matrices and several equation of state are made

48

available for the program to refer to. In case of Ammonia-Water solution, five data

matrices were stored in memory for easy access. They were :

1. the properties of saturated ammonia

2. the Ammonia-Water concentration

3. the aqua ammonia enthalpy

4. the aqua ammonia specific volume

5. the superheated ammonia enthalpy.

The properties of saturated liquid and vapor of ammonia [151 had a temperature

range between 30° to 150°F and pressure between 60 to 430 psia. This daU matrix

included in it the saturation temperature and pressure, saturated liquid specific

volume, and saturated liquid and vapor enthalpies.

The aqua ammonia concentration data [131 was accessed by knowing the

temperature and the pressure of the solution. The temperature ranged from 30° to

260°F and pressure from 50 to 500 psia.

The aqua ammonia enthalpy data (131 was invoked by suplying the temperature

and the mixture concentration. The temperature ranged from 30° to 260°F and the

concentration from 0% to 100%.

Lastly, the superheated ammonia data matrix [131 contained pressure,

temperature, and superheated ammonia enthalpy. The temperature range covered

by this data matrix was between 50° to 260°F and pressure between 50 to 400 psia.

In case of Lithium Bromide-Water, the number of data matrix is smaller since

there are several correlations that can be used to replace some of these data

matrices. The matrices used in conjunction with Lithium Bromide-Water system

analysis were :

1. the specific volume of saturated liquid water

49

2. the LiBr aqueous specific volume data

3- the superheated water vapor data.

The specific volume of saturated liquid water [ 161 had a temperature range

between 30° to 250°F by which it was determined.

The LiBr aqueous specific volume data was obtained from specific gravity data

1171. The specific volume matrix was used to specify the LiBr aqueous specific

volume by knowing the temperature and the concentration of the solution. The

temperature ranged from 0° to 100°C while the concentration from 10% to 60%.

The superheated water vapor data [ 161 comprised of pressure, temperature, and

superheated water vapor enthalpy. It had a temperature range from 30° to 240°F

and pressure from 0.05 to 20 psia.

In accessing these data matrix, two subroutines were used. One of them was

utilized to determine the saturation properties of the refrigerant. It was a single

linear interpolation subroutine. The other subroutine used for the rest of the data

matrices which was a double linear interpolation subroutine.

The saturation properties subroutine was invoked by using pressure as the

calling variable. The subroutine then checked whether the passed over pressure

was inside the range of the data. Say that the pressure was inside the range then the

subroutiae proceed to examine the data rows. If that pressure was found, a group of

data would be supplied to the calling program. A single linear interpolation would

be performed if the pressure fell in between two data points.

The second subroutine was slightly more complex. It was called by passing the

calling variables, one for each axis of the two dimensional array. The first thing the

subroutine would do was to check whether the two passed over variables were inside

the ranges of the horizontal and vertical axes. Four possibility may occur in

50

locating the desired data:

1. both passed variables match exactly with the coordinates of the axes in

which the data will be directly brought to the calling program.

2. one variable matches excactly with the coordinate while the other one does

not in which case the subroutine will perform a single Hnear interpolation.

3. none of the variables matches the coordinate in which case the subroutine

will perform a duble linear interpolation.

4. either one of the variable or both fall onto a nonexisting data in which case

a flag will tell the calling program.

As explained earlier, the program would checked whether the strong aqueous

solution had higher concentration in comparison with the weak solution. In this

analysis, the difference between strong and weak concentrations was limited to as

low as 1% (one per cent).

Again as discussed before that in the first stage of the program, the high and low

pressures were guessed. Many low and high pressure combinations are possible for

a certain conditions on which the AHT to operate. To determine an optimum

combination, the program equipped with two incremental loops. The first one was

provided to select the low pressure level. It began from zero and increased by 5 psia

(for Ammonia-Water) or 0.0875 psia (for Lithium Bromide-Water) until it reached a

certain pressure in which the flags of the two subroutines confirmed that

everything was fine. The second one was to select the high pressure level. It began

from 405 psia (for Ammonia-Water) or 25 psia (for Lithium Bromide-Water) and

decreased by the same amount as it was increased in the low pressure selection until,

again, the flags of the subroutines said OK. Then the two pressure levels had to pass

51

various checkpoints as described in the program's flow diagram before the program

could proceed further.

CHAPTER5

RESULTS AND DISCUSSIONS

Calculation Results and Discussions

Similar to the refrigerating systems, AHT systems can be made multi-stage.

Multi-stage configurations are obtained by adding several additional components to

the exixting single-stage configuration. The necessity of building multi-stage

system depends on the temperature required for the output heat which is, in turn,

dictated by the process that utilizes it. Since this thesis is focused on single-stage

AHT systems, the multi-stage systems then fall outside the scope of this research. In

line to this limitation, the following ranges of parameters were arbitrarily chosen

in this study:

T < 250°F(120°C) 0

110°F(43°C)<T , <190°F(88°C) wh

50°F(10°C)<Ts <80°F(27°C)

The choice was resulted from the judgment that the output temperatures up to 250°F

were still inside the region a single-stage could handle for the chosen waste heat

and sink temperatures. Another point that made up the decision was the available

data matrices used in analyzing the systems.

The main objective of this investigation is to discover the ability of temperature

boosting that can be achieved for fixed values of T with varying T | while the

amount of the waste heat available was set at an arbitrary value of 10.000 Btu/hr.

Thus by fixing the values of T, and the amount of waste heat, the only independent

52

53

variables left to be input are the waste heat temperature available and the desired

output temperature. This situation reflects the actual conditions where the waste

heat temperature varies from one application to the other and so is the desired

output heat temperature.

In order to determine the feasible operation, an output heat temperature was

chosen within the specified limit and the waste heat temperature was set at a slightly

lower value. With a constant output temperature, the waste heat temperature was

gradually lowered. The program would go through many pressure combinations

which, in the end, would terminate at the combination that was free from the

limitations checked in the program or at the combination which would not allow for

AHT operation. Then the process was repeated as to give as many combinations as

possible for analysis.

Having the results from those combinations, the combinations that yielded the

highest exergy efficiency were separated from the rest as the best operating

conditions. This routine was done many times by varying the sink temperature and

changing the working fluid combination used. The analyzed results the were plotted

as in Fig. 19 and 20.

It can be seen from the figures that Ammonia-Water solution gives higher

output temperature in comparison with LiBr-water solution for fixed combinations

of sink and waste heat temperatures. From Fig. 20, the temperature boost (the

difference between the output heat and the waste heat temperatures) between 255°

to 88.5°F is obtainable using aqua ammonia solution and between 21.5° to 87°F using

Lithium Bromide-Water solution. Although. Fig. 19. ammonia water can achieve

higher output heat temperature but the operating range that can be covered by

54

(U

u

260 f

250--

240..

2 3 a .

22CL.

21Q._

2 200..

B

H 1904-

(U

« 1804-p c u 3 1704. o

1 6 a .

1 5 a -

140_.

130

4% < AX < 8% (NH -H^O)

2% < AX < 6% (LiBr-H^O) /

/ tJ?' 4.

Nn3 -H2O LiBr-H20

100 110 120 130 140 150 160 170

Waste Heat Tempera tu re , F

Fig.19. Output Heat Temperature as Functions of Waste Heat and Condenser Sink Temperature

55

o O CNI CN 33

!I! 1 1 U CO eo

O r iH

O

/—s

o CN 33 1 CO

»w'

s (X)

V

X <

o CN 1 M CQ •H H4 ^^

^S vO

V

X <

>3- CN

o o o

CJ^

Pu

OJ u 3

4-1 to 5-1 01 C

e 0) H 4-1

CO Q«

a

O ..^ CO

a>

a

a o

s a>

o V) C o u a 3

«.»

o o

0Q a> u 3

•^^ u (U a. a a>

o Csl o

CXI

4 *qsoog aan^Hiaduiai o

56

Lithium Bromide-Water solution is wider. Also for both figures the range of

concentration differences (the difference between strong and weak concentrations)

for Ammoni-Water solution is higher, between 4% and 8% in comparison with

Lithium Bromide-Water solution, between 2% and 6%. The lower bound of the

concentration difference was obatined for higher temperature boost while the

upper bound for lower temperature boost. Or in other words, for a fixed sink

temperature, the higher the desired output heat temperature the lower the

concentration difference and the lower the desired output heat temperature the

higher the concentration difference.

It is obvious from the figures that the lower the sink temperature the higher

the output heat temperature can be attained and hence the temperature boost and

vice versa. Also, the lower the sink temperature the wider the range of operation

for Ammonia-Water solution while it has no effect in case of Lithium Bromide-Water

solution.

A typical result obtained by fixing the temperature of the waste heat available

and sink temperature while varying the desired output heat temperature can be

seen in the following six figures. These figures can give some ideas on how the

systems behave as the waste heat and sink temperatures are held constant while the

output heat temperature fluctuates which may happen during real operation.

In Fig. 21 and 22 the temperature boost. COP. and exergy efflciency are plotted

against output heat temperature. In case of Ammonia-Water the temperature boost

between 25° and 87°F are obtainable for 50°F sink and 130°F waste heat

temperatures. The bigger portion of the COP is almost constant at 50% while the

exergy efficiency is within 53-59% band. These values show a relative insensiUvity

of the two indicators of performance toward the variations in the desired

57

55 T

50

45

4 0 4 s>«

o 35

30--

25--

20- -

1 0 0 -

9a-

80--

70-

6 0 -

5 0 -

Amraonia-Water T , =130 °F wh T =50 °F

s

o 40--

H301.

20-

l a .

0

150

N

V , .

AT

COP

\

\

\

-.70

--60

-.50

40

..30

20

160 170 180 190 200 210 220

Output Heat Tempera tu re , F

Fig.21. Performance Characteristics of AHT (Ammonia-Water System)

58

55 T

50--

45..

5^

^ 40 o CJ

35

30..

o

<

100-

90.

80-

70-

60-

50.

40-

30.

20-

10.

0

LiBr-Water T ,=130 OF wh T =50 °F s

AT

COP

-•- •+• + •+•

80

470

60

..50

--40

..30

20

135 140 150 160 170 180 190 200

Output Heat TEmperature (°F)

225

Fig.22. Performance Characteristics of AHT (LiBr-Water System)

59

temperature. An interesting thing depicted by the graphs. Fig. 21. is that the COP

and exergy efficiency have different tendencies. The COP begins to slope down

sharply after 185°F while the exergy efflciency after 195°F and the increase of

efficiency below 195°F is steeper in comparison with the increase in COP below

185°F. This difference is because the COP does not take into account the work

supplied to the solution pumps. Thus according to COP the best temperature boost is

55°F while according to exergy efficiency it is 65°F. Judging from the definitions of

COP and exergy efficiency, the 65°F temperature boost is thus a more realistic result

since the COP is not an exhaustive measure of the potential of the system's

performance.

Beginning from 195°F for COP and 200°F for exergy efficiency, the curves are

drastically sloping down. These can be explained that as the output temperature is

steadily increased the waste heat consumed by the evaporator to vaporize the

refrigerant increases as well. While the generator consumption of the waste heat

decreases because the amount of refrigerantbecomes lesser. This causes the ratio of

refrigerant absorbed by the aqueous solution in the absorber decreases and hence

the useful heat generated. In turn, the ratio of the useful heat rate to the available

waste heat in determining the COP drops drastically. On the other hand, although

the availability of the produced heat is greater for higher output temperatures but it

is outgrowth by the summation of the work supplied to the pumps and the constant

availability of the waste heat in reference to the fixed sink temperature. This causes

the drop in exergy efficiency. At the very end of the temperature boost curve, the

value of the COP is 23% and the value of the exergy efficiency is 20%. This indicates,

in case of the exergy efficiency, that the potential of heating the same quantity of

the heating medium to be recycled back into the process is low.

60

Figure 22 which corresponds to the behaviors of LiBr-water system has the

same explanations attributed to the ammonia-water system. It is seen in this figure

that although the temperature boost obtainable is lower in comparison to

ammonia-water but its COP and exergy efficiency yield higher values. The best

operating condition, for the fixed waste heat and sink temperatures, is when the

output heat reaches 150°F based on COP. While according to exergy efficiency the

maximum occurence is when the output assumes the value of 190°F. Comparing the

two systems, at the best operating conditions the exergy efficiency for

Ammonia-Water solution is 59% while it is 64% for Lithium Bromide-Water solution.

Figure 23 and 24 contain the curves for mass flow rates of the refrigerant and

absorbent as well as the difference in concentration for the same set of conditions

cited in Fig. 21 and 22. It can be seen in these figures that both flow rates increase

as the desired output heat temperature increases: on the other hand, the

concentration difference decreases as the output heat temperature increases. These

two figures can serve as a practical judgment in deciding the range of operation on

which the AHT to be designed. Since the two mass flow curves jump drastically when

the output heat temperature attains the value of 200°F for Ammonia-Water and

around 180°F for Lithium Bromide-Water. They are even more severe when one is

interested in the volumetric flow rates. Because the specific volume of the liquids

decrease as temperature increases which makes the volumetric flow rates even

bigger as the desired output temperature marches on. This fact, from a practical

point of view, may cause trouble when one comes to the stage of spefying the

solution pumps. For it is known that a pump is specified not only by the head needed

but also by its flow capacity. Thus when it is decided to cover the whole range of the

output temperature, one may find difficulties in choosing the right pump that can

61

tr\ >^ cn CN r H O (J^

(^^s / q i ) ^ui r^ vo 0 0 m CO CN

•i h H h •+• 4-o

— H

X >.4 CO

< E E I ! I I

(U 4-i CO :is I

CO • H c o e

ft , o o

13

O i n II

M

i:fc; ^ fo ro CN

• ^ ;;ir CN

(%) XV

i n

o

—h o O

— ( -lO

ro O

O

o

Ul ^ 2

(Das/ q i ) Ul

1 -

Tir

o CN CN

O i H CN

O O CN

O

o CX3

o

. . O

O i n

in CN o

o CN O

o

}-l

3 4-1 CO V4 (U a. E 0) H

CO OJ X u D.

a o

a

U

I

d o a a

<

d u

d o

'5 d u d o d vi v>

2 ti

Pi

tZ

VI

CVJ

(Z

62

Ul B ( 0 3 S / q-[) Ul

o —t-

o i n

o CO CN

X < 1

I

CO

E

I I

u d) 4-1 CO :2 1 U PQ •H hJ

i^ O

Pu o o .H O II i n

Xi II 3 (0

i n CN

o CN

o m o CN

O o CN

o

o 00

o

O

o m

o

in cn

0) u 3 u CO U u d a> (-1 a>

d o "cS u d u d o

d c4 (/)

ri

o

(%) XV

in .-H O O

m o

CN i H O

CVJ

OH

Ul , a ( 0 3 8 / q x ) Ul

63

handle the wide variation of the volumetric flow rate. Hence a practical range

should be decided before hand depending on the requirement of the process in

which the upgraded heat to be used.

In line with Fig. 23 and 24. Fig. 25 and 26 contain curves of Circulation Ratio

(the ratio between the refrigerant and the absorbent rates) and the work consume

by the two pumps as the percentage of the useful heat. Thus as the flow rates

increase with the increase in the desired temperature, the Circulation Ratio and the

work percentage increase as well. This means that when the flow rates jump

drastically the two curves jump sharply accordingly. Here in these two figures one

can see that indeed the isentropic work of the two pumps are very small. For

Ammonia-Water solution the Circulation Ratio is ranging from 0.25 to 7.1, while for

Lithium Bromide-Water it is ranging from 0.3 to 48. These values indicate that the

refrigerant circulated in the Lithium Bromide-Water system is relative higher in

comparison with ammonia-water system.

Although the Circulation Ratio is an indication to the magnitude of pump work

needed but it is not the absolute measure of the work. This argument is clearly

demonstrated by the work percentage curves. For Ammonia-Water system, it is

ranging from 0.4% to 585% while for Lithium Bromide-Water system it is from

0.00285% to 0.038%. The reason for this occurence is that, will be showed latter, the

pressure difference that should be produced by the set of pumps in Lithium

Bromide-Water system is far smaller that the pressure difference through the

Ammonia-Water system. Although the speciflc volume in the inlet to the solution

pump for Lithium Bromide-Water is higher than the speciflc volume for the

Ammonia-Water. But the soeciflc volume of the refrigerant in Ammonia-Water

40..

g 30

o •H 4-1 CO

OC

c o

•H 4-1 CO

rH 3 a u

•H CJ

20..

10--

0

Ammonia-Water

T , =130 °F wh T =50 °F s

CR PWR

150 160 170 180 190 200 210

Output Heat Temperature, F

--7

. .6

- - 5 ^s

CXi

+ 4 g

J o

a. E

2 £

-1

0 220

64

Fig.25. Circulation Ratio and PercenUge of Pump Work for Ammonia-Water System

65

40--

30-.

^9

cn I o

X Pi

P-,

u o

20..

I 10-Pi

0

LiBr-Water

T , =130 °F wh

T =50 °F s

CR PWR

-.50

40

-.30

20

o • H 4-1 CO Pi C o CO

i H 3 O )-i •H U

-.10

0

135 140 150 160 170 180 190 200 205

Output Heat Temperature, F

Fig.26. Circulation Ratio and Percentage of Pump Work for LiBr-Water System

66

system is higher than the refrigerant in Lithium Bromide-Water system as the

output heat temperature increases.

Table 1 and 2 serve to explain the influence of concentration difference to each

system's performance. The process involves in constructing the tables constitute

one sort of routine that was done to obtain the favorable operating conditions. The

tables were found by fixing the condenser sink, waste heat, and output heat

temperatures. Each table is divided into two sections : cases Ithrough 5 and 6

through 10. Each section corresponds to a fixed evaporator pressure. In each

section, the condenser pressure is varied which results in difference concentration

differences. It is obvious from Table 1. cases 1 through 5> that the various

concentration differences yield different system's performance. From 1 to 3 the

performance is getting better; while from 3 to 5, it is showing a decreasing

tendency.

As the condenser pressure is increased, the circulation ratio and the condenser

temperature increased as well. The increase in CR means that the relative amount of

refrigerant in reference to the amount of weak solution circulated in the system

decreases. Although in physical plane both of the mass flow rates increase but the

increase of the refrigerant flow rate is outgrowth by absorbent flow rate. The

growth in the magnitude of the CR implies the increase of the work needed by the

pumps. While the effect of increasing the condenser pressure is the increase in

weak concentration because this concentration is a function of waste heat

temperature and condenser pressure. On the other hand, the value of the strong

concentration stays constant since it is the function of the constant output heat

temperature and evaporator pressure. This explains the decrease in concentration

difference from case 1 to case 5-

67

Table 1. Influence of AX Variations for NH3-Water Solution.

T = AO F, T . = 170 F, T = 220 F s ' wh 0

Case AX n COP CR T T AP P

[•/.] [•/.] [•/.] C-] C F] C F] [nsial Cpsia]

1 9.95 57.7A 50.52 5.206 63.32 133.24 240 365

2 7.40 57.96 49.73 7.000 74.79 133.24 225 365

3 5.05 58.19 49.04 10.257 m.77 '33.24 210 365

4 3.10 56.63 47.10 16.710 86.29 138.24 195 365

5 1.15 38.32 33.45 45.043 91.47 138.24 160 365

6 11.15 57.83 50.57 4.533 68.32 141.50 255 380

7 7.75 53.63 49.93 5.529 76.83 141.50 235 380

3 4.95 59.25 49.22 10.222 84.50 141.50 215 380

9 3.00 57.55 47.21 16.867 89.79 141.50 200 380

10 1.05 36.53 31.49 48.190 94.74 141.50 185 380

Table 2. Influence of AX Variations for LiBr-Water Solution.

\ - ' " '• T„h = " » '- ^0 = 220 F

Case

1

AX

C7.]

13.77

n

C7.]

53.26

COP

CX]

51.78

CR

[-3

5.016

T c

C F]

60.40

T e

C F3

150.37

AP

[psia]

3.49

P e

Cpsia]

3.75

68

5.01 65.15 51.91 12.026 89.93 150.37 3.05 3.75

3 1.91 67.27 50.70 29.897 100.34 150.37 2.79 3.75

4 1.02 65.57 48.55 55.255 103.26 150.37 2.70 3.75

5 0.17 47.33 34.76 317.140 105.98 150.37 2.62 3.75

6 13.32 60.04 51.92 4.931 69.32 157.85 4.14 4.50

7 7.19 65.54 52.13 3.371 90.27 157.85 3.79 4.50

3 2.38 70.65 51.28 23.250 106.20 157.85 3.36 4.50

9 1.58 70.64 50.33 34.459 108.73 157.85 3.27 4.50

10 0.82 67.84 47.55 65.453 111.11 157.85 3.18 4.50

69

With reference to Fig. 12 and 13 together with the tables; it is seen that as the

weak concentration decreases, the enthalpy at point 1 decreases accordingly. Since

enthalpies at point 2 and 3 are directly proportional to the enthalpy at point 1 hence

both of them show a decreasing tendency. Also, the enthalpy at point 7 which

corresponds to the saturated liquid refrigerant enthalpy. On the other hand, the

enthalpies at point S and 9 increase because the increase in the condenser pressure

yields an increase in the refrigerant specific volume of the liquid refrigerant. The

remaining enthalpies at point 4.6. and 10 stay constant which caused by either

individually or collectively of the constant strong concentration, evaporator

pressure and temperature.

In turn, the increase of the refrigerant mass flow rate combined with the total

effect of the changes in the enthalpies at point 9 and 10 causes the increase in the

heat transferred to the evaporator and out of the condenser. The opposite case takes

place in the generator where the heat transferred into it decreases as the total effect

of several phenomena. They are : the increase of enthalpy at point 8. the constant

enthalpy of point 6. the decrease in enthalpy of point 1. and the faster growth of the

mass flow rate of the strong solution in comparison to the mass flow rate of the

refrigerant. But the prononced effect of these changes is the decrease in the heat

transferred from the absorber which is mainly due to the decrease in the entahlpy

of point 3-

The net effect of the increase and decrease in heat transferred rates in the

various components is the increase in exergy efficiency of cases 1 through 3 But

from case 3 onward the decrease in the system's performance becomes significant

which is mainly contributed by the decrease in the heat produced in the absorber

and the steady increase in the work needed by the pumps. In spite of the increase in

70

thermodynamic availability of the heat produced by the absorber as the output heat

temperature increases.

An interesting phenomena from the cases of the first section of Table 1 and

Table 2 is that the COP does not have the same trend as the exergy efficiency. The

COP seems to betray the exergy efficiency by showing decreasing values when the

efficiency is still increasing.

The explanations rendered to the first section of Table 1 are applicable for the

cases in the second section of the same table. It is obvious from this table that the

highest exergy efficiency obtainable in the second section is higher than the first

section. This nature tends to be repeated as the evaporator pressure is increased

until a certain value of the evaporator pressure. The upper limit, theoretically,

corresponds to the saturation pressure of the refrigerant at the specified waste heat

temperature. But certainly when the evaporator pressure equals the refrigerant

saturation pressure at the waste heat temperature, the refrigerant will assume the

waste heat temperature which does not allow for the heat transfer to take place. This

very low temperature difference will dictate, theoretically, the heat transfer surface

area of the evaporator to be infinite. Another phenomenon occurs as the pressure

increased toward the upper limit is the ability to obtain variations in concentration

difference decreases. The second sections of Table and 2 corresponds to the

evaporator pressures that near the upper limit for each solution for the specified

limiting conditions.

Again, the explanations attributed to the Ammonia-Water solution above are

applicable to Table 2 for Lithium Bromide-Water solution. By comparing the two

tables, one can easily see that the Lithium Bromide-Water solution shows a

71

preferable operating performance within the fixed sink, waste heat, output heat

temperatures, and evaporator pressure.

Application Example

To give a concrete example on the application of AHT system, consider a plant

with the following information:

1. the plant produces 100,000 Btu/hr waste heat

2. it uses city water as cooling medium with temperature 55^

3. due to the main process fluctuation, the waste heat temperature is varying

but always than l%^f

4. the plant is interested in boosting the waste heat temperature to 212 F for use

in one of the facilities it has.

In deciding the AHT system to be installed, the engineers study two aqueous

solutions: Ammonia-Water and Lithium Bromide-Water. The following information

will be used as minimum criteria to choose the system to be employed:

1. the exergy efficiency of the system

2. the COP of the system

3. the CR of the system and the work consumed by the pumps

4. the flow rates to be handled by the pumps

5. the pressure difference to be supplied by the pumps

6. the concentrations of the weak and strong solutions.

The results based on the provided data are tabulated as in Table 3 and 4. This

process simulates the effect of varying the waste heat available with sink and output

72

Table 3. Waste Heat Temperature Variation for NH3-Water Solution.

T = 55 F, T^ = 212 F, P^ = 102.5 osia

uh

C F]

139

n

ill

58.26

COP

C7.]

47.63

CR

C-]

PWR

C7.]

Q. 0-

8.68 1.32 16.056

AP '1 -a e

Ccuft/hr] Ccuft/hp] Cpsia] Cpsia]

2.413 365.0 262.5

141 58.68 48.32 6.99 1.55 12.687 2.370 372.5 270.0

143 53.78 43.77 5.53 1.33 9.395 2.339 385.0 282.5

145 58.59 49.00 4.66 1.20 8.252 2.321 395.0 292.5

147 58.27 49.14 4.29 1.13 7.548 2.308 397.5 295.0

149 57.93 49.25 4.06 1.03 7.107 2.298 397.5 295.0

73

Table 4. Waste Heat Temperature Variation for LiBr-Water Solution.

T^ = 55 F, TQ = 212 F, P^ = 0.2625 psia

uh

C F]

COP CR

C7.] C7.] C-]

PWR

C7.]

°1 Ccuft/hr]

%

Ccuft/hr]

%

Cpsia]

AP

Cpsia]

139 48.75 38.49 100.68 7.8700 165.790 0.975 1.9400 1.6775

141 62.35 50.56 12.36 0.0156 15.453 0.766 2.7883 2.5258

143 62.88 50.72 11.46 0,0145 14.283 0.764 2.7683 2.5058

145 62.43 50.87 10.65 0.0135 13.241 0.761 2.7551 2.4926

147 61.99 51.00 9.91 0.0127 12.295 0.759 2.7490 2.4865

149 61.55 51.12 9.25 0.0119 11.436 0.757 2.7502 2.4877

74

heat temperatures are held constant. The first consequence by holding these

variables constant is that the condenser pressure is also constant. This is because

the condenser pressure is directly proportional to sink temperature. Thus the

different values in the work needed by the pumps for each case is due to the

variations in pressure difference, mass flow rates, and specific volumes of the

solutions.

From the calculations, no result could be obtained for waste heat below 133 F so

that this value becomes the lower bound if the other two temperatures to be held

constant. The step in varying the waste heat temperature was taken to be 2^, hence

the upper bound for the waste heat temperature is 149 F. It can be seen from the

tables that both solutions yield the same temperature boost, that is 69^. if the exergy

efficiency is taken as the most important criteria.

It is obvious, for Ammonia-Water system, that the variation of the waste heat

temperature from 139 to 149^ raises only slight changes in the exrgy efficiency.

In other words, th 10 F variation in the waste heat temperature is not accompanied

with a proportional variation in part of the exergy efficiency. Again, from the

table, it is seen that the COP and the efficiency does not follow the same trend : the

COP increases throughout the steps while exergy efficiency increases at first and

then decreases. The same situations are generally applicable in the case of Lithium

Bromide-Water system with the exception of the 139 F waste heat temperature. It is

probablydesirable to install a system that can cover the whole range: from 139 to

149^ for Ammonia-Water and from 141 to 1490F for Lithium Bromide-Water system.

But not like Lithium Bromide-Water system which shows a slight variation on

the volumetric capacity of both the refrigerant and aqueous solutions, the

Ammonia-Water system shows variation as big as twice the minimum volumetric

75

capacity in the aqueous solution for relatively small change in the pressure

difference. Certainly, one would exclude 139^ waste heat temperature operation in

case of Lithium Bromide-Water system. This makes the operating range of the

Lithium Bromide-Water system a bit narrow. Also of interest is the higher exergy

efficiency of Lithium Bromide-Water system in comparison with the Ammonia-

Water system.

CHAPTER 6

CONCLUSIONS AND RECOMMENDATIONS

Conclusions

A study of single-stage AHT system using two binary aqueous solutions has been

conducted. The study was done by developing a simulation program suitable for each

solution that contains the governing equations of the system. It is seen from the

figures and tables that this system has potential in recovering part of the rejected

heat into useful product with good efficiency. Thus, opening the possibility for the

system to be used in reducing the energy consumption and reducing the heat

pollution to the surrounding environment.

However, as the result of proposing two aqueous solutions as working fluids, each

working fluid combination has advantages and disadvantages over the other. These

advantages and disadvantages can be used as general tool in selecting the working

fluid for the system. The main advantages of using Ammonia-Water are that it can

yield a higher temperature boost and lower circulation ratio in comparison with

Lithium Bromide-Water solution. Although the circulation ratio is not a real

measure of the work supplied to the pumps but it serves as an indication of the ratio

between the absorbent and the refrigerant circulated inside the system. Throughout

all the graphs and tables exergy efficiency and COP of Lithium Bromide-Water show

higher values and it covers wider range of operation. It is also apparent that the

operating pressure of Lithium Bromide-Water system is lower than operating

pressure of Ammonia-Water system, it is even below atmospheric pressure in some

76

77

cases. The lower pressure difference in turn results in lower amount of work needed

to operate the pumps. This lower value is desirable from the standpoint of reducing

the consumption of any form of high-grade energy. But the low operating pressure

dictates the use of purging system to maintain the desired pressure level which is

not necessary in Ammonia-Water system. However, the high operating pressure in

Ammonia-Water system may need the system's components to be designed in

accordance with higher code for pressure vessel which, certainly, are more

expensive than the ones constructed using regular method.

Unlike Ammonia-Water solution. LiBr is completely non-volatile fluid. This

causes the refrigerant (in this case water) is free from absorbent carryover. This is

not true for Ammonia-Water solution since water as the absorbent is not completely

non-volatile, thus some of the water vapor usually trapped in the refrigerant flow

and carried along into the absorber. The carried water vapor causes detrimental

effect to absorption process since the amount of refrigerant becomes smaller, in

turn the output heat produced in the absorber is decreased and hence the exergy

efficiency. To overcome this drawback, a rectifying column is frequently installed

between the condenser and evaporator to reduce absorbent carryover. Another

advantage of Lithium Bromide-Water solution is that LiBr is a non-toxic liquid while

ammonia causes irritation. Thus Lithium Bromide-Water is a safer working fluid for

AHT system.

78

Recommendation

It is recommended for further research the study of multi-stage AHT system for

temperature boosting. Since by applying multi-stage system the temperature boost

obtained would be higher than single-stage system. This would broaden the

applicability of AHT in recovering the rejected heat.

It would also be beneficial to relax some of the assumptions used in this thesis to

evaluate their influence in the system's performance. For example, give some

provision on the pressure drops in the pipings. Also, by specifying effectiveness for

each heat transfer device to make the system behaves more closely to reality. It may

also of interest to conduct analysis on the possible ways of losing availability in the

system which will give way in achieving higher efficiency systems.

REFERENCES

1. Blue, J. and Arehart. J. "A Pocket Reference of Energy Facts and Figures," Oak Ridge National Laboratory, Oak Ridge. Tenn., Dec. 1980.

2. Perez-Bianco. H.."Heat Pump Concepts for Industrial Use of Waste Heat," Oak Ridge National Laboratory Report for the Department of Energy, ORNL/TM-7655.1981.

3. Grossman, G. and Perez-Bianco, H,"Conceptual Design and Performance Analysis of Absorption Heat Pumps for Waste Heat Utilization," ASHRAE Transactions, vol. 88, Part 1, paper no. 2691.1982.

4. Tepp, Ch„ "History and Prospects of Heat Transformation, "IIR-XVIth International Congress of Refrigeration Proceedings TOME I, Paris, 1983.

5. Grossman, G. and Childs, K. W.,"Computer Simulation of a Lithium Bromide-Water Absorption Heat Pump for Temperature Boosting," ASHRAE Transactions, vol. 89, Part IB, paper no. AC-83-05,1983.

6. Huntley, W. R.."Performance Test Results of a Lithium Bromide-Water that Uses Low Temperature [60^0 (HOOp)] Waste Heat,' Final Report, Prepared by the Oak Ridge National Laboratory for the U.S. Department of Energy, ORNL/TM—9072, June 1984.

7. Kripalani. V. M.; Murthy, S. Srinivasa; and Murthy, M. V. Krishna,"Performance Analysis of a Vapour Absorption Heat Transformer with Different Working Fluid Combinations," Journal of Heat Recovery Systems, vol. 4, No. 3,1984, pp. 129-140.

8. Stephan, K. and Seher, D.,"Heat Transformer Cycles-I. One- and Two-Stage Processes," Journal of Heat Recovery Systems, vol. 4, No. 5,1984, pp. 365-369.

9. Stephan, K. and Seher, D.,"Heat Transformer Cycles-II. Thermodynamics Analysis and Optimization of a Single-Stage Absorption Heat Transformer," Journal of Heat Recovery Systems, vol. 4, No. 5.1984, pp.371-375.

10. Grossman, Gershon,"Multistage Absorption Heat Pumps for Industrial Applications," Final Report, Oak Ridge National Laboratory, ORNL/Sub-83-43337/1, Nov.1984.

11. Grossman, G,"Multistage Absorption Heat Transformer for Industrial Application," ASHRAETransactions, vol. 91, Part 2B, paper no. HI-85-41 No. 1, 1984.

79

80 12. Grossman. G. and Michelson, E.," A Modular Computer Simulation of Absorption

Systems." ASHRAETransactions. vol. 91. Part2B, paper no. HI-85-36 No. 2.1985.

13. Macriss, R. A.; Eakin. B. E.; Ellington, R. T.; and Huebler, J.,"Physical and Thermodynamic Properties of Ammonia-Water Mixtures," IGT, Chicago. 1%4.

14. McNeely. L. A.,"Thermodynamic Properties of Aqueous Solutions of Lithium Bromide." ASHRAETransactions. 85.413.1979.

15. ASRE. "RefrigerantTables. Charts, and Characteristics." New York. 1956.

16. Reynolds. W. C.."Thermodynamics." 2nd. ed.. McGraw-Hill. 1968.

17. Foote Mineral Co.."Technical Data: Lithium Bromide." Bulletin 145, Pennsylvania.

APPENDIX

A. Output Sample for LiBr-Water System

B. Output Sample for Ammonia-Water System

C. Ammonia-Water Data Matrices

D. Specific Volume of LiBr-Water Solution

81

82

Appendix A

<<<<<< LI Br DATA FOR ANALYSIS : >>>>>>

Available Waste Heat, QWHA [Btu/hr] Temperature of Waste Heat. TWHA [deg.F] Temperature of Condenser Sink, TSINK [deg.F] Temperature of Useful Heat, TOHN [deg.F]

lOOOOO 135 55 170

<<<<<< CALCULATION RESULTS : >>>>>>

Point

I 2 3 4 5 6 7 8 9 10

Temp. [deg.F] 135.000 135.000

O.OQO 170.000 140 0

135 60

,250 000 000 ,667

0.000 135.000

Press. [Psia] 0.262

W,

925 ,000 925 ,000 ,000

0.262 0.262 1-925 1 .925

1 . 0, 1 . 0, 0,

Fract ion LiBr 0.493 0.493 0.493 0.601 0.601 0.601 1.000 I .000 1 .000 1 .000

Flow [lb/lb Refg]

0.493 0.493 0.493 0.601 0, 0, 1 , 1 , 1, 1 ,

601 601 000 000 000 000

Enthpy. [Btu/lb]

51.282 51 . 73, 80. 54, 54,

1121,

290 584 377 063 063 225

28.678 28.683

1120.197

Condenser Pressure [Psia] Evaporator Pressure [Psia] Condenser Temperature [deg.F] Evaporator Temperature [deg.F] Strong Aqua Concentration Weak Aqua Concentration Sp. Volume @ Station 1 [cuft/lbm] Sp. Volume 9 Station 9 [cuft/lbm] Refrigerant Flow Rate [Ibm/hr] Absorbent Flow Rate [Ibm/hr] Refgrnt/Absrbnt Flow Rate [Ibm/hr] Net Heat Input to Generator [Btu/hr] Heat Transfer Rate-Condenser [Btu/hr] Heat Transfer Rate-Evaporator [Btu/hr] Heat Transfer Rate-Absorber [Btu/hr] Pump A Work [Btu/hr] Pump B Work [Btu/hr] The Total Pump Work [Btu/hr] The Exergy Efficiency [Fraction] Coefficient of Performance [Fraction] Circulation Ratio [Fraction] Pump Work % of Useful Heat*[7.] Temperature Difference [deg.F] Concentration Difference

2.6250D-01 1.9246D+00 6.0667D+01 1.2465D+02 6.0091D-01 4.9257D-01 2.4212D-02 1.6041D-02 4.65980+01 2.58440+02 3.0504D+02 5.39170+04

-5.0910D+04 5.08620+04

-5.3872D+04 2.2996D-01 2.2721D+00 2.5021D+00 6.00510-01 5.14140-0 1 5.54620+00 4.91940-03 1 .03460+0 1 1.08350-01

83

Appendix B

<<<<<< NH3 DATA FOR ANALYSIS >>>>>>

Available Waste Heat, QWHA [Btu/hr] Temperature of Waste Heat. TWHA [deg.F]

of Condenser Sink. TSINK [deg, of Useful Heat, TOHN [deg.F]

Temperature Temperature

F]

100000 170 60 220

<<<<<< CALCULATION RESULTS >>>>>>

Point

1 2 3 4 5 6 7 8 9 10

Temp. [deg.F] 170.000 170,

0. 220, 177, 0,

170, 74,

000 000 000 500 000 000 792

0.000 170.000

Press. [Psia] 140.000 365.000

0.000 365.000

0.000 O.OQO

140.000 140.000 365.000 365.000

W.Fraction NH3 0.408 0.408 0.408 0.482 0, 0. 1 , 1 , 1,

482 482 000 000 000

Flow [lb/lb Refg]

0.408 0.408 0.408 0.482 0.482 0, 1 1 . I

482 000 000 000

1 .000 1 .000

Enthpy. [Btu/lb]

45.040 45.870 100.751 101.892 53.871 53.871

692.000 125.971 127.074 662.900

Condenser Pressure [Psia] Evaporator Pressure [Psia] Condenser Temperature [deg.F Evaporator Temperature [deg. Strong Aqua Concentration Weak Aqua Concentration Sp. Volume (a Station 1 [cuft Sp. Volume @ Station 8 [cuft Refrigerant Flow Rate [Ibm/h Absorbent Flow Rate [ibm/hr] Refgrnt/Absrbnt Flow Rate [1 Net Heat Input to Generator Heat Transfer Rate-Condenser Heat Transfer Rate-Evaporato Heat Transfer Rate-Absorber Pump A Work [Btu/hr] Pump B Work [Btu/hr] The Total Pump Work [Btu/hr] The Exergy Efficiency [Fraction] Coefficient of Performance [Fraction] Circulation Ratio [Fraction] Pumo Work T. of Useful Heat [7,] Temperature Difference [deg.F] Concentration Difference

] F]

/Ibm] /Ibm] r]

bm/hr] [Btu/hr] [Btu/hr]

r [Btu/hr] [Btu/hr]

1.4000D+02 3.6500D+02 7.4792D+01 1.38240+02 4.8200D-01 4.0800D-01 1.9938D-02 2.6500D-02 8.99170+01 6.2942D+02 7.1934D+02 5.1820D+04

-5.0896D+04 4.8180D+04

-4.9726D+04 9.9233D+01 5.2262D+02 6.2186D+02 5.7960D-01 4.9726D-01 7.0000D+00 1.2907D+00 3.17560+01 7.4000D-02

Appendix C

AHMUNIA UAlA

84

VF h h h G

.10.00

.»1.00

33.UO 3 H . 0 U 3 i > . u O . l o . O U 3 7 . 1 0 . d b . U U 3 V . 0 0 " t O . U O ^ i . U U

' t j . U O

<»>.oo

^v.oo t>o.uu b l . O U

S 3 . 0 0

b b . o O ^ b . O U I > 7 . 0 0 b o . o o b v . o o o t . u o 6 1 . 0 0 6 ^ . 0 0 b j . O O O ^ . O O toS.OU O b . 0 0 6 7 . 0 0 b b . o O 6 V . U 0 7 0 . 0 0 V I . 0 0 7 2 . 0 0 ? : J . O O 7 < t . 0 0 7 t ) . 0 0 / 6 . 0 0 7 / . 0 0

aV.7^ 61.00

6.i.;>V 6t.Vl 66.<;6 OV .t>3 6V.O^ 70.Hj 71.b?

V ' t . o o 7 6 . . > 1 7 7 . OJ 7 y . J b bo.vo b^.t>t> b t . i b b t > . u 2 b y . * » v b v . IV V O . V l

9 b . 0 6 V V . V l

l O l . b O 1 0 3 . 7 0 i o : > . 6 0 1 0 / . O O 1 0 * ^ . 6 0 X l l . o O 1 1 3 . 0 0 l i d . / o i i / . u O l ^ O . O O l i l ^ . l O 1 2 ' * . 3 0 1 ^ 6 . 1 ) 0 l ^ b . o O 1 3 1 . 1 0 1 3 3 . t o i 3 : > . / o l 3 b . l O i < » o . : j o i * » 3 . 0 0

0 . 0 ^ : > o o L . C V P l O O . O c I M O O . O ^ S i O 0 . 0 ^ : ^ 1 0 0 . 0 ^ 1 ) ^ 0 O . 0 <i! >^ 0

0 . 0 < . ^ 3 0 0 . 0 2 3 3 0 0 . 0 ^ ^ 3 0 L-. O i !)«» O 0 . 0 ^ >*« O 1 . U i t)*«0 U . 0 ^ 1 > J O 0 . 0 < ^ D 3 0

u.o^ :><o O . C <:!:.> O O . U ^ f ^ o O ( . . 0 . . ' 3 6 L

O . U ^ D / 0 0 . 0 ^ : > / o o . o * : t > / o O . O ^ ^ b O O . O ^ 5 b 0 o . o < : U > 0 U . O z S - y O 0 . 0 < : :>vU 0 . 0 2 . 5 V O O . U k c O O l i . O ^ f t i j O o . 0 < : o O o 0 . O ^ c i O O . L < . O i O c . t ^ t ^ o (. . O i ^ o Z O U , 0 ^ 6 ^ U o . 0 <: b<^ 0 0 . 0 ^ ^ 3 0 U . L <: 0 3 O O . 0 <:' o t O 0 . 0 < : o ^ 0 o , o . : t>«« t» o . 0«: o:> o o . o < : t - D O » - . 0 i C 3 0 V.' . «.• <: t o O

7 > . /O 7 o . b C 17 . v a 7 V . C . 0 o O . i O b l . < . 0 b ^ . j O B 3 . * « 0 b t . o u b t > . 7 o b b . b O b 7 . VO b V . O O V O . 1 0 V l . < . 0 V 2 . 3 0 V 3 . 1 / 0 V H . C O V I ) . /O V b . c O V 7 . V 0 V V . I O

1 0 0 . < ; 0 l O l . j O

l O Z . H O I t J . 3 0 i o < t . v o i O i > . t o lOO.VO 10b. 10 iov.^:o lit.JO iii.:>u i 12. cO 113.70 11^.to llo.Oo 117.10 llb.jO i l V . ' t O 1 ^ 0 . 3 0 1 ^ 1 . 7 0 1 / 2 . b O 1 / t . l O 1<^3 . lO i / O . / O 1<: < . t o 1 / b . ^ o

t-^o.:>o c 2 C . 7 0 O 2 l . 0 0 O / 1 . 2 0 O4^i . :>o 6 2 1 - 7 0 6 / ^ . 0 0 fc22.2C o ^ / . s o 6 2 ^ . 7 0 6 2 3 . 0 0 6 2 3 . 2 0 6 / 3 . « t O 6 2 3 . / O O / 3 . V 0 6 2 * t . l O O 2 H . < « 0 6 2 < « . 6 0 6 / < t . b O 6 2 3 . 0 0 o / b . / o 6 / 3 . 3 0 6 2 : > . 7 0 6 / & . V 0 O / O . I O 6 2 0 . 3 C 6 < : o . t > o 6 / O , 7 0 6 2 O . V 0 t 4 i 7 . 1 0 O / 7 . 3 O 6 2 7 . 3 0 O / I . 7 O 6 / V . V O 6 / b . O O 6 2 b . ^ 0 6 / b . <« 0 6 2 1 . 6 0 o ^ b . b O 6 / t . V O O / V . I O 6 i V . J O 6 / V . ' t O 6 2 V . 0 0 o 2 V . b U fc/V.VO 6 3 U . 1 0 6 3 0 . / O

85

7 B . 0 0 7 V . 0 0 6 0 . 0 0 b i . O O b 2 . 0 U b . d . 0 0 bH.OO b b . u O bb.OO 6 7 . 0 0 bb.ou bv.oo vo.oo V l . O O V 2 . 0 0 V j . O O 9<« .00 V 3 . 0 0 V 6 . 0 0 V 7 . 0 0 Vb.OO

vv.oo 100.00 iOl.OO 102.00 lOj.OO lOt.OO iOb.OO 106.ou 107.00 lOb.oU lov.oo 1 1 0 . 0 0 1 1 1 . 0 0 1 1 2 . 0 0 1 1 3 . O O l l H . O O l l t > . 0 0 1 1 6 . 0 0 1 1 7 . O O l i b . 0 0 I I V . O O 1 2 0 . 0 0 1 / 1 . 0 0 1 2 2 . 0 0 1 / j . O O 1 2 t . O O 1 2 b . 0 0 1 / 6 . 0 0 1 / / . 0 0 1 2 b . 0 0 K . V . 0 0 1 3 0 . 0 0 1 3 1 . 0 0 1 3 / . 0 0

1^7.VO lt>0.30 1^3.00 id:>.oo lbb.30 161.00 163.60 16O.t0 lOV./O 172.O0 17H.bU 17 /. /O Ibo.oo Ib3.o0 lb6.60 IbV.oO 1V2. to lV3.t>0 19b.VO /O/.IO /o:>.30 200.00 211.vo 213./O /lb.60 //o.oo 22t.00 22b.VO 232.bO /30.00 /3V.70 /t3.30 /t7.00 /.bO.bO /!)<•.50 /bb.-O 26/./O /6o.^0 //O.lO / 7 H . 1 0 /7b./O /b/.jo ^b6.«t0 /V0.60 ^Vt.tO A V V . 1 0 3 0 3 . t o 3 0 7 . o O 3 1 / . 1 0 3 l o . H O 3 2 0 . t o - > / 3 . 10 3 / V . t O J 3 J . 7 0 3 3 b . 0 0

U . 0 2 6 ' U O . O / o o O O . O / o / O O . O / o / O u . O / O o O O . O / O o O O . O / O b O O . 0 ^ Ol o 0 . 0 / O V O 0 . 0 / oV O r . o / /oC 0 . 0 / /OO O . 0 2 / 1 0 0 « 0 < . 7 l O 0 . 0 2 7 i O 0 . 0 / / / O U . O ^ /21I O. 0 / 7 3 0 0 . 0 / 7 3 0 0 . 0 / /••o 0 . 0 / 7 H O O . O / / t O C . 0 2 / 3 0 0 . 0 / / 3 0 0 . 0 / V o O 0 . 0 / /OO O . 0 2 7 o 0 u . t / 7 / 0 t > . 0 < : 7 / 0 0 . 0 / /viO 0 . 0 2 7 b 0 0 . 0 ^ 7vo L . 0 / 7 V 0 U . 0 / 7 V 0 0 . 0 2 b o o o . u / o o O 0 . 0 / b l O O . O / o l 0 0 . 0 / b / O 0 . 0 / e / o O . o 2 b j 0 O . O / C 3 0 o . o / c t o O . O / L 1 O 0 . 0 / b y 0 0 . 0 / b > 0 0 . 0 / 0 0 u O.O/troO 0 . 0 / b / O U . o / o / O 0 . 0 / b r t O O . 0 / uo 0 0.O2fcV0 o.u/cvo o. t / vo 0

129 .70 1 3 0 . 0 0 1 3 2 . 0 0 I 3 3 . I O 13<» .J0 I 3 b . < t 0 1 3 6 . 6 0 I 3 7 . 0 O 1 3 b . V O I H O . I U I H I . A O I H / . H O l t 3 . i > 0 l t ^ . 7 0 l*•t>.^0 I H 7 . 0 0 i H b . / O It^V.Mi I b O . b O 1 3 1 . «0 I 3 / . V O l 3 t . C 0 l b 5 . » 0 1 5 6 . t u 1 3 7 . 6 0 1 3 b * lO 1 3 V . V 0 l o l . l O l o / . J O 1 0 3 . :>0 l o t , 0 0 l o b . 0 0 1 0 7 . 0 a l o b . / o lov . to 1 / 0 . o O 17 1 . 60 1 / 3 . 0 0 1 7 ^ . / O 1 / 3 . t 0 1 / 6 . 0 U 1 / 7 . 6 0 1 7 V . 0 0 1 bO . 4.0 1 b 1 . t o I b 2 . o 0 l o 3 . vtt l e b . i o

l b 6 . 3 0 l b 7 . 3 0 I b b . /O l o v . v o I V I . I O i v ^ . J O 1 V 3 . b O

6 3 0 . t O 6 3 0 . b 0 6 3 0 . 7 0 6 3 0 . b O 6 3 1 . 0 0 6 3 1 . 1 0 6 J l . J O 6 J 1 . t o 6 3 1 . 3 0 0 3 1 . 7 0 6 3 1 . b O O 3 1 . V 0 6 3 2 . 0 0 0 3 £ . 1 0 C3<. . 3 0 O 3 2 . 3 0 6 3 4 . 3 U 6 3 / . O O 6 J 2 . 7 0 c j / . b O 6 3 / . V 0 O 3 2 . V 0 6 3 3 . 0 0 O J 3 . 1 0 6 3 3 . 2 0 6 3 3 . 3 0 6 3 3 . t o b j 3 . ^ 0 0 3 3 , b o 0 3 3 . 0 O 0 3 3 . 0 0 0 3 3 . / O t 3 3 . 7 0 6 3 3 . 6 0 6 3 3 . bO O 3 3 . V 0 O J 3 . V 0 O J J . V O 6 3 t . 0 0 O j t . 0 0 O J t . O O O J t . O O 6 J M . 0 0 O J t . O O t J t . O O O J t . O O O J t . O O 0 3 t . 0 0 O j t . 0 0 O J t . O O t J t . 0 0 0 3 t . 0 0 O J t . O O C 3 t . 0 0 6 j t . 0 0

86

133.UO iJt.OO 13b.ou 136.0U 137.00 l3b.oO 139.00 ItO.UO Itl.OO l^^.OO lt3.00 Itt.OO l^b.OO Itb.OO 1^7.00 Itb.OO 1^9.OU IbU.OO

3«f2.U0 3HO.60 350.vO 3bb./o 3b9.30 j6j,VO 36d.to 372.VO 3 77.30 3b/.b0 3b7.o0 3 V j . 1 0 t o o . 0 0 t o o . b O t l 2 . 3 0 H l V . J O t 2 6 . o 0 H 3 3 . U 0

0 . 0 2 9 0 0 U.O^VlO 0 . 0 / 9 1 0 O . O / V / 0 0 . 0 / V / O C . O / V 3 0 0 . 0 / V 3 0 0 . 0 / V t O 0 . 0 / V p O o.o^v:.o O.O/VOO O.O^iVOU O . O / V / 0 O . O / V / 0 0 . 0 / V b o O . O / Vo o 0 .0 /V - rO 0 . 0 / V > 0

1 9 4 . 7 0 ivb.vo 1 V 7 . 1 0 I V O . J O I v v . b O 2 0 0 . 7 u 201 .VO / 0 3 . 10 2 0 4 . 3 0

2 0 o . /O ^ O / . V O 2 0 9 . 10 ^ 1 0 . J O ^ 1 1 . b O / I / . 7 0 / 1 3 . VO / l b . 1 0

o 3 t . 0 0 6 3 t . 0 0 6 3 t . 0 0 6 3 t . 0 0 C 3 t . 0 0 O 3 t . C 0 0 3 t . 0 U O 3 t . 0 0 e 3 t . 0 0 6 3 t . O 0 6 3 t . 0 0 0 3 t . 0 0 6 3 t . ( i 0 6 3 t . 0 O 6 3 t . 0 0 6 3 t . O O C 3 t . 0 0 COt.OO

AgUA AMMONIA C O N C E N T K A T I O N O A T A :

U.OO 3 0 . 0 0 t o . 0 0 5 O . 0 0 oo.oo 7 0 . 0 0 b o . o o 9 O . 0 0

iCO.OO l l O . O O 1 2 0 . 0 0 1 3 0 . 0 0 I t O . O O IbO.OO 1 6 0 . 0 0 1 7 O . 0 0 IbO.OU 1 9 0 . 0 0 2 0 0 . 0 0 / l O . O O 2 2 0 . 0 0 2 3 0 . 0 0 I t O . O O 2bO.OU ^ 6 0 . 0 0

3 0 . 0 0 0 0 . 0 0 0 0 . 7 t 3 0 . 6 / 0 O .bVb O.bbO O.bOO O . t b b 0 . t 3 0 u.too 0 . 3 / 0 0-3t^0 O . j i o o . / b b 0 . 2 b O 0 . / / b o./oo 0 . 1 7 b O . l b o 0 . 1 / b 0 . 1 0 3 o.ovo o.o/o O.ObO 0 . 0 3 0

oo.oou O.OL'U 0 . 0 0 0 C.UOO O.uVO O.bOU 0 . 7 0 0 0 . 6 b O 0 . 3 V 0 0 . 3 b 3 0 . 3 1 U 0 . t 7 3 O . t t O O . t i O 0 . j / 3 O . 3 t 0 O.J^O O. /VO 0 . / 7 0 O . / t O O . 2 13 0 . 1 V 3 0 . 1 / 3 0 . IPO 0 . l.>0

KkLbbuKt

ljO.Ot..O 2 0 0 . 0 0 0 t . t to t .OOO C . 0 00 O.O 00 0 . 0 00 o.vvo O.b Vb o.7:>o O.O 73 O.O 10 O.boO 0 . 3 ^ 0 0 . t f c 3 O . t c O 0 . 4 . . b O . t o O 0 . J /b 0.3:^0 0 . 3 / 3 O . J 0 3 0 . / <3 O . / b b 0 . 2 J > 0 O . / C3

o.ooo t . 0 0 0 0 . 0 0 0 6 . 0 0 0 o.ooo 0 . 0 00 o.ooo O.vbb O.bbO U./<:b O.o7b O .o lO O.b 70 0 .P3O O. tVO

U . t j O U . t 0 3 O .3b0 O . 3 0 0 0 . 3 3 0 0 . 3 0 b 0 . 2 73 0 . / b 3

300.oco 0.000 0.000 0.000

o.ooo 0 . 0 0 0 0 . 0 0 0 o.ooo o.ooo 0 . 0 0 0 0 . 0 0 0 0 . 9 / 3 O . b l b O . 7 3 0 O . O / b 0 . 6 / 3 O . b / O 0 . 3 3 0 O. tVO 0 . t 3 b O . t 3 0 O . t l U 0 . 3 b O O.3O0 0 . 3 3 0

too.000 300.000 0.000 O.OOO 0.000 O.OOO 0.000 O.OOO 0.000 0.000 o.too o.oou o.ooo 0 . 0 0 0 O . V J O O . b / 3 0 . 7 3 0 0.O9O O.OtO O.bVO O . b t O o . b i o 0 . t 7 3 O.tPvi U . t / 3 O.tOO

0 . 0 0 0 O.ouO o .ooo O .UliO 0 . 0 0 0 o.ooo 0 . 0 0 0 0 . 0 0 0 o.ooo u.ooO 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 o.vvo O.bbO 0 . 0 2 0 O . / t b O.OVO 0 . O 2 b O.bVU 0 . 3 b 0 0 . 3 2 0 0 . '«d0 0 . t o 3

87

0 00 3 30 0 0 0 D 3 3 0 30 0 0 0 0 0 0 00 O3033000030003030330000

3 3 0 3 0 3 3 3 3 0 T N 3 S . ' % N a S S a o n 7 > 3 N n.f A nO"* 0 O > 3-^>J>i ' C O O O O O oc O 0'^'^'^!^

0 0 0 0 0 0 0 0 0 3 0 0 0 30 0 0 0 3 0 0 00 0 3 0 3 3 3 3 3 0 3 0 3 0 3 3 0 0 D 3 3 0 0 3

3 3 0 3 0 0 3 9 .roao r"M3(*>4-3P» .fO O.'O 3 rg-n r / A.Q'*-O OOOO-^.-vJ >Ji*l "O 0 O O O O 0 0 0 0 O^'^'^i^"*'"*

3 3 3 3 3 3 3 3 0 3 3 3 3 3 3 3 3 3 3 0 0 3 3 3 3 3 3 3 3 3 3 0 3 3 3 3 3 3 3 3 3 3 3 3 3 3

N 0 0 O O O O O O O O O" "*-"*' ! .'*

3 3 0 0 0 3 3 3 3 3 3 3 3 3 0 3 3 3 0 3 0 3 3 3 3 - 3 3 3 3 3 3 3 3 3 0 3 3 3 3 3 ^ 3 3 3 3

i;333ONJ04"-«J0ANl}A.N C T O O 3 n.i> T A A 0.'"i'« 3>/« J-^-^

.U r>J

>Jjo r 3

o o o o o o 0,0 OO o<*-"«»"»'-r»(i"*

3

u 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 - , 3 3 3 3 J j 3 J 3 3 3 J 3 3 J J - 3 0 J 3

3 3 3 r 3 0 O ^ 4 > O ^ » A - f* n> t -< '3>J OT r\ >j.n n-r AA o."*.'» o7>7> J3-« J >4 J O A - < a - O J * A - « O N 0 T 3 r V -4r* Njr* ONjn'irrno O'-'* o > j»3 3 --vi " n « r T -*000*JOOO 0OO0OO^'">'^ "-f.-. *.

2 a r

<

3 u

33 3 3 03 3 3 33 3 3 0 3 3 3 0 3 0 3 0 3 0 3 3 3 3 3 3 3 3 0 3 3 3 3 3 3 3 0 J 3 3 3 3 3

3 0 M i ^ f oeuntZi 0 3 0 N O r 3 T 3 0 - H O > J J\ '^r r A A 0Of* 'XJ»> i3^O3-« ,>J<Nn. *>4 ' - rA O O O O O O O O O O OO'**'**"* '*"*'*' "*''*

r 0 3 0 3 0 3 0 3 3 3 3 3 0 0 3 3 0 3 0 0 3 3 3 a: 33 333 33 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 0 • ^. . • • • • • • • « • • • • • • • • • • • * * * a. 3 3 3 3 3 3 3 3 3 3 3 J3J333;j 33333 3 4\ or* JO J* 3-^'^4.0 .X.A O.'^ .O^ 3-^<N'O.T A O

3 O 3 3 0 5 3 3 3 0 O 3 0 0 3 0 O O 0 3 O 0 O 0 0 3 3 3 A A A 3 3 3 3 0 3 3 A A n 0 3 3 3 0 3 3 3 0

^ N 5 » 3 . 4 N f 0 0 0 > 4 # O a ' 4 t 0 3 3 3 0 3 0 0 0 I "M.-O r A O. ' * > O . ^ N * l A 0

o.-^-nof* A * T o o a - ^ OO 3 .f A O Or-BÔN-^t O

0 0 0 0 3 3 0 3 0 3 0 0

• ^ O O O O O O O O O O O

0 0 3 3 0 3 O 3 3 3 0 0 O 3 3 0 0 0 3 3 3 O O 0 O

J*.'"."* 04" OM OOJOf*A.n o n • ^ r o o s o o o o o

0'nN'-40 3.'>4-nvA oso 'N *•••• 0^4 3 0 0 0 0 o o o AN-Î -<'Nn.r AO 0 > 3 - * > T M i l -«.

3 . ' N O N a . f N > > > r o 3 *>.-<>* rr\ 0 0 ' • ^ o M 3 r>JfN4 >J N >4 N •«4'\J'>J *!<*> > 0 0 0 3 3 3 3 3 3 0 0

0 0 0 0 0 3 0 0 0 0 0 0

O O O 3 0 0 0 0 3 3 0 0 0 0 3 3 0 0 0 3 0 0 0 0 0 X J A A * > J > A 3 0 n * ^ ^ . f - * 0 > 0 - H 3 3 0 0 3 3 0

O >4 — 3 ^ *» O A O " * O 0 > 3 3 - « - < N 3 3 3 0 0 3 0

Mil l ~t-i

O A < M O ' ^ 0 ( V J > O A A S 3 - < > J N < » n r T A O ( * - » 3 >i.>J N N >4.N ^ Ni'g >J X « 3 0 3 3 3 O 0 3 3 3 0 • • • • • • • • • • • •

0 3 0 0 0 3 0 0 0 3 0 0

O O O O O O O O O 3 0 0 0 0 0 0 0 0 3 3 0 3 0 0 0 r » A ( » . Of«» O r f * 3 * « » r - ^ « A N ' > 0 - n 0 3 3 3 0 3 0

O 0 A f n > J - 4 > o n A > » » O O < > . 0 . ' * » > 3 0 0 0 0 0 O ( * » 0 A r n - ^ | -< :N .n A 0 ' - O T « 0 i I I I I I I t

} A O O f f > 1 0 " ^ o o * » 3 3 3 -< - * NifM ^•<^ t (\ o

^ 0 0 0 3 3 3 3 3 3 0 0

• • * • « • • • • ! • • 0 0 0 0 0 0 0 0 0 3 3 0

O 3 3 O O 0 0 3 O O O 0 0 0 0 0 0 0 0 0 3 0 0 0 0 oÂoa^-osms n a - n t j . r i a i i B - n o . t i a s o o o o <>N-<o jâ.'-A TNa>-<'^J r Ai^ 0 3 - 4 0 3 3 o

SJâr*-A f-n>j-^ I -«.<».>• A of^ a 3 « H >-« I i I I I I I I

o o >-<-r ai>4.0 "H o^j->j 3 > > 3 3 3 - « - « >J.>* *> T 3 ^ ^ > J N >J.'>4 - ^ N . N V N 0 0 0 0 0 3 3 0 3 3 0 0

• • • • • • • • • • • • 0 0 0 0 0 0 0 3 0 O O O

0 3 3 3 0 3 3 3 3 3 3 3 3 3 3 3 0 3 3 3 0 3 3 3 0 A 3 3 t O ' * 0 . ' > > 4 J « 0 •O^J."* "VJ A a - « f " * 3 <> O > 0

0 - 4 3 > a r « - O A . r ' > J - « 0 - < ^ J T A O a 7 » 3 N ^ T A 3 - « 3 o ' ^ o n T ^ N - 4 T - H > i . " n T A O . ' * > 3 - » > J - ' > - • - J A ^ O T ' - N O A 3 0 7 « J « J ' > 3 3 3 - « - « > i 3 . ^ - 4 . ^ - < - ^ M .M "NJ IN'î >J A 3 0 3 3 3 0 3 3 3 3 3

3 3 3 3 3 3 3 3 3 3 3 3

2 0 3 0 3 0 0 3 3 3 0 0 3 3 3 3 3 0 3 0 3 0 0 0 0 0 T A j > o o > 3 3 a r > ^ i - H ' n o o 3 . ' g A o - < 4 " 0 0 3 > J

f - 3 J» O a . " ^ O O A."n N " 3 - 0 4 . 0 A O . ^ O J - * - J T A O < 3 > 0.>» O A ^ r •0.>J'H . .^-J O T A O i " J » 0 - « ^ O 4" a: - • I I I I I I I t I - I H - * - * - *

z u 3 Z 3 3 3 0 3 3 0 3 3 3 3 0 0 3 3 0 3 3 0 3 0 0 3 3 0 3 OJ^ A J A V > \ « 3 a >4 3 >«T 3 J - * J . - . ^ - < n . — > 3 3

3 " l -n 'Irsj -^ -^ J a " - J- .^ O.'^ > 3 - N < ^ ' > 0 i - * O 3 ^ j^ i i -ô . '^r ' l -^ l - 4 ^ ' i r o » 5 J > 3 - 4 w '— r ' - 3 - r 3 3 o a a j j > j > J » 3 3 - *

T 3 3 3 3 3 3 3 3 3 3 3

3 3 3 3 3 3 3 3 3 3 3 3

3 * * > 3 > J . T 0 JJ«^ " l . ^ 3 — . ^ • • o o o a o > o » >

' • > 3 3 3 3 3 3 - J 3 JOO • « • • • • • • • * • « 3 3 0 3 3 3 3 3 3 J 3 3

3 3 3 3 3 3 3 3 0 3 3 3 3 3 3 0 0 3 3 3 3 0 3 3 3 N .r 3 O.-O 7 > > 4 3 3 J ' a 3 A - n N - 4 3 J« a "* O A - t 3 3

s . - * ! ^ o o A A >fr - "^ a > 3 - 4 N t T T A or*' 3 > 3 - ^ O A r - n N - H l - 4 N " A o . ^ o > 3 - « N.*»-r A . - * a

M i l l - » - • - « - . - « - « - « - « 4 3

3 4 > 4 ' ^ 4 " . A a 3 3 ^ T O o . ^ i ^ . ' ^ i ^ * " ^ ' . u a a a

N 3 3 3 3 J 3 3 3 J 3 3

3 3 0 3 3 3 0 3 3 3 3 3

3

3 J 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 0 3 3 3 0 - • V J 3 O O 0 3 J T . ^ « 1 3 ' ' ^ 3 T J ' 4 - 3 A 3 3 3 3 3 3

3 0 0 A A T A A O O " " ' ' a 0 > > O -*~* N ."O n <l >t A . > \ j . H | - » g n . I ' A O " * 0 3 » J > 4 ' > 4 ' A 3 — U . ^ O

J £ 3 3

:>

3 O . ^ * - O > 0 — >J f A ' * 3 J O O O O**"***^ " " ^ ^ 3 - . . H - < ' ^ - < - < ' ^ - < - < " . « — « - • 3 3 j 3 J O 3 3 3 3 J • • • • • • • • • • • • 3 3 3 3 3 3 0 J 3 3 3 3

-i

4 E

3

£ <

4 3 J <

O 3 A >• O J" V J»(»- T<M3>J»J>3">JA>.^nn4'a-r 3 J 3 3 3 33j»>7>^j»a«oJ->j>^3'^N.'nro 3 o o a a oai (*»' i*"f '*'' '*"'*' '*"' aaaaaa

-«rg n4•AO.'•aJ>^-«^J O 4" AO'^ a >3-«'>i

0 3 3 3 0 3 0 3 3 3 3 3 3 3 3 3 3 3 3 3 0 0 0 3 0 0 3 3 3 3 3 3 3 0 0 3 3 3 3 3 3 3 3 3 0 0 3 0 3 3

0 3 3 3 3 3 3 3 3 3 3 3 0 0 3 3 3 3 3 3 0 3 O O O

n .t*\os^ a>3-*"«J'»-fA Oiâ j>3-4<M o T A O

Z

o £ £ 4 4 3 3 <

O O O O ' ^ ^ - ' ^ n T A O O 0 0 0 0 0 0 0 0 0 0 0 0

3 3 0 0 0 3 0 3 3 3 33 • * • • • * • • ! • • • 0 3 0 3 3 3 0 0 3 3 0 0

0 3 0 3 3 33 0 3 3 0 0 0 3 0 3 33 3 3 3 3 3 O • • • • • • « • . • • • 3 3 0 3 3 0 0 3 3 3 0 ^

<<4oa3.>4ro 0 3 >4 -t^* '•t'^'^ N.N

89

Appendix D

<N CN

c > 4 c o i o o o o « . r * r > . c o r - ^ « o . ^ o a f M « o o < « r o 3 C ' j ^ o . - « i o .—• »-• »—• •..« •.—• •—I •—1 »-« »-4 .—I C

~ o m c o — « « a - ' ^ c o « » - c o r ^ c o c o r ^ — « > o o * » - o o c M « o o i n in ^^ «r CO CO c-j -.* —< o o Os

• o ( N > o < o r » . o o i ^ ( N m r o ^ -a » o ^ C M i n o o r ^ c o ^ o s . * - c > ( N . o » - « i n o « . c * > r > . < N i n c 3 i n i n ' « r ^ - M < N c > 4 ^ ^ - ^ o o e A 0 < 3 ^ ^ ^ C » C 3 0 < 3 < 3 0

b

\ •P '4-D U

L_i

c o •H -p

O 0)

OO in

« : * - r > . « » - o o » . < c » 4 * r c o c > c M ' a f 4 c>j •^ a* CO CM «r -o <<>•.-< r>* CM -o o «- CN CO r>. .»-» ij-> o <«»-i n « » * « * - c o < N c ^ « - ^ ^ ^ o o o N o o o o o o o c > o o ^

* » - o c o f M i n o — < « * - i n ' . ^ c o • r - o o i n c o c o o c ^ j o j o o i - . ^ ^ i n o « r c o c M r » « . ^ H i n o « « r i n * » - « « » - C O C N C s | ^ ^ - ^ O C K C r % 0 C 3 0 0 0 0 0 0 0 0 0

u.

. ^ •n ca

CM CM »-•

«*-o .^-«

V.-I

CO o in v ^

O

r- o o m ^>4

<3

«»• CN «*-^f ^ 1 ^

o

CM CO • « » •

*r <r~4

«3-

CM in •!»• CN

g^ CO .-H .—4

o o

-^ C«4 s OO CO V.H ..>4

o o

~o r<-i CO CN ^ • ^

<3

O^ r t> CM v-«

o

CO CO CM CM «« o

-o CO ^ CM *^ o

o in -o ^ ^-4

C^

*o *- o ^ v-4

o

CO r o .—4

.—• o

-o CO o V..4

- o

of CO «»• o ^ o

Os •«»-

« » •

o .m-4

o

-r «*• CTs OS

<-> O

CO » . i ^

CTs OS

o o

in •>»-'f Os

o o

r CO <vi CN o< o

l-

•H

J L i-i

Q

CO

CO W3

o in

o c M - - H C N O . . o ^ r c M i n c M i n . r - O C M t ~ < ^ < * > ' ^ < ^ — * 0 3 ~ 0 C N c o t o C M r - . — H i n ^ ^ t - c o c o ^ r ^ r c o c o c v i c M - ^ - ^ o c r s C N C 3 0 0 0 0 0 0 0 0 0 C D

>

• G. if}

»

CO

CQ

—1

CO -o CO *r m-^

o

c-CO » » •

^-4

o

00 >:»-r~ ^r . 1

o

o

CN CN CM *r V—4

<?

CO CO CM «»• «.-. o

CM CO .^H

^ . 1

o

in

C-J •o r CO ^•^ •o

CO o r«» CO ^ F ^

o

Ul • « * •

-o CO ^m^

o

C4

9 •IN •>4 CO »—4

o

in r v H

CO •^H

o

•o ^-i • ^ ^

CO *—• o

«

CO r~ -o CM W 4

O

CO CO -o c>< ^^ o

??; m (N ...-• •o

8

« * •

c-.^ CS4

. o

1^ CO o CM •.- o

rn O o CM • r - *

<3

in CO

CO CO in .- . o

OS « * •

•.—« . • ^

o

O" m *r ^ ^ o

.o CN <z> «—< "O

r CM Os O <^ o

« » •

CN CO o V—4

o

in

(N CO CO o wH

o

CO *r CO o ^-4

o

in ^•H

CO o ^•^ o

o in

-o «r CO OS <-.• c<

.o CO O N

O o

-o CO r-Os o o

in in

in CO CO CN o o

8 «-o OS C o

CO r-CM tN <_> O

-o

PERMISSION TO COPY

In presenting this thesis in partial fulfillment of the

requirements for a master's degree at Texas Tech University, I agree

that the Library and my major department shall make it freely avail

able for research purposes. Permission to copy this thesis for

scholarly purposes may be granted by the Director of the Library or

my major professor. It is understood that any copying or publication

of this thesis for financial gain shall not be allowed without my

further written permission and that any user laay be liable for copy

right infringement.

Disagree (Permission not granted) Agree (Permission granted)

Student's signature Student's signacu

Date

^/1^/&'7

Date

PERFORMANCE ANALYSIS OF ABSORPTION HEAT TRANSFORMER ...

Documents

Transcript of PERFORMANCE ANALYSIS OF ABSORPTION HEAT TRANSFORMER ...