ET101 Basic Heat Pump DemonstratorET101 Basic Heat Pump Demonstrator-1 24 Kl.1,0 bar 5 15 DIN 0...

Experiment InstructionsET101 Basic Heat Pump

Demonstrator

24-1Kl.1,0

bar

5

15

DIN

0

1

-1

-0.5

Kl.1,0bar

5

10DIN

9

0

24

Experiment Instructions

Publication no.: 916.000 00B 101 12 10/2009

ET 101 Basic Heat Pump Demonstrator

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Table of Contents

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 Unit description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2.1 Unit construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2.2 Unit function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.3 Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.4 Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.5 Care and maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4 Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4.1 Cyclic process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4.2 Example: Steam plant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

4.3 Example: Heat pump. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

4.4 Comparison: Heat pump/Refrigerator . . . . . . . . . . . . . . . . . . . . . . . 11

4.5 Heat pump process in the p-h diagram . . . . . . . . . . . . . . . . . . . . . . 12

4.5.1 Construction of a p-h diagram. . . . . . . . . . . . . . . . . . . . . . . 14

4.5.2 Ideal cyclic process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

4.5.3 Actual cyclic process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

4.6 Output coefficient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

4.6.1 Determining the output coefficient from the p-h diagram . . 17

5 Operation of the heat pump. . . . . . . . . . . . . . . . . . . . . . . . . . . 18

5.1 Experimental determination of the useful heat flow . . . . . . . . . . . . . 18

5.1.1 Performing the measurement . . . . . . . . . . . . . . . . . . . . . . . 18

5.1.2 Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18


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6 Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

6.1 Worksheet: Measured value recording . . . . . . . . . . . . . . . . . . . . . . 20

6.2 lg p - h diagram of refrigerant R 134 a. . . . . . . . . . . . . . . . . . . . . . . 21

6.3 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

6.4 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23


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1 Introduction

The ET 101 heat pump demonstrator representsa fully functional model of an water/water heatpump.

The bench-top unit covers the following areas oftuition in the field of heating and refrigeration engi-neering:

- Familiarisation with the basic construction ofheat pumps

- Components of thermal engines, heat pumpsand refrigeration systems

- Familiarisation with cyclic processes

- Working with p-h diagrams

- Basics of refrigeration engineering

The bench-top unit exclusively contains compo-nents which are also used in industrial heat pumpsand refrigeration systems.

The unit is primarily intended for producing quali-tative assessments. Quantitative measurementscan, however, also be carried out.

Always follow the safety regulations (Chapter3) when using the unit!

The ET 101 heat pump demonstrator unit is inten-ded for use in education and training. Its use inindustrial environments in particular is forbidden.


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1 Introduction 1

2 Unit description

2.1 Unit construction

1. Frame 8. Water tank2. Manometer for high-pressure side (HP) 9. Condenser3. Expansion valve with 10.Compressor4. Temperature sensor 11.Filler valve5. Manometer for low-pressure side (LP) 12.Pressostat6. Sight glass (refrigerant) 13.Main switch7. Evaporator

24-1Kl.1,0

bar

5

15

DIN

0

1

-1

-0.5

Kl.1,0bar

5

10DIN

9

0

24

13

12

1 2 3 5

11 10 9 8

6

4

7


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2 Unit description 2

2.2 Unit function

The ET 101 heat pump demonstrator includes acomplete heat pump with original refrigeration en-gineering components. The temperature sink is awater tank, from which heat energy is drawn. Thisheat is fed back in a second water tank. Thesystem is characterized by the following features:

- The entire system is laid out clearly on a wallchart.

- Original refrigeration engineering compo-nents mean the setup is practice-oriented.

- An environmentally friendly refrigerant(R134a, CFC-free) is used.

- The robust construction of the unit means itis ideally suitable for use in erveryday tuition.

The expansion valve fitted in the system is athermostatic expansion valve with an evaporatortemperature sensor, and is set to a minimum eva-porator outlet temperature of Tv= -2°C.

The delivery side of the compressor is protectedagainst overload by a Pressostat.

A sight glass in front of the expansion valve allowsthe flowing refrigerant to be observed.

2.3 Operation

The unit is switched on by throwing the mainswitch. No other settings need to be made!

The compressor has an overload protection deviceprovided by a thermostatic switch. If the switch istripped, switch off the main switch, allow the sy-stem to cool, and then switch it back on again.

2.4 Commissioning

Prior to commissioning the system into operation,the two plugs on the tops of the manometers mustbe cut off to render the manometers functional.


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Also, wait a few minutes for the refrigerant to settlebefore starting up.

The system is started up by connecting the com-pressor to the mains power. The compressor isthen activated by throwing the main switch.

2.5 Care and maintenance

The unit is maintenance-free. The system shouldbe protected against frost.

Please do not make any alterations to the com-pressor, the expansion valve or the Pressostat.They are factory-set to enable the unit to functionproperly.


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3 Safety

Important! Electrical voltage.

You should therefore observe the following safetyinstructions:

- Before opening the main switch cabinet andworking on the electrics, disconnect themains plug!

- Protect the main switch cabinet against waterincursion!

- In case of danger switch off the mainswitch and disconnect power to the sy-stem by unplugging the mains plug!

- Never manipulate the service product circuit(by opening up screw fittings or the like)! Thesystem is under pressure!

The service product (refrigerant R134a) is environ-mentally hazardous and may escape, so

- Suction off the refrigerant properly beforecarrying out repairs!

- Do not adjust the Pressostat. It is factory-set!

- Do not adjust the expansion valve!

- If the compressor’s thermostatic switch is trip-ped, allow the system to cool off. Check theoperating pressures after restarting!

- Danger of burns! The pipework from thecompressor to the condenser becomes veryhot. Do not touch it during operation!


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3 Safety 5

4 Theory

4.1 Cyclic process

The basis for the functioning of a heat pump is athermodynamic cyclic process.

In a thermodynamic cyclic process a service me-dium (e.g. R134a) passes through various chan-ges of state in a pre-set sequence. The changesof state are repeated cyclically, so the servicemedium repeatedly returns to its initial state. Thatis why the process is termed a cyclic process.

Change of state refers to compression, expansion,heating or cooling:

- Compression means absorption of mechani-cal energy

- Expansion means discharge of mechanicalenergy

- Heating means absorption of thermal energy(heat)

- Cooling means discharge of thermal energy

In a change of state the state variables such aspressure, specific volume or temperature of theservice product, change. Gas or easily evaporatedliquids may be used as the service product. Pureliquids are unsuitable, because they are incom-pressible.

Skilful sequencing of various changes of state cancause thermal and mechanical energies to beexchanged by way of the service product; that is,the service product acts as an energy transfermedium.

The changes of state do not need to occur atclearly separated intervals. Often heat is dischar-ged during compression, for example. The variati-ons involved in changes of state is interlinked.Compression, for example, generally leads to

Heat absorption

Heat discharge

Com

pres

sion

Exp

ansi

on

Fig.: 1


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4 Theory 6

- an increase in temperature T

- an increase in pressure p

- a reduction in volume V

For gases, this interlinking of state variables canbe described with the so-called thermal state equa-tion for ideal gases:

p⋅v = R⋅T (4.1)

In this, p is the absolute pressure, v the specificvolume (volume referred to mass), R the specificgas constant and T the absolute temperature (inKelvins).

In observing the change of state of a gas, a distin-ction must be made between two states:

- 1 - State of the gas before the change of state

- 2 - State of the gas after the change of state

The cases in which one of the state variablesremains unchanged (=constant) during the changeof state are of special significance, and so havetheir own designations:

Special cases of the state equationDesignation: Isobaric

Change of state Isochoric Change of state isothermic Change of state

Condition: p = constant v = constant T = constantState equation: v1

v2 =

T1T2

p1

p2 =

T1T2

p1

p2 =

v2v1

Gay-Lussac’s law Boyle-Mariotte’s law


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4 Theory 7

A change of state without heat discharge is termedan isentropic change of state (the specific entropy,see Chapter4.5, remains constant), a change of statewithout exchange of heat is termed an adiabaticchange of state.

In pure compression or expansion without heatdischarge or absorption (isentropic or adiabaticrespectively), the necessary mechanical energyW1,2 for the change of state from state 1 to state2 is calculated as

W1,2 = m R

κ−1(T1−T2) (4.2)

or

W1,2 = m R

κ−1(p1 v1−p2 v2) . (4.3)

κ is the isentropic exponent,

m is the mass of the gas.

For isochoric heating or cooling (i.e. same volume,but increasing or decreasing temperature) the fol-lowing applies for input or output heat quantity Q1,2

Q1,2 = m⋅cv (T2−T1) (4.4)

Cv is the specific heat capacity of the gas under

observation at constant volume. A distinction mustbe made between two kinds of specific heat ca-pacity:

- Heating from T1 to T2 causes a pressure increa-se, the volume remains constant: cv

- The heating brings about an increase in volu-me, the pressure remains constant: cp

From the specific heat capacity the isentropic ex-

ponent κ is produced as:


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4 Theory 8

κ = cp

cv (4.5)

In reality, ideal gases are practically never encoun-tered. The observation of changes of state withliquids or vapours as with common service pro-ducts for heat pumps is much more complicated,and uses other state variables such as entropy orenthalpy, with the aid of caloric state equations.

4.2 Example: Steam plant

Steam plant (steam turbines, steam locomotives)is the oldest application of a cyclic process. As willbe shown, a steam plant is, so to speak, thereverse of a heat pump.

The steam plant uses water as its service product.The cyclic process can be divided into four con-secutive changes of state:

- First the water is compressed by a low pressureby means of the feed water pump in the highlypressurised steam boiler. The mechanicalenergy Win is used up in the process.

- In the steam boiler the water is evaporated byaddition of heat energy Q

.in. The temperature

rises, the pressure remains constant.

- The hot, high-pressure steam flows into theturbine. There the steam gives off its internalenergy in the form of mechanical energy Wout

to the turbine blades. The pressure and tempe-rature fall again.

- Finally the steam condenses in the condenser,with further heat being discharged Q

.out.

The condensate is routed back to the boiler feedwater pump and the cycle begins again. The ser-vice product, water, thus circulates in the cyclic

Feed water pump

Steam plant circulation process

Turbine

Steam

Steam boiler

Liquid

Q.

out

W.

in

Q.

in

W.

out = Pout

Condenser

Fig.: 2


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4 Theory 9

process. That is why the process is termed aclosed cyclic process.

Cyclic processes in which the service product con-tinually has to be replaced, and is not recycled, aretermed open cyclic processes. These also includethe spark-ignition and diesel processes with whichmodern car engines operate.

In the steam plant shown, therefore, heat energycan be converted into mechanical energy (with aspecific waste heat flow). Machines in whichprocesses of this kind occur are termed thermalengines (TE). These also include cyclic processeswith purely gaseous service products, as in gasturbine plants or hot-air engines (Sterling engine).

4.3 Example: Heat pump

Whereas the steam plant process concentrates onthe conversion of thermal energy into mechanicalenergy, the heat pump utilises the effect of heattransport. The term "heat pump" can be explainedby the following illustration: heat is pumped from alow temperature level to a high temperature level,using up mechanical energy. The mechanicalenergy is not lost, but is also discharged at thehigher temperature level, in the form of thermalenergy.

In a heat pump the cyclic process of the steamplant is run through in reverse order. Consequent-ly, the direction of the heat flow is also reversed:

- A compressor compresses the vaporous ser-vice product, whereby mechanical energy Win

is absorbed.

Input heat energy

Mechanical

useful energy

TE

Waste heat flow

Fig.: 3


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4 Theory 10

- In the condenser the heat Q.

out is drawn off ofthe service product (at the same temperature)and the medium is liquefied.

- In an expansion valve pressure is relievedfrom the liquid service product, thereby coolingit down.

- An evaporator evaporates the service product,with heat absorption Q

.in.

The service product is now fed back to the compres-sor and the cyclic process begins again.

4.4 Comparison: Heat pump/Refrigerator

In terms of function, the heat pump is identical tothe refrigerator. There, too, heat is pumped from alow energy level 1 (from the refrigerator) to a higherenergy level 2 (in the environment). Whereas in thecase of the heat pump the output heat Q

.ab is used,

the benefit for the refrigerator comes from the inputheat Q

.zu.

The consumption should be equivalent to the re-quired mechanical energy Win.

The advantage of processes with vaporous/ liquidservice product lies in the high energy transferdensity. During evaporation the service mediumabsorbs the evaporation heat with low temperaturedifferences. In condensation it discharges it again.The evaporation heat in the service products usedis very much greater than the quantity of heat to betransferred via the specific heat capacity of thesteam.

Example: Water

The quantity of heat required to evaporate 1 kg ofwater is 2256 kJ, whereas a temperature increaseof that steam from 100°C to 200°C only requires199 kJ of heat (at 1 bar in each case).

Q.

out = Q.

usef

W.

in

W.

in

Q.

in

Q.

out

Q.

in = Q.

usef

T1<T2

T1<T2

Refrigerator

Heat pump

Abb.: 4

Heat pump circulation process

Evaporator

CompressorSteam

Expansion valveLiquid

Q.

out

Q.

in

W.

in = Pin

Condenser

Fig.: 5


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4 Theory 11

A high energy density saves a lot of money: com-pact high-performance systems can be con-structed.

The heat pump process can also be easily carriedout with a purely gaseous service product. Sy-stems based on the Sterling principle are con-structed, but are highly complex and expensive.

4.5 Heat pump process in the p-h diagram

The changes of state in a cyclic process can beadvantageously plotted in a p-h diagram.

In the p-h diagram the pressure p is plotted overthe specific enthalpy h.

Enthalpy H is designated as the total energy con-tent of a gas or vapour. It is composed of theinternal energy U, a measure for the thermal ener-gy content of a substance, and the displacement

work p⋅V.

H = U + p⋅V (4.6)

Referred to the mass, here too specific variablesare obtained:

h = u + p⋅v (4.7)

with the specific internal energy u=u0+cv(T−T0)

Because basically only differences are being ob-served, u0 and T0 are in principle freely selectablereference points.


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4 Theory 12

At this point it is beneficial to define another keystate variable, the entropy S. The entropy can beillustrated based on a bucket placed in an enclosedroom and filled with water:

In state 1 the water in the bucket has the tempera-ture T; the air temperature is the same, so heatexchange is not possible.

If the bucket is left standing for a few days, thewater evaporates (state 2) and turns to water va-pour within the room (provided the air is able toabsorb the water). The temperatures are still equal,and no energy could reach the outside beyond thesystem limit. The enthalpy of the water has there-fore remained the same, but the entropy has in-creased! Why is that?

The water molecules are now evenly distributedaround the room, and are in the natural steadystate. This is the state with the lowest degree of"order", that is, with the maximum "disorder". Toget the water vapour back into the bucket, that is,to increase the degree of order, work would needto be expended.

The entropy is a measure for the order of substan-ces. It assumes the highest value in the state ofmaximum disorder. All substances naturally striveto achieve the state of maximum entropy!

The unit of entropy S is J/K, the unit of the specificentropy s (referred to the mass) is J/kgK.

Water

State1 State 2

Water vapour

System limit

Fig.: 6


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4 Theory 13

4.5.1 Construction of a p-h diagram

Each of the various service products has its ownp-h diagram, in which the liquid-phase, wet-steamand hot-steam zones are plotted. Wet steam me-ans that the service product is a mixture of liquidand steam. The temperature in the wet steam zoneprecisely corresponds to the boiling point. In thehot steam zone the service product is pure steam(superheated steam); the temperature is alwaysabove boiling point.

Curves for constant temperatures T (isotherms),constant steam content x and constant entropy s(isentropes) can also be plotted.

The curve x=1 (steam content 100%) always deli-mits the wet steam zone from the hot steam zone;the curve x=0 (liquid content 100%, steam content0%) is the borderline between the liquid phase andthe wet steam zone.

In the wet steam zone the isotherms always runhorizontally!

Liquid phase

x=0

SuperheatedsteamWet steam

x=1

T=const.

Enthalpy h

Pre

ssur

e lo

g p

Fig.: 7


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4 Theory 14

4.5.2 Ideal cyclic process

The changes of state resulting in the heat pumpcyclic process are now transferred into the p-hdiagram:

1-2 : Isentropic compression until final compression temperature with superheating of the service medium, no heat discharge

2-2’ : Isobaric cooling until condensation temperature, discharge of thesuperheating enthalpy h2,2’

2’-3 : Isobaric condensation, discharge of thecondensation enthalpy h2’,3

3-4 : Relaxation in the wet steam zone, noenthalpy discharge, cooling and partialevaporation

4-1 : Isobaric evaporation, absorption of theevaporation enthalpy h4,1

Heat pump cyclic process

Evaporation

Compression

Ralaxtion

h2,2’ +h2’,3

h4,1

h1,2

21

34

Condensation

Fig.: 8

x=0

Superheated steam

Wet steam

x=1

T=const.

Enthalpy h

Pre

ssur

e lo

g p

p-h-Diagram of a heat pump

22’3

4 1

Fig.: 9


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4 Theory 15

4.5.3 Actual cyclic process

The main difference between the actual and theideal cyclic process is that the compression is notisentropic (i.e without discharge of heat), but runsalong the line 1*-2* due to internal friction in theservice product steam and heat losses in the com-pressor. Thus, more work must be expended onthe compressor to achieve the same final pressu-re.

Moreover, superheating 1-1* of the service productsteam prior to compression is necessary, to relia-bly exclude the possibility of drops of liquid enteringthe compressor. The compressor would otherwisebe damaged by liquid impacts.

Liquid subcooling 3-3* is used to reduce the portionof steam at the inlet into the evaporator. As a result,more evaporation heat 4*-1 can be absorbed.

4.6 Output coefficient

To be able to assess the efficiency of a heat pump,an output coefficient is introduced. It correspondsto the efficiency of thermal engines, and is deter-mined from the ratio between work and benefit.The benefit is the output heat flow Q

.out, the work

is the input power Pin or the input mechanical

energy W.

in

ε = Q.

out

W.

in =

Q.

usef

Pin . (4.8)

In contrast to the efficiency, which is always lessthan 1, the output coefficient is generally greaterthan 1. The output coefficient must therefore notbe designated as the efficiency.

1

T=const.

1*

2’ 2 2*3* 3

4* 4

Superheatedsteam

Wet steam

Actual p-h-diagram of a heat pump

Enthalpy h

Pre

ssur

e lo

g p

Fig.: 10


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4 Theory 16

The output coefficient becomes greater than 1, dueto the fact that the input heat Q

.in is delivered "free"

from the environment, and so is ignored as work.

4.6.1 Determining the output coefficient from the p-h diagram

The amounts of energy converted in the cyclicprocess can be taken directly as enthalpy differen-ces from the p-h diagram. Thus, the output coef-ficient can be determined for the ideal process ina simple manner:

ε = Qout

Win =

h2 − h3

h2 − h1

(4.9)

For the real process with induction gas superhea-ting and liquid subcooling:

ε = h2

∗ − h3∗

h2∗ − h1

∗ . (4.10)

In general, the output coefficient increases as thetemperature difference between the absorptionand discharge sides decreases. Also, a highertemperature level resulting from the service pro-duct used brings about a higher output coefficient.

1

1*

2’ 2 2*3* 3

4* 4

Superheatedsteam

Wet steam

Output coefficient from p-h-Diagram

h2*-h3*

h2*-h1*

T=const.

Fig.: 11


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4 Theory 17

5 Operation of the heat pump

The unit is not designed for quantitative measure-ments or experiments; the measurements andevaluations described therefore serve only as anaid to general understanding of heat pumps and toqualitative verification of the conditions described.

5.1 Experimental determination of the useful heat flow

5.1.1 Performing the measurement

- Fill two vessels with cold water of approxima-tely 25°C

- Position the vessels (8) as shown underneaththe condenser and the evaporator. The bottom,upside-down, vessel, supports the top one.

- Measure the water temperatures in the twovessels with two laboratory thermometers)

- Switch on the compressor by throwing themain switch (13)

- Record and plot the measured values on theworksheet in the Appendix

5.1.2 Evaluation

Defined and measured variables:

t - Time in sec.m - Water quantity per water vesselpHP - Pressure upstream of the condenserpLP - Pressure at the inlet into the compressorTHP - Temperature of water being heated TLP - Temperature of water delivering heat

24-1Kl.1,0

bar

5

15

DIN

0

1

-1

-0.5

Kl.1,0bar

5

10DIN

9

0

24

pHP pLP

THP 8 TLPFig.: 12


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5 Operation of the heat pump 18

The resulting heat delivered to the water beingheated between states 1 (at the beginning) and 2(at the point of measurement) is

Qout = m⋅cp⋅(THP2−THP1) (5.1)

with cp = 4,19kJ⁄(kg⋅K) - specific heat capacity of

water.

The output heat power (useful heat flow) is thus

Q.

out = Qout

t (5.2)

The input power is composed of the input mecha-nical power Pin (compressor) and the heat powerdrawn from the second water vessel Q

.zu (in the

case of a refrigerator the cold output):

Q.

in = m⋅cp⋅(TLP1−TLP2)

t (5.3)

In determining the output coefficient ε this drawn-off heat flow is not taken into account:

ε = Q.

out

Pin (5.4)


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5 Operation of the heat pump 19

6 Appendix

6.1 Worksheet: Measured value recording

Water vessel content:__________________ ml

Time t [sec] pHP [bar] pLP [bar] THP [°C] TLP [°C]


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6 Appendix 20

6.2 lg p - h diagram of refrigerant R 134 a

Reclin 134 aMollier h-lg p- diagram for 1,1,1,2 tetraflourethane CH2F-CF3 calculated with the aid of the state equation of U.K. RombuschPressure p in barVolume v in dm3/kgTemperature t in °CEnthalpy h in kJ/kgEntropy s in kJ/(kg K)Reference point h= 200.00 kJ/kg,s’=10000kJ/(kgK) at t=0°C


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6 Appendix 21

6.3 Technical data

Compressor:

Type: Piston compressor

Power consumption: 104 Wat 5 / 40 °C

Cold output: 278 Wat 5 / 40 °C

Manometer with temperature scale for R134a:Measuring ranges: -1... 9 bar

-1... 24 barDiameter: 160 mm

Expansion valve:Temperature sensor set to Tv=-2 °C

Pressostat for pressure monitoring:Switch off compressor at 17 barSwitch on compressor at 13 bar

Refrigerant: Reclin R134a

4 Water vessels, plasticCapacity: each 1.7 l

Power supply 230 V / 50 Hz, 6AAlternatives optional, see type plate

Dimensions:

WxHxD 750x600x350 mm3

Weight: 25 kg


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6 Appendix 22

6.4 Index

AActual cyclic process. . . . . . . . . . . . . . . . . . . . . . . . . . . 16adiabatic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

BBoyle-Mariotte. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

CCaloric state equation . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Change of state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Closed cyclic process . . . . . . . . . . . . . . . . . . . . . . . . . . 10Compression. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Compressor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Condenser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2, 9, 11Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Cyclic process. . . . . . . . . . . . . . . . . . . . . . . 6, 9, 11, 15, 16

DDiesel process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Disorder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Displacement work . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

EEfficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Energy transfer density . . . . . . . . . . . . . . . . . . . . . . . . . 11Energy transfer medium . . . . . . . . . . . . . . . . . . . . . . . . . 6Enthalpy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Enthalpy difference . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Entropy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8, 13Evaporation enthalpy . . . . . . . . . . . . . . . . . . . . . . . . . . 15Evaporation heat. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Evaporator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Expansion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Expansion valve . . . . . . . . . . . . . . . . . . . . . . . . . . . 3, 5, 11

FFeed water pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Frost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

GGas constant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Gay-Lussac. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7


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HHeat discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Heat exchange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Heat pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3, 10Heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6High-pressure side (HP) . . . . . . . . . . . . . . . . . . . . . . . . . 2Hot (superheated) steam . . . . . . . . . . . . . . . . . . . . . . . 14

IIdeal cyclic process. . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Ideal gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Internal energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Isentropes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Isentropic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Isentropic exponent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Isobaic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Isochoric . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7, 8Isothermic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Isotherms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

KKappa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

LLiquid content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Liquid impacts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Low-pressure side (LP). . . . . . . . . . . . . . . . . . . . . . . . . . 2

MManometer plugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Measured values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Mechanical energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Nncompressible. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

OOpen cyclic process . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Output coefficient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Overload protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Pp-h diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Pressostat. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2, 5

RR134a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Refrigeration system. . . . . . . . . . . . . . . . . . . . . . . . . . . 11Refrigerator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11


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SSpark-ignition process . . . . . . . . . . . . . . . . . . . . . . . . . 10Specific heat capacity . . . . . . . . . . . . . . . . . . . . . . . . 8, 19State equation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7state equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9State variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Steam boiler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Steam content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Steam plant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Sterling engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Sterling principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Superheated steam . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Superheating enthalpy . . . . . . . . . . . . . . . . . . . . . . . . . 15

TTE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Thermal engine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Thermal state equation . . . . . . . . . . . . . . . . . . . . . . . . . . 7Thermodynamic cyclic process. . . . . . . . . . . . . . . . . . . . 6Turbine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

UUnit construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

WWater vessel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Wet steam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14


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