Ijri te-03-013 modeling and thermal analysis of air-conditioner evaporator

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International Journal of Research and Innovation on Science, Engineering and Technology (IJRISET)

MODELING AND THERMAL ANALYSIS OF AIR-CONDITIONER EVAPORATOR

Potireddi Sriram1, S.Raja Sekhar2.

1 Research Scholar, Department of Mechanical Engineering, Godavari Institute of Engineering And Technology, Andhra Pradesh, India.2 AssociateProfessor, Department of Mechanical Engineering, Godavari Institute of Engineering And Technology, Andhra Pradesh, India.

*Corresponding Author:

Potireddi Sriram,Research Scholar,Department of Mechanical Engineer-ing, Godavari Institute of Engineering And Technology, Andhra Pradesh, India.Email: [email protected]

Year of publication: 2016Review Type: peer reviewedVolume: III, Issue : I

Citation:Potireddi Sriram, Research Scholar "Modeling And Thermal Analysis of Air-Conditioner Evaporator" International Journal of Research and Innovation on Science, Engineering and Technology (IJRISET) (2016) 92-97

INTRODUCTION TO AIR CONDITIONER

An air conditioner, often referred to as AC is a home ap-pliance, system, or mechanism designed to dehumidify and extract heat from an area. The cooling is done using a simple refrigeration cycle. In construction, a complete system of heating, ventilation and air conditioning is re-ferred to as "HVAC". Its purpose, in a building or an au-tomobile, is to provide comfort during either hot or cold weather.

Air conditioning system basics and theories

A simple stylized diagram of the refrigeration cycle: 1) condensing coil, 2) expansion valve, 3) evaporator coil, 4) compressor.

In the refrigeration cycle, a heat pump transfers heat from a lower-temperature heat source into a higher-tempera-ture heat sink. Heat would naturally flow in the opposite direction. This is the most common type of air condition-ing. A refrigerator works in much the same way, as it pumps the heat out of the interior and into the room in which it stands as it pumps the heat out of the interior and into the room in which it stands.

This cycle takes advantage of the way phase changes work, where latent heat is released at a constant tem-perature during a liquid/gas phase change, and where varying the pressure of a pure substance also varies its condensation/boiling point.

Refrigeration cycle

INTRODUCTION TO EVAPORATOR

It is in the evaporators where the actual cooling effect takes place in the refrigeration and the air conditioning systems. For many people the evaporator is the main part of the refrigeration system and they consider other parts as less useful. The evaporators are heat exchanger surfaces that transfer the heat from the substance to be

Abstract

Air conditioning evaporator works by absorb heat from the area (medium) that need to be cooled. It does that by main-taining the evaporator coil at low temperature and pressure than the surrounding air. Since, the AC evaporator coil contains refrigerant that absorbs heat from the surrounding air, the refrigerant temperature must be lower than the air.

In our project we have modeling an air-cooled evaporator for a home 1.5ton air conditioner. Presently the material used for coils is copper and the material used for fins is copper or aluminum. A 3D model of the evaporator is done in para-metric software Pro/Engineer.

To validate the temperatures and other thermal quantities like flux and gradient, thermal analysis is done on the evapo-rator coil by applying properties copper and suitable material like aluminum. And also we are varying inside cooling fluid Hydrocarbon (HC) and Hydro chloroflouro carbon (HCFC).The best material for the evaporator of our design can be checked by comparing the results.

Thermal analysis is done in ANSYS.

International Journal of Research and Innovation in Thermal Engineering (IJRITE)

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cooled to the refrigerant, thus removing the heat from the substance. The evaporators are used for wide variety of diverse applications in refrigeration and air conditioning processes and hence they are available in wide variety of shapes, sizes and designs. They are also classified in different manner depending on the method of feeding the refrigerant, construction of the evaporator, direction of air circulation around the evaporator, application and also the refrigerant control.

In the domestic refrigerators the evaporators are com-monly known as the freezers since the ice is made in these compartments. In case of the window and split air conditioners and other air conditioning systems where the evaporator is directly used for cooling the room air, it is called as the cooling coil. In case of large refrigeration plants and central air conditioning plants the evaporator is also known as the chiller since these systems are first used to chill the water, which then produces the cooling effect.

In the evaporator the refrigerant enters at very low pres-sure and temperature after passing through the expan-sion valve. This refrigerant absorbs the heat from the sub-stance that is to be cooled so the refrigerant gets heated while the substance gets cooled. Even after cooling the substance the temperature of the refrigerant leaving the evaporator is less the than the substance. The refrigerant leaves the evaporator in vapor state, mostly superheated and is absorbed by the compressor.

COOLING LOAD CALICULATIONS

Floor Volume= length*Width*height= 8*10*2.8=224m3Door area =w*h = 1.53*2.32 =3.55m2

Wall thickness =0.254mNo of systems =34Window area =1.325*2.75=3.65m2

No of windows = 3 =3*3.65 = 10.95m 2

No of lights = 4 =4*40 = 160 wattsFlorescent co-efficient = 1.25Total lighting load = 160*1.25 = 200WSolar heat gain factor (SHGF)South wall = 140W/m2

North wall =120W/m2

West wall = 340W/m2

East wall = 60W/m2

Overall coefficient of heat transfer (U) W/m2KUWALL = 1.56W/m2KUROOF= 5.675W/m2KUFLOOR = 159W/m2KUDOOR =142W/m2KUWINDOW =4.70W/m2KEquivalent temperature difference (te)te of north wall =90Cte of south wall =110Cte of west wall =110Cte of east wall =60Cte of roof =190Cte of floor =2.40CNo of persons =40Sensible heat load per person =117WLatent heat load per person =50WVentilation required per person =0.28m3/min Outdoor Conditions:Dry bulb temperature =380C RH =60%

W1=0.015kg/kg of dray air ratio Indoor conditions: Dry bulb temperature =270C RH=60%W2 =0.011kg/kg of dry air ratio

Assumptions:

Using a factor of 1.25 for florescent lightRoom latent heat load with 4% factor of safety Estimation of sensible Heat gain South wall area = 28*10 = 28m2

North wall area = 28*10 = 28m2

East and west wall area = 22.4m2

Equaling temp diff te0C

South wall Sensible heat gain = UAH =1.56*28*110 = 480.4WNorth wall Sensible heat gain = 1.56 *28*90 = 393012WEast wall Sensible heat gain =1.56*22.4*110 =384.384WWest wall F Sensible heat gain =1.56*22.4*60 =2090664WFloor Area Sensible heat gain =159*80*2.40 = 30528WRoof Area Sensible heat gain = 5.675*80*190 =8626WDoor Area Sensible heat gain = 142*3.55*90 =4536.9WSouth wall = 3.65*4.70*2*110 =377.41WNorth wall = 3.65*4.70*1*90 154.395W

Solar Heat Gain through South glass:

Area of windows* SHGE for south = 3.65*2*140=1022m2

Total Sensible heat gain per person* No of persons = 117*40 = 4680WQ* Total No of persons per person* No of persons =50*40 =2000WAmount of In filter air (vi) = length* Width*height*no of air changes /60 = 224*1/60 = 30733m3/minSensible heat gain due to infiltration air =0.02044*V1*(tdb1 - tdb2) = 0.02044*3.73*(38-27) =0.83865kWTdb1 = outside temp Tdb2 = inside temp Latent heat gain due to infiltration Air =50*V1*(w1 – w2) = 50*3.73*(0.015-0.011) = 0.746kWSensible heat gain for computer = wattage per system*no of systems

= 450*36=16200W

Total room Sensible heat (RHS) = 1.0495 (heat gain form walls + windows + solar heat gain through glass + heat gain form persons + due to infiltration + due to ventilation +due to lightening +due to computers)

= 1.045(556.115+1022+0.8386532+16200+200+63) = 23754.892W

Total Room latent Heat (RHL) = 1.05*(from persons + un-filtered air +ventilation). = 1.05(4680+3.733+10.95) = 5070.2576WTotal heat=28825.15/3530 = 8.16tons Hence we can take 9tons.6x 1.5 ton Split AC’s

INTRODUCTION TO CAD

Computer-aided design (CAD), also known as Computer-Aided Design and Drafting (CADD), is the use of com-puter technology for the process of design and design-

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documentation. Computer Aided Drafting describes the process of drafting with a computer. CADD software, or environments, provides the user with input-tools for the purpose of streamlining design processes; drafting, docu-mentation, and manufacturing processes.

DATA POINTS

CURVES GENERATION

PIPES SECTON

PLATES FINAL MODEL

INTRODUCTION TO FEA

Finite Element Analysis (FEA) was first developed in 1943 by R. Courant, who utilized the Ritz method of numeri-cal analysis and minimization of variation calculus to ob-tain approximate solutions to vibration systems. Shortly thereafter, a paper published in 1956 by M. J. Turner, R. W. Clough, H. C. Martin, and L. J. Top established a broader definition of numerical analysis. The paper cen-tered on the "stiffness and deflection of complex struc-tures".

By the early 70's, FEA was limited to expensive main-frame computers generally owned by the aeronautics, au-tomotive, defense, and nuclear industries. Since the rapid decline in the cost of computers and the phenomenal in-crease in computing power, FEA has been developed to an incredible precision. Present day supercomputers are now able to produce accurate results for all kinds of pa-rameters.

FEA consists of a computer model of a material or de-sign that is stressed and analyzed for specific results. It is used in new product design, and existing product re-finement. A company is able to verify a proposed design will be able to perform to the client's specifications prior to manufacturing or construction. Modifying an existing product or structure is utilized to qualify the product or structure for a new service condition. In case of structural failure, FEA may be used to help determine the design modifications to meet the new condition.

THERMAL ANALYSIS OF EVAPORATOR USING COP-PER FOR TUBE AND PLATE – HYDROCARBON FLUID

Imported Model through IGES Format (Initial graphical exchanging specification) it is used to convert 3d parts/assembly’s between graphical software’s

Tube Material - CopperElement Type: solid 20 nodes 90Material Properties: Thermal Conductivity – 63W/mKSpecific Heat – 14 J/kg KDensity - 0.00007500 kg/mm3

Plate Material - CopperElement Type: solid 20 nodes 90Material Properties: Thermal Conductivity – 63W/mKSpecific Heat – 14 J/kg KDensity - 0.00007500 kg/mm3

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Meshed model- meshing is used to deconstruct complex problem (model) into small problems (elements) to solve in numerical method.

Above image is showing Temperature distribution on object

Above image is showing Thermal Gradient-rate of change of tem-perature per unit distance.

THERMAL ANALYSIS OF EVAPORATOR USING COP-PER FOR TUBE AND AL [AL99.0 (1100)] FOR PLATE – HYDROCARBON FLUID

Above image is showing Temperature distribution on object.


THERMAL ANALYSIS OF EVAPORATOR USING COP-PER FOR TUBE AND AL 204 FOR PLATE – HYDRO-CARBON FLUID



THERMAL ANALYSIS OF EVAPORATOR USING COP-PER FOR TUBE AND PLATE – HYDROCHLORO-FLOUROCARBON FLUID


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THERMAL ANALYSIS OF EVAPORATOR USING COP-PER FOR TUBE AND AL [AL99.0 (1100)] FOR PLATE HYDROCHLOROFLOURO- CARBON FLUID


THERMAL ANALYSIS OF EVAPORATOR USING COP-PER FOR TUBE AND AL 204 FOR PLATE – HYDRO-CHLOROFLOUROCARBON FLUID


RESULTS

Thermal analysis for fluid Hydrochlorofluorocarbon

Nodal Tem-perature (0C)

Thermal Gradient (K/mm)

Thermal Flux (W/mm2)

Copper TubeCopper Plate

16 0.658e-11 0.415e-11

Copper TubeAl 99 Plate

16 0.186e-11 0.41e-11


16 8.93 1.34

Thermal analysis for fluid Hydrocarbon

Nodal Tem-perature (0C)

Thermal Gradient (K/mm)

Thermal Flux (W/mm2)

Copper TubeCopper Plate

16 0.4e-11 0.252e-11


16 0.683e-11 0.15e-11


16 4.719 2.973

CONCLUSION

In our project modeling and analysis is done for air-cooled evaporator for 1.5ton air conditioner.

3D Modeling is done using Pro/Engineer.

Performed Thermal analysis on the evaporator by taking tube material as copper and varying the plate materials. We also did analysis by varying refrigerant Hydrocarbon and Hydro fluorocarbon.

In thermal analysis, we analyze the thermal properties like nodal temperature, thermal gradient and thermal flux.

By observing the results, for hydrocarbon or hydro fluoro-carbon, by using plate material Al 204 has more thermal conductivity.

So using Al 204 is advantageous.

When comparing Hydrocarbon and Hydro fluorocarbon, using Hydro fluorocarbon is more advantageous since its thermal conductivity is more.

FUTURE SCOPE

In further I would like to do experimental investigation on the above conditions and CFD analysis to provide some more accurate results and provisions.

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REFERENCES

1.HASHIM SAHAR MOHAISEN (2014) Modling and Ther-mal Analysis of Air Conditioner Evaporator, SEMAR GROUPS TECHNICAL SOCIETY. Pages:4156-4160

2. Kiran.B.Parik(2013)ANALYSIS AND VALIDATION OF FIN TUBE EVAPORATOR, International Journal of Ap-plication or Innovation in Engineering & Management (IJAIEM), 430, 443

3.S.LAKSHMI SOWJANYA,(2013) Thermal Analysis of a Car Air Conditioning System Based On an Absorption Re-frigeration Cycle Using Energy from Exhaust Gas of an Internal Combustion Engine, Advanced Engineering and Applied Sciences: An International Journal, 47- 53.

4.S. Sanaye, (2012) Thermal Modeling of Mini-Channel and Laminated Types Evaporator in Mobile Air Condition-ing System, International Journal of Automotive Engi-neering, 68-83.

5.Ananthanarayanan P N (2005) 'Refrigeration & Air Con-ditioning', Tata McGraw-Hill..3rdedition, pp.398 - 424.

6.Arora, Domkundwar. (2004) 'A course in Refrigera-tion & Air Conditioning', DhanpatRai& Co., 7thedition, pp.6.1- 6.23.

7.Lorentzen G. and Pettersen J. (1993) A New, Efficient and Environmentally Benign System for Car air-condi-tioning, International Journal Refrigeration, 161.

8.Arora C P (2002) 'Refrigeration & Air Conditioning', Tata McGraw Hill., 2nd edition, pp.301-314, 339 - 356, 427 - 456.

9.Ballaney PL (2003),* Refrigeration & Air Conditioning' Khanna Publishers., 13th edition, pp. 483 - 542.

10.Domkundwar&Domkundwrar. (2005) 'Heat & Mass Transfer- Data Book', DhanpatRai& Co., 2nd edition,

11.Horuz I (August 1999), 'Vapor Absorption Refrigera-tion in Road Transport Vehicles', Journal of Energy En-grg. Volume 125, Issue 2, pp. 48-58.

12.Manohar Prasad. (2000) 'Refrigeration & Air Condi-tioning', New Age International Publishers., 3rd edition, pp. 188 - 225. 13.Manohar Prasad. (2000) 'Refrigeration & Air Condi-tioning - Data Book'. New Age International Publishers., 2nd edition.

14.Vicatos G. (1995) Heat and mass transfer characteris-tics: Design and optimization of absorption refrigeration machines, PhD thesis, University of Cape Town South Af-rica

AUTHORS

Potireddi Sriram,Research Scholar, Department of Mechanical Engineering, Godavari Institute of Engineering And Technology, Andhra Pradesh, India.

S.Raja Sekhar,AssociateProfessor, Department of Mechanical Engineering, Godavari Institute of Engineering And Technology, Andhra Pradesh, India.

Ijri te-03-013 modeling and thermal analysis of air-conditioner evaporator

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