International Journal of Research and Innovation on Science, Engineering and Technology (IJRISET)
International Journal of Research and Innovation in Thermal Engineering (IJRITE) 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.
Abstract Air conditioning evaporator works by absorb heat from the area (medium) that need to be cooled. It does that by maintaining 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 parametric software Pro/Engineer. To validate the temperatures and other thermal quantities like flux and gradient, thermal analysis is done on the evaporator 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. *Corresponding Author: Potireddi Sriram, Research Scholar,Department of Mechanical Engineering, Godavari Institute of Engineering And Technology, Andhra Pradesh, India. Email: psriram365@gmail.com Year of publication: 2016 Review Type: peer reviewed Volume: 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
In the refrigeration cycle, a heat pump transfers heat from a lower-temperature heat source into a higher-temperature heat sink. Heat would naturally flow in the opposite direction. This is the most common type of air conditioning. 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 temperature 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 AIR CONDITIONER An air conditioner, often referred to as AC is a home appliance, 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 referred to as "HVAC". Its purpose, in a building or an automobile, 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.
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 92
International Journal of Research and Innovation on Science, Engineering and Technology (IJRISET)
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 commonly 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 pressure and temperature after passing through the expansion valve. This refrigerant absorbs the heat from the substance 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=224m3 Door area =w*h = 1.53*2.32 =3.55m2 Wall thickness =0.254m No of systems =34 Window area =1.325*2.75=3.65m2 No of windows = 3 =3*3.65 = 10.95m 2 No of lights = 4 =4*40 = 160 watts Florescent co-efficient = 1.25 Total lighting load = 160*1.25 = 200W Solar 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/m2K UWALL = 1.56W/m2K UROOF= 5.675W/m2K UFLOOR = 159W/m2K UDOOR =142W/m2K UWINDOW =4.70W/m2K Equivalent temperature difference (te) te of north wall =90C te of south wall =110C te of west wall =110C te of east wall =60C te of roof =190C te of floor =2.40C No of persons =40 Sensible heat load per person =117W Latent heat load per person =50W Ventilation 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 light Room 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 = 480.4W North wall Sensible heat gain = 1.56 *28*90 = 393012W East wall Sensible heat gain =1.56*22.4*110 =384.384W West wall F Sensible heat gain =1.56*22.4*60 =2090664W Floor Area Sensible heat gain =159*80*2.40 = 30528W Roof Area Sensible heat gain = 5.675*80*190 =8626W Door Area Sensible heat gain = 142*3.55*90 =4536.9W South wall = 3.65*4.70*2*110 =377.41W North 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 = 4680W Q* Total No of persons per person* No of persons =50*40 =2000W Amount of In filter air (vi) = length* Width*height*no of air changes /60 = 224*1/60 = 30733m3/min Sensible heat gain due to infiltration air =0.02044*V1*(tdb1 - tdb2) = 0.02044*3.73*(38-27) =0.83865kW Tdb1 = outside temp Tdb2 = inside temp Latent heat gain due to infiltration Air =50*V1*(w1 – w2) = 50*3.73*(0.015-0.011) = 0.746kW Sensible 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 + unfiltered air +ventilation). = 1.05(4680+3.733+10.95) = 5070.2576W Total 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 ComputerAided Design and Drafting (CADD), is the use of computer technology for the process of design and design93
International Journal of Research and Innovation on Science, Engineering and Technology (IJRISET)
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, documentation, and manufacturing processes. DATA POINTS
INTRODUCTION TO FEA Finite Element Analysis (FEA) was first developed in 1943 by R. Courant, who utilized the Ritz method of numerical analysis and minimization of variation calculus to obtain 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 centered on the "stiffness and deflection of complex structures". By the early 70's, FEA was limited to expensive mainframe computers generally owned by the aeronautics, automotive, defense, and nuclear industries. Since the rapid decline in the cost of computers and the phenomenal increase 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 parameters.
CURVES GENERATION
FEA consists of a computer model of a material or design that is stressed and analyzed for specific results. It is used in new product design, and existing product refinement. 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 COPPER 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
PIPES SECTON
PLATES FINAL MODEL
Tube Material - Copper Element Type: solid 20 nodes 90 Material Properties: Thermal Conductivity – 63W/mK Specific Heat – 14 J/kg K Density - 0.00007500 kg/mm3 Plate Material - Copper Element Type: solid 20 nodes 90 Material Properties: Thermal Conductivity – 63W/mK Specific Heat – 14 J/kg K Density - 0.00007500 kg/mm3
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International Journal of Research and Innovation on Science, Engineering and Technology (IJRISET)
Meshed model- meshing is used to deconstruct complex problem (model) into small problems (elements) to solve in numerical method.
Above image is showing Thermal Gradient-rate of change of temperature per unit distance.
THERMAL ANALYSIS OF EVAPORATOR USING COPPER FOR TUBE AND AL 204 FOR PLATE – HYDROCARBON FLUID
Above image is showing Temperature distribution on object Above image is showing Temperature distribution on object.
Above image is showing Thermal Gradient-rate of change of temperature per unit distance.
THERMAL ANALYSIS OF EVAPORATOR USING COPPER FOR TUBE AND AL [AL99.0 (1100)] FOR PLATE – HYDROCARBON FLUID
Above image is showing Temperature distribution on object.
Above image is showing Thermal Gradient-rate of change of temperature per unit distance.
THERMAL ANALYSIS OF EVAPORATOR USING COPPER FOR TUBE AND PLATE – HYDROCHLOROFLOUROCARBON FLUID
Above image is showing Temperature distribution on object.
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International Journal of Research and Innovation on Science, Engineering and Technology (IJRISET)
RESULTS Thermal analysis for fluid Hydrochlorofluorocarbon Nodal Temperature (0C)
Thermal Gradient (K/ mm)
Thermal Flux (W/mm2)
Copper Tube Copper Plate
16
0.658e-11
0.415e-11
Copper Tube Al 99 Plate
16
0.186e-11
0.41e-11
Copper Tube Al 204 Plate
16
8.93
1.34
Above image is showing Thermal Gradient-rate of change of temperature per unit distance.
THERMAL ANALYSIS OF EVAPORATOR USING COPPER FOR TUBE AND AL [AL99.0 (1100)] FOR PLATE HYDROCHLOROFLOURO- CARBON FLUID
Thermal analysis for fluid Hydrocarbon Nodal Temperature (0C)
Thermal Gradient (K/ mm)
Thermal Flux (W/mm2)
Copper Tube Copper Plate
16
0.4e-11
0.252e-11
Copper Tube Al 99 Plate
16
0.683e-11
0.15e-11
Copper Tube Al 204 Plate
16
4.719
2.973
CONCLUSION Above image is showing Thermal Gradient-rate of change of temperature per unit distance.
THERMAL ANALYSIS OF EVAPORATOR USING COPPER FOR TUBE AND AL 204 FOR PLATE – HYDROCHLOROFLOUROCARBON FLUID
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 fluorocarbon, by using plate material Al 204 has more thermal conductivity. So using Al 204 is advantageous.
Above image is showing Thermal Gradient-rate of change of temperature per unit distance.
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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International Journal of Research and Innovation on Science, Engineering and Technology (IJRISET)
REFERENCES
AUTHORS
1.HASHIM SAHAR MOHAISEN (2014) Modling and Thermal 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 Application 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 Refrigeration Cycle Using Energy from Exhaust Gas of an Internal Combustion Engine, Advanced Engineering and Applied Sciences: An International Journal, 47- 53.
Potireddi Sriram, Research Scholar, Department of Mechanical Engineering, Godavari Institute of Engineering And Technology, Andhra Pradesh, India.
4.S. Sanaye, (2012) Thermal Modeling of Mini-Channel and Laminated Types Evaporator in Mobile Air Conditioning System, International Journal of Automotive Engineering, 68-83. 5.Ananthanarayanan P N (2005) 'Refrigeration & Air Conditioning', Tata McGraw-Hill..3rdedition, pp.398 - 424. 6.Arora, Domkundwar. (2004) 'A course in Refrigeration & 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-conditioning, International Journal Refrigeration, 161.
S.Raja Sekhar, AssociateProfessor, Department of Mechanical Engineering, Godavari Institute of Engineering And Technology, Andhra Pradesh, India.
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 Refrigeration in Road Transport Vehicles', Journal of Energy Engrg. Volume 125, Issue 2, pp. 48-58. 12.Manohar Prasad. (2000) 'Refrigeration & Air Conditioning', New Age International Publishers., 3rd edition, pp. 188 - 225. 13.Manohar Prasad. (2000) 'Refrigeration & Air Conditioning - Data Book'. New Age International Publishers., 2nd edition. 14.Vicatos G. (1995) Heat and mass transfer characteristics: Design and optimization of absorption refrigeration machines, PhD thesis, University of Cape Town South Africa
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