SIMULATION STUDY ON HEAT TRANSFER RATE ON AIR CONDITIONING CONDENSER BY VARYING MATERIAL PROPERTIES AND ORIENTATION

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1 SIMULATION STUDY ON HEAT TRANSFER RATE ON AIR CONDITIONING CONDENSER BY VARYING MATERIAL PROPERTIES AND ORIENTATION MUNIGONDA VIJAY KUMER M.TECH (theral engineering) MLR Institute of Technology, Hyderabad. P. GEETA KRISHNA M.Tech (assistant professor) MLR Institute of Technology, Hyderabad. ABSTRACT: Air conditioner condensers are a heat exchanger device; AC condenser units are grouped according to how it rejects the heat to the ediu (surround air). The priary coponent of a condenser is typically the condenser coil, through which the refrigerant flows. Since, the AC condenser coil contains refrigerant that absorbs heat fro the surrounding air, the refrigerant teperature ust be higher than the air. In this project designed an air-cooled Condenser fins for an air conditioner. Presently the aterial used for coils is Copper and the aterial used for Fins is Copper or aluiniu G Al Cu 4IMG 204 whose theral conductivity is W/ K. the condenser fines design using coputer aided software catia. We are optiizing the design paraeters by changing the thickness of the fin for the sae length without failing the load conditions. To validate the teperatures and other theral quantities like flux and gradient, theral analysis is done on the condenser fines by applying copper for coil and Fin aterials G Al Cu 4IMG 204, Aluiniu Alloy Al99 and Magnesiu alloy. Heat flux, directional heat flux, convection, Theral analysis is done in ansys. And also we are varying inside cooling fluid Hydrocarbon (HC) and Hydro chloro flouro carbon (HCFC). The best aterial and best fluid for the condenser of our design can be checked by coparing the results. Optiization is done by changing the thickness of the catia is a paraetric 3D odelling software and ansys is analysis software. Key words: ac condenser, G Al Cu 4IMG 204, Aluiniu Alloy Al99 and Magnesiu alloy, catia, theral analysis 1. INTRODUCTION In systes involving heat transfer, a condenser is a device or unit used to condense a substance fro its gaseous to its liquid state, by cooling it. In so doing, the latent heat is given up by the substance, and will transfer to the condenser coolant. Condensers are typically heat exchangers which have various designs and coe in any sizes ranging fro rather sall (hand-held) to very large industrial-scale units used in plant processes. For exaple, a refrigerator uses a condenser to get rid of heat extracted fro the interior of the unit to the outside air. Condensers are used in air conditioning, industrial cheical processes such as distillation, stea power plants and other heatexchange systes. Use of cooling water or surrounding air as the coolant is coon in any condensers A condenser unit used in central air conditioning systes typically has a heat exchanger section to cool down and condense incoing refrigerant vapor into liquid, a copressor to raise the pressure of the refrigerant and ove it along, and a fan for blowing outside air through the heat exchanger section to cool the refrigerant inside. A typical configuration of such a condenser unit is as follows: The heat exchanger section wraps around the sides of the unit with the copressor inside. In Page No:801

2 this heat exchanger section, the refrigerant goes through ultiple tube passes, which are surrounded by heat transfer fins through which cooling air can ove fro outside to inside the unit. There is a otorized fan inside the condenser unit near the top, which is covered by soe grating to keep any objects fro accidentally falling inside on the fan. The fan is used to blow the outside cooling air in through the heat exchange section at the sides and out the top through the grating. These condenser units are located on the outside of the building they are trying to cool, with tubing between the unit and building, one for vapor refrigerant entering and another for liquid refrigerant leaving the unit. Of course, an electric power supply is needed for the copressor and fan inside the unit 1.2 ABOUT CONDENSER COIL: Heat transfer enhanceent techniques have been one of the ain theral engineering research fields since the fuel crisis in 1970s. Active, passive and copound heat transfer enhanceent ethods have been developed. Helical coils, additives to fluids, swirl flow devices, rough and extended surfaces are all passive enhanceent techniques while application of electric, acoustic and agnetic fields and fluid /syste vibration are active techniques (Bergles, 2002). Passive ethods were preferred due to their siplicity in anufacturing, lower cost and longer operating life. Many researchers are currently interested in investigating flow boiling inside channels with sall diaeters due to their high surface area to volue ratio and the increase of heat transfer coefficients leading to high heat transfer rates (Thoe, 2010). The heat transfer coefficient is inversely proportional to the channel diaeter (α=nu k/d). As a result, decreasing the channel diaeter would result in higher heat transfer coefficient. Additionally, for the sae cross sectional flow area, dividing the flow to large nuber of channels produces larger surface area for heat transfer copared to flow in single tube with large diaeter leading to high heat transfer rates. 1.3 EQUATION FOR CONDENSER COIL: For an ideal single-pass condenser whose coolant has constant density, constant heat capacity, linear enthalpy over the teperature range, perfect crosssectional heat transfer, and zero longitudinal heat transfer, and whose tubing has constant perieter, constant thickness, and constant heat conductivity, and whose condensible fluid is perfectly ixed and at constant teperature, the coolant teperature varies along its tube according to: Where: x is the distance fro the coolant inlet; T(x) is the coolant teperature, and T(0) the coolant teperature at its inlet; TH is the hot fluid's teperature; NTU is the nuber of transfer units; is the coolant's ass (or other) flow rate; c is the coolant's heat capacity at constant pressure per unit ass (or other); h is the heat transfer coefficient of the coolant tube; P is the perieter of the coolant tube; G is the heat conductance of the coolant tube (often denoted UA); L is the length of the coolant tube. 1.4 TYPES OF CONDENSERS In the world of Heating, Ventilation, and Air Conditioning (HVAC), condensers happen to be a topic of great iportance. Instead of confusing inforation, the goal is to provide soe basic inforation on the different types of condensers and their applications. Page No:802

3 There are three other condensers used in HVAC systes. Water-cooled Air-cooled Evaporative 1.5 APPLICATIONS: Air cooled If the condenser is located on the outside of the unit, the air cooled condenser can provide the easiest arrangeent. These types of condensers eject heat to the outdoors and are siple to install. Most coon uses for this condenser are doestic refrigerators, upright freezers and in residential packaged air conditioning units. A great feature of the air cooled condenser is they are very easy to clean. Since dirt can cause serious issues with the condensers perforance, it is highly recoended that these be kept clear of dirt. Water cooled Although a little ore pricey to install, these condensers are the ore efficient type. Coonly used for swiing pools and condensers piped for city water flow, these condensers require regular service and aintenance. They also require a cooling tower to conserve water. To prevent corrosion and the foring of algae, water cooled condensers require a constant supply of akeup water along with water treatent. Depending on the application you can choose fro tube in tube, shell and coil or shell and tube condensers. All are essentially ade to produce the sae outcoe, but each in a different way. Evaporative While these reain the least popular choice, evaporative condensers can be used inside or outside of a building and under typical conditions, operate at a low condensing teperature. Typically these are used in large coercial airconditioning units. Although effective, they are not necessarily the ost efficient. CHAPTER-2 LITERATURE REVIEW With the advent of coputers, the study of various coponents of a doestic air conditioning syste under a range of operating conditions has becoe possible through atheatical odeling, saving thus a huge aount of tie and oney. Subsequently, siulation of an air conditioning syste deands a thorough knowledge on siulation techniques. Hence an elaborate literature survey has been conducted and it is presented in this section. Jaeel and Syed (1999) have developed a therodynaic odel to siulate the working of actual refrigeration syste. Siple cycle used for the analysis showed that the super heating has ore influence on the COP of the syste. Using this odel, the COP and other syste paraeters were calculated with ± 2% accuracy. Liang and Wong (2001) conducted experients and developed a odel to exploit the possibility of applying the equilibriu two-phase drift flux odel to siulate the flow of refrigerant R134a in the capillary tube expansion device. The details of flow characteristics of R134a in a capillary tube, such as distribution of pressure, void fraction, dryness fraction, phase s velocities and their drift velocity relative to the center of the ass of the ixture are presented. Corberan et al (2004) predicted a odel to calculate the ass flow rate of refrigerant in a capillary tube by eans of the conservation equations (ass, oentu and energy) over individual control volues and included in IMST- Page No:803

4 ART, software for siulation and design of refrigeration equipent. The addition of capillary tube odel allows calculating the superheat at the evaporator giving the capillary tube geoetry. A siulation with different operative conditions and capillary geoetry is done and the results are copared for R22 with those given by ASHRAE correlations. Li et al (2004) presented a general odel forat for Adjustable Throat Area Expansion Valves (ATAEV), including TEV and EEV that utilizes anufacturer s rating data. Model structures for three types of valve geoetries are derived. The odel forat for ATAEV was validated by using anufacturer perforance rating data and the flow through the adjustablearea expansion device is not chocked. Two odel forats and paraeter estiation procedures were considered and their predictions were copared with laboratory easureents. The non linear odeling approach only requires data at a rating condition to obtain paraeters and gave good predictions over a wide range of operating conditions when copared with laboratory data. Sarntichartsak et al (2007) conducted experients on inverter air conditioner with variation of capillary tube using R22 and R407C and predicted odel. The two zone odel, the distributed odel and cobined odel were copared to estiate the optial charge inventory. The odel prediction agrees with the experiental data in the range of HZ. Beghi et al (2009) reported soe results of a research project aied at deriving siple, high-perforance, adaptive and robust control algoriths for EEV to control dry expansion evaporators superheat teperature. The adaptation schee is based on the on-line identification of asiplified, first order plus dead tie (FODPT) odel of the process. The Zhaung-Atherton ethod is then used to derive a new set of ProportionalIntegral-Derivatives (PID) paraeters, which allow the syste to iprove the closed- loop perforance. The control algorith has been evaluated by restoring to a detailed, a particular virtual prototyping software environent. The algorith exhibits better perforance than other auto tuning approaches, such as the one based on relay feedback. The perforance has been evaluated by resorting to standard indexes such as Integral Squared Error (ISE) and Integral Squared Tie Weighted Error (ISTE). CHAPTER DESIGN AND MODELLING OF ENVIRONMENT TEST CHAMBER CATIA offers a solution to shape design, styling, surfacing workflow and visualization to create, odify, and validate coplex innovative shapes fro industrial design to Class-A surfacing with the ICEM surfacing technologies. CATIA supports ultiple stages of product design whether started fro scratch or fro 2D sketches. CATIA is able to read and produce STEP forat files for reverse engineering and surface reuse Fig1.4: Sketcher of condenser coil CHAPTER ANALYSIS OF TEST CHAMBER ANSYS is general-purpose finite eleent analysis software, which enables engineers to perfor the following tasks: Page No:804

5 1. Build coputer odels or transfer CAD odel of structures, products, coponents or systes 2. Apply operating loads or other design perforance conditions. 3. Study the physical responses such as stress levels, teperatures distributions or the ipact of electroagnetic fields. 4. Optiize a design early in the developent process to reduce production costs. 5. A typical ANSYS analysis has three distinct steps. 6. Pre Processor (Build the Model). 4.2 ANALYSIS OF RESULTS: In this chapter, the results obtained for the analysis of enivarental chaber syste for the original profile and dynaic structural analysis are discussed. And also explained the graphs plotted by coparing those results. Material Data Magnesiu alloy Loads: Teperature: Density Coefficient of Theral Expansion Specific Heat Theral Conductivity 1800 kg ^ C^ J kg^-1 C^-1 26 W ^-1 C^-1 Total heat flux: Aluiniu Alloy Al99 Density 2700 kg ^-3 Coefficient of Theral Expansion 22 C^-1 Specific Heat 900 J kg^-1 C^-1 Theral Conductivity W ^-1 C^-1 g al cu 4ig 204 Theral Error: Density 7810 kg ^-3 Coefficient of Theral Expansion 17.1 C^-1 Specific Heat 119 J kg^-1 C^-1 Theral Conductivity 220 W ^-1 C^-1 Mesh: Type Miniu Maxiu Teperatur e 40. C C Total Flux Heat e- 012 W/² e+00 6 W/² Ther al Error 8.487e Directional Heat Flux e+00 6 W/² e+00 6 W/² Page No:805

6 Total heat flux: Aluiniu Alloy Al99 : Teperature: Theral Error: Total heat flux: Theral Error: Object Nae Miniu Maxiu Teperatur e 40. C C Total Heat Flux e- 011 W/² e+00 7 W/² Thera Directional l Error Heat Flux e+00 e W/² e W/² CONCLUSION: Object Nae Miniu Maxiu Teperatur e 40. C C g al cu 4ig 204: Teperature: Total Heat Flux e- 012 W/² e+00 5 W/² Thera l Error e Directional Heat Flux e+00 5 W/² e+00 5 W/² In this project I have designed an air conditioner condenser. Present used aterial for fin is Aluinu alloy 204.I has odeled the condenser in 3D odeling software catia v5. To optiize the condenser for best result, theral analysis is done on the condenser. Analysis is done using fin aterials Aluinu Alloy 204, Aluinu Alloy 99 and Magnesiu alloy. And also by changing the condenser fines angle. By observing the theral analysis results, by using fin aterial Aluinu alloy Al99, theral flux is ore than by using other two aterials. So by using Aluinu alloy A99, the heat transfer rate increases and also Aluinu alloy A99 is less theral error. Magnesiu alloy is ore teperature value is obtained I have optiized the Page No:806

7 condenser to changing the fines inclination angle, by changing the thickness of the fin. By observing optiization results, the optiu thickness value for decreased volue is 1.So I conclude that using condenser with fin thickness of 1 and fin aterial Aluinu alloy Al99 gives better result. References Bejan, A., and Kraus, A. (2003). Heat Transfer Handbook. J. Wiley. Bell, K. J. and Owhadi, A.(1969). Local heat transfer easureents during forced convection boiling in a helically coiled tube. Proceedings of the Institution of Mechanical Engineers, 184(3C): Agostini, B., Bonteps, A. (2005). Vertical flow boiling of refrigerant R134a in sall channels. International Journal of Heat and Fluid Flow 26: Bi, Q., Chen, T., Tian, Y., Chen, X. (1997). Experiental Study on steawater two-phase flow frictional pressure drops in helical coils. Nuclear Science and Techniques 8(3): Akhavan-Behabadi, M. A., Aria, H., and Sheirani, F. M. (2009). Flow boiling heat transfer of HFC-134a inside helically coiled tubes. In Proceedings of International Conference on Applications and Design in Mechanical Engineering (ICADME), Malaysia. Bianco, V., Manca,O., and Nardini, S. (2011). Nuerical investigation on nanofluids turbulent convection heat transfer inside a circular tube. International Journal of Theral Sciences 50: Akhavan-Behbadi, M.A., Hashei, S.M.(2010).Pressure drop characteristics of nanofluid flow in horizontal coiled tube under constant heat flux. In: Biennial Conference in Engineering Systes Design and Analysis, ASME, Turkey. Cary,V.P. (1992).Liquid-vapor phasechange phenoena: an introduction to the therophysics of vaporization and condensation processes in heat transfer equipent. Heisphere publisher. Balakrishnan, R., Santhappan, J. S. and Dhasan, M. L. (2009). Heat transfer correlation for a refrigerant ixture in a vertical helical coil evaporator. Theral Science 13(4), Bradshaw, C., Groll, E.A.,Gariella, S.V.(2011). A coprehensive odel of a iniature-scale linear copressor for electronics cooling. International Journal of Refrigeration (2011), 34: Bergles, A. E. (2002). ExHFT for fourth generation heat transfer technology. Experiental Theral and Fluid Science, 26: Page No:807