Reviewed Paper Volume 2 Issue 9 May 2015 International Journal of Informative & Futuristic Research ISSN (Online): 2347-1697 Performance Comparison of R22 and R290 Refrigerants Using Smaller Paper ID IJIFR/ V2/ E9/ 008 Page No. 3109-3114 Subject Area Key Words Smaller Diameter, Retrofitting, Condenser Tube, R290, C.O.P Mechanical Engineering Sumit Bardiya 1 Prof. R.S. Powar 2 Prof. P R Kulkarni, Aniket Shahapure 3 Assistant Professor Department of Mechanical Engineering Sharad Institute of technology College of Engineering, Yadrav, Maharshtra Professor & Head Department of Mechanical Engineering, Dr. J. J. Magdum College of Engineering, Maharashtra Dean Academics, Dr. J. J. Magdum College of Engineering, Maharashtra M.Tech. Student, Sharad Institute of technology College of Engineering, Yadrav, Maharshtra Abstract R22 that has been used predominantly in air conditioning and in medium and lowtemperature applications contains ozone depleting chlorine atoms and hence will be phased out eventually. This paper presents the experimental performance study of a split-air-conditioner using ozone friendly alternative refrigerant. The existing splitair-conditioner originally designed for R22 as the working fluid was retrofitted with R290, and the performance of the system was evaluated and compared with its performance when R22 was used. The conventional condenser tubes were modified with 5mm diameter tubes.r22 and R290 refrigerants are compared on the basis of their overall performance by using5mm condenser tubes at number of heat load conditions. Refrigerant R290 gives better results than R22 by using 5 mm condenser tubes. The performance of R290 refrigerant with 5mm condenser tubes is 15-20% more than R22 with 5mm condenser tubes. The reduction in material of the condenser tubes that is copper is about 20% as well as the quantity of refrigerant required is reduced by 70%. www.ijifr.com Copyright IJIFR 2015 3109
1. Introduction This paper discusses about the performance of R290 refrigerant with 5mm condenser tube. Generally, people in technical field face the problem of lack of energy efficient as well as environment friendly air conditioning system. As well as the cost is also an important factor while selecting a system. In order to lower the cost, the smaller and compact system which saves material as well as refrigerant is to be developed, which needs minimum investment.[4] Recent studies and reports regarding refrigeration and air conditioning sector shows that, reducing the diameter of condenser tubes increases the heat transfer considerably, which further results in increased energy efficiency. Additional benefits are smaller and lighter condenser tubes. Manufacturer and distributor also get the advantage of reduced refrigerant charge and less material. This is also associated with reduced cost in increasing competitive market. [1] In the 1980 s, tubes with internal grooves were developed. Because these internal grooving were found to have a big impact on efficiency, they quickly became popular in the market. These internally modified smaller tubes have been in commercial application since approximately 2005. The causes why engineers are drifting towards smaller diameter condenser tubes are such as government mandates of energy efficiency rating, coefficient of performance (COP) and cost.[4] Refrigerant R290 is one of the substitutes of refrigerant R22. We can say that R290 is one of the best substitutes for R22 if it is used with smaller diameter condenser tubes. Refrigerant R290 has higher pressure than R22 so quantity required reduces. R290 has zero global warming potential as well as zero ozone layer depletion potential. If it is used with less concentration then it is least harmful. So we can say that R290 is best substitute for R22 when used with smaller diameter condenser tubes. 2. Abbreviations and Units The units used for all the calculations and analysis values are in S.I. unit system. COP = Coefficient of performance h1, h2, h4 = Enthalpies at different points TL = Lowest temperature TH = Highest temperature N = Number of blinks on energy met T = Time required for 10 blinks E = Energy meter constant (Here it is 3200) 3. Experimental Setup The split-air-conditioner is composed of the basic components of vapour compression refrigeration system: a hermetically sealed compressor, a condenser, a capillary tube and an evaporator, and such attachments as blower and fans. The schematic diagram given below represents the experimental air-conditioner setup. The unit is retrofitted with refrigerants R22 and R290 respectively. To measure the compressor power, a wattmeter was used. Room temperature was measured with help of precision thermometer. Temperatures of condenser inlet, outlet and evaporator inlet, outlet were measured with thermocouples. A digital hygrometer was used to measure the relative humidity of 3110
the room. Refrigerant pressures at high pressure side and low pressure side were measured using precision Bourdon s tube pressure gauges.[6] Figure 3.1: Schematic diagram of the experimental split-air-conditioner 4. Retrofitting Procedure The procedure of Devottaet al. (2005) was followed. The system was first tested with R22 in order to obtain the baseline data. After the completion of all tests with R22, the air conditioner was retrofitted with R290. The R290 is alternative refrigerant of R22, so it is compatible with the lubricating oil used for R22. During retrofitting, the R22 was removed from the system, then the system was kept on air pressure for one day, then the R290 was charged into the system with standard charging procedure. 5. Experimental procedure Test was conducted on split A.C. by using refrigerant R22 with 5mm diameter condenser tubes. For this case theoretical, actual, Carnot COP and compressor work was calculated. Similarly these four parameters for refrigerant R290 with 5mm condenser tubes were calculated. The heat calculation was made for different parameters such as heat loss through wall, roof, window and floor as well as heat gain due to 5 persons. For more smooth results of COP, external heating provision was made while conducting tests. The heat was given in 6 uniform steps of 200W. For first reading, no external heat was given. While conducting second test, heat load of 200W was given. This procedure was carried out in six steps such as 0W, 200W, 400W, 600W, 800W and 1000W.All openings and peep holes for room were perfectly insulated. The window was insulated with sheet of polystyrene with size of window. During the cooling load calculation, the thickness of polystyrene and window glass was taken into consideration. 6. Performance Parameters Analysis The power consumption of the compressor (Wc), the fan in the condensing unit (Wf) and the blower in the evaporating unit (Wb) were measured separately. The total power consumption (Wt) is obtained using equation Wt = Wc + Wf + Wb 3111
Refrigeration capacity (Qevap) was calculated using the mass flow rate of refrigerant (m) and enthalpy difference between inlet (h4) and outlet (h1) of the evaporator: Qevap = m (h1 h4) The actual coefficient of performance (COP) for the system is computed at the steady-state when the minimum temperature is achieved in the conditioned room and it is obtained as the ratio between the refrigeration capacity (Qevap) and the total power consumption (Wt). The total power consumption was used in below equation not just the compressor power in order to obtain the actual overall COP of the system. [6] Theoretical COP was calculated by using following procedure. The room volume was calculated so as to analyze the refrigerating effect, the window was insulated with polystyrene sheet, the heat transfer coefficient of polystyrene is considered while analysis. While calculating Carnot COP, lowest and highest temperature is considered, for that purpose refrigeration table is used. Carnot COP was calculated by following formula, When smaller diameter tubes are used, there is pressure drop, so compressor has to do more work, so calculation of compressor work is necessary. 7. Results Figure 7.1: COP of the system 3112
Figure 7.2: Compressor Work Of the System Figure 7.3: calculating Carnot COP, lowest and highest temperature 7. Conclusion In this investigation a modified condenser model was developed and integrated into an airconditioning system. A base condenser model was chosen and modified for 5mm tubes. From this study, it is concluded that the decreased area of condenser ensures more heat transfers in condenser i.e. input power goes on lower side. Increased surface contact between tube and refrigerant will offer more heat transfer to the surroundings. As compared with R22, R290 gives better performance in all aspects in combination with reduced diameter condenser tubes. Increased Energy Efficiency Ratio, reduced power consumption, reduced 3113
condenser tubes material and weight, reduced use of quantity of refrigerant are the primary advantages of R290 over R22. Following results were obtained by performing test on the split AC: Theoretical COP for R290 is 15-20% greater than theoretical COP for R22 with 5mm condenser tubes. Reduction in condenser tube material i.e. copper by about 20% is achieved by using 5mm condenser tubes. Reduction in mass of refrigerant by 70% is achieved by using R290 instead of R22. Requirement: - R22 1.5kg, R290 0.45kg. References [1] Robert Weed & John Hipchen, The Benefits of Reduced Diameter Copper Tubes in Evaporators and [2] Condensers,http://www.microgroove.net/sites/default/files/ashrae_conf._paper_6755_final.pdf [3] International institute of refrigeration, Intergovernmental organization for the development of [4] refrigeration,http://www.iifiir.org/userfiles/file/webfiles/summaries/tabl_r22_en.pdf [5] International institute of refrigeration, Intergovernmental organization for the development of [6] refrigeration,http://www.iifiir.org/userfiles/file/webfiles/summaries/tabl_r290_en.pdf [7] Goodman, Thefutureof air condition,smalleris smarter, air conditioning and [8] heating.www.achrnews.com/ext/.../283661_467205_goodman_smartcoil.pdf [9] Microgroove technical literature [10] http://www.microgroove.net/technical.literaturehttp://www.microgroove.net/technical-literature [11] BukolaOlalekanBolaji, Performance of A R22 split-air-conditioner when retrofitted with ozone friendly refrigerantswww.erc.uct.ac.za/jesa/volume23/23-3jesa-bolaji.pdf [12] A. Bhatia, HVAC Made Easy: A Guide to Heating& Cooling Load Estimation, PDHonline Course M196 (4 PDH) 3114