EXPERIMENTAL STUDY ON A DOMESTIC REFRIGERATOR USING LPG AS A REFRIGARANT

International Journal of Mechanical Engineering and Technology (IJMET) Volume 6, Issue 11, Nov 2015, pp. 43-49, Article ID: IJMET_06_11_005 Available online at http://www.iaeme.com/ijmet/issues.asp?jtype=ijmet&vtype=6&itype=11 ISSN Print: 0976-6340 and ISSN Online: 0976-6359 IAEME Publication EXPERIMENTAL STUDY ON A DOMESTIC REFRIGERATOR USING LPG AS A REFRIGARANT Ajeet Kumar Rai, Amit Kumar, Pravin Kumar and Ayaj Ahamad Ansari Mechanical Engineering Department, SSET, SHIATS Allahabad ABSTRACT This project is devoted to feasibility study of substitution of LPG (60% Propane and 40 % commercial Butane) as refrigerant instead of R134a in a domestic refrigerator. An experimental performance study on a VCR system with LPG as refrigerant was conducted and compared with R134a.The VCR system was initially designed to operate with R134a. Experimental results showed that the LPG refrigerant with charge of 40g worked well at loaded condition as it took 30 min. to bring down the temperature of 500g of water from 30 degree Celsius to 6.8 degree Celsius. LPG charge of 60g worked well under unloaded condition. It took 5 minutes to bring down evaporator temperature from 30 degree Celsius to 0 degree Celsius. Power consumed by compressor while working with LPG as refrigerant is considerably low. Key words: Vapor Compression Refrigerant System, LPG Cite this Article: Ajeet Kumar Rai, Amit Kumar, Pravin Kumar and Ayaj Ahamad Ansari. Experimental Study on A Domestic Refrigerator Using LPG as A Refrigarant, International Journal of Mechanical Engineering and Technology, 6(11), 2015, pp. 43-49 http://www.iaeme.com/currentissue.asp?jtype=ijmet&vtype=6&itype=11 1. INTRODUCTION In developing country like India, most of the vapour compression based refrigeration, air conditioning and heat pump systems continue to run on halogenated refrigerants due to its excellent thermodynamic and thermo-physical properties apart from the low cost. However, the halogenated refrigerants have adverse environmental impacts such as ozone depletion potential (ODP) and global warming potential (GWP). Hence, it is necessary to look for alternative refrigerants to full fill the objectives of the international protocols (Montreal and Kyoto) and to satisfy the growing worldwide demand. In earlier days, ethyl chloride was used as a refrigerant which soon gave way to ammonia as early as in 1875. At about the same time, sulphur dioxide in 1874, methyl chloride in 1878 and carbon dioxide in 1881, found application as refrigerant. During 1910-30 many new refrigerants, such as N2O3, CH4, C2H6, C2H4, C3H8 were http://www.iaeme.com/ijmet/index.asp 43 editor@iaeme.com

Ajeet Kumar Rai, Amit Kumar, Pravin Kumar and Ayaj Ahamad Ansari employed for medium and low temperature refrigeration. Hydrocarbons were, however, found extremely inflammable. Dichloromethane, Dichloroethylene and Monobromomethane were also used as a refrigerant for centrifugal machines. A great break through occurred in the field of refrigeration with the development of freons. Freons are a series of fluorinated hydrocarbons, generally known as fluorocarbons, derived from methane, ethane, etc., as bases. With fluorine, chlorine sometimes bromine in their molecules, these form a series of refrigerant with wide range of normal boiling point to satisfy the varied requirements of different refrigerating machines. The presence of fluorine in the molecule makes the compound non-toxic and imparts other desirable physical and physiological characteristics. Plank has given individual treatment to some 50 inorganic and organic refrigerant. Among the most common inorganic refrigerant are ammonia, water, carbon dioxide. Presently, the most commonly used organic refrigerant are the chloro-fluoro derivatives of CH4 and C2H6. The fully halogenated ones with chlorine in their molecule are chlorofluorocarbons, referred to as CFCs. Those containing H atoms in the molecule along with Cl and F atoms are referred to as hydro-chloro-fluoro carbons or HCFCs. Simple hydrocarbons are HCs, Thus, we have HCs, HFCs, HCFCs and CFCs. Alsaad and Hammad (1998) investigates the result of an experimental study carried out to determine the performance of a domestic refrigerator when a propane/butane mixture is used as a possible replacement to the traditional refrigerant CFC 12. The used propane/butane mixture is liquefied petroleum gas (LPG) which is locally available and comprises 24.4% propane, 56.4% butane and 17.2% isobutane. The refrigerator worked efficiently when LPG was used as refrigerant instead of CFC 12. The evaporator temperature reached -15C with COP value of 3.4 at a condenser temperature of 27 C and an ambient temperature of 20 C. Fatouh and Kafafy (2006) made an attempt to test Liquefied petroleum gas (LPG) of 60% propane and 40% commercial butane as a drop-in substitute for R134a in a single evaporator domestic refrigerator with a total volume of 10 ft3 (0.283 m3). Continuous running and cycling tests were performed on that refrigerator under tropical conditions using different capillary tube lengths and various charges of R134a and LPG. Continuous running and cycling results showed that R134a with a capillary tube length of 4 m and charge of 100 g or LPG with capillary tube lengths from 4.0 to 6.0 and charge of 50 g or more satisfy the required freezer air temperature of 12 C. The lowest electric energy consumption was achieved using LPG with combination of capillary tube length of 5 m and charge of 60 g. This combination achieved higher volumetric cooling capacity and lower freezer air temperature compared to R134a. The performance of the refrigerator using hydrocarbons as refrigerants was investigated and compared with the performance of refrigerator when R-134a was used as refrigerant by Sattar et al (2007). The effect of condenser temperature and evaporator temperature on COP, refrigerating effect, condenser duty, work of compression and heat rejection ratio were investigated. The energy consumption of the refrigerator during experiment with hydrocarbons and R-134a was measured. The results show that the compressor consumed 3% and 2% less energy than that of HFC-134a at 28 C ambient temperature when iso-butane and butane was used as refrigerants respectively. The energy consumption and COP of hydrocarbons and their blends shows that hydrocarbon can be used as refrigerant in the domestic refrigerator. The present work has been started with the objective to perform the experimental study on the system using LPG as refrigerant. http://www.iaeme.com/ijmet/index.asp 44 editor@iaeme.com

Experimental Study on A Domestic Refrigerator Using LPG As A Refrigerant 2. EXPERIMENTAL SETUP Figure 1 Photograph of the experimental setup The above photograph shows the experimental setup. The detailed specifications of the different components of the setup are given. Components of domestic refrigerator Hermetically sealed reciprocating compressor Type Hermetic reciprocating Refrigerant R134a Number of cylinders One Stroke volume 6.64 cm 3 Power supply 1 phase, 220 240 V Current 6 A (starting), 1.2 (running) Frequency 50 Hz Speed 2900 rpm Air-cooled condenser Type Wire-on-tube Tube material Steel Tube diameter (inner/outer) 4.76/6.18 mm Outer surface area 0.724m 2 Maximum working pressure 40 bar Type Roll bond-type Material Aluminium Length of evaporator panel 1184 ± 1 mm Thickness of evaporator panel 1.2 ± 1 mm Passage way surface of panel 0.35 m 2 Volume capacity of panel 0.024 m 3 http://www.iaeme.com/ijmet/index.asp 45 editor@iaeme.com

Ajeet Kumar Rai, Amit Kumar, Pravin Kumar and Ayaj Ahamad Ansari Outlet tube diameter Maximum working pressure Capillary Tube Material Inner diameter Outer diameter Length Initial charge 6.5 mm 20 bar Copper 0.78 ± 0.02 mm 2.0 ± 0.05 mm 2.75 ± 0.03 m (40-90) g Time (min) Observation Table Table 1 Study of performance of 40g LPG as refrigerant in VCR system with 500 g of water at 29 o C in evaporator temp. T 6 ( o C) Compressor inlet temp. T 1 ( o C) Compressor outlet temp. T 2 ( o C) Condenser Outlet temp. T 3 ( o C) inlet temp.t 4 ( o C) outlet temp. T 5 ( o C) Suction press. (Lps) (Psi) At start 29 29.2 28 29.4 27.9 28 40 46 2 24.8 28 28.3 30.1 24.4 26.6 4 120 4 23.7 26.8 42.7 34.3 21.8 25.4 2 120 6 22.7 25.8 43.8 35.3 17.8 22.9 0 120 8 21.6 23.3 44.7 35.4 13.6 18.9 0 115 10 19.1 20.8 44.4 35.1 12.5 13.3 0 115 12 17.9 16.6 44.1 35 11.4 12.2 0 110 14 16.8 12.7 43.9 34.8 10.2 11 0 115 16 15.7 10.2 43.9 34.8 9.8 10.1 0 110 18 14.6 9.1 43.9 34.8 9.4 9.8 0 110 20 12.1 8 43.9 34.7 9.7 9.6 10cmHg 110 22 11 7 44.1 34.6 9.2 9.4 10cmHg 110 24 9.9 6.8 44.4 34.6 9 9.3 0 110 26 8.8 6.8 45 34.3 8.9 9.3 0 110 28 7.8 6.4 45.4 34.2 8.9 9.2 10cmHg 110 30 6.8 6.3 45.8 34 8.8 9 10 cm Hg 110 3. RESULTS AND DISCUSSION In this project LPG gas (used in kitchen for cooking purpose) was used as refrigerant in domestic refrigerator of 165 litre capacity, basically designed for R-134a as refrigerant. No alteration has been made by us in the basic design of any component or capillary length of refrigerator. We tested the performance of refrigerator by charging 40g of LPG and checked its performance. Experiment has been performed under load of 500g water kept in steel vessel. Temperature of water, initially was 27 degree Celsius and was brought down at 7 degree Celsius. Reading from various temperature sensors (fixed at various points), Pressure gauge (fixed at compressor inlet and compressor outlet), Ammeter and Voltmeter were taken at an interval of two minutes each. We found that Ammeter reading fluctuates between 0.5A to 1A and voltmeter reading fluctuated in the range of 210V to 220V. For further calculation we took these values as 0.5A and 215V as these values were more consistent. Discharge press. (hps) (Psi) http://www.iaeme.com/ijmet/index.asp 46 editor@iaeme.com

Low pressure side (Psi) High pressure side (Psi) Compressor temp. (oc) Experimental Study on A Domestic Refrigerator Using LPG As A Refrigerant 50 45 40 35 30 25 20 15 10 5 0 Time (min.) Figure 2 compressor temp. vs time graph of 40g LPG refrigerant. 122 120 118 116 114 112 110 108 Time (min.) Figure 3 HPS vs time graph of 40g LPG refrigerant. 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0-0.5 Time (min.) Figure 4 LP S vs time graph of 40g LPG refrigerant. http://www.iaeme.com/ijmet/index.asp 47 editor@iaeme.com

temperature ( o C) Ajeet Kumar Rai, Amit Kumar, Pravin Kumar and Ayaj Ahamad Ansari 30 25 20 15 10 5 0 time (min.) Figure 5 temp. vs time graph of 40g LPG refrigerant. COP is calculated assuming cycle to be ideal vapour compression cycle and taking dryness fraction as 0.95. LPS = 0.69 bar h f =83.41kJ/kg, h g =516.33 kj/kg, h fg =432.92 kj/kg HPS= 8.28 bar h g = 593.951kJ/kg= h 2, h f = 250.52 kj/kg= h 3 = h 4 COP= (h 1 -h 4 )/ (h 2 -h 1 ) = 2.45 Experiments were conducted at no load condition, took 6.5 minute to bring down the Temperature from 30 0 C to 0 0 C. Pull down time is 6.5 minutes. Analysing above data we can infer that LPG charge of 40g worked well at loaded condition as it took 30 min. to bring down the temperature of 500g of water from 30 degree Celsius to 6.8 degree Celsius in comparison to 90g of R-134a which took 26 min. to bring down the temperature from 27 degree Celsius to 7 degree Celsius. 4. CONCLUSION The performance of a domestic refrigerator was investigated using LPG as refrigerants. Although the refrigerator has been designed for 105 g R134a, it was capable to work with LPG. Nevertheless, energy consumption analysis indicated that the HFC compressor should be changed to a HC compressor for hydrocarbon refrigerants. Results showed that energy consumption was reduced, for the refrigerator while working with a HFC type compressor charged with the optimum amount of LPG charge, in comparison with the base refrigerator. The proposed LPG seems to be an appropriate long-term candidate to replace R134a in the existing refrigerator, except capillary tube length and initial charge Literature review on safety analysis showed that in case of a sudden leakage of total amount of hydrocarbon refrigerants, it would not result in explosive conditions. If same experiment was conducted on the refrigerator designed for LPG, better results are expected. http://www.iaeme.com/ijmet/index.asp 48 editor@iaeme.com

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