Domestic refrigerator with water cooled condenser – A Review

The paper reviews the possibilities of researchers in the field of performance of the domestic water cooled refrigerators and its utilization in commercial and industrial applications. Here, it is found that the performance of water cooled condenser depends on the inlet temperature, compressor pressure and condensing temperature. The recovery of waste heat from the water cooled condenser is utilised increasing the temperature of cold water. This hot water can be utilised in various domestic as well as industrial applications. The power consumption required for refrigeration can be optimised by using mathematical modelling.

cooling was 2.5 m 3 . Investigations were undertaken by varying the voltage to the thermoelectric module (50, 100, and 150 VDC), water mass flow rate and air velocity passing through the TE heat exchangers: 10, 15 l/min and 2.5, 5 m/s, respectively. It was found that this system can heat up the 120 litres to 50°C within 2 hours. The cooling capacity was 176 W. After that, the cooling capacity decreased as a result of the increase of water temperature returned from the tank and circulated through TE water/solid heat exchanger. Finally, under design consideration used in this study, the optimum conditions for operating the hot water production and cooling as well are: 100 VDC, water flow rate of 15 l/min and air velocity at 2.5 m/s. The corresponding highest coefficient of performance of the hybrid system is about 3.12. Jie Ji et al. [7] the technology of using a heat pump for space conditioning and domestic hot water heating in residences has been developed for half a century. The earlier airto-water heat pumps and water-heating heat pumps suffered from drawbacks like high costs, unreliable operation, and inflexible applications. They were not well positioned in the market to attract customers. This paper introduces a novel air conditioning product that can achieve the multi-functions with improved energy performance. The basic design principles and the laboratory test results are presented. The results showed that by incorporating a water heater in the outdoor unit of a split-type air-conditioner so that space cooling and water heating can take place simultaneously, the energy performance can be raised considerably. S. C. Walawade [8] for the protection of global environment and from the point of fuel consumption, energy saving is one of the key matters. So it is important that a effective effort should be made for conserving energy through waste heat recovery too. The main objective of this paper is to study "Waste Heat recovery system for domestic refrigerator". Author attempts to utilize the waste heat from condenser of refrigerator. In minimum constructional, maintenance and running cost, this system is much useful for domestic purpose. It is effective alternative method to improve the efficiency of domestic refrigerator and reuse the waste heat. The author finds it technically and economically feasible. Y. A Patil & H .M. Dange [9] refrigerator has become an essential commodity rather than luxury item. The heat absorbed in refrigerated space and the compressor work added to refrigerant is too rejected to ambient through a condenser. The heat recovery from the household refrigerator is by thermo siphon. From the experimentation it was found that after recovering heat from the condenser of the domestic refrigerator its energy consumption get reduced than conventional refrigerator. The maximum temperature achieved in water tank with 100 litre of water is 45ºC at the full load condition. If the water tank contains 50 litres of water then it gets heated to 45 ºC in just 5 to 6 hrs. After that performance of the system gets decreased. So it needs regular use of that hot water. Thakre S. H. [10] Waste heat recovery is the process of capturing waste heat (thermal) energy for beneficial purposes. Energy savings and efficiency improvements of energy systems are important tasks on the path towards a more sustainable future. Conventional power stations convert only about 33% of their input heat to electricity. The remaining 67% emerges from the turbines as lowgrade waste heat with no significant local uses so it is usually rejected to the environment. The present work is based on these low conversion efficiencies, strongly suggesting to find productive uses for this waste heat.
N. B. Chaudhari [11] Heat recovery set up from condenser of a refrigerator was developed using thermo siphon system. It eliminates the need of circulating pump. Theoretical COP without heat recovery is about 1.88 and with heat recovery system it is 2.53. The actual COP of air-cooled condenser system is 1.078 and for water cooled with heat recovery system practically COP is 3.79. Sukani Sunny et. al. [12] proposed the thermo electrical module of refrigeration system to increase the efficiency of the system in terms of refrigerating capacity. Lakshya Soni [13] the heat recovery technique of refrigeration system provides a compound air-cooling and water-cooling. By using this system result shows improvement in COP and reduction in power consumption.
The temperature difference obtained between the water inlet and outlet exceeds more than 10 0 C. The hot air by this system gives the temperature up to 46 0 C. D.S. Kim et. al. [14] A comparison is made by authors between the different solutions both from the point of view of energy efficiency and economic feasibility. Solar electric and thermo-mechanical systems appear to be more expensive than thermal absorption systems. Absorption and adsorption are comparable in terms of performance but adsorption chillers are more expensive and bulkier than absorption chillers. Vivek Sahu et. al. [15] presents the experimental and theoretical analysis of domestic refrigeration system by using wire-on-tube condenser with different spacing of wire, operating parameters like heat transfer rate , condenser pressure and condenser temperature. Refrigerating effect is increased by using wire-on-tube condenser comparatively power consumption remains same as with air-cooled condenser in a domestic refrigeration system. Rahul Patel et.al. [16] In this paper performance COP, refrigeration capacity, condensation effect and compressor work done of domestic refrigerator is studied through an experimental set up where air-cooled condenser is replaced by water-cooled condenser. It is observed that in the case of water cooled condenser, there is drop-in condenser pressure as well as evaporator pressure relative to air cooled condenser. In case of water cooled condenser, power consumption of compressor decreases relative to the air-cooled condenser. Romdhane Ben Slama [17] the quantity of heat released on the level of the condenser is 3 to 4 times the electric power consumed by the compressor, and even with an operation discontinuous of the compressor (presence of thermostat), this energy is equivalent the useful energy delivered by two m² of solar collectors, which generally receives the solar water heaters installed. Therefore the coupling of the refrigerator to the water-heater can be only one success in the heating of water and the rise in its temperature to an acceptable threshold. Sagar Patil In this paper, experimental study performance of water cooled condenser is compared with the air-cooled condenser in a domestic refrigeration system. To perform the experiment 165L refrigerator is selected which is designed to work with R-134a. The result shows that the COP of air-cooled condenser is between the range 2-2.5 and the COP of water cooled condenser is between the ranges 3.6 -4. Thus the conclusion is made that the COP of the water-cooled condenser is higher than air-cooled because of the lower pressure difference between evaporator & condenser at 40-watt condition.
G.G. Momin et. al. [28] aim of the paper is to recover waste heat from condenser unit of a household refrigerator to improve the performance of the system. The heat recovery from the household refrigerator is by thermo siphon. From the experimentation it was found that after recovering heat from the condenser of the domestic refrigerator its power consumption get reduced than conventional refrigerator. A summary of research work done by different researchers shown in the

Conclusion
It is found from the literature review that most of the research carried out is for recovery and utilization of partial 43 superheat from the condenser, which is further used for various applications. By the result of literature review here we identify the research problem that many researchers' tries to use of water cooled condenser in domestic refrigeration system to increase the COP of system. But no one has proposed the commercial domestic refrigerator with utilization of optimum power. The power utilization can be done through the mathematical modelling of vapour compression system with water cooled condenser.