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Domestic Refrigerator With Water Heater


About Project:

Dhruv Patel

Student Team : Dhruv Patel
College Name: Gandhinagar Institute Of Technology, Gandhinagar
Category: Electrical, Instrumentation & Related Fields

Brief About Project : Modified Domestic refrigerator has two interesting novel functions. The waste heat of compressor is used to heat water, through a heat exchanger and in the process of removing heat, the life of compressor is extended and its efficiency goes up. Thus the power consumption also goes down because compressor has to work less.
The lukewarm water thus generated can be used cleaning kitchen utensils, washing clothes, bathing etc.  Through this modified design daily 100 liters of lukewarm hot water can be produced while the cooling capacity of the refrigerator is increased by about 20 per cent . This may also reduce the consumption of electricity.

Dr Nilesh M Bhatt

Director, Gandhinagar Institute of Technology

Email ID : director@git.org

Fossil fuel resources are fast depleting and hence we are experiencing a steep rise in the energy cost. For any country, living standard is always measured in terms of per capita power and industrial growth depends upon reliable and uninterrupted power supply. Therefore in this era of energy crisis it is very much essential to explore alternative sources of energy and at the same time it is very important to conserve the energy too. In last decade, sufficient efforts have been made to reduce power consumption of compressor and for effective utilization of refrigerating effect produced by the evaporator for various refrigeration and air conditioning applications. Domestic refrigerator is such an application, where lots of efforts have been made to reduce power consumption of compressor, to reduce heat loss from the refrigerator by applying better insulation and for effective utilization of cooling effect by different evaporator designs. But still attention is not given to utilize heat rejected by the condenser which is approximately twice of the compressor input. The paper deals with the utilization of heat rejected by the condenser by way of generating lukewarm water. Lukewarm warm water is normally required for cleaning kitchen utensils, washing clothes, bathing etc. These requirements of lukewarm water can be partially for fully met by the heat rejected by the condenser of domestic refrigerator. This will bring significant saving of Liquefied Petroleum Gas (LPG) or electricity which otherwise required to generate hot/lukewarm water for the said purposes.

Dhruv Patel Dhruv Patel

  1. The paper deals with simultaneous generation of hot and cold utilities in the form of lukewarm water generation and normal refrigeration. To generate lukewarm water, water to refrigerant heat exchanger (water cooler condenser) needs to be designed and to be incorporated in the refrigerant circuits.
  2. It was intended to incorporate storage type water heater with domestic refrigerator. Hence a water cooled condenser consists of stainless steel tank and copper coil brazed thereon (similar to water cooler storage tank) was designed and incorporated in series with existing air cooled condenser. The storage tank capacity is 50 liter. Additional controls are not required since normal air cooled condenser still present in the refrigerant circuit. Mass and temperature of water, freezer temperature and refrigerant temperature at three locations of condenser and power consumption of the refrigerator were measured at regular interval. Daily 100 liter of lukewarm hot water can be produced with standard 165 L refrigerator. With water cooled condenser in action cooling capacity was increased by about 20%, power consumption was reduced by about the same magnitude i.e. 20%. The additional cost of the modification was about Rs 3500 which includes some of the cost components which can be totally eliminated in mass production. With the present cost of LPG for domestic purpose (Rs30/kg) the modification brings monthly saving of about Rs 150. Compare to electric water heater, there will be monthly saving of Rs. 300. Thus the simple payback period compared to LPG heating and electric heating is about 2 and 1 year respectively. This can be reduced further if carbon credit earned due to energy saving is considered.
  3. Looking to total number of refrigerator units working world wide, there will be significant reduction of CO2 emissions also. Thus generation of lukewarm water along normal refrigeration is economically viable, technically feasible and environment friendly solution to present energy crisis.
  4. Keywords: Energy saving, Waste heat recovery, Refrigerator, Water heater, Emission reduction

Posted on:

July 18, 2014

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