Heat Based Refrigeration System

            Heat Based Refrigeration System

1.1 Introduction:

           Cooling systems based on the absorption refrigeration principles have become increasingly popular among researchers in the recent years because of environmental concerns and improved energy utilization. Vapor absorption refrigeration cycle differs from Vapor compression refrigeration cycle in the way by which compression of the refrigerant is achieved. Vapor compression refrigeration cycle uses the highest quality form of energy, i.e., electricity, whereas Vapor absorption refrigeration use low quality form of energy, i.e., heat, to obtain the liquid refrigerant at the desired pressure and temperature [1].

          Compared with Vapor compression refrigeration cycles, Vapor absorption refrigeration have low COP value, but still Vapor absorption refrigeration are attractive because of their ability to use waste heat or low grade heat, including solar or geothermal, as energy sources to get refrigeration [2]. Also Vapor absorption refrigeration make use of the substances that are not ozone depleting and do not cause global warming. Thus, Vapor absorption refrigeration are a useful means for converting waste heat into useful refrigeration without causing any environmental damage. The most commonly used absorbent/absorbate pairs for absorption refrigeration cycles are NH₃–H₂O and LiBr–H₂O. When the required refrigeration temperature is 0 ^oC or less, NH₃–H₂O refrigeration cycles are mostly used while in the case of LiBr–H₂O cycles the minimum refrigeration [2].

          Global warming and climate change, human activities and other harmful natural events lead to an increasing in average global temperatures. This is caused primarily due to increase in “greenhouse” gases such as Carbon Dioxide (CO₂). In conventional vapour compression refrigeration process, the compressor consumes electrical energy which is obtained from the combustion of fossil fuels. Thus, in order to mitigate the imminent threat, we need to restrict the use of vapour-compression refrigeration process by some alternative refrigeration process. Absorption refrigeration system utilizes low-grade heat or waste heat for refrigeration instead of electrically driven compressor [3].

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