Energy performance of a compression refrigeration cycle using environment-friendly refrigerants

Abstract

An integrated power and cooling cycle is planned, which is theoretically analyzed with various working fluids to evaluate the performance, and also the environmental impact of the selected fluids is discussed. The proposed cycle has the cooling system as Vapour compression refrigeration and power cycle as Organic Rankine Cycle. Both the cycles are using the same fluid and the cycles are physically combined. Hence, the power and cooling cycles have been combined as a single cycle. Working fluids are selected under the condition that they can work on both cycles. It was also important to make it necessarily certain that the fluid attained a superheated state after compression in Vapour compression refrigeration and after expansion in Organic Rankine Cycle. The performance of the cycle is analyzed for the selected fluid under normal operating conditions. Since there is significant variation in the maximum and minimum values of critical temperatures for each of the selected fluids, a common interval of maximum and minimum temperature cannot be assigned to all the fluids for the cycle. The cycle has been analyzed for the following conditions, first by fixing the refrigeration capacity alone, second by fixing the turbine output alone, and also by varying the condenser temperature. The obtained COP values vary from 1.7 to 3.14. The maximum COP value obtained for R124 refrigerant is 3.14 at an evaporator temperature of −24 ℃. Similarly, the efficiency of the power cycle is varied from 18% to 25%. The refrigerant R114b holds the maximum value of 25.18% at a boiling temperature of 197℃.. The environmental effect of the chosen working fluids is examined in terms of Global warming potential, ozone depletion potential, toxicity, and flammability.