Energetic and exergetic analysis of a novel mixture for an absorption/compression refrigeration system: R245fa/DMAC

Working fluids are selected due to their low GWP (global warming potential). Results relative to the new organic absorbent are compared with those relative to the classical water/ammonia working fluids. Investigated parameters are the COP, the irreversibility and the exergetic efficiency. Results show that the performance coefficient of the system working with the new fluids is similar to that relative to the Ammonia/Water system, the optimum value is about 45% when working with R245fa/DMAC, while the same optimum value is achieved for an intermediate pressure of 600kPa with the classical one. Furthermore, the system using the new proposed pair uses lower threshold temperatures, between 60°C and 80°C as optimum COP, which allows the use of low temperature energy sources. Results of the exergetic analysis indicate that irreversibility of the system working with R245fa/DMAC is lower than that of the system working with Ammonia/Water of about 10kW, for 3kW as refrigeration power, for the optimum operating conditions and so is the exergetic efficiency. It is noted from this study that the major gain brought by this new pair is the diminution of the threshold temperatures from those that go to 120°C to 80°C and even 60°C for such heat pumps. We retain the advantages of introducing this organic absorbent in the refrigeration production field.