Theoretical analysis of a new two-stage absorption-transcritical hybrid refrigeration system

Until now, a lot of low grade heat with temperatures of 40 similar to 55 degrees C, such as the condensing heat of a compression refrigeration system, hasn't been utilized to achieve cooling of 7 degrees C. The classical two-stage absorption refrigeration system is usually used to utilize heat sources as low as 55 similar to 65 degrees C. The absorption-compression refrigeration techniques show good potential. They still meet great difficulty in making use of 40 similar to 55 degrees C heat. Besides, it has been proved that transcritical cycles can work well under very wide operation temperatures. As a result, a transcritical subsystem is used to combine a two-stage absorption refrigeration one in this hybrid refrigeration system. R744 is chosen for the transcritical subsystem and the LiBr-H2O pair for the absorption subsystem. Based on the models of this new system, theoretical study is carried out on its performance. The main effects are discussed on the COPnet (the ratio of low grade heat powered refrigeration capacity to the generator heat consumption, which cut off that mechanical work powered) in this context. Results show that the proposed system can recycle the 40 similar to 55 degrees C condensing heat and COPnet can be improved by 2.5 similar to 55 % in utilizing 45 similar to 55 degrees C low grade heat, compared with the classical two-stage absorption refrigeration system.