Energy and advanced exergy analyses of novel ejector-compressor partially coupled refrigeration cycle for buildings with less solar energy

Abstract

Solar-driven ejection-compression refrigeration is helpful for building space cooling but is based on the precondition of solar heat being infinite and free. This is not valid in many cases, such as multistorey buildings in metropolises with limited space. Even worse, in the carbon-neutral future, space surrounding buildings will be occupied by PV (photovoltaic) panels in priority. Therefore, a potential ejector-partially coupled enhanced compression refrigeration cycle consuming less heat is presented. Models of the new cycle for a multistorey building are established. Then, energy comparison and advanced exergy analysis are conducted. The analysis results first show that the new cycle needs no auxiliary system. Powered by limited low-grade heat, its C O P e increased by 20.66% and total annual cost reduced by 7.8%, compared with the traditional ejector-compressor cycle. Advanced exergy analysis also finds that the order of improvement potential is compressor (4739.45 W), evaporator (4329.85 W), and condenser (2843.51 W), according to the sum of avoidable exergy destruction. This is different from the results of conventional exergy analysis. The sensitivity analysis of the ejector components' efficiencies is investigated, which has seldom been reported for refrigeration system with ejector. The results reveal that once the efficiencies of ejector components reach a certain point (0.94), the performance no longer improves. Generally, this work provides a potential ejection-compression cycle, demonstrates system improvement direction through advanced exergy analysis, and reveals good understanding of the system.