Experimental investigation on a -40 °C low-temperature freezer using ejector-expansion refrigeration system

The ejector-expansion freezer refrigeration system (ERS) has been proposed to recover part of the expansion work in the throttling process and improve cycle efficiency. In this paper, the performance characteristics of a -40 °C low-temperature freezer adopted with the standard ERS are experimentally investigated under various operating conditions, and several important parameters are also examined in detail. Additionally, the performance of the freezer prototype is compared between using the ERS and a conventional vapor compression freezer refrigeration system (CRS). The experimental results show that the lower evaporation temperature can be obtained by ERS, the pressure lift ratio of ejector can reach more than 1.25, the compressor compression ratio and power consumption are reduced due to the effective pressure lifting effect of the ejector. Furthermore, when the ambient temperature is 20/25/32 °C, the maximum refrigeration capacity and COP of the ERS based prototype can be improved by 17.0% and 15.9%, respectively. Meanwhile, the energy consumption of ERS can be reduced by 6.2%, 21.7% and 38.9% compared to that of the CRS based prototype, respectively. This validate that the ERS offers a significant energy-saving potential to low-temperature freezers.