Switch loss of a frost-free refrigerator-freezer with parallel dual-evaporator refrigeration system and its mitigation

Abstract

The parallel dual-evaporator system has energy-saving potential in frost-free refrigerator-freezers, since it can provide proper evaporating temperature difference for the refrigerator and the freezer, respectively. However, energy loss is generated during the transition period of switches between refrigerating (R-) and freezing (F-) cycles in actual use. In this article, switch loss of a frost-free refrigerator-freezer with parallel dual-evaporator refrigeration system is studied experimentally. Results show that the transition process after F- to R-cycle switch takes 7.17 min and consists of three stages according to R-evaporator’s feeding: short feeding (1.83 min), no feeding (2 min), and continuous feeding (3.34 min). The starvation in R-evaporator during the first two stages leads to switch loss for the refrigerator-freezer, by consuming 23.3% electric energy but yielding only 6.9% capacity for an entire R-cycle. The pump-down (P/D) action before R-cycles accelerates refrigerant’s pumping from F-evaporator and feeding to R-evaporator, thus recovering part of the capacity loss. However, the introduction of P/D is not necessarily energy-efficient because P/D itself consumes considerable electric energy. By contrast, R- to F-cycle switch has little effect on refrigerator-freezer performance due to instant feeding. Dynamic simulation on the transition process will be provided in the future.

Additional information

Funding

This research is supported by the National Natural Science Foundation of China [No. 51876154].