Experimental study on the shunting performance of a rectifying nozzle-type critical distributor under variable operating conditions of a multiparallel evaporator

In this study, we analyzed the relationship between the refrigerant distribution of a multiparallel evaporator and the structural design of a distributor to address uneven distribution of gas–liquid refrigerants in multiparallel evaporators under variable operating conditions. Herein, we proposed the shunting concept of "flow pattern setting and critical distribution" and designed a theoretical model for a rectifying nozzle-type critical distributor (RNCD). We built the experimental bench of a multiparallel evaporator using an RNCD and compared the cooling time of each cold storage, the superheat of each branch pipe, the cooling capacity of each cold storage, and the pressure drop of the distributor. Further, we investigated the shunting performance of the RNCD. The experimental results showed that the evaporation temperatures were −32 °C to −24 °C when cold storage temperatures of −22 °C to −14 °C, respectively. The unevenness of superheat at the outlet of each evaporator branch pipe of the RNCD was 0.0884–0.1275, while the unevenness associated with the refrigeration capacity of each cold storage was 0.1424–0.1714. This study provides basic research information to solve the problem of uneven refrigerant distribution when considering gas–liquid two-phase flow in multiparallel evaporators under variable operating conditions.