Research On Dual-loop Coupled Refrigerator/Freezer With Two-stage Throttling And The First-stage Flash Subcooling

Compared with the independent dual-loop vapor compression refrigeration system,the dual-loop coupled refrigerator/freezer refrigeration system has a greater energy efficiency ratio and greater energy-saving potential.However,in the process of its productization,it was found that the condensation temperature of the freezing loop dropped significantly during the dual-loop coupling operation,which caused the condenser to fail and restricted its energy-saving potiential.Aiming at the problem,this paper proposes a dual-loop coupled refrigerator/freezer system with two-stage throttling and the first-stage flash subcooling.By adding a throttling expansion device between the freezing condenser and the coupled subcooler,the state of equal pressure between the two is blocked.By adjusting the throttling capacity of the throttling device and the amount of refrigerant charge,the appropriate design conditions of this system are sought,which ensure that the system can provide a certain energy-saving effect with stable operation.The main research outcomes are as follows:1.A theoretical model of a dual-loop coupled refrigerator/freezer system with twostage throttling and the first-stage flash subcooling was established.The feasibility of the “maximum subcooling condition” on the refrigerating side and the “optimal subcooling condition” on the freezing side as design conditions was introduced through qualitative analysis.2.The simulation process was analyzed in detail and the design conditions of the system were determined quantitatively through theoretical simulation.Relevant simulation tests had been performed since then.The results showed that the design conditions could effectively ensure the requirements of variable operating conditions of the refrigerator/freezer.Compared with independent operation,the coupled operation had a system COP of about 9% Promotion.3.An experimental device platform for the dual-loop coupled refrigerator/freezer system with two-stage throttling and the first-stage flash subcooling was designed and built.Based on the ideal vapor compression refrigeration cycle,its components were selected and designed.4.Relevant experimental tests were performed on the experimental platform,which proved the correctness of the theoretical simulation results.It was determined through experiments that the two-stage throttling mode and the method for redetermining the design conditions were effective.Compared with independent operation,the fully coupled operation had a system COP of about 8.9% to 9.5% promotion.The result was slightly lower than the original dual-loop coupled refrigerator/freezer system in the ideal state,but the stability and reliability of the system under variable operating conditions was improved.