Study On The Characteristics Of Cascade System In Blood Cold Storage

In recent years,with the rapid increase in the demand for blood and blood supply at the blood station,and the development of cold storage technology,some blood stations have begun to use integrated large-scale cold storage of plasma to replace the cryogenic blood storage refrigerator with low inventory capacity and high cost.This paper combines with a cold storage project in Tianjin University to simulate cryogenic preservation of RH-negative blood(-80 ℃)by blood stations around the world.This paper analyzes and studies the cycle characteristics of R404A/R508 B cascade refrigeration system though theoretical calculation and experimental analysis of thermodynamic properties.Theoretical analysis and simulation mainly focus on the system condensing temperature,evaporation temperature,the temperature difference of cascade-condenser,condensation side subcooling of high and low temperature cycle,condensing temperature of R508 B low temperature cycle and other thermodynamic parameters on COP,mass flow ratio of high and low cycle of R404A/R508 B cascade system and summarize the key factors affecting the performance of the system,and proposes related system parameter optimization recommendations:(1)Meeting the conditions of R508 B compressor discharge pressure within the design pressure range of the unit,reduce the condensing temperature;(2)Appropriately reduce the temperature difference of heat transfer in the cascade-condenser;can both improve COP of R404A/R508 B cascade refrigeration system;(3)There is an optimal R508 B low-temperature condensing temperature that maximizes the COP value of the system,and the optimal COP of R404A/R508 B cascade refrigeration system is 0.687,the condensing temperature of R508 B is about-33 degree right now;(4)Propose a reformation scheme that appropriately mixes the high-temperature exhaust gas and the suction gas and it proved that the system performance is effectively improved;(5)The analysis and formulation of the R404A/R508 B cascade refrigeration system in the installation,operation of non-condensable gas mis-entry the system and refrigerant leakage due to the safety protection and other emergency treatment solutions.Based on the theoretical analysis,system design and experimental study of the cascade refrigeration cycle,it provided theoretical and data basis for the research and has a certain guiding significance for performance optimization and promotion of ultra-low temperature cascade cycle.