Research On CO₂ Two-Stage Compressed Regrigeration Cycle And Flash Intercooler

In this thesis, the theoretical analysis, computer simulation and experimental study have been completed about natural refrigerant CO₂ as work fluid in two-stage compression refrigeration system and in flash intercooler.Comparisons are taken between CO₂ two-stage compression cycle with flash intercooler and single-stage compression cycle. The different effects are analyzed that temperature of evaporating, temperature of gas cooler outlet and efficiency of compressor bring to the coefficient of system performance. It is concluded that the best high pressures exist in either two-stage or single-stage compression systems. On the same condition, the coefficient of two-stage is larger than single-stage's.This thesis also contains comparisons between CO₂ two-stage compression cycle with flash intercooler and with medial gas cooler. The different effects are analyzed that temperature of evaporating and temperature of gas cooler outlet bring to the coefficient of system performance. It is concluded that the best high pressure and best intermediate pressure exist in either two-stage compression systems.The model of flash intercooler is founded and simulative calculation is completed. Based on simulations, the effects of parameters to the CO₂ outlet temperature in pipe are analyzed.The CO₂ two-stage compression refrigeration system is built in the laboratory. The components of system are explained in this paper. Through the comparisons between simulated values and experiment values of CO₂ outlet temperature in pipe, it is found that the tendencies are very similar, and this approves simulation is correct. Using the experiment values, a heat exchange equation about CO₂ pool boiling out pipe is founded. The results will give helps for study and design of CO₂ flash intercooler.