A helium refrigeration cycle was designed to provide 17.5K refrigeration for Cold Neutron Source (CNS) in China Advanced Research Reactor. In order to optimize the cycle performance, different cycle processes with LN2 pre-cooling or with expander pre-cooling are analyzed and calculated. Based on thermodynamic and exergy analysis of different cycle modes, thermodynamic parameters, exergy loss, exergy efficiency and cooling capacity of the systems are obtained and analyzed, respectively. It is shown that the system performance and exergy efficiencies of the cycles with LN2 pre-cooling and with parallel connected expander have better results. Besides, some effect factors on the exergy efficiency of cycle and the exergy loss of components, such as compression ratio of compressor, isentropic efficiency of expander, cold energy loss, temperature difference in heat exchangers, are discussed. The exergy efficiency of system can be improved by 3.6% through adding a thermal insulation shield in the cold box.
展开▼
