冷中子源逆布雷顿循环氦制冷机性能分析和优化

运用能量守恒和(火用)分析方法,对冷中子源氦制冷逆布雷顿循环过程进行热力分析和(火用)分析.找出了系统(火用)效率和各部件(火用)损失随着压缩机压比、膨胀机等熵效率、跑冷量、换热器冷热流体平均温差变化的规律,并提出减小循环跑冷量、换热器内冷热流体温差,以及提高压缩机压比、膨胀机等熵效率、物料分配均匀度以提高循环性能和系统(火用)效率的措施.基于换热器内部冷热流体温差分布对循环性能影响的分析,设计了膨胀机预冷循环方案,该方案的(火用)效率相对于基本循环提高了24 %.

The performance analysis and optimization of helium cryogenic cooling system with reverse Brayton cycle for cold neutron source

By the method of exergy analysis and conservation of energy,the performance of reverse Brayton cycle based on helium cryogenic cooling system of cold neutron source was analyzed.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,and temperature difference in heat exchangers are discussed.The influence regularities of those factors on the cycle performance are obtained.In order to optimize the cycle performance,some methods are recommended in this paper,i.e.decreasing cold energy loss or the temperature difference of heat transfer in heat exchangers,furthermore increasing the compression ratio of compress and the isentropic efficiency of turbo-expander or improving uniform distribution of helium gas in heat exchangers are also efficient ways.As an example,a cycle with a pre-cooling unit by turbo-expander is preliminary designed.It is found that the exergy efficiency is significantly improved by 24% comparing with the basic cycle.