【摘要】 针对如何获得1.8K的超流氦提出了直接节流、预冷与节流相结合、抽真空以及抽真空与节流过程相结合的4种方案.同时针对各个方案给出了过程进行的温—熵图、流程简图以及实现过程的主要设备.借助于各个方案进行过程的温—熵图,对这4种方案进行了详细的对比分析和计算,确定了各个方案最终可以获得的超流氦液体率.抽真空及抽真空与节流过程相结合的方案最终获得的超流氦液体率分别约为100%、90.3%.但这两种方案所需要的设备比较复杂,成本较高.直接节流方案和节流与预冷相结合的方案要求的设备相对比较简单,但直接节流方案没有利用低温饱和超流氦蒸汽的冷量,而节流与预冷相结合的方案利用低温饱和超流氦蒸汽的冷量进行预冷,使其最终的超流氦液体率与直接节流方案相比提高了近12%.更多还原

【Abstract】 Several plans on how to obtain the 1.8 K superfluid helium fitting for the system were put forward, including direct throttling, throttling process accompanied with pre-cooling, vacuum pumping and vacuum-pumping accompained with throttling process. Comparison and analysis between these plans were given, and the temperature-entropy figure, flow diagram, and equipments realizing the scheme of each progress were put forward. The liquid ratios of superfluid helium of the four different methods are determined through the T—S figure. The method of vacuum pumpng can give 100% superfluid helium ration in theory, but the equipment is complicated and the cost is high. The final liquid ratio of superfluid helium by vacuum-pumping accompanied with throttling process is 90.3%, and the complexity and the cost of the equipment is similar to the vacuum pumping plan. The equipments of direct throttling and throttling process accompanied with pre-cooling are simple compared to the above two methods. The throttling process accompanied with pre-cooling makes use of the cold energy of the saturated superfluid helium vapor of 1.8 K and the liquid ratio of this method can increase 12% compared to direct throttling method.更多还原