低温氮气膨胀制冷的热力学设计与分析

Thermodynamic Design and Analysis on Refrigerating by Low Temperature Nitrogen Expansion

针对大型液氮储罐漏热而产生的冷量浪费和液氮气化而产生的超压问题,根据绝热膨胀制冷原理、节流膨胀原理,设计分别以刚性容器绝热放气、索尔文活塞膨胀以及节流膨胀等三种制冷方法,并对这三种方法的实际制冷性能进行了分析。分析结果表明:刚性容器绝热放气、索尔文活塞膨胀、节流膨胀的理论制冷量分别为19. 34 k J/kg、27. 43 k J/kg、10. 76 k J/kg,实际制冷量分别为14. 51 k J/kg、12. 14 k J/kg、9. 37 k J/kg,索尔文活塞膨胀的理论制冷量最大,刚性容器绝热放气的实际制冷量最大。由于索尔文活塞膨胀的机械结构与热力过程的复杂性,使得索尔文活塞膨胀的效率最低。该研究结果为减少大型低温储罐的损耗提供了新的解决方向。

To solve the problems of cooling energy waste and overpressure of liquid nitrogen storage tanks, on the basis of adiabatic expansion cooling principle and throttling expansion principle, three measures are designed. Adiabatic degassing of rigid containers, piston expansion of Solon refrigerators, and capillary expansion throttle valves are used. Actual refrigeration performance of these three methods is analyzed. The result indicates that theoretic cooling capacity of rigid containers, solon refrigerators, and capillary expansion throttle valves are 19.34 kJ/kg、27.43 kJ/kg、10.76 kJ/kg and actual cooling capacity are 14.51 kJ/kg、12.14 kJ/kg、9.37 kJ/kg. Theoretic cooling capacity of solon refrigerators is highest among these three devices and actual cooling capacity of rigid containers is highest. As mechanical structures and thermal cycle process of solon refrigerators are complicated, efficiency of solon refrigerators is lowest. The result also provides a new solution to reducing losses of liquid nitrogen storage tanks.