Abstract: The differential throttling effect of liquid ammonia, μ_H=(T/p)_H＞0，for the isoenthalpy throttling process of liquid ammonia from high pressure to low and moderate pressure, means a refrigerating effect.The magnitude of the integral throttling effect ΔT_H depends on the states (T,p) before and after throttling.Given the post-throttling pressure p₂,the refrigerating extent ΔT_H is larger when the initial temperature is lower and the pressure is higher before throttling.The relationship of enthalpy with pressure and the computing method of ΔT_H for the liquid ammonia were derived.The deviation was small for the calculated refrigerating extent ΔT_H in comparison with the experimental value, which met the requirements for practical use.It was found that a refrigerating extent from 7.5℃ to 15℃ could be obtained in the ammonia-synthesis system with a moderate operating pressure.To benefit from lower energy consumption and production cost, the refrigeration working procedure in the present ammonia-synthesis system could be replaced by exploiting the self-generating refrigerating effect from the throttling effect of liquid ammonia, as well as some techniques of cold quantity reclaiming and energy saving.

Key words: 液氨, 节流效应, 冷却度, 冷量

摘要： 高压至低、中压空间的液氨等焓节流过程中，液氨的微分节流效应，μ_H=(T/p)_H＞0，为制冷效应，积分节流效应的ΔT_H数值与节流前后的状态（T、p）有关，当节流后压强p₂一定，节流前压强p₁愈高，温度T₁愈低时，冷却度ΔT_H就愈大.推得了液氨焓与压力的关系式及ΔT_H的计算方法，冷却度ΔT_H的计算值与实验测定值误差很小，能满足指导实际工作的需要.在中压法氨合成系统中应用，分别可以获得7.5℃与15℃的冷却度，应用液氨等焓节流效应，适当配合冷量回收与节能的技术措施，在有条件的氨合成系统中，可以革除冷冻工序，实现冷量自给，获得节约能耗、降低成本的效益.

关键词: 液氨, 节流效应, 冷却度, 冷量