中文摘要：

目的 用Pitzer模型计算NaCl-NH_4Cl-H_2O三元体系的冰点。方法 根据Pitzer模型,从浓度计算溶液的冰点值,并将计算结果与空气湿度冰点测定法、步冷曲线冰点测定法的测量值比较。结果 三种方法所测冰点值一致。结论 NaClNH_4Cl-H_2O三元体系的冰点值可由Pitzer模型通过溶液浓度计算得到。

英文摘要：

OBJECTIVE To calculate freezing point of NaC1 - NH4C1 - H：O temary system by Pitzer model. METHODS The freezing point of the system is calculated by Pitzer model from the concentration, and then it was compared with those determined by air humidity cryoscopy and cooling curve cryoscopy. RESULTS The Pitzer model calculations are comparable to the measurements of air humidity cryoscopy and cooling curve cryoscopy. CONCLUSION The freezing point of NaCl - NH4 Cl - H2O ternary system can be calculated according to Pitzer model.