[bmim]Zn_2Cl_5/NH_3溶液的比热容和过量焓

Heat capacity and excess enthalpy of [bmim]Zn_2Cl_5/NH_3 binary system solution

测定了离子液体[hmim]Zn2Cl5在T=（323．15～1173．15）K范围内的热重曲线，结果显示[bmim]Zn2Cl5在T〈637．15K时具有很高的热稳定性。通过DSC测试得到[bmim]Zn2Cl5的比热容数据，在T=（251．15～383．15）K范围内可以用一个圆锥曲线很好地拟合。实验测定了[bmim]Zn2Cl5（2）＋NH，（1）二元体系溶液的摩尔过量焓，其中氨的摩尔分数x1=（0．60～0.95），温度值为T=288．15K，303．15K，318．15K，333．15K。采用NRTL模型对过量焓数据进行拟合，得出二元可调参数和非随机参数。过量焓数据的测量误差和最大拟合偏差分别小于4．8％和4．3％。在[bmim]Zn2Cl5比热容和[bmim]Zn2Cl5／NH3过量焓数据的基础上，计算了氨质量分数W1=（0～1）、温度范围T=（273．15～343．15）K条件下[bmim]Zn2Cl5／NH3溶液的焓，所得焓浓图对于研究[bmim]Zn2Cl5／NH5吸收式制冷系统性能至关重要。

We measured thermogravimetric curve for ionic liquid [ bmim] Zn2Cl5 at T= （323, 15 - 1 173.15） K. Results show that [ bmim] Zn2Cl5 has higher thermal stability at T 〈 637.15 K. We acquired heat capacity data of [ bmim] Zn2Cl5 through DSC scan, which could be well fitted with a conic curve at T= （251.15 -383.15） K. We measured mole excess enthalpy of binary system [ bmim ] Zn2Cl5 （2） ＋ NH3 （ 1 ） for ammonia molar fractions x1 = （0.60 - 0.95） at T= 288.15 K, 303.15 K, 318. 15 K, 333. 15 K. We employed NRTL model to fit excess enthalpy data and acquired binary adjustable parameters and non-random parameters. Measurement error and maximum fitting deviation of excess enthalpy data are respectively less than 4.8% and 4.3%. Based on heat capacity of [ bmim] Zn2CI5 and excess enthalpy data of [ bmim] Zn2Cl5/NH3, we also calculated the enthalpy of [ bmim] Zn2Cl5/NH3 solution for ammonia mass fractions of w1 = （0 - 1 ） and temperature scope T = （273. 15 - 343. 15） K. The obtained enthalpy-concentration diagram is essential to the investigation of the thermodynamic performances of [ bmim] Zn2Cl5/NH3 absorption refrigeration system.