吸收与络合吸附复合作用的离子液体型化学热泵工质对物性研究

For the current chemical heat pump, developing new working pairs is one of the most important ways to seek a great technological breakthrough. This proposal put forwards a new idea for the working pairs of new type chemical heat pump, in which ionic liquids with outstanding characteristics will be considered. Small molecules which can provide lone pair electrons as ligands are chosen as the refrigerants, and the ionic liquids containing specific metal ions are chosen as the absorbents, which can be used as the receptor to form complexes with the refrigerants. One of the most prominent features of the proposed working pairs is that, both dissolution heat and complex reaction heat will be comprised in the transform processes, and so the new type chemical heat pump proposed will show the advantages of both absorption and adsorption heat pump. In addition, the absorption capacity of the new kind heat pump is larger than the traditional adsorption heat pump, and also it can overcome the defects of them, including the difficulties of heat and mass transfer, adsorbent expansion, agglomeration and the attenuation of adsorption abilities. NH3-[BMIm]Zn2Cl5 and NH3-[CnMIm]2NiCl4 are chosen as the typical research objects in this proposal. The studies on vapor-liquid phase equilibrium, thermodynamic properties and heat and mass transfer characteristics of the binary solutions will be carried out by using experimental method, and reviewed by using numerical simulation and CFD methods. The theoretical model of the relevant properties will be conducted, and the equation of state, the enthalpy-concentration diagram and the heat and mass transfer empirical formula of the system will be obtained, which will provide theoretical supports of those functional binary mixtures for the future application in various fields.

新工质对的研发是寻求化学热泵技术重大突破的主要途径，本申请提出一种利用离子液体功能材料的卓越特性开发新型化学热泵工质对的新思路。制冷剂选择能够提供孤对电子的小分子，吸收剂选择含某种金属离子的离子液体，可作为受体与小分子反应生成络合物。此类工质对的最突出特征在于复合作用，其转化的化学能既包含溶解热又包含络合反应热，兼具吸收式热泵和吸附式热泵的优点，吸收能力强于传统吸收式热泵工质对，克服了吸附式热泵传热传质困难、吸附剂膨胀、结块和性能衰减等痼疾。拟具体以NH3－[BMIm]Zn2Cl5和NH3-[CnMIm]2NiCl4两种化学热泵工质对为代表开展研究。着重通过实验测试研究溶液气液相平衡、溶液热力学性质、传热传质特性和热泵系统循环特性等，辅以仿真计算和数值模拟进行复验，最终建立相关物性的理论模型，得到上述混合体系的状态方程、焓浓图和传热传质规律等基础认知，为其未来在相关领域的应用提供理论支持。

吸收式制冷是一种高效、安全的中低品位能回收利用技术。离子液体型吸收式制冷工质对能够克服传统工质对固有的腐蚀、结晶、纯化困难等缺陷，近年来备受瞩目。本项目提出了以含金属卤化物的离子液体作为吸收剂构成新型化学热泵工质对，其特征在于兼具吸收式和吸附式热泵的优点，吸收能力强于传统吸收式工质对，传热传质和回热强于吸附式工质对。以NH3为制冷剂，离子液体[bmim]Zn2Cl5或 [emim]Cu2Cl5为吸收剂开展了以下具体研究工作：.1.采用静态法测量了[bmim]Zn2Cl5/NH3在323.15~563.15 K温度范围内的饱和蒸气压，发展了UNIFAC模型，获得了二元溶液的P-T-x图。.2. 采用TG-DSC 方法研究了[bmim]Zn2Cl5的热稳定性并得到其比热容参数。测量了溶液在288.15~333.15 K温度范围内的过量焓参数，发展了NRTL关联模型。.3. 对[bmim]Zn2Cl5/NH3吸收式制冷单效循环热力特性进行了仿真分析，与NaSCN/NH3吸附式系统和LiBr/H2O吸收式系统进行了对比。.4. 对[emim]Cu2Cl5/NH3的气液相平衡、溶解热等参数进行了实验测量，对其制冷循环系统进行了仿真分析，与LiBr/H2O体系进行了对比。.5.基于[mmim]DMP/CH3OH溶液的气液相平衡数据，发展了全浓度范围的UNIFAC模型和预测过量焓参数的Wilson模型。对[mmim]DMP/CH3OH单效循环、双效串联和并联吸收式制冷系统进行了动态建模与仿真模拟。.6. 测定了[mmim]DMP/CH3OH和[mmim]DMP/H2O溶液热导率，发展了预测离子液体二元溶液热导率的Random Mixing模型。.研究结果表明：NH3在[bmim]Zn2Cl5中的溶解度要远远高于在其他常规离子液体中的溶解度，且 [bmim]Zn2Cl5的比热容较低，[bmim]Zn2Cl5/NH3溶液的过量焓适中，这都有利于[bmim]Zn2Cl5/NH3吸收式系统热力性能的提升。 [bmim]Zn2Cl5/NH3吸收式系统的热力性能与LiBr/H2O系统接近，且在制冷温度较低的制冷工况和吸收温度、冷凝温度较高的热泵工况下均具有良好的热力性能和可接受的循环倍率，具有很大的工业应用潜质和良好的商业开发前景。.本项目的成果推动了吸收式制冷领域的理论发展和技术进步。