京津冀区域太阳能土壤源热泵系统热力学分析与评价

Solar and ground source as a clean renewable energy has been paid attention to by all over the world. The research focus on the scientific evaluation of the overall performance of the solar ground source heat pump system and effective exploration of its energy saving potential of the cooling and heating for the building. In this project, by using the finite time thermodynamic theory, the general characteristics of the relationship between solar ground source heat pump performance parameters and the internal as well as the external thermodynamic parameters will be obtained. It can reveal the coupling characteristics of energy conversion and transfer processes in solar source, ground source and absorption heat pump.The finite time thermodynamic performance bounds which are more accordant with the actual energy consumption processes than classical thermodynamics are obtained, and so as to find the way to improve the overall performance of the system. Considering the annual dynamic operating characteristics of the system, the calculation method of temperature frequency cooling/heating season performance coefficient and annual performance coefficient are established.The influence mechanism of solar-ground heat source characteristic parameters and system circulation parameters on system performance parameters is expounded in order to reflect objectively the dynamic characteristics of the system, further more, the relationship between energy supply (solar and ground source) and energy utilization(cooling and heating for building) in Beijing-Tianjin-Hebei region is clarity, which can reveal the influence law of the regional difference of heat source and the multifarious demand of the cool and the heat load on the system performance, and so as to provide scientific basis and theoretical guidance for the application of solar ground source heat pump in Beijing-Tianjin-Hebei region.

太阳能和土壤源作为清洁的可再生能源已备受世界瞩目，科学评价太阳能土壤源热泵系统性能与有效挖掘其供冷供热的节能潜力已成为研究重点。本项目首先利用有限时间热力学理论分析方法，获得太阳能土壤源热泵系统性能参数和系统内外部热力参数间的一般特性关系，揭示太阳能—土壤热—吸收式热泵三者间进行能量转换与传递过程的耦合特性，求得比经典热力学更符合实际用能过程的有限时间热力学性能界限，指明提高系统整体性能的途径，再从系统全年动态运行特性出发，建立制冷/供热季节性能系数以及全年性能系数的温度频段计算方法，阐明太阳能土壤源热源特性参数及系统循环参数对系统性能参数的影响机制，客观反映系统的全年动态特性，在此基础上，明确京津冀区域供能（太阳能和土壤源）与用能（空调制冷供热）间的相互关系，揭示热源的地区差异性以及空调冷热负荷需求多样性对系统性能的影响规律，为太阳能土壤源热泵在京津冀区域推广应用提供科学依据和理论指导。

本项目围绕可再生能源在制冷空调领域应用的关键问题，利用热力学分析方法，揭示太阳能-土壤源热泵系统全年动态运行特性，获得太阳能和土壤源供能与全年空调供冷供热用能间的关系，寻找太阳能-土壤源热泵高效稳定运行的途径，并对其热力性能、环境影响和经济性进行全面评价和多目标优化。通过采用ANSYS软件对土壤热交换器单管及管群地下温度场进行全年动态模拟，以单位钻孔深度换热量最大为目标，得到了两支管间距、钻孔半径以及钻孔深度等设计参数的优化取值，得到了土壤源热泵系统经历一个供冷供热完整循环时，单管及管群周围的土壤温度变化规律；在此基础上，提出槽式太阳能集热与溴化锂-水双效吸收式制冷机/热泵相结合的系统，并对基础型以及两种蓄能型太阳能-土壤源吸收式制冷/热泵进行系统设计，研究各子系统间的最佳匹配关系；在TRNSYS平台上构建了系统仿真模型，并利用实验数据及文献资料对该系统的主要部件分别进行了模型验证，针对北京地区气候条件以及太阳能/土壤源特性，分析了夏季供冷/冬季供热典型日、代表周和整个供冷/供热季的系统动态性能，揭示了系统主要设计参数和运行参数对系统动态性能的影响规律；应用全生命周期评价方法，对太阳能-土壤源热泵系统的设备材料生产，运输安装及运行三个阶段进行分析，分别计算了三个阶段的污染物排放量，整个生命周期内系统的全球变暖潜值，酸化潜值，粉烟尘潜值以及环境影响负荷等环境评价指标，对太阳能-土壤源热泵系统进行全面的环境影响评价；在此基础上，同时考虑环保性和经济性，以均值年费用和环境影响负荷为优化目标函数，利用带精英策略的非支配排序遗传算法（NSGA II），对太阳能-土壤源热泵系统进行多目标优化，对蓄能型太阳能制冷/热泵系统，通过能源、经济和环境（3E）综合分析，建立3E性能评价指标，并进行多目标优化，运用LINMAP及TOPSIS决策方法得到系统优化设计值。本项目的研究结果可为加快太阳能土壤源热泵推广及提升可再生能源占比提供科学依据。