带三相蓄能的太阳能吸收式制冷空调系统理论与实验研究

Solar air conditioning adopts renewable energy refrigeration technology. At present, solar air conditioning is very difficult to be applied with high efficiency and large scale due to solar instability, not harmonious factors between the solar air conditioning supply and the cold demand of air conditioning user. This project adopts lithium bromide-water solution as energy storage medium in three phase medium (crystal, solution and vapour) accumulator. The problem of coordination, stability and high efficiency between the solar energy and user cold load will be solved in a way of three phase polymorphism energy storage using lithium bromide hydrate, LiBr solution and vapour. The new system flow of solar absorption refrigeration and air conditioning with three phase accumulator and the new structure of lithium bromide-water three phase accumulator are researched on, and experimental study on multiple condition will be carried on. The aims of this project are to clarify the dynamic characteristics of three phase energy storage medium in three phase accumulator under the internal and external composite disturbance and coupling characteristics with solar air conditioning, to reveal the optimal matching between three phase energy storage medium in energy storage/release processes and the instability of solar air conditioning. Entransy theory is applied to analysis and optimize of the heat and mass transfer process with three phase polymorphism in three phase accumulator and thermodynamic optimization is used to optimize the solar air conditioning system with three phase accumulator. Combined with experimental research, the corresponding optimal operation rules are obtained by taking "minimum entransy dissipation" and "minimum entropy generation" as optimization objectives, respectively. The optimal performance evaluation method of three phase energy storage system is obtained. Therefore, the scientific basis and theoretical guidance are provided for a three phase energy storage technology in solar air conditioning of high efficient and reasonable utilization.

太阳能空调采用可再生能源制冷技术，因受太阳能的不稳定、空调制冷与空调用冷之间的不协调等因素影响使其难于高效化和规模化应用。本项目采用溴化锂水溶液作为蓄能介质的固液气三相蓄能器，以其结晶水合物、溶液和蒸气三相多态的蓄能方式解决太阳能和空调冷负荷的协调、稳定及高效利用问题。项目研究带三相蓄能器的太阳能吸收式制冷空调新流程以及溴化锂-水三相蓄能器新结构，并进行多工况的实验研究；阐明三相蓄能器内介质在内外复合扰动作用下的动态特性及其与太阳能空调的耦合特性；揭示蓄/释能过程与太阳能空调不稳定性的优化匹配问题。引入"火积理论"分析三相蓄能器内三相多态的传热传质过程及优化，利用热力学优化理论研究带三相蓄能器的太阳能空调系统动态优化，结合实验研究，揭示实现"火积耗散最小"和"熵产生最小"优化目标的相应运行规律，获得三相蓄能系统性能最优评价方法，为三相蓄能技术在太阳能空调中的高效利用提供科学依据和理论指导。

本项目研究溶液化学蓄能的科学问题，将三相蓄能技术应用于太阳能空调领域，创新性地进行了蓄能设备和系统流程设计，有效地解决太阳能空调高效稳定运行问题。通过对三相蓄/释能过程及蓄能型太阳能空调系统进行深入的热力学研究，揭示了三相蓄/释能过程动态特性及其与太阳能空调耦合特性。理论研究方面，通过建立三相蓄/释能过程热力学模型，推导出了特性参数和循环参数间的解析式，并对恒温和变温热源溴化锂-水工质对的三相蓄能系统进行动态模拟，通过MATLAB模拟计算，利用数值分析方法，获得了循环参数对特性参数的影响规律；基于热力学优化理论，以系统火用效率、系统总熵产和结晶率为优化目标，对三相蓄能系统进行设计参数优化，确定了溴化锂-水工质对的三相蓄能系统设计运行工况优域，分析了循环参数对系统最优性能的影响规律；同时还开展了三相蓄/释能过程及蓄能系统的能量分析、火用分析和熵产分析，获得了三相蓄能系统性能最佳评价方法；通过深入分析太阳能集热系统性能的主要影响因素及其影响规律，进一步确定了三相蓄能系统与太阳能吸收式制冷系统的优化匹配以及高效运行规律，并对太阳能吸收式制冷空调系统进行了经济性分析；实验研究方面，设计了溴化锂水—工质对的三相蓄能实验装置，确定了溴化锂—水工质对的三相蓄能器的结构形式及其与吸收式制冷系统的连接方式和容量匹配关系；研制了太阳能空调专用槽式太阳能集热器，设计建造了230平米槽式太阳能集热实验系统，并对集热系统性能进行了实验测试，获得了冬/夏典型日集热系统测试数据，分析了多个运行参数对集热系统性能的影响规律。鉴于三相蓄能器内部的气液固转变的复杂问题，本项目的研究结果可为三相蓄能技术在太阳能空调中的高效利用提供科学依据。