基于单效吸收/双源压缩制冷的复合热泵系统耦合机制及动态特性研究

Solar absorption refrigeration cycle and solar absorption/compression cascade refrigeration cycle have the advantages of solar air conditioning systems. However, it is very difficult to apply them as cold/heat sources to meet the rooms’ demands for cooling/heating capacity every day and night all the year round, besides, their energy utilization efficiency is low. Oriented to the temperature-humidity-independent control air-conditioning as the application object, the project establishes the LiBr single-effect absorption/dual-source compression hybrid heat pump systems driven by combination of solar and electric energy. The new system not only uses cooling capacity, which a solar-powered single-effect absorption refrigeration cycle produces in high evaporating temperature, to remove the sensible heat in the rooms and heat of condensation from the electricity-driven vapor compression refrigeration cycle (EDVCRC), but also applies cooling capacity which the EDVCRC produces in low evaporating temperature to assume the latent heat load in the rooms. Especially, it uses the dual-source two-compressor heat pump sub-cycle to realize all-weather refrigeration or heating. The new cycle not only achieves cold/ thermal energy cascade production and utilization, but also remarkably increases the utilization efficiency of solar and electric energy and expands temperature ranges of solar utilization. In the project, optimization of thermodynamic and thermoeconomic design of the new system, the mechanisms of the transfer and conversion of the energy and mass are studied. The system state space model is also set up based on modern control theory to explore the dynamic behavior of the new system. The key scientific problems involved in this cycle are studied intensively, namely, the system coupling and energy grade matching problem, and the dynamic response characteristics of the system. In the meantime, experimental study is carried out to verify the theoretical study. The research contributes to expanding the scientific theory of the cascade refrigeration cycle and opening up a new idea for analyzing the dynamic mechanisms of the complex refrigeration system.

太阳能吸收制冷、太阳能吸收/压缩复叠制冷具有太阳能空调优点，但很难全年全天候持续保证房间冷热需求，还存在能源利用率低问题，本项目以温湿度独立控制空调系统为应用对象，通过太阳能单效吸收制冷所提供的高蒸发温度下冷量被梯级利用消除空调显热负荷及压缩制冷冷凝热，以压缩制冷所提供的低蒸发温度下冷量承担空调潜热负荷，并通过双源双压缩机热泵子系统实现全天候制冷或制热，从而构建一种基于单效吸收/双源压缩制冷的复合热泵系统，新系统实现冷量/热能梯级制备与利用，提升能源利用率，扩大太阳能利用温区。本项目从热工学角度研究系统热力学和热经济学优化设计、能质传输与转换机理，还从现代控制论角度建立系统状态空间模型探索系统动态行为特征，重点对所涉及子系统耦合与能量品位匹配机理、系统动态响应特性关键科学问题进行深入研究。同时，开展实验研究验证理论。本研究拓展复叠制冷科学理论，还为复杂制冷系统动态机理分析开辟新思路。

为解决太阳能吸收制冷机在低蒸发温度下的效率偏低、间歇运行的问题，同时为了克服空气源热泵的能耗高、季节匹配性差的缺点，本项目构建一种单效吸收/双源压缩复合热泵系统，建立了太阳能单效吸收/双源压缩复合制冷系统的热力学数学模型，研究了吸收制冷子系统发生温度、蒸发温度、环境温度与该新型复合热泵系统的循环特性之间关系；建立了该新型复合热泵系统的逐时能耗模型，研究组成新系统各部件之间及各子系统之间的能质分配规律，比较并评估三种系统的节能性和经济性；运用遗传算法研究了该新型复合热泵系统的优化运行参数；运用传统㶲分析方法研究组成新的系统各部件的㶲损，采用高级㶲分析方法研究各部件不可逆性的改进潜力；开展了基于超声作用的溴化锂水溶液发生过程空化特性研究，提出了多超声协同强化吸收式制冷系统的溴化锂水溶液发生过程方法，开展多超声协同强化溶液发生器的气泡动力学特性研究；研究溴化锂单效吸收/双源压缩制冷所耦合而成新型复合热泵系统的动态模拟的建模方法，建立新系统内各部件热动力学状态空间模型并进行动态数值仿真。搭建太阳能单效吸收制冷子系统试验台,在中央与地方共建项目经费支持下建立了太阳能单效吸收/双源压缩复合制冷系统示范工程项目。本研究以温湿度独立控制空调系统为应用对象，提出了“制冷系统的冷能梯级利用、多能互补的冷热源协同供给”思想，实现冷量/热能梯级制备与利用，从深层次揭示了太阳能单效吸收/双源压缩复合制冷系统的热物理过程和基本规律，丰富了复合热泵技术体系，同时为复杂制冷系统动态机理分析开辟新思路。