基于增强型复合吸附剂和深度回热回质的高效吸附制冷研究

Adsorption refrigeration has advantages of energy saving and environmental protection but low energy efficiency and larger size limits its development. Hence, its performance needs to be improved via aspects of adsorbent and cycle. Carbon nanoparticle has porous structure, good heat transfer performance and promotion in adsorption reaction. It can form enhanced composite adsorbent with expanded graphite and metal chloride, while improving simultaneously adsorption and heat and mass transfer performance. In deep heat and mass recovery cycle, adsorption heat is fully recovered and cycle adsorption quantity is further enlarged by cascade heat and mass recovery processes. This project focuses on research of adsorption characteristics and enhanced heat and mass transfer of enhanced composite adsorbent and thermodynamics characteristic of deep heat and mass recovery cycle. Based on experiments, adsorption characteristics and enhanced heat and mass transfer of enhanced composite adsorbent can be presented, their influence factors can be obtained, promotion of carbon nanoparticle in adsorption reaction can be identified and optimal preparation method can be got. Based on theoretical analysis, deep heat and mass recovery cycle can be built, relationship between number of stages and cycle performance can be presented, extreme thermodynamics characteristic can be identified and optimal number of stages can be obtained. Based on enhanced composite adsorbent-ammonia working pair and novel cycle, mathematical model and experimental setup of efficient adsorption refrigeration system can be established. Numerical and experimental investigation can be performed. This project can provide a new idea and a new method for efficient adsorption refrigeration driven by low-grade heat.

吸附制冷具有节能环保的优点，但能量利用效率低和体积庞大的缺点限制了其发展，需要从吸附剂和循环两方面进行性能提升。碳纳米添加剂具有多孔结构、较佳导热性能以及对吸附反应的提升作用，可与膨胀石墨、金属氯化物形成增强型复合吸附剂，实现吸附和传热传质性能的双重提升。深度回热回质吸附循环通过多级回热回质，实现吸附热深度回收及循环吸附量的显著增大。本项目通过实验研究，揭示基于碳纳米添加剂增强型复合吸附剂的吸附特性和传热传质强化机理，明确吸附和传热传质性能的影响因素，阐明碳纳米添加剂对吸附反应的作用机制，获得最佳配制方法；通过理论分析，构建深度回热回质吸附循环，阐明级数对性能的影响和其极限特性，获得最优级数。在此基础上结合基于碳纳米添加剂增强型复合吸附剂-氨工质对和新型循环，构建高效吸附制冷系统，通过数值建模和搭建实验装置，开展数值优化和实验验证研究，为实现低品位余热高效利用的吸附制冷提供新思路和新途径。

吸附制冷具有节能环保的优点，但能量利用效率低和体积庞大的缺点限制了其发展，需要从吸附剂和循环两方面进行性能提升。本项目通过金属氯化物、膨胀石墨和碳纳米添加剂制备了增强型复合吸附剂，并开展其吸附特性和传热传质强化机理研究。经实验结果表明，通过碳纳米添加剂可将复合吸附剂的吸附量从0.35kg kg-1提升至0.51kg kg-1，导热系数从0.3 W m-1 ℃-1提升至2W m-1 ℃-1，揭示了碳纳米添加剂作用机制：改善膨胀石墨二维特性，形成三维框架基质材料，提升传热性能同时为吸附反应提供更多弹性空间，避免膨胀结块问题，有效提升吸附性能。本项目通过理论分析，构建深度回热回质吸附循环并开展其热力学特性研究，阐明级数对性能的影响和其极限特性，获得最优级数。在此基础上，进一步研究了吸附制冷系统优化运行，提出非对等吸附-解吸时间的新型运行策略，实现COP和SCP的双提升，且COP的提升幅度达到53%。通过本项目的研究，为实现低品位余热高效利用的吸附制冷提供新思路和新途径。