高频大幅波动光源下太阳能聚光吸附制冷强化传热传质过程光-温-压耦合机理研究

The project is proposing an adsorption refrigeration system with heat and mass transfer enhancement powered by solar energy using the compound parabolic concentrator (CPC) units. The novel system composed of the adsorbent bed with the CPC units, the adsorbent finned tubes enhancing heat transfer and the micro-pump enhancing mass transfer, which is expected to make the best of the advantages of each part. The adsorbent bed can be heated up and conduct heat rapidly by using the solar CPC units, besides, the adsorption refrigeration system can desorb the refrigerant rapidly with the micro-pump of enhancing mass transfer so that the coefficient of performance of the solar adsorption refrigeration system can be improved greatly. The project studies the inherent laws of the variation of temperature and pressure in the adsorbent bed based on the frequent and sharp changing of solar irradiation. And the desorbed mechanism of the activated carbon-methanol under the condition of non-equilibrium pressure caused by the mass transfer enhancement could be mastered from the research. In addition, the theory of thermal design for the coupling characteristics of the solar concentrating heat flux with the heat and mass transfer enhancement could be acquired. The project aims to get the key and substantial progress in the performance of adsorption refrigeration system with the solar concentrating adsorbent bed and the heat and mass transfer enhancement. The research results would be the beneficial supplements to the existing research results and related theories in this field.

本项目提出了一种强化传热传质的太阳能复合抛物面聚光吸附式制冷系统，即该系统将太阳能聚光吸附床、强化传热翅片吸附管和强化传质循环泵结合起来，使其能够综合发挥各部分的优势。吸附床通过聚光能实现快速升温、迅速传热，再借助管路强化传质实现快速解吸、充分脱附，以期能有效提升系统制冷效率。项目针对太阳能利用中普遍存在的太阳辐射强度波动性现象，从中解构出典型太阳辐射的高频大幅波动性变化，并以此为出发点展开研究，剖析出太阳聚光光源高频大幅波动性对吸附床温度、压力特征影响规律；掌握强化传质引起的非平衡压力（高温低压）下制冷剂解吸机理；获得太阳能聚光吸附床热流分布特征与强化传热传质耦合的热设计理论。本项目将取得太阳能聚光强化传热传质下吸附制冷系统性能的关键实质性进展，其研究成果也是该领域既有研究成果及相关理论的有利补充。

项目围绕太阳能吸附制冷中光-温-压耦合的关键问题，建立了太阳能CPC聚光强化传质吸附制冷相关数学模型，设计、优化并搭建了一套CPC聚光太阳能吸附制冷系统进行实验研究。对太阳能CPC聚光器下吸附管的传热特性进行了理论模拟，构建了翅片管式吸附床的非稳态传热模型，对比研究了不同热流密度下有、无翅片的管内吸附工质的传热特征，翅片式吸附管的非稳态传热最大温差为4.1 °C，掌握了吸附床非稳态热响应的规律，从而获得了管内压力及吸附剂的解吸特性。为进一步改进和强化系统制冷效率，提出了聚光情况下的强化解吸方式，并与自然解吸工况进行对比研究，获得了在不同太阳辐射条件下，由于光源波动引起的温度和压力变化响应特性。掌握了系统的强化解吸特性，在不同天气条件下，系统COP均比无强化传质解吸高50%以上。构建了强化传质的系统模型，对非稳态供热条件下强化传质和降压解吸机理进行了阐释，揭示了稳态传质下的非稳态加热解吸机理。研究了不同冷凝温度对强化传质解吸的影响，发现当冷凝温度从30 °C降至20 °C时，系统COP提高了28.3%。最后在非稳态聚光和强化解吸的基础上，对太阳能聚能-光热转化-热质传输-制冷效率的相互耦合和综合能效提出了进一步改进和优化。提出了双床回质及强化回质的太阳能连续制冷新系统，实现了高效的能量利用，为进一步的规模化太阳能吸附制冷提供了理论支撑。