高效吸附制冷循环过程中强化传热传质的实验及模拟研究

【作者】 方利国；

【导师】 谭盈科；

【作者基本信息】 华南理工大学 ， 化学工程， 1997， 博士

【摘要】 吸附制冷是一种噪音小、耗电少、无污染的环保型制冷方法．吸附制冷的核心部分是吸附工质对，其功能和压缩式制冷中的压缩机相似．选择合适的工质对是吸附制冷的关键之一．本文在总结前人经验的基础上，通过详细的理论分析及实验研究，提出了吸附制冷工质对选择的一系列具体准则．这些准则为利用人工智能在分子水平上设计工质对构建了基本模式，并创立了工质对选择新方法-经济工质对法．该法是一种定量选择工质对的方法，克服了以往定性方法的不确定性，利用该法，确定了本论文实验的工质对． 确定了吸附工质对后，吸附剂性能的好坏直接影响着吸附制冷的性能．本文首先建立并优化了吸附剂吸附能力回归公式，在理论分析的基础上，提出了吸附剂吸附性能强化的关键是提高吸附剂的有效吸附量，而有效吸附量和吸附剂的具体应用条件有关，从而开创了吸附剂吸附性能强化的新思路，并在此基础上提出了几种强化方法，取得了较满意的结果．对于吸附剂导热性能，本文推导了床层等效导热系数的计算公式．通过理论分析，提出了对吸附剂挤压成形、直接添加高导热材料及在利用导热高分子材料在吸附剂表面形成交联网络的方法强化吸附剂导热性能的方法．对于这些方法进行了实验及理论研究，证明是行之有效的． 吸附制冷性能评价指标的确定及建立不仅影响着吸附制冷操作条件及各项其它参数的优化，同时制约着人们对吸附制冷的认识及推广应用．本文首先在建立常规的通用COP指标的基础上，结合吸附制冷的具体特点，提出和建立了有效能利用率、有效吸附量(即理论制冷量)及热力经济效率等多种评价指标，满足了不同目的评价及优化的要求，并分析了操作条件及吸附剂性能等各项参数对各种性能指标的影响，提出了各项参数优化的范围及方向，为吸附制冷机的设计和应用提供了理论依据． 本文还建立了三层次的吸附床传热传质耦合模型，引入了导热流体和吸附剂的轴向导热，使模型更趋合理．编写了能自动调整时间步长，保证离散化计算收敛的计算机动态模拟程序，并进行了实验和模拟结果的比较研究，实验结果和理论模拟计算结果趋于一致． 本文将温度波理论引入动态模拟结果分析中，建立了温度波长的计算公式，分析了各种参数对温度波的影响，提出了连续吸附制冷中需解决的一系列问题，为连续吸附制冷提供了理论及实验依据． 本文还在前面实验及理论分析的基础上，提出了一种新型的混合式吸附制冷模式，为充分利用太阳能及吸附制冷的实际应用，开辟了一个新的途径．更多还原

【Abstract】 Adsorptional refrigeration has a character of low noisy, electricity-saving and no damage to environment. Its main component is the adsorbent-adsorbate couple. The adsorber filled with adsorbent has the same function as the compressor of conventional vapor-compression refrigeration. How to select a suitable adsorbent-adsorbate couple is the key technique to the adsorption refrigeration. A series of concrete principles for selecting adsorbent-adsorbate pair were proposed in this paper by the detailed theoretical analyses and experimental studies after summing up lots of experiences of the former researchers. These principles built up a basic model for designing the working pairs at a molecular level by utilizing artificial intelligence. In the same time, the author also developed a new method for selecting working pair named " the economical working pair method " . Thismethod overcame the indefiniteness of the qualitative method and could select working pairs quantitatively. The working pair of this study was found by this method.For a given pair, the adsorption capacity of the adsorbent directly affects the function of the adsorption refrigeration system. An optimal equation for the adsorption capacity of adsorbent was set up first in this paper. Then, based on the theoretical analyses, the idea was proposed that the key problem for enhancing the adsorption capacity of adsorbent is to increase the effective amount adsorbed in adsorbent which is related to the applicating conditions . Then a new idea for enhancing the adsorption capacity of adsorbent was developed. By this idea, several methods for enhancing the adsorption capacity of adsorbent were set up and some nice results have been obtained. On the respect of the heat transfer of adsorbent bed, an equation for calculating the effective thermal conductivity of adsorbent bed was set up. By the theoretical analysis, some methods such as shaping adsorbent bed by a compressing process, dispersing high thermally conductive additives into the adsorbent bed and directly coating high thermal conductive polymers to the surface of adsorbent have been individually developed. Their feasibility was proven by the theoretical and experimental studies.The criterion of evaluating the function of an adsorption refrigeration system not only affects the optimization of performance conditions and geometrical parameters, but also restricts the recognition and widespread application of it. Various criteria such as the utilization ratio of effective energy, the effective amount adsorbed and the efficiency of thermal economy have been proposed and described based on the conventional criteria of COP after considering the unique characteristics of adsorption refrigeration. These criteria could meet with the更多还原