摘要
非共沸混合工质在蒸发器和冷凝器中的相变过程是一个定压变温过程，作为高低温热源的环境介质，在两器中也是一个变温过程，从热力学角度而言，如果工质和热源的温度变化过程相匹配，即始终保持一个均匀的、适中的换热温差，则换热不可逆性可以大大减小，从而提高循环效率。逆向布莱顿循环具有输出膨胀功的特点，本文从理论和实验两方面分析探讨了非共沸混合工质应用于逆向布莱顿热泵循环的性能。
工质的T—S相图在循环模拟、设计和分析中发挥着十分重要的作用，循环的路径与相图的饱和状态线之间的相对位置关系，对整个系统的运行状态和设备的设计选型有很大影响。本文对有关工质在T—S图上的相边界形状，特别是气相饱和线的形状进行了分析研究。
选用非共沸工质的一个重要原因是为了利用其温度滑移特性以匹配热源流体的温度变化，减少换热过程的不可逆性。过小的温度滑移值，无法发挥其优越性，而过大的温度滑移反而可能增大换热损失。本文第四章对非共沸混合工质的温度滑移特性，以及与温度滑移密切相关的焓变的线性特性进行了详细研究。
基于循环的热力学分析和从热力学角度选择的工质，采用RKS状态方程对几种非共沸混合工质进行了循环模拟计算，详细讨论了工质成分等参数对系统性能的影响。
实验研究以理论为指导，验证了理论数值分析，在得到本课题的一些重要结论的同时也发现了一些不足，为本课题的进一步研究提供了依据。
The phase change of non-azeotropic refrigerants in evaporator and condenser is a isobaric&non-isothermal process. And the heat source in the two heat exchanger is also non-isothermal. In the view of thermodynamics, if the heat exchange processes of the refrigerants and the heat source match well, the irreversibility of the heat exchange process will be much more less and the efficiency of the cycle will be higher. Utilizing the non-azeotropic refrigerants and the two phase expanse work of the expander, this thesis, theoretically and experimentally, analyzes and explores thoroughly the cycyle performance in the heat pump system of the Reveser-Brayton Cycle.
The T-S phase diagram of working substance is very important for cycle simulation, design and analysis. The relative location of cycle process lines and the saturation curve of the T-S phase diagram playes an important role in the design of the equipment and operation of the system. This thesis analyzes the shape of the saturation curve of some working substances' T-S phase diagram, especially the shape of the saturated vapor line.
To take advantage of the temperature glide matching of working substances and heat resources is an very importment reason of using non-azeotropic refrigerants. If the glide is small, the advantage is difficult to be taken, and if the glide is too big, the irreversibility of the heat exchange process would be much more bigger either. This thesis also analyzes the temperature glide of some non-azeotropic refrigerants, and the characteristic of enthalpy change during the phase change process, which has much correlativity with the temperature glide.
In order to attain the nature of this research object, by the thermodynamic analysis and selecting refrigerants from the view of thermodynamic, it, used RKS equation of
BSTRACT
state, carried out simulating the cycle with multiplex non-azeotropic refrigerants, and discussed in details the impacts of many restriction on the cycle performance, which involved the component of the refrigerants etc.
The experimental study verified the theoretical results. Ultimately, a few important conclusions were obtained and some problems were found, which provide the direction for further study.
引文
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