制冷剂分液器性能研究

发布时间：2019-05-07 01:29

【摘要】：在制冷系统中，制冷剂经过节流装置后，变成气液两相状态流入蒸发器。制冷剂能否均匀等量地分配到蒸发器的各个支路，对蒸发器的性能乃至整个制冷系统都有至关重要的影响。分液器是一个重要的辅助装置，使用于蒸发器前，将气液两相的制冷剂均匀地分配到蒸发器各个支路的装置。经过大量的实地调研和查阅分液器相关专利和文献，发现现有分液器在实际应用中仍然存在分配不均导致换热效率下降、出风温度不均影响舒适度等问题。在此基础上，测试了多种不同分配机理的分液器的性能，并且研究了质量流量、干度等工作条件、几何结构以及安装倾斜角和毛细管等对其分配均匀造成影响的因素。建立了分液器仿真模型，通过数学方法进行分析，提出优化方案。优化后模型最终通过实验验证。论文主要内容如下：一、搭建分液器性能测试平台，可以测量分液器出口每条支路的质量流量及干度。对于压降型、离心式和储液式分液器，分别对两种不同结构的样件进行测试，，对比了三种分液器的分配均匀性、压降等信息，并且在实验的基础上分析了质量流量、入口干度等工作条件对分液器分配特性的影响。二、通过流体计算软件FLUENT建立仿真模型，基于Eulerian-Eulerian分析方法，模拟分液器内部流动状况以及均匀分配机理。对比实验结果，CFD仿真值质量流量偏差在15%以内，说明CFD能准确模拟分液器分配特性。通过CFD模拟计算，后处理分析其内部流场（相分布、压力分布、速度场），研究影响三种分液机理的分液器的关键尺寸参数对性能的影响。三、相比压降式和离心式分液器，储液式分液器性能受到质量流量和干度以及安装角度变化的影响较小，而且结构简单，具有深入研究的价值。文章使用田口方法，对直径、高度以及入口管直径等重要参数进行了分析和优化。通过CFD计算了九个不同参数正交排布的模型，深入分析影响其分配性能的原因并提出优化方案，设计了性能最优的分液器。通过实验测试了优化后的分液器，验证了上述分析。四、实验研究了安装倾斜角度和毛细管长度对分液器分配均匀性的影响。通过对比，分析了质量流量、干度对安装角度和毛细管长度变化引起的分配不均程度的影响。基于Matlab，建立了分液器数值计算模型，定量地分析了毛细管长度对分液器制冷剂分配的影响，并且通过与实验结果对比，验证了其准确性。
[Abstract]:In the refrigeration system, the refrigerant flows into the evaporator when the refrigerant passes through the throttling device and becomes a gas-liquid two-phase state. Whether refrigerant can be evenly distributed to each branch of the evaporator is of great importance to the performance of the evaporator and even to the whole refrigeration system. The distributor is an important auxiliary device, which distributes the gas-liquid two-phase refrigerant evenly to each branch of the evaporator in front of the evaporator. Through a large number of field investigation and review of relevant patents and literatures, it is found that there are still some problems in the practical application of existing separators, such as the reduction of heat transfer efficiency caused by uneven distribution, and the influence of uneven outlet temperature on comfort and so on. On this basis, the performance of the splitter with different distribution mechanisms is tested. The working conditions such as mass flow rate, dry degree, geometric structure, installation inclination angle and capillary tube are studied to influence the distribution uniformity. The simulation model of the separator is established, and the optimization scheme is put forward through the analysis of the mathematical method. Finally, the optimized model is verified by experiments. The main contents of this paper are as follows: first, the performance test platform of the divider can be built to measure the mass flow rate and dry degree of each branch at the outlet of the splitter. For the pressure drop type, centrifugal type and liquid storage type separators, the samples with two different structures are tested, and the distribution uniformity and pressure drop information of the three separators are compared, and the mass flow rate is analyzed on the basis of the experiment, and the distribution uniformity and pressure drop of the three kinds of separators are compared, and the mass flow rate is analyzed on the basis of the experiment. The influence of working conditions such as inlet dryness on the distribution characteristics of the separator. Secondly, the simulation model is established by the fluid calculation software FLUENT. Based on the Eulerian-Eulerian analysis method, the internal flow state and the uniform distribution mechanism of the separator are simulated. Compared with the experimental results, the mass flow deviation of the CFD simulation value is less than 15%, which indicates that CFD can accurately simulate the distribution characteristics of the splitter. The internal flow field (phase distribution, pressure distribution, velocity field) was analyzed by CFD simulation, and the influence of the key size parameters on the performance of the separator was studied. Thirdly, compared with the pressure drop type and centrifugal separator, the performance of the liquid storage separator is less affected by the change of mass flow rate, dry degree and installation angle, and the structure is simple, so it has the value of in-depth study. In this paper, Taguchi method is used to analyze and optimize the important parameters such as diameter, height and diameter of inlet pipe. The orthogonal arrangement model of nine different parameters is calculated by CFD. The reasons that affect its distribution performance are analyzed deeply and the optimization scheme is put forward. The optimal hydraulic divider is designed. The optimized splitter is tested by experiment, and the above analysis is verified. Fourthly, the effects of installation tilt angle and capillary length on the distribution uniformity of the separator are studied experimentally. The influence of mass flow rate and dry degree on the distribution unevenness caused by the change of installation angle and capillary length was analyzed. The numerical calculation model of the separator based on Matlab, is established, and the effect of capillary length on refrigerant distribution in the separator is analyzed quantitatively. The accuracy of the model is verified by comparing with the experimental results.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB657

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