Stirling refrigerator fly it? Stirling refrigerator temperature field simulation and experimental study

Stirling refrigerator fly it? Compared with the conventional vapor compression refrigerating machine, a Stirling refrigerator having a refrigeration wide temperature range, low starting current, easy to adjust cooling capacity, high efficiency, and no refrigerant pollution. Since the Stirling refrigerator has obvious advantages in terms of energy saving and environmental protection, and therefore as a refrigerator, freezer, cold source for which a small-capacity refrigerator has a considerable advantage. Stirling refrigerator cabinet has been designed, and the cooling temperature of 193K when the refrigerator cabinet distribution were measured field refrigerator temperature change, and use the software Fluent refrigerator temperature field was simulated, and the simulation results of the experiment the results were compared to obtain difference between the two, and analyzed its causes. The study found that the presence of a certain temperature gradient inside the casing, a smaller cold end of the system area is not conducive to transfer of cold. In the research field of refrigerator temperature, Wu Xiaohua and other problems for the arrangement of the refrigerator and the freezer compartment of the refrigerator, the study found that the freezing chamber and the lower freezer food storage and more help reduce energy consumption of the refrigerator; Ding Guoliang, etc. for different internal structure type refrigerator analyzed and compared, to study the interior of the refrigerator and the evaporator shelf, the distance between the door impact, the separator and the thermal conductivity of the interior of the refrigerator and the temperature distribution inside the flow field, the temperature of the refrigerator is proposed to optimize methods field. Korean LG\’s Kim et al employ a Stirling refrigeration cycle of the refrigerator cooling 60L, so that the refrigerator temperature is maintained at 273K, results show that the steam expansion refrigeration system with respect to the 25% energy saving system. Using a thermosyphon system and the warm end of the cold head heat the free-piston Stirling cooler system Green et al. Oxford University research showed that the 17% energy saving system than conventional refrigeration equipment. Previous research aimed at refrigerator temperature field in the field of refrigeration technology, commonly used to preserve food in the refrigerator for analysis. With the deepening of research and development of technology, people are required refrigeration temperature is getting lower and lower. In this paper, the market demand for low-temperature refrigerator temperature field areas were analyzed, and the Stirling refrigerator temperature field research. Experimental Study 1 About 1.1 experimental apparatus and conventional refrigerator Stirling refrigerator differ greatly. The Stirling refrigerator uses a unitary free piston Stirling cooler as a heat sink, the principle is the helium gas expansion refrigeration, and therefore not a throttle system and an evaporator. Cold head of a Stirling refrigerator to refrigerator cold transmission efficiency has great impact on the overall efficiency of the Stirling refrigerator system. forEffectively improve the cooling efficiency of the refrigerator system, it is necessary to transfer cold detailed analysis techniques. Direct cold transfer mode is a Stirling refrigerator cold head directly into the interior of the refrigerator, which is advantageous in that a simple structure, is a simple, basic embodiment of the cold transfer. Stirling refrigerator direct-cooling type is shown in Fig.1. thermocouple measurements were taken five distribution points outside and inside the box, numbered from 110 to 114 and 105 to 109. Each of the access points are thermocouples, the ambient temperature is the ambient temperature experiment 293K. Specific experimental procedure as follows: ① with foil tape numbered thermocouples deposited in each of the measurement distribution, and is connected to the data acquisition module respective channel; ② the data acquisition module into the Agilent data collection instrument, open collecting instrument and set good parameters of each channel; ③ connecting the experimental apparatus in Figure 3; ④ connection and configure the instrument channel parameters; ⑤ power connection refrigerator, open the refrigerator, while the data acquisition and recording starts. 1.3 Experimental results and data analyzed within 14h of the outer wall housing a small temperature change, and stabilized after 10h. Found through experiments that the outer wall of the tank slightly below ambient temperature, which shows good insulation properties box. Since the number of the temperature profile is approximately 105 to 109 measurement points where the temperature is given only to the inside walls of the measuring points the temperature change of the number 105. Internal cabinet temperature increases gradually decreased with time, several times a slight recovery in the middle, and the temperature measuring point closer the cold head, the lower the temperature, the temperature difference of about cabinets 20 ℃, large temperature gradients, may be small and low temperature refrigeration For placement machine. Simulation 2 Stirling refrigerator Analysis 2.1 Experimental parameters and environment setting box holding the housing interior dimensions 300mm × 200mm × 300mm, thickness 1mm material is stainless steel; outer dimensions of 400mm × 300mm × 400mm, thickness 2mm material is stainless steel, the insulation layer having a thickness of 60mm, the inside of vacuum insulation panel, the outer polyurethane foam insulation. <；20W的要求。

由于物理模型的复杂性，在实际模拟过程中假定箱体内空气流动形式为稳定层流和非边界流动；箱体内流体为牛顿流，空气不可压缩，所有固体的密度、比热、导热系数、黏度均为定。表1为斯特林冰箱各种材料模拟参数。

2.2模拟结果及分析

采用三维绘图软件建立斯特林冰箱箱体模型，利用ANSYS Fluent14.5前处理软件ICEMCFD 14.5对箱体进行网格划分，并对网格进行质量检查，建立合适的网格。图8为箱体模型网格建立示意图。网格划分完成后，设定相应材料的物性参数，设定相应的边界条件为：①流动边界条件：所有固体边界面上流体满足无滑移边界条件；②热边界条件：通过实验测温系统测量箱体各个外表面的温度；箱体内开孔处冷源温度设定为一定值，即冷头温度。通过迭代法对所设定模型进行求解计算，最终得到箱体模型的温度场分布。图9为箱体内腔温度场分布情况。

Comparative Experiment 3 Analysis and simulation results of an ambient temperature of 293K, 243K temperature control box, the box to meet the heat load Experimental Stirling refrigerator in the temperature field, the temperature of each measuring point measurement, cabinets and the air temperature field of the finite element analysis, to giveTo simulate the temperature of each measuring point calculation. Table 2 is a comparison of experimental and simulated results for each measuring point. The simulation results lower than the experimental results by comparing the analysis found. This is subject to experiment and model materials processing environment is limited. Box body, the box processing technology problem exists; albeit modest net volume box, but due to the cold head of the refrigerator small heat dissipation area is small, resulting in the amount of cold produced by the refrigerator can not pass out well; Simulation model is too idealistic, small changes in physical parameters such as the actual flow field is not taken into account. Non-uniform temperature distribution inside the tank is due to long-running cold head of a Stirling refrigerator, the cold head frosting, increased thermal resistance, so that the cooling capacity can not be effectively transferred in the housing. Therefore, in future studies should focus on research transfer mode Stirling refrigerator cold head and the housing of the vacuum treatment, to avoid frosting. CONCLUSION According to the actual requirements and physical characteristics simulation model Stirling refrigerator, a Stirling refrigerator body model established using ANSYS Fluent software simulation calculation, to give a final temperature of tank space field distribution. Direct cooling using Stirling refrigerator experimental subject, by constructing a thermocouple data acquisition distribution Stirling refrigerator cabinet temperature field measurement bench, temperature field curve obtained. The experimental results and simulation results of the measuring points are compared and analyzed. In the horizontal direction, a direction away from the cold head temperature gradually increased; on the vertical axis, little change in the air temperature, the temperature distribution more uniform. Uneven distribution of some of the higher temperature of the object storage temperature requirements disadvantageous. In order to reduce the temperature difference, the cold head of Stirling refrigerating machine may be placed in the middle portion of the casing, heat pipe cold transfer, the need to ensure the insulation effect of the casing, using an airgel vacuum insulation panel to solve the problem of bonding with the polyurethane plate .