直接蒸发式太阳能喷射制冷系统的模拟分析与研究

发布时间：2018-03-05 05:16

  本文选题：太阳能喷射制冷　切入点：平板集热发生器　出处：《河北工程大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着全球范围内能耗的增加和空气的污染,能源和环境问题引起广泛的公众关注。考虑到诸多因素,开发和利用太阳能是解决能源与环境问题最有效的方法之一,对于节能与环保的太阳能喷射制冷系统的研究已逐步成为热点。本课题通过数值模拟与实验相结合的方法,对直接蒸发式太阳能喷射制冷系统进行了研究。系统省却了传统太阳能制冷系统的发生器,制冷剂在集热发生器内直接吸热蒸发,不仅为喷射器提供动力,还减少了中间换热设备。用喷射器代替传统制冷系统的压缩机,系统结构简单、运行维护费用低。首先对直接蒸发式太阳能喷射制冷系统进行了热力学分析,然后分别针对太阳能集热发生器、喷射器、蒸发器、冷凝器、膨胀阀和循环泵建立了数学模型,主要对太阳能集热发生器和喷射器进行了设计计算。再次基于相变理论,太阳辐照度为800W/m2、进口速度0.047m/s、出口压力2.65MPa工况下,对集热发生器进行数值模拟,研究管内制冷剂的相变情况,分别得到了管内含气率和管壁温度的变化趋势,不同管截面上的温度变化情况。基于气体动力学理论,发生温度80℃、蒸发温度5℃、冷凝温度36℃工况下,确定了喷射器的结构参数。通过数值模拟得到了喷射器内流体的速度、压力、温度的变化规律,模拟表明在喷嘴出口和混合室圆柱段截面处有激波产生,会引起此处速度降低,压力和温度提高,同时也分析了结构参数和运行参数对喷射制冷系统性能的影响。结果显示,工作压力2.65MPa、蒸发温度5℃、冷凝温度36℃时,喷射器的喷嘴距0mm,混合室圆柱段直径10mm的喷射器性能最好,喷射系数能达0.32,系统COP达0.36。最后基于R134a搭建直接蒸发式太阳能喷射制冷系统实验台,并安装了温度和压力传感器,结合数据采集系统,实现了系统的自动化测试。
[Abstract]:With the increase in global energy consumption and air pollution, energy and environmental problems have attracted widespread public concern. Considering many factors, the development and utilization of solar energy is one of the most effective solutions to energy and environmental problems. The research on energy saving and environmental protection solar ejector refrigeration system has gradually become a hot spot. The direct evaporative solar energy jet refrigeration system is studied. The system eliminates the generator of the traditional solar energy refrigeration system, and the refrigerant evaporates directly in the collector, which not only provides the power for the ejector. The compressor with ejector instead of traditional refrigeration system has simple structure and low cost of operation and maintenance. Firstly, the thermodynamic analysis of direct evaporative solar energy jet refrigeration system is carried out. Then the mathematical models of solar energy collector, ejector, evaporator, condenser, expansion valve and circulating pump are established respectively. The design and calculation of solar energy collector and ejector are mainly carried out. The solar irradiance is 800W / m2, the inlet velocity is 0.047m / s, and the outlet pressure is 2.65MPa. The heat collector is numerically simulated to study the phase change of the refrigerant in the tube, and the variation trend of the gas content and the temperature of the tube wall is obtained. Based on the theory of gas dynamics, the temperature of 80 鈩，

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