高效相变蓄冷换热管实验研究及性能优化

发布时间：2018-06-19 11:29

本文选题：高温供冷 + 相变蓄冷　；参考：《上海交通大学》2014年硕士论文

【摘要】：在我国能源短缺，电力紧张的情况下，蓄冷空调技术在空调系统中的应用可以起到平衡电网负荷的作用。而目前常见的相变蓄冷换热装置的换热性能普遍不佳，影响了该技术的应用推广。因此，如何有效的强化相变蓄冷换热装置的换热过程是目前研究的热点。本文设计了一种新型高效相变蓄冷换热管，对其换热性能进行了实验研究。在此基础上建立了数学模型，从结构参数及运行参数两方面进行了理论分析及性能预测。主要研究工作如下：（1）结合当前国内外学者的研究成果，对常见的相变蓄冷材料及相变蓄冷换热装置进行了总结与概括。通过横向对比与分析，选择管肋式换热管，结合有机复合相变蓄冷材料进行研究，以提高相变蓄冷系统的换热性能。（2）以油酸、癸酸、月桂酸为基液配置了有机复合相变材料，并通过添加适量纳米粒子改善了材料的传热特性。基于此材料研制了高效管肋式相变蓄冷换热管。在典型高温供冷运行工况下，对相变蓄冷换热管蓄冷、释冷两个过程进行了实验研究。实验结果表明，该管肋式相变蓄冷换热管的蓄冷量及释冷量分别为470KJ及450KJ，平均蓄冷功率为112.7W，平均释冷功率为106.8W。相比于目前常用的封装球相变蓄冷器，该新型管肋式相变蓄冷换热管的换热速率可以提高近40%。（3）采用焓-多孔度法建立该管肋式相变蓄冷换热管的数学模型。通过有限元分析软件Fluent，在第二类边界条件下使用凝固/融化模型进行求解，研究相变材料的温度变化及相界面移动过程。数值模拟结果与实验相对比，蓄冷过程相对误差为8.3%，释冷过程相对误差9.7%，数值模拟结果与实验测试结果吻合度较好（4）研究了相变蓄冷换热管的结构参数以及载热流体运行参数对管肋式相变蓄冷换热管性能的影响。通过数值计算研究了直肋、环肋的强化换热效果；分析表明，当环形肋片间距为40mm，，直肋片密度为9，肋片厚度为1.5mm，直肋宽度为37.5mm时该管肋式相变蓄冷换热管的换热速率最高。相比于实验结果，采用优化结构参数的相变蓄冷换热管可以提高换热速率30.5%。通过计算在不同载热流体温度及载热流体流量的情况下相变蓄冷换热器换热速率，研究了载热流体运行参数对相变蓄冷换热管性能的影响。（5）以该相变蓄冷换热管为换热单元，可以通过并联组合成不同蓄冷量的相变蓄冷换热器。在提高相变蓄冷系统的换热性能的同时，可以灵活的适应不同制冷量的要求。
[Abstract]:In the situation of energy shortage and power shortage in China, the application of cold storage air conditioning technology in air conditioning system can balance the load of power grid. At present, the heat transfer performance of phase change storage heat exchanger is generally poor, which affects the application of this technology. Therefore, how to effectively enhance the heat transfer process of phase change storage heat exchanger is a hot topic at present. In this paper, a new type of high efficiency phase change heat storage tube is designed and its heat transfer performance is studied experimentally. On this basis, the mathematical model is established, and the theoretical analysis and performance prediction are carried out from two aspects: structure parameters and operation parameters. The main research work is as follows: 1) combined with the current research results of domestic and foreign scholars, the common phase change storage materials and phase change heat exchanger are summarized and summarized. In order to improve the heat transfer performance of the phase change storage system, the tube rib heat transfer tube was selected and the organic composite phase change storage material was used to improve the heat transfer performance of the phase change storage system through transverse comparison and analysis. (2) oleic acid, sebacic acid, Lauric acid was used as the base solution of organic composite phase change material, and the heat transfer property of the material was improved by adding proper amount of nanoparticles. Based on this material, the high-efficiency tube rib phase-change heat transfer tube was developed. In the typical high temperature cooling operation condition, the two processes of phase change heat storage tube storage and cold release are studied experimentally. The experimental results show that the cold storage capacity and release rate of the ribbed phase change heat storage tube are 470KJ and 450 KJ respectively, the average storage power is 112.7W and the average cool-releasing power is 106.8W. Compared with the encapsulated spherical phase change accumulator, the heat transfer rate of the new tube rib type phase change storage tube can be increased by nearly 40%. 3) the mathematical model of the tube rib type phase change heat storage tube is established by using enthalpy-porosity method. By using the finite element analysis software Fluent. the solidification / melting model is used to study the temperature change and phase interface movement of the phase change material under the second boundary condition. The numerical simulation results are compared with the experimental results. The relative error of the cold storage process is 8. 3 and the relative error of the release process is 9. 7. The numerical simulation results are in good agreement with the experimental results. (4) the structural parameters of the phase change heat storage tube and the operation parameters of the heat carrying fluid are studied. Effect of ribbed phase change storage tube on performance. The heat transfer effect of straight rib and ring rib is studied by numerical calculation, and the results show that the heat transfer rate of the tube is the highest when the space of ring rib is 40mm, the density of straight rib is 9, the thickness of rib is 1.5mm, and the width of straight rib is 37.5mm. Compared with the experimental results, the phase change heat transfer tube with optimized structure parameters can increase the heat transfer rate by 30.5%. The heat transfer rate of phase change heat storage heat exchanger is calculated under different temperature and flow rate of heat carrier fluid. The effect of operation parameters of heat carrier fluid on the performance of phase change heat storage tube is studied. Using the phase change heat storage tube as heat exchanger unit, the phase change heat storage heat exchanger with different storage capacity can be formed in parallel. While improving the heat transfer performance of phase change storage system, it can adapt to different refrigerating capacity flexibly.
【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】：TB657.5

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