翅片管式蒸发器低温结霜工况性能实验研究

发布时间：2018-07-07 08:26

本文选题：翅片管蒸发器 + 结霜工况　；参考：《河南科技大学》2014年硕士论文

【摘要】：在低温制冷系统中，翅片管蒸发器表面结霜现象很常见，霜的产生一方面增加了热阻，另一方面减少了空气流通面积，导致蒸发器的换热性能恶化。尤其是在低温高湿环境下，蒸发器的结霜将直接影响蒸发器乃至整个系统的安全与稳定运行，所以对蒸发器结霜工况动态性能的实验和模拟研究就显得尤为重要。本文利用包括一个封闭的带加热，加湿、风速控制的风道循环系统和蒸汽压缩式制冷系统的换热器低温结霜工况性能实验系统，测试在不同的的入口空气温度、湿度、流速等环境参数下，翅片管式蒸发器低温结霜工况的结霜量，制冷量，COP、进出口空气侧压降和能量传递系数的变化以及制冷量、COP、空气侧压降等随霜层增长的变化情况，分析环境参数对翅片管蒸发器性能的影响，，并对蒸发器试件不同工况下的融霜时机进行了定量分析。建立了结霜工况下翅片管蒸发器空气侧流动和换热的分布参数仿真模型，模型考虑了在气流方向上蒸发器结构、霜层厚度以及湿空气状态等参数沿程变化的影响。编制了适用于不同空气流态和蒸发器结构的翅片管蒸发器动态结霜过程模拟计算程序，对蒸发器的结霜量、制冷量、能量传递系数和进出口空气侧压降等性能参数进行计算，并通过对比分析实验结果和模拟计算结果发现，在6小时的结霜过程中，实验值和模拟计算值的误差最大值在14%以内，两者间吻合较好，证明了所建立的分布参数模型的准确性，并可用模型进行结霜工况下翅片管蒸发器性能的正确预测和优化分析。在此基础上，进一步分析蒸发器的结构参数对蒸发器性能的影响和霜层密度和厚度的变化规律，并对如何抑制结霜，提高蒸发器的综合换热性能进行了分析，提出了4点改进建议。对翅片管蒸发器低温结霜工况性能研究，为环境参数优化、蒸发器结构设计改进和融霜周期的确定提供了重要的实验依据和设计参考。
[Abstract]:Frosting on the surface of finned tube evaporator is very common in low temperature refrigeration system. On the one hand, the formation of frost increases the thermal resistance, on the other hand, it reduces the air circulation area, which leads to the deterioration of heat transfer performance of evaporator. Especially in the low temperature and high humidity environment, the frosting of evaporator will directly affect the safe and stable operation of evaporator and even the whole system, so the experimental and simulation study on the dynamic performance of evaporator frosting condition is particularly important. In this paper, an experimental system for the performance of heat exchangers under low temperature frosting conditions including a closed air channel circulation system with heating, humidification, wind speed control and steam compression refrigeration system is used to test the air temperature and humidity at different inlet. Under the environmental parameters such as flow rate, the frosting rate, the refrigerating capacity of the finned tube evaporator under the condition of low temperature frosting, the change of the inlet and outlet air pressure drop and the energy transfer coefficient, and the variation of the refrigerating capacity and the air side pressure drop with the increase of the frost layer, The influence of environmental parameters on the performance of finned tube evaporator was analyzed. The simulation model of air side flow and heat transfer parameters of finned tube evaporator under frosting condition is established. The influence of evaporator structure, frost thickness and wet air state along the flow direction is considered in the model. A simulation program for dynamic frosting process of finned tube evaporator with different air flow states and evaporator structures has been developed. The performance parameters of evaporator, such as frosting amount, refrigerating capacity, energy transfer coefficient and inlet and outlet air side pressure drop, have been calculated. By comparing and analyzing the experimental results and the simulation results, it is found that the maximum error between the experimental values and the simulated ones is within 14% during the frosting process of 6 hours, which is in good agreement with each other. The veracity of the established distributed parameter model is proved, and the model can be used to predict and optimize the performance of finned tube evaporator under frosting condition. On this basis, the influence of evaporator structure parameters on evaporator performance and the variation of frost density and thickness are further analyzed, and how to restrain frosting and improve the comprehensive heat transfer performance of evaporator is analyzed. Four suggestions for improvement are put forward. The research on the performance of finned tube evaporator under low temperature frosting condition provides an important experimental basis and design reference for the optimization of environmental parameters, the improvement of evaporator structure design and the determination of frost melting cycle.
【学位授予单位】：河南科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB657

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