人字形微翅片管和涟漪纹管对流蒸发和冷凝的传热机理研究

发布时间：2018-06-25 04:59

本文选题：人字形微翅片管 + 涟漪纹管　；参考：《浙江大学》2016年博士论文

【摘要】：在过去的几十年里,强化传热技术有了很大的发展。强化传热技术,能够提高换热设备的效率,减小重量和体积。不过随着工业不断的发展,对于传热技术的要求也越来越高,需要对强化传热技术进行更多的研究。另外,随着人们对于环境问题越来越多的关注,寻找新一代制冷工质来替代有温室效应的制冷剂,也迫在眉睫。本文对光管、人字形微翅片管和涟漪纹管三种铜管进行了实验研究,铜管的外径是12.7mm,内径是11.43mm,实验测量的单管长度是1.9m,换热工质采用R22,R410A和R32三种不同制冷剂。单相实验采用R22为换热工质,制冷剂的饱和温度为49℃,制冷剂质量流速为130-246.8kg/(m2s),热流量为6.43-14.9kW/m2。实验结果表明,光管的单相换热系数最低。人字形微翅片管的单相换热系数明显高于光管,为光管的1.16-1.35倍。涟漪纹管的单相换热系数最高,是光管的1.75-1.95倍。光管的单相换热系数明显比Gnielinski关联式的预测值要高出很多,是关联式预测值的1.24-1.31倍。光管内的单相压降最低,人字形微翅片管的压降比光管要大,随着雷诺数的增大,人字形微翅片管与光管的压降趋于接近。涟漪纹管的压降最高,是光管的2.14-2.70倍。涟漪纹管的综合性能因子是1.34-1.40,说明涟漪纹管的综合性能是很好的,人字形微翅片管的综合性能因子是0.91-1.37。冷凝实验采用R22,R410A和R32为换热工质,质量流速为56.2-178.5kg/(m2s),热流密度为9.9-30.4kW/m2。其中R22和R410A的冷凝饱和温度为47℃,进出口干度分别是0.8和0.2；R32的冷凝饱和温度为45℃,进出口干度分别是0.8和0.1。光管的冷凝换热系数最低,人字形微翅片管的冷凝换热系数最高,大约是光管的2.3-3.2倍。涟漪纹管的冷凝换热系数大约是光管的1.3-2.0倍。采用光管内冷凝换热关联式对光管实验结果进行对比,关联式分别采用：Haraguchi关联式,Shah关联式,Dobson和Chato关联式和Cavallini关联式。对人字形微翅片管内冷凝换热系数也和关联式进行对比,关联式采用：Kedzierski和Goncalves关联式,Cavallini关联式和Olivier关联式。并且对三种制冷剂的换热系数进行对比,分析不同制冷剂的换热效果。蒸发换热实验采用了三种不同的制冷剂,分别是R22,R410A以及R32,制冷剂的蒸发饱和温度选取6℃。其中,制冷剂R22和R410A的进出口干度分别是0.1和0.9,制冷剂R32的进出口干度分别是0.1和0.8。制冷剂的质量流速为53.1-140.9kg/(m2s),热流密度为13.9-36kW/m2。光管内蒸发换热系数是最低的。涟漪纹管的蒸发换热系数是最高的,人字形微翅片管的蒸发换热系数介于光管和涟漪纹管之间。采用Wojtan提出的流型分析方法对蒸发过程的流型进行分析,发现蒸发实验过程处于弹状流+分层流/波状流和分层流/波状流区域,并没有达到环形流的状态。另外对光管内的蒸发换热系数采用修正的Wojtan关联式和Liu关联式进行对比。人字形微翅片管和涟漪纹管的气液两相压降采用R22为工质,进出口平均干度是0.55。人字形微翅片管的压力损失比光管的理论值要高很多,涟漪纹管的两相压降最高。人字形微翅片管的压降和关联式的吻合程度很高。
[Abstract]:In the past few decades, the enhancement of heat transfer technology has developed greatly. The enhancement of heat transfer technology can improve the efficiency of heat transfer equipment and reduce the weight and volume. However, with the continuous development of industry, the demand for heat transfer technology is becoming more and more high. More research on heat transfer technology is needed. In addition, with the environment of people The problem is more and more concerned. It is also imminent to find a new refrigerant to replace the refrigerant with the greenhouse effect. In this paper, three kinds of copper tubes, such as light tube, human shaped micro fin tube and ripple tube, are studied experimentally. The outer diameter of the copper tube is 12.7mm, the diameter of the tube is 11.43mm, the length of the single tube is 1.9m, the heat exchanger uses R22, R410A And R32 three different refrigerants. The single-phase experiment uses R22 as the heat exchanger, the saturation temperature of the refrigerant is 49 C, the mass velocity of the refrigerant is 130-246.8kg/ (M2S). The heat flux is 6.43-14.9kW/m2. experimental results show that the single-phase heat transfer coefficient of the tube is the lowest. The single-phase heat transfer coefficient of the human shaped micro fin tube is obviously higher than that of the light tube, which is the 1.16-1 of the light tube. .35 times. The single-phase heat transfer coefficient of ripple tube is the highest, which is the 1.75-1.95 times of the light tube. The single-phase heat transfer coefficient of the light tube is much higher than that of the Gnielinski correlation formula. It is the 1.24-1.31 times of the correlation prediction value. The single-phase pressure drop in the tube is the lowest, the pressure drop of the human shaped micro fin tube is larger than the light tube, and with the increase of the Reynolds number The pressure drop of the shaped micro fin tube is close to that of the light tube. The pressure drop of the ripple tube is the highest and the 2.14-2.70 times of the light tube. The comprehensive performance factor of the ripple tube is 1.34-1.40, which indicates that the comprehensive performance of the ripple tube is good. The comprehensive performance factor of the human shaped micro fin tube is that the 0.91-1.37. condensation experiment uses R22, R410A and R32 as the heat exchanger. The mass flow rate is 56.2-178.5kg/ (M2S), and the heat flux density is 9.9-30.4kW/m2., and the condensation saturation temperature of R22 and R410A is 47, 0.8 and 0.2, respectively. The condensation saturation temperature of R32 is 45, the dry degree is 0.8 and the 0.1. tube has the lowest condensation heat transfer coefficient, and the condensation heat transfer coefficient of the human shaped micro fin tube is the highest. It is about 2.3-3.2 times of the light tube. The condensation heat transfer coefficient of ripple tube is about 1.3-2.0 times of the light tube. The correlation formula of the light tube is compared with the condensation heat transfer correlation in the light tube. The correlation formula is used for the Haraguchi correlation, the Shah correlation, the Dobson and Chato correlation and the Cavallini correlation. The condensation heat transfer in the tube of the human shaped micro fin tube is used. The correlation formula is also compared with the correlation formula: Kedzierski and Goncalves correlation, Cavallini correlation and Olivier correlation. And the heat transfer coefficient of the three refrigerants is compared and the heat transfer effect of different refrigerants is analyzed. The evaporation heat transfer experiment uses three different refrigerants, R22, R410A and R32, respectively. The evaporation saturation temperature of the agent is 6 degrees centigrade, of which the dryness of the refrigerant R22 and R410A is 0.1 and 0.9 respectively. The mass flow rate of the refrigerant R32 is 0.1 and the 0.8. refrigerant is 53.1-140.9kg/ (M2S). The heat flux is the lowest in the 13.9-36kW/m2. tube, and the evaporation heat transfer coefficient of the ripple tube is the evaporation heat transfer coefficient is the lowest. The evaporation heat transfer coefficient of the human shaped micro fin tube is between the light tube and the ripple tube. The flow pattern analysis method proposed by Wojtan is used to analyze the flow pattern of the evaporation process. It is found that the evaporation experiment process is in the elastic flow + stratified flow / wave flow and the stratified flow / wave flow region, and does not reach the state of the annular flow. In addition, the light tube is not reached. The internal evaporation heat transfer coefficient is compared with the modified Wojtan correlation and Liu correlation. The gas liquid two phase pressure drop of the human shaped micro fin tube and ripple tube adopts R22 as the working medium. The average dry degree of the import and export is the pressure loss of the 0.55. shaped micro fin tube higher than that of the light tube, and the two phase pressure drop of the ripple tube is the highest. The pressure drop of the finned fin tube is highly consistent with the correlation.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TK124

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