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首页> 外文期刊>International Journal of Refrigeration >Experimental studies on the evaporative heat transfer and pressure drop of CO{sub}2 in smooth and micro-fin tubes of the diameters of 5 and 9.52 mm
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Experimental studies on the evaporative heat transfer and pressure drop of CO{sub}2 in smooth and micro-fin tubes of the diameters of 5 and 9.52 mm

机译：直径为5和9.52 mm的光滑和微翅片管中CO {sub} 2的蒸发传热和压降的实验研究

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摘要

Carbon dioxide among natural refrigerants has gained a considerable attention as an alternative refrigerant due to its excellent thermophysical properties. In-tube evaporation heat transfer characteristics of carbon dioxide were experimentally investigated and analyzed as a function of evaporating temperature, mass flux, heat flux and tube geometry, Heat transfer coefficient data during evaporation process of carbon dioxide were measured for 5 m long smooth and micro-fin tubes with outer diameters of 5 and 9.52 mm. The tests were conducted at mass fluxes of from 212 to 6.56 kg m{sup}(-2)s{sup}(-1), saturation temperatures of from 0 to 20 ℃ and heat fluxes of from 6 to 20 kWm{sup}(-2). The difference of heat transfer characteristics between smooth and micro-fin tubes and the effect of mass flux, heat flux, and evaporation temperature on enhancement factor (EF) and penalty factor (PF) were presented. Average evaporation heat transfer coefficients for a micro-fin tube were approximately 150 - 200% for 9.52 mm OD tube and 170-210% for 5 mm OD tube higher than those for the smooth tube at the same test conditions. The effect of pressure drop expressed by measured penalty factor of 1.2 - 1.3.5 was smaller than that of heat transfer enhancement.
机译：天然制冷剂中的二氧化碳由于其优异的热物理性质而作为替代制冷剂受到了广泛关注。实验研究了二氧化碳在管内的蒸发传热特性，并根据蒸发温度，质量通量，热通量和管的几何形状进行了分析，并测量了5 m长的光滑微管中二氧化碳蒸发过程中的传热系数数据翅片管，外径为5和9.52毫米。测试在212至6.56 kg m {sup}（-2）s {sup}（-1）的质量通量，0至20℃的饱和温度和6至20 kWm的热通量{sup}下进行（-2）。提出了光滑和微翅片管之间的传热特性的差异，以及质量通量，热通量和蒸发温度对增强因子（EF）和损失因子（PF）的影响。在相同的测试条件下，微翅片管的平均蒸发传热系数比外径光滑管的平均蒸发传热系数高150-200％，外径为5mm的管约为170-210％。用测得的罚因子为1.2-1.3.5表示的压降影响小于传热增强的影响。

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