【作者】 熊剑；

【导师】 张正国；

【作者基本信息】 华南理工大学 ， 化学工程， 2010， 硕士

【摘要】 本文研究了饱和蒸汽温度为39℃时,不同制冷工质R22、R134a、R410A和R407C在紫铜光管和螺旋槽花瓣形翅片管管外的冷凝传热性能。文章通过对实验数据的处理和对实验结果的分析,为螺旋槽花瓣形翅片管的工业应用提供一定的参考数据。通过测量各实验管进出口温度、管外饱和蒸汽温度,计算出各实验管的总传热系数,利用威尔逊图解法分离得出螺旋槽花瓣形翅片管管内对流传热系数。再由分离出的公式计算出管外冷凝传热系数。通过误差传递公式,对以实验数据计算得出的螺旋槽花瓣形翅片管的总传热系数K的相对误差进行了分析,结果表明:本实验冷凝器的总传热系数K的相对误差为2.05%。通过改变冷凝温度、冷热水的进出口温度,考察了各制冷工质的总传热系数、管外冷凝传热系数以及管内外热阻等参数。由于螺旋槽花瓣形翅片管能够有效切割管外冷凝液膜,降低传递热阻,螺旋槽花瓣形翅片管有效的提高了R22、R134a、R410A和R407C的管外冷凝传热性能,在相同的壁温差下,R22、R134a、R410A和R407C在螺旋槽花瓣形翅片管管外的冷凝传热系数是紫铜光管的8.60~13.16倍、7.76~11.54倍、10.14~16.28倍、5.52~5.82倍;在相同的热负荷下,螺旋槽花瓣形翅片管对各制冷工质总传热系数明显大于紫铜光管;在实验范围内,各实验管外的冷凝传热系数R410A>R22>R134a>R407C,这主要是由制冷工质的热物理性质决定的,热物理性质强的制冷工质在管外的冷凝传热系数要大于热物理性质弱的;对实验管内外热阻进行分析,发现对于R22、R134a和R410A,在管内雷诺数约小于28000时,冷凝时螺旋槽花瓣形翅片管的管内热阻占主导,是冷凝过程的控制热阻;在管内雷诺数约大于28000时,R22冷凝时螺旋槽花瓣形翅片管的管外热阻占主导,是冷凝过程的控制热阻;对于R407C,在实验范围内,螺旋槽花瓣形翅片管的管外热阻占主导,管外热阻是冷凝过程的控制热阻。更多还原

【Abstract】 In this paper, the condensation heat transfer performance of R22, R134a, R407C and R410A on a purple copper plain tube and a helical groove petal-shaped fin tube were investigated at saturation temperature of 39℃. By means of processing experimental data and analyzing the experimental results, the reference data of helical groove petal-shaped fin tubes for industrial applications was provided.By means of measuring inlet and outlet temperature of each experimental tube, saturated vapour condensation temperature outside of each tube, the overall heat transfer coefficient of each experimental tube was calculated. Besides, the convection heat transfer coefficient was obtained by using wilson plot technology. The heat transfer coefficients(HTCs) on each tube were calculated by the formula of seperation. What’s more, basing on the Erro-transmission formula, a relative errors of overall heat transfer coefficient K have been analyzed. A final results show that relative errors of K is 2.05%.By means of altering condensing temperature, inlet and outlet temperature of each experimental tube, the overall heat transfer coefficient,condensation HTCs and thermal resistance were discussed. The experiment results show that the helical groove petal-shaped fin tube could improve the heat transfer performance of R22, R134a, R407C and R410A effectively, for the reason that a helical groove petal-shaped fin tube could cuts condensation film which is outside of a tube and reduce transfer resistance. Under a same temperature difference between outside-inside pipe, the condensation HTCs of R22, R134a, R407C and R410A on a helical groove petal-shaped fin tube are 8.60～13.16, 7.76～11.54, 10.14～16.28 and 5.52～5.58 times than those on a purple copper plain tube; Under the same heat load, the overall heat transfer coefficient of a helical groove petal-shaped fin tube is larger than a purple copper plain tube obviously; In the experimental range, the HTCs on each tube show that R410A>R22>R134a>R407C, which depend on a thermophysical properties; for R22, R134a and R410A, the inside thermal resistance of the enhanced tubes is the main resistance when Reynolds number is less than 28000, the outside thermal resistance of the enhanced tubes is the main resistance when Reynolds number is less than 28000. For R407C, the outside thermal resistance of the enhanced tubes is the main resistance.更多还原