Research On Condensation Heat Transfer And Enhancement Of Different Refeigerants On Helical Groove Petal-shaped Fin Tubes

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.