Evaporation heat transfer characteristics of R-410A in 7 and 9.52 mm smooth/micro-fin tubes

Flow boiling heat transfer with HFC mixtures in a smooth horizontal tube. Part I: Experimental investigations

“…The experimental heat transfer coefficients obtained during the evaporation of R404A are depicted in Figs Many data have been reported in the Literature that are comparable with those obtained in the course of our experimental work, even though obtained with different sets of experimental conditions (range of variation of vapour quality, evaporation pressure, refrigerant mass flow-rate, heat flux, test tube diameter) [6][7][8][9].…”

Double tube heat exchanger with novel enhancement: part 3—convective condensation

“…Micro-fin tubes have been successfully implemented in the two-phase flow of refrigerants for effective tube-side performance. This success is because of their ability to significantly improve the heat transfer coefficient [26][27][28][29] with only a moderate increase of the friction penalty. The passage geometry of the corrugated tube differs from the microfin tubes by virtue of having corrugations on both inner and outer surfaces.…”

Evaporation heat transfer and pressure drop of R-410A in three 7.0 mm O.D. microfin tubes having different inside geometries

“…Inoue et al [12] also obtained higher heat transfer coefficient (1.2 to 1.5 times) for R-410A than for R-22 from the evaporation test in a 8.0 mm microfin tube with 18 degree helix angle. Kim et al [13] tested two microfin tubes (9.5 mm O.D with 25 degree helix angle and 7.0 mm O.D with 18 degree helix angle) using R-410A for a rather narrow range of mass flux (70 kg/m 2 s ~ 211 kg/m 2 s) The heat transfer enhancement factor ranged from 1.8 to 2.5 for 9.5 mm O.D. microfin tube and from 1.1 to 1.6 for 7.0 mm O.D.…”

“…For 7.0 mm O.D. tube, Kim et al [13] and Hu et al [20], all with 18 degree helix anlge and large apex angles (53 and 40 degree), are the only two avaliable studies other than Hitachi's general investigation [14]. Considering that 7.0 mm O.D.…”