Augmentation of in-tube evaporation and condensation with micro-fin tubes using refrigerants R-113 and R-22

The effect of oil on heat transfer and pressure drop during evaporation and condensation of refrigerant inside augmented tubes

“…Khanpara [119] and Khanpara et al [120][121][122] published results from an extensive investigation attempting to optimize micro-fin geometry. Evaporation was investigated with R-113 and R-22 in both electrically and fluid heated tubes.…”

“…Khanpara [119] and Khanpara et al [149] tested the condensing performance of several micro-fin tubes with both R-22 and R-113. With R-113, heat transfer was enhanced by as much as 3.8 times for some conditions, but the enhancement factor was more typically in the range of 2.0 to 2.2 for the better tubes.…”

“…[118] Spiral micro-fin ? Khanpara et al [119][120][121][122] Spiral micro-fin R-22,R-113 Panchaletal. [110] Spirally fluted R-11,R-114 Reid et al [111] Micro-fin and low-fin [131][132][133] Twisted tape R-113 Reid et al [111] Twisted tape R-113 [142][143][144] Internal flns R-113 Tatsumietal.…”

Heat transfer and pressure drop during condensation of refrigerant 134a in an axially grooved tube

“…, (9) equations (18), (19) 1 author to whom comments should be addressed; (217- (6) equation (13) equation (12) Enhancement of tube heat transfer without an equivalent increase of pressure drop is an active area of investigation in the refrigeration and air conditioning fields [1][2][3][4][5][6][7][8][9][10][11][12][13]. "Micro-fin" enhancements are of special interest because little, if any, additional material is required for inscribing the internal tube surface with structures that can result in high heat transfer increases.…”

“…Most studies have investigated "helical" micro-fin tubes [3,[5][6][7][8][9][10][11][12][13] that are more readily available commercially. Additionally, many of the experimental studies have obtained average results rather than local heat transfer and pressure drop data.…”