The effect of vapour super-heating on hydrocarbon refrigerant condensation inside a brazed plate heat exchanger

This paper investigates the effect of vapour super-heating on hydrocarbon refrigerant 600a (Isobutane), 290 (Propane) and 1270 (Propylene) condensation inside a brazed plate heat exchanger. Vapour super-heating increases heat transfer coefficient with respect to saturated vapour, whereas no effect was observed on pressure drop. The super-heated vapour condensation data shows the same trend vs. refrigerant mass flux as the saturated vapour condensation data, but with higher absolute values. A transition point between gravity controlled and forced convection condensation has been found for a refrigerant mass flux around 15-18 kg m(-2) s(-1) depending on refrigerant type. The super-heated vapour heat transfer coefficients are from 5% to 10% higher than those of saturated vapour under the same refrigerant mass flux. The experimental heat transfer coefficients have been compared against Webb (1998) model for forced convection condensation of super-heated vapour: the mean absolute percentage deviation between the experimental and calculated data is +/- 18.3%. HC-1270 shows super-heated vapour heat transfer coefficient 5% higher than HC-600a and 10-15% higher than HC-290 together with total pressure drops 20-25% lower than HC-290 and 50-66% lower than HC-600a under the same mass flux. (C) 2011 Elsevier Inc. All rights reserved.