A distributed enthalpy model for the calculation of humid air condensers with long narrow channels using a modified Merkel method

A distributed enthalpy model for flow condensation of humid air in long narrow channels is presented in this paper. The model is based on the Merkel method which treats the simultaneous heat and mass transfer between humid air and wet surfaces, with the condensate interfacial waviness effect modified by several correction methods. Experimental data obtained from condensation tests at constant wall temperature conditions are used to validate the model. Results show that the presented model is capable of predicting the distributions of fluid temperature, specific humidity and condensate flow rate in the channel with adequate accuracy. This distributed enthalpy model is simple for condensation calculations in condensers such as plate-fin heat exchangers.