A Model for Condensation Inside Minichannels

Abstract

Present authors have measured heat transfer coefficients (Cavallini et al. [1, 2]) and pressure drops (Cavallini et al. [3, 4]) during condensation of R134a, R410A and R236ea inside a flat multiport mini-channel tube with a 1.4 mm hydraulic diameter. The experimental heat transfer coefficients (α) have been compared against correlations available in the literature and no correlation was able to predict α in all the experimental conditions. The present paper suggests a heat transfer model for condensation inside minichannels, based on analogy between heat and momentum transfer. The proposed procedure takes into account the effect of the entrainment rate of droplets from the liquid film. The model is applied to the annular, annularmist flow. A simplified version of the model is also presented. Comparisons between present authors’ data and predicted values show the satisfactory behaviour of both versions of the models.