Theoretical and Experimental Analysis of Heat Transfer and Condensation in Micro-Ribbed Tubes

The thermal transmission coefficient for a micro-ribbed tube has been determined using theoretical relationships and the outcomes of such calculations have been compared with experiments conducted using a R1234yf refrig-erant undergoing condensation. In particular four theoretical single-phase flow and three multi-phase flow mod-els have been used in this regard. The experimental results show that: the Oliver et al. criterion equation overestimates the experimental results as its accuracy is significantly affected by the specific conditions realized inside micro -fin tubes; the Miyara et al. criterion equation prediction error is less than 15%; the Cavallini et al. approach gives the highest prediction accuracy; the Goto et al. model overestimates the test data. Such results are critically discussed and some indications for the improvement of such models are provided.