Flow boiling heat transfer deterioration characteristics and its criterion in horizontal helically-coiled tube

An investigation was experimentally carried out with R134a to explore flow boiling heat transfer deterioration characteristics and its prediction criterion in horizontal helically-coiled tubes. The results show that in high quality area, the inside wall temperature soars generally and then the outer wall temperature rises in low mass flow rate; but their take-off point spacing is small and rising point is about the quality of 0.73. The inside and outside wall temperature soars nearly simultaneously in high mass flow rate, and rising point is about the quality of 0.78. The relationship between the critical heat flux and the quality and the influence of heat flux on the average heat transfer coefficient are analyzed. Based on the experimental results, the prediction model of heat transfer deterioration for flow boiling heat transfer in the horizontal helically-coiled tube is developed. It is verified that the predicted values are in agreement with the experimental values. © 2015, Southeast University. All right reserved.