Study on the criterion of the onset of heat transfer deterioration for supercritical CO2 in upward flow

Abstract

Supercritical fluid heat transfer deterioration (HTD) tends to lower the heat transfer capacity and should be avoided in designing and optimizing heat transfer equipment. It is essential to establish accurate criteria for predicting the onset of HTD. In this study, an experimental investigation of supercritical CO2 in a heated tube with diameters of 8 and 14.5 mm was conducted. By integrating the data obtained from this experiment with experimental data from the published literature, a large dataset covering a wide range of parameters was constructed. Eleven HTD criteria that are only applicable to other fluids and ten HTD criteria that can be applied to supercritical CO2 were compared and evaluated with the experimental dataset. Results show that most of the correlations established for other fluids cannot be directly adapted to CO2. The criteria that only consider mass flux are not accurate for predicting the onset of HTD. With a detailed analysis of the influence pattern of each system parameter on HTD, a new criterion incorporating multiple influencing factors was established. Excellent prediction accuracy of the new criterion was observed from the validation with the experimental dataset.