Numerical Investigation on the Condensation of Various Refrigerants Outside Horizontal Plain and Low Finned Tubes at Low Temperatures

In the liquefied natural gas (LNG) intermediate fluid vaporizer (IFV), the condensation of refrigerants outside the LNG tubes is the main factor affecting the regasification efficiency. In this paper, the condensation heat transfer characteristics of refrigerants outside horizontal plain and low finned LNG tubes are investigated at low temperatures through numerical simulation. Based on the VOF model and Lee phase change model, the CFD model is validated with the experimental data for the plain and low-finned tubes. For the plain tube, dimethylether (DME) shows the best heat transfer performances in the seven candidate refrigerants. For the low-finned tubes at high heat flux, the retention angle decreases as heat flux increases. The analytical model overpredicts the retention angle at high heat flux and large fin density. The difference in heat flux between flooded and unflooded regions decreases as wall subcooling increases. The tubes with a fin height of 0.3 mm and a fin density between 25–34 fins per inch show high heat transfer performance for the IFV-condenser. In the four heat transfer correlations, the Honda correlation has the highest prediction accuracy under the IFV condition, with a deviation between −10% and 57%.