LNG vaporizers using various refrigerants as intermediate fluid: Comparison of the required heat transfer area

Abstract

The intermediate fluid vaporizer (IFV) has wide applications in the re-gasification of cryogenic fluids, especially the liquefied natural gas (LNG). In this study, numerical calculations have been conducted to compare the required heat transfer areas of the IFVs utilizing candidate refrigerants of propylene, propane, isobutane, butane and dimethylether and operating under various saturation temperatures. The results show that the heat transfer area of the evaporator increases while that of the condenser decreases with the saturation temperature. The limiting heat transfer steps are identified as the external boiling of dimethylether, isobutane and butane in the evaporator, and the external condensation for all the refrigerants in the condenser. Considering both the required total heat transfer area and the saturation pressure, it is found that propylene and dimethylether are promising refrigerants for an IFV system, besides the widely reported use of propane. These results are of help for assessing the applicability of a refrigerant and its saturation condition in an IFV at the design phase.