Thermal performance analysis of intermediate fluid vaporizer for liquefied natural gas

The intermediate fluid vaporizer (IFV) is a new kind of vaporizer for liquefied natural gas (LNG). A thermal model was established based on the energy balance among the three typical parts of IFV, namely, evaporator, condenser and thermolator, whose mutual coupling and constraints were fully considered. Calculation codes were developed to solve the energy balance equations, in which the formulation of experimental correlations and thermal property codes were incorporated into the iteration. The temperature, pressure and mass flow rate of the inlet LNG and seawater, as well as the heat transfer area of the three parts, were known parameters. The outlet temperature of natural gas (NG) and seawater, the surface and total heat transfer coefficients in the three parts, and the propane saturation temperature were the solution parameters. The effects of the temperature and mass flow of inlet seawater, the pressure, and mass flow rate of inlet LNG on the solution parameters were systematically investigated. The intrinsic link, in terms of the heat transfer performance inside the IFV, was revealed. The outlet temperature of seawater and NG increased with increased temperature and mass flow rate of the inlet seawater and with reduced inlet mass flow rate of LNG. The increased inlet pressure of LNG significantly improved the NG outlet temperature, but this increment has mild influence on the outlet temperature of seawater. The propane saturation temperature also increased with increased temperature and mass flow rate of inlet seawater and with reduced inlet LNG mass flow rate, whereas, it was not sensitive to the inlet LNG pressure. (C) 2014 Elsevier Ltd. All rights reserved.