The intermediate fluid vaporizer (IFV) is a typical vaporizer of liquefied natural gas (LNG),which in general consists of three shell-and-tube heat exchangers (an evaporator,a condenser,and a thermolator).LNG is heated by seawater and the intermediate fluid in these heat exchangers.A one-dimensional heat transfer model for IFV is established in this paper in order to investigate the influences of structure and operation parameters on the heat transfer performance.In the rated condition,it is suggested to reduce tube diameters appropriately to get a large total heat transfer coefficient and increase the tube number to ensure the sufficient heat transfer area.According to simulation results,although the IFV capacity is much larger than the simplified-IFV (SIFV) capacity,the mode of SIFV could be recommended in some low-load cases as well.In some cases at high loads exceeding the capacity of a single IFV,it is better to add an AAV or an SCV operating to the IFV than just to increase the mass flow rate of seawater in the IFV in LNG receiving terminals.