Electric fluid heater employing pressurized helium as a heat transfer medium

摘要

An electric fluid heating apparatus includes a closed hollow metallic vessel filled with substantially pure gaseous helium at a pressure from about 30 psl absolute to about 100 psl absolute. At least one electric resistance heating element is disposed in the vessel and surrounded by the pressurized helium which acts as a heat transfer medium to conduct heat from the resistance element to the vessel walls by conduction and convection. The vessel is positioned within a closed container having walls spaced from the vessel to define a fluid flow path for the fluid to be heated. A baffle between the container and vessel divides the flow path into an inlet chamber in which the fluid entering the flow path is preheated and an outlet chamber in which the fluid is heated by contact with the vessel walls prior to discharge from the container through a metal outlet conduit passing through the vessel in contact with the helium for transfer of additional heat to the fluid.