Abstract: Relatively small diameter heat pipes having generally horizontally arranged evaporator sections and inclined or vertically oriented condenser sections are provided with a flow separator for conducting working fluid vapor from the evaporator section to the condenser section and liquid working fluid is returned to the evaporator section in the flow passage formed between an outer cylindrical tubular member and an inner cylindrical member forming the flow separator. The flow separator may be formed as a cylindrical tube positioned within the outer tubular envelope such that the ends of the flow separator are open and are spaced from the end closures of the outer tube by a small distance. The hydraulic radius of the inner tube flow path is equal to or greater than the hydraulic radius of the annular passage formed between the tubes.

Abstract: A system for recovering waste heat from a stream of heated gas is disclosed. The system includes a convection heat transfer chamber, a boiler tank, and a plurality of heat pipes thermally interconnecting the convection heat transfer chamber with the boiler tank. Each of the heat pipes includes an evaporator section which is disposed in heat transfer relation with a stream of heated gas flowing through the convection heat transfer chamber, and a condenser section disposed in heat transfer relation with a volume of water disposed within the boiler tank. The evaporator sections and condenser sections are totally enclosed within the convection heat transfer chamber and boiler tank, respectively, and are connected in closed cycle fluid communication with each other.

Abstract: A system for recovering waste heat from a stream of heated gas is disclosed. The system includes a convection heat transfer chamber, a boiler tank, and a plurality of heat pipes thermally interconnecting the convection heat transfer chamber with the boiler tank. Each of the heat pipes includes an evaporator section which is disposed in heat transfer relation with a stream of heated gas flowing through the convection heat transfer chamber, and a condenser section disposed in heat transfer relation with a volume of water disposed within the boiler tank. The evaporator sections and condenser sections are totally enclosed within the convection heat transfer chamber and boiler tank, respectively, and are connected in closed cycle fluid communication with each other.

Abstract: A unit for recovering thermal energy which utilizes a plurality of unique heat pipes, and the method and apparatus for fabricating the heat pipes is disclosed. The heat pipes are disposed horizontally and are filled with a volume of working fluid sufficient to cause the liquid phase to travel in either direction by gravity. Circumferential capillary grooves in the side walls of the heat pipes transport the liquid phase vertically above the liquid level to increase the area of the liquid-vapor interface. Additionally, the solid metal strips which form the grooves provide a low impedance thermal path from the walls of the heat pipe to the liquid-vapor interface where evaporation and condensation occur. These two factors significantly increase the efficiency of the system. A divider plate having an X-shaped cross section separates the liquid phase from the high velocity vapor phase to prevent slugging under high energy transfer conditions.

Abstract: A thermal transfer system comprising a closed, generally horizontally disposed tubular envelope having heat transfer fins mounted at axially spaced points along its outer surface is disclosed. The interior surface of the tubular envelope has a large number of small circumferentially extending capillary grooves characterized by a restricted opening relative to the base of the grooves. A liquid phase/vapor phase working fluid is contained within the envelope with the liquid phase normally comprising about 50 to about 75 percent of the volume of the envelope at normal operating temperatures. A liquid phase return tube rests on the bottom of the envelope and is open at both ends. The liquid phase return tube has an inside diameter of about 30 to about 40 percent of the inside diameter of the tubular envelope and has a length of between about 65 percent and about 85 percent of the length of the envelope.

Abstract: Hydrogen barriers which comprise liquid metals in which the solubility of hydrogen is low and which have good thermal conductivities at operating temperatures of interest. Such barriers are useful in nuclear fuel elements containing a metal hydride moderator which has a substantial hydrogen dissociation pressure at reactor operating temperatures.