A tunnel wick 100,000 watt-inch heat pipe.

The tunnel wick is a new type of heat pipe artery which can prime in a gravity environment by temperature-induced pressure differences between interior and exterior. The paper discusses the concept and its application in the design of room-temperature high-transport-capacity heat pipes. The analytical model of the system is summarized; and performance data obtained with the aid of a related computer program is included. Test data verifying the concept is presented for several pipes, including an eight-foot-long, 0.9-inch ID heat pipe, using ammonia working fluid, with a transport capacity in excess of 150,000 watt-inches. A brief discussion of potential applications for this type of heat pipe includes a variable conductance device to serve as a radiator header and a high capacity heat transport system.