Investigation of gravitational effects on a variable conductance heat pipe utilizing liquid crystal thermography

Abstract

Observations were made of the operation of a gas loaded, variable conductance heat pipe two inches in diameter and sixty inches long. The heat pipe was operated in the horizontal and vertical positions while input power was varied from twenty five to one hundred fifty watts. Liquid crystal thermographic techniques were used to observe the temperature gradients existing when non-condensible gases both heavier and lighter than the working fluid had been introduced. Methanol was used as the working fluid; krypton and helium were the non-condensible gases. Isothermal maps, photographs of liquid crystal displays, and summarized temperature data for the various operating conditions are presented.