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An IBM Personal Computer (PC) version of the Groove Analysis Program (GAP) was developed to predict the steady state heat transport capability of axially grooved heat pipes for a specified groove geometry and working fluid. In the model, the heat transport capability of an axially grooved heat pipe, usually governed by the capillary limit, is determined by the numerical solution of the governing equation for momentum conservation with the appropriate boundary conditions. This paper discusses the theory behind the development of the GAP model. It also presents many useful capabilities of the model. Furthermore, correlations of flight test performance data using GAP are presented and discussed.

This paper presents the test results and data correlation for the Heat Pipe Performance Flight Experiment which was a Class D middeck experiment flown aboard the Space Shuttle Columbia (STS-52) in October of 1992. Three categories of heat pipe performance were examined: static mode, operation under applied acceleration, and re-wicking capability. Two aluminum/freon axially grooved heat pipes, ten copper/water axially grooved heat pipes, and four fibrous wick copper/water variable conductance heat pipes were tested. Ground and flight test results for the axially grooved heat pipes are discussed and correlated with analytical models. Correlation of flight test data for cryogenic axially grooved oxygen heat pipes and a description of the Groove Analysis Program (GAP) is also presented.

This paper presents the analytical results of a thermal hydraulic study to determine an “optimum” two-phase heat pipe/heat exchanger radiator panel configuration for the Space Station Freedom. The study was based on using conventional axially grooved heat pipes in combination with integral two-phase heat exchangers. Various design parameters were traded to arrive at an optimized panel design that satisfied the thermal requirements. For two-phase flow across a radiator array consisting of eight panels with fourteen heat pipes per panel, small diameter lines acting as flow restrictions are needed at the exit of each heat exchanger to balance the flow across each panel and the radiator array. The paper also presents the test results with a representative subscale heat pipe/heat exchanger radiator panel. In general, the heat pipes exhibit transport capabilities that exceed the design requirements. Balanced flow across each heat exchanger was also demonstrated.