Pressure Controlled Heat Pipe for Precise Temperature Control

Abstract

This paper discusses the design and test of a pressure controlled heat pipe (PCHP) for spacecraft thermal management. The PCHP combines a conventional grooved aluminum-anmionia heat pipe with a variable-volume noncondensable gas reservoir to create a heat pipe whose conductance can be precisely controlled. Testing showed that a prototype PCHP was capable of maintaining a stable evaporator temperature within O.IK despite wide swings in heat load and heat sink temperature. A similarly-sized variable-conductance heat pipe (VCHP) yielded temperature swings of over 3.5 K for the same variation of heat load and sink temperature. Using a non-optimized control system, the PCHP was capable of maintaining evaporator temperature within 0.05K over time. The PCHP had a much faster transient response than other devices such as heated-reservoir VCHPs, as well as providing a means for changing the set point temperature after assembly. The PCHP is a significant advance over other means of temperature control, even in its current non-optimized state.

NIM gas controlled sodium heat pipe

“…As a result, these heat pipes can be maintained isothermally. These heat pipes are also called variable conductance heat pipes (VCHPs) and are applied to precision spacecraft thermal control [2], electronics temperature control, and accurate temperature measurements [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22].…”

Pressure Controlled Heat Pipe Solar Receiver for Regolith Oxygen Production with Multiple Reactors

“… Accept non-uniform flux from the solar concentrators  Provide uniform heat flux to the vessels with lunar regolith  Switch Power from one reactor to another as required  Prevent the temperature from dropping when cold regolith is added  Dump excess heat as required All of these requirements can be met with a solar receiver that has Pressure Controlled Heat Pipes (PCHPs) and Constant Conductance Heat Pipes (CCHPs). A PCHP is a variation on a Variable Conductance Heat Pipe (VCHP) that permits control over heat pipe operation by varying the gas quantity or the volume of the gas reservoir 4 . A schematic of a pressure controlled heat pipe is shown in Figure 1, where a linear actuator drives bellows or a piston to modulate the reservoir volume.…”