DEVELOPMENT OF 500 W AMMONIA LOOP HEAT PIPE FOR SPACECRAFT THERMAL CONTROL
A Loop Heat Pipe (LHP) has been developed at ISRO Satellite Centre, Bangalore for thermal control of electronic packages on board. An LHP is a two-phase passive device which can transport heat to a long distance from source to sink within a loop. The manufacturing, assembly and testing of 500W ammonia LHP is presented in this paper. The evaporator of a LHP is characterized in a test rig with tube-in-tube heat exchanger at adverse elevations of 0 mm (horizontal) and 500 mm. The performance of evaporator is studied at different heat loads ranging from 100 to 500 W in a test rig with tube-in-tube condenser at a fixed temperature of 5°C. The characterized evaporator is assembled with condenser made up of aluminium extrusions and is mounted on a cold plate with thermal grease as interface material. The thermal performance of the LHP is evaluated at different heat loads in ambient and in thermo vacuum chamber with cold plate at different varied temperatures. The acceptance tests on LHP are also carried out in order to verify proper operation of LHP before integrating in a satellite. The paper reports the manufacturing, testing and aspects of acceptance tests.