Model Simulation of a Two Loop Heat Pipe Thermal Control System in Low Earth Orbit

The Loop Heat Pipe has become increasingly popular among spacecraft engineers for its operational reliability and robustness. At first glance, the LHP seems like a simple capillary-pumped heat transport device. In reality, the thermodynamics and fluid dynamics in the LHP form a complex system, especially during transient operation. The LHP performance varies with power input and sink temperature, but perhaps more importantly, with transitions from one condition to another. In addition, when multiple LHPs are thermally coupled, a change in one LHP can result in a detrimental effect on another. In this paper, model simulations of a thermal control system having two LHPs will be presented to show the system performance during the expected on-orbit thermal conditions of low Earth orbit.