Loop heat pipes (LHPs) are used in multiple terrestrial and space applications. Transient analysis of conventional and advanced loop heat pipes with complex radiators under varying conditions where the heat load and the effective sink temperature change in time can be best accomplished using Thermal Desktop™.
This paper presents a transient model of a LHP developed using Thermal Desktop™ (Sinda/Fluint). It includes the evaporator connected to the reservoir and condenser with fluid transport lines with bends, flow balancers, and connectors. The condenser is bonded to a honeycomb panel with two face-sheets spreading thermal energy across the radiating surfaces. The model was correlated to the thermal-vacuum test data.
The modeling provided better understanding of the critical transient fluid-flow mechanisms encountered in the LHP under transient operational conditions. Analysis of the numerical results shows that the secondary wick should be transporting liquid from the reservoir to the primary wick during transient operation where the sink temperature is decreasing or the evaporator heat load is being reduced.