Fluid-thermal coupling simulation based on a multi-evaporator loop heat pipe with gas-coupled pipelines

Abstract

A multi-evaporator loop heat pipe (MeLHP) is a kind of special-shaped loop heat pipe (LHP) for specific heat transfer scenarios, such as multiple discrete heat sources and large area heat sources. It often utilises the gas coupling method with parallel pipelines to enable the centralised heat dissipation of multiple heat sources to a single heat sink. Not only inherits the flexible, long-distance and efficient heat transfer characteristics of the normal LHP, a MeLHP further exhibits special characteristics caused by pipeline layout and flow distribution due to its special structure. Based on the theory of flow resistance network and thermal resistance network, a MeLHP shunt model is proposed to describe the coupled relationship of fluid heat transfer between the submodules in the MeLHP. The model can calculate the temperature and pressure distribution of the prototype in steady operation. Validation against prototype experiments shows that the model can estimate evaporator wall temperature with a mean residual error of 0.7 %, with all predicted values falling within ±5 %. It also provided a theoretical support for the anisotropic heat sharing characteristics under different heating power distributions. Each case converges within 50s benefit from the employing of the nodal network method, representing a substantial improvement in efficiency compared with traditional CFD tools. Based on the function of performance prediction, the model can be extended to MeLHPs with similar topologies, thereby supporting the future system-level thermal design.