Investigation of a gravity-immune chip-level spray cooling for thermal protection of laser-based wireless power transmission system

Aiming to enhance the on-board thermal protection platform for the space laser-based wireless power transmission (WPT) system which is essential for the development of distributed space systems, an improved gravity-immune closed-loop spray cooling system with an ejector loop is proposed in this paper. The gravity-immunity features its design of the novel fluidic loop, uncovering the reliability of the future in-orbit test and potential of the practical deployment of the spacecraft thermal management. The biggest innovation of the fluidic loop lies in the integration of the spray cooling loop and an ejector loop which is to create a local low pressure area without any rotary mechanical components for the purpose of consistently removing the liquid–vapor mixture from a relatively high pressure in the spray chamber guaranteeing a relatively high operation efficiency. Ground-based experimental set-up was established to test the feasibility of the system's operation mechanism, based on which thermal tests were organized to study the practical heat dissipation capability in both continuous and periodic operating tasks. The largest critical heat flux (CHF) could go or be up to 705 W/cm² and optimal efficiency at CHF was calculated to be 9.34% in the continuous mode. Additionally, nozzle inlet temperature with high subcooling degree is preferred in the periodic mode.