Experimental investigation on a mechanically pumped two-phase cooling loop with dual-evaporator

This paper describes a well-known space activate thermal control system, two-phase mechanically pumped cooling loop (MPCL) with two evaporators, in ground-based testing. Each evaporator has an outer diameter of 3 mm and a length of 10 m and the total loop of the system is about 40 m. Tests conducted mainly included stable operation tests under sinusoidal temperature boundary condition and unbalanced heat load tests. Experimental data showed that the loop operated stably at about 30 °C variation of the boundary temperature without any temperature overshoot. Meanwhile, the operating temperature could be controlled within ±0.1 °C of the set point temperature with the new design based on TECs. Furthermore, heat load unbalanced between the two evaporators was also successfully demonstrated that the loop has a heat transport capability to deal with the maximal unbalanced heat loads limitation as Top_Load/Bottom_Load = 0 W/160 W or Top_Load/Bottom_Load = 130 W/0 W. When the heat load limitation is reached in one evaporator and a dry-out appears, some heat load employed on the other side such as 10 W will recover it to the set point evaporation temperature. In conclusion, important performance characteristics demonstrated by this MPCL included: (1) operation of the system about 30 m with a mechanical pump; (2) robustness and reliability of an MPCL with multiple evaporators; (3) effectiveness of TECs in controlling the MPCL operating temperature; (4) dealing with a large unbalanced heat load among MPCL evaporators; and (5) easy recovery from the pulse boiling or a dried out state.