| Popis: |
This paper describes the development and testing of a miniaturized multi‐evaporator hybrid loop heat pipe (ME‐HLHP), a centralized thermal bus architecture proposed as the next‐generation thermal management system for future small spacecraft. The ME‐HLHP maximizes the advantages of capillary pumped loops (CPLs) and loop heat pipes (LHPs) and mitigates their shortcomings via the use of a secondary LHP‐type evaporator that supplies a small amount of excess liquid flow (“core sweepage”) to each evaporator within a multi‐evaporator parallel network. To validate ME‐HLHP technology, single, dual, and quad‐evaporator breadboard test loops were designed, fabricated, and tested. Breadboard components included miniaturized, cylindrical Teflon wick evaporators for low control power, counter‐flow condensers for freeze tolerance, a back pressure regulator for heat load sharing, a co‐located flow regulator for radiator switching, a cold‐biased heat exchanger for temperature control, and a secondary evaporator/reservoir for core sweepage. With ammonia as the working fluid, a total of 21 tests were carried out with the quad‐evaporator test loop. The results indicated quad‐evaporator transport from 8–280 W, single‐evaporator transport from 2–100 W, maximum heat flux of 30 W/cm2 evaporator conductance of 5–8 W/K, heat load sharing greater than 95%, condenser switching, condenser freeze tolerant design, temperature control of +/− 0.25 K with a variable set‐point, rapid start‐up, control power of 2–3 W, and Teflon evaporator (233–353 K) temperature cycling for durability. This paper will detail all aspects of the study. |
