Challenges involved in implementing Pumped Fluid Loop thermal control systems in high power Nano and microsatellites

Traditional active control techniques such as mechanically pumped fluid systems have been demonstrated successfully on larger conventional satellites, but these techniques are still considered immature for small satellite applications due to various factors. Increasing demand towards small satellite missions among research institutions, universities, and private organizations as a result of less development cost and time, requires improved thermal control technologies to meet the thermal requirements. Presently, most of the CubeSat missions adopt passive thermal control techniques (PTCS) as none of the active systems are well developed for the smaller form factors. Two-phase passive loop heat pipes and active systems such as single-phase and two-phase mechanically pumped fluid loop systems (MPFL) are considered to be efficient systems for any type of satellites with stringent requirements and these systems can transport heat between multiple locations through forced convection. MPFL systems are not a readily available solution to small satellite thermal engineers as there are difficulties such as the radiator, heat exchanger, and fluid loops design constraints, fluid characteristics, mass, and limited available power, etc. Some of the conceptual designs for MPFL are still being proposed, developed, and tested but no satellites have flown in the near past with one of such systems. This paper identifies and explicitly summarizes all the key challenges involved in MPFL thermal control system designs for nano and microsatellites for accommodating cryogenic instruments, miniaturized high power instruments, and space electronics.