Keeping It Cool in the Air

Keeping It Cool in the Air

Many advanced electronics and photonics systems for future spacecraft and military aircraft, including phased array detectors, radar systems, and fiber laser systems, require effective cooling at very uniform temperature over large areas. Many of these cooling needs can be addressed only with advanced Thermal Management Systems (TMSs). Creare has been actively developing innovative solutions for these systems. The development efforts in this area range from conceptual thermal architecture design, system design trade-off study, critical component hardware design and fabrication, and prototype system integration and demonstration.

The extreme thermal environments and the absence of a constant body force make it very challenging for two-phase TMSs to provide reliable, stable cooling. For example, spacecraft microgravity environments and military aircraft variable acceleration environments present unique challenges to a two-phase TMS, especially for vapor-liquid phase separation. Ineffective vapor-liquid separation in a two-phase pumped loop can cause vapor ingress into the liquid circulation pump, causing the circulation flow rate to abruptly decrease which could lead to thermal runaway in payloads. Similarly, in a vapor compression system, ineffective vapor-liquid separation can cause liquid ingress into the vapor compressor, reducing its reliability.

Gravity Insensitive Condenser

Gravity Insensitive Condenser to recover water from humid process flow for NASA’s Regenerative Life Support System.

For NASA’s future remote sensing science missions, Creare is developing an innovative reconfigurable two-phase pumped loop design. The loop has innovative design features to maintain the temperature of payload electronics within a very tight range of ±30 mK even during most rapid heat sink thermal transients anticipated for spacecraft. The design is made possible by Creare’s membrane vapor-liquid phase separator, actively controlled two-phase accumulator, and freeze-tolerant condenser/radiators. The phase separator incorporates a unique capillary structure with a very large surface area to enable effective vapor-liquid phase separation by surface tension effects. The energy-efficient, active control mechanism in the accumulator precisely regulates the loop pressure to tightly control its cooling temperature. The freeze-tolerant condenser/radiators with variable thermal conductance allow spacecraft to rapidly increase their heat rejection capacity when they emerge from the shadow of planets or moons.

Weibo Chen received his Ph.D. in Mechanical Engineering from The Ohio State University. Dr. Chen’s fields of interest include a wide range of thermal and fluid engineering problems, particularly in two-phase flow thermal management systems, cryogenic cooling systems, and advanced heat exchangers, pumps, and compressors for these systems.  Dr. Chen is pictured above, along with Contracts Administrator Sarah Teffner.

This story was featured in the Fall 2016 edition of Creare’s People & Technology newsletter.