DESIGN OF A TRANSIENT, TEMPERATURE CONTROL SYSTEM FOR A LOW-TEMPERATURE INFRARED OPTICAL TEELESCOPE UTILIZING A RAMAI R-COOLED THERMOELECTRIC ASSEMBLY AS THE CONDENSER OF A TWO-PHASE COOLING SYSTEM

摘要

The design of a thermal management system for an airborne, infrared, optical telescope system is described. This system provides transient thermal management for the optical elements of the system beginning at a high-temperature soak condition of 71°C (159.8℉) on the ground to a low-temperature operating condition of -30°C (-22℉) to -40°C (-40℉) within 45 min after aircraft takeoff. An active cooling system is employed to enable this rapid cooldown. In addition to the low-temperature requirement, the mirrors and lenses must be cooled so that temperature gradients across the optical elements are on the order of 1°C (33.8℉) to 2°C (35.6℉). The ambient air available for ground cooling is specified by the military environment to be 55°C (131.0℉). As the aircraft takes off and climbs to an altitude of 11,582.4 m (38 kft), the ambient air temperature decreases to a low-temperature of -22°C (-7.6℉) for steady, level flight at at Mach 0.9, this ambient air temperature results in a ram air inlet temperature on the order of 13.5°C (56.3℉), after the air is captured and diffused to Mach 0.2 prior to entry into a ram air heat exchanger. This ram air heat sink is used to provide a chilled liquid for cooling of optical elements and the turret housing the system.