Design and test of a two-phase monogroove cold plate

A two-phase cold plate has been designed, fabricated, and tested as a candidate heat acquisition component in a two-phase Space Station thermal management system. Derived from the high flux monogroove heat pipe, the cold plate provides fine grooved surfaces from which evaporation occurs. Subcooled liquid enters the plate from a pumped supply in response to a valve that is controlled by an ultrasonic sensor that detects liquid inventory. Essentially, single phase vapor exits the plate. While Freon-11 or ammonia could be used as the working fluid, initial testing has been done with Freon-11. Stable heat loads of 4.0 kW (0.88 W/sq cm) have been achieved with uniform heat input to the 0.58 by 0.87m aluminum cold plate. Nonuniform loads of 3.5kW (1.5 W/sq cm) have also been achieved over half the plate area. Temperatures on the plate mounting surface have been relatively uniform, with a standard deviation of + or - 2.2C at a flux level of 0.76 W/sq cm. Under these conditions, the temperature drop between the plate and vapor was 4.2C. A small amount of liquid carryover evident in the exit vapor stream was measured to be less than 2 percent of mass flow.