Automatic Circulation Control of Working Fluid in Liquid Droplet Radiator

Abstract

Liquid Droplet Radiator (LDR) is an important candidate for disposing large quantities of waste heat more than 1 MW which will be handled by large space structures such as Space Power Satellite. The working fluid is heated through a heat exchanger by the waste heat generated in a large structure in space. Then, the working fluid is emitted in space through nozzles of the droplet generator toward a droplet collector as multiple streams of droplets. During the flight in space, the droplets lose thermal energy via radiative heat transfer. After the cooled droplets are captured by the droplet collector, the working fluid is recycled to the heat exchanger by a circulating pump. The automatic control system on the circulation of working fluid in a liquid droplet radiator has been built using a programmable logic controller. The proportional control of flow rate with the term of the variation of the counter flow in the gear pump and the relaxation of the change of an target flow rate has succeeded within 5 percent at the automatic circulation control of the working fluid from 100 ml/min to 200 ml/min and from 200 ml/min to 100 ml/min.