Liquid droplet radiator thermal characteristics

Abstract

The effects of droplet size, emissivity, and spacing on the liquid droplet radiator (LDR) performance space heat rejection system are investigated. The procedures for predicting surface emissivity of semitransparent droplets as a function of absorptivity and radius are examined. The relation between absorptivity, reflectivity, transmissivity, and emissivity is studied. It is observed that for droplets in the 25-200 micron range the radius affects emissivity. The thermal performance of an array of droplet streams is described using a thermal radiation model. Droplet temperatures are calculated; it is shown that outside droplet streams are more effective than interior droplets for arrays in the range of radius to spacing ratio from 0.05-0.2. Temperature distributions as a function of droplet size, emissivity, and velocity are presented. The heat transfer performance of a LDR is evaluated in terms of fin effectiveness. The equivalent sheet emissivities of droplet streams are examined.