Liquid Droplet Radiator Based on Results of Microgravity Experiments

Paper number

IAC-08.C3.3.4

Author

Prof. Tsuyoshi Totani, Hokkaido University, Japan

Coauthor

Mr. Yuta Niki, Hokkaido University, Japan

Coauthor

Prof. Harunori Nagata, Hokkaido University, Japan

Year

2008

Abstract

Disposing of large quantities of waste heat is one of the technical issues that must be considered in order to realize large space structures, which handle high power (from megawatts to gigawatts), such as the SPS.  The liquid droplet radiator (LDR) is an important candidate for resolving this issue.  Its lightweight structure, high resistance to meteorite impacts, small storage volume requirement at launch and easy deployment in space make it a very attractive heat rejection system.

The LDR, which consists of a droplet generator, a droplet collector, a circulating pump and a heat exchanger, circulates working fluid as follows.  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 from the droplet generator to the droplet collector 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.

We have cleared the thresholds between splashing and capturing of a single stream of droplets at a droplet collector from experiments under microgravity and a vacuum.  We have calculated the waste heat that LDR disposes under the condition capturing droplets at a droplet collector.

As the result, the LDR of which the width of the droplet generator is 65.1 m, the distance from the droplet generator to the droplet collector is 147 m and the thickness of droplet streams is 0.998 m can dispose waste heat of 6.13 MW.  We reported the change of waste heat to the diameter and velocity of droplets, the size of LDR, and the working fluids.

Abstract document

IAC-08.C3.3.4.pdf

Manuscript document

(absent)