As permanent space stations increase in size, there is anattendant increase in the amount of electrical powerthey dissipate. To keep station compartment tempera-tures from exceeding prescribed limits, it is necessaryto transfer the dissipated heat to space. A novel heatrejection scheme that has been proposed for this purpose is termed a Liquid Droplet Radiator (LDR).The heat is first transferred to a high vacuum oil, whichis then injected into outer space as a stream of smalldroplets. The stream is allowed to traverse a distance L,over which it cools by radiating energy to outer space atabsolute zero temperature. The droplets are then col-lected and routed back to the space station.Consider conditions for which droplets of emissivity??0.95 and diameter D?0.5 mm are injected at a tem-perature of Ti?500 K and a velocity of V?0.1 m/s.Properties of the oil are ??885 kg/m3, c?1900 J/ kg?K,and k?0.145 W/m?K. Assuming each drop to radiate todeep space at Tsur?0 K, determine the distance Lrequired for the droplets to impact the collector at a finaltemperature of Tf?300 K. What is the amount of thermalenergy rejected by each droplet?
Spectral Classes O’s and B’s o High masses > 6 M sun o High temperatures > 12,000K o High luminosity > 1,000 L sun o Short lives < 1 billion years o Burn Hydrogen, Helium, Oxygen, Carbon… up to Iron A’s, F’s, G’s o Moderate stars o Generally long lived Up to 20 billion years K’s & M’s...
