6.Hl4 Current technology allows compressor efficiency = .85 and turbine efficiency = .9 Also, BAl rad 6 steel rad 8 kg/m 2 15 kg/m 2 And, as stated in VI.H.4, Tl= 295°K (see VI.G) (see VI.G) A computer program was written to investigate the behavior of the Brayton heat pump system, with T 4 and T 2 varying across the envelope depicted in Figure 6.H4. As an example of the results, consider t~e case of T 4 = 100°K, near its lower limit (see VI.H.4). Pthermal' m, Mrad can then be calculated as functions of T2. Figure 6.H5 graphs these quantitites. When T 2 = 295°K, this corresponds to the passive radiator investigated in section VI.8.4, since neither compressor nor turbine do any work. The values graphed match those calculated in section VI. 8. 4. 500°K, 2.79xl0 6 kg Pthermal 2.93xl0 7 watts m = 170 kg/sec This cuts the passive radiator mass by 74% at the cost of a 28% increase in mass flow and a 523% increase in electrical power input (the passive radiator case required 5.6xl0 6 watts for colony operations and lifestyle).
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