The Effect of Maximum Allowable Payload Temperature on the Mass of a Multimegawatt Space Based Platform

Calculations were performed to determine the mass of a space based platform as a function of the maximum allowable operating temperature of the electrical equipment within the platform payload. Two computer programs were used in conjunction to perform these calculations. The FIRST program was used to determine the mass of the platform reactor, shield, and power conversion system. The second program was used to determine the mass of the main and secondary radiators of the platform. The main radiator removes the waste heat associated with the power conversion system and the secondary radiator removes the waste heat associated with the platform payload. These calculations were performed for both Brayton and Rankine cycle platforms with two different types of payload cooling systems: a pumped-loop system (a heat exchanger with a liquid coolant) and a refrigerator system. The results indicate that increases in the maximum allowable payload temperature offer significant platform mass savings for both the Brayton and Rankine cycle platforms with either the pumpedloop or refrigerator payload cooling systems. Therefore, with respect to platform mass, the development of high temperature electrical equipment would be advantageous.