and feeds the cooled gas into the rotor cavity. The alternator is cooled by a combination of the cooled gas and liquid coolant from the heat rejection system. Ducting and structural ties connect the BRU with the balance of the PCU and receiver. The recuperator and cycle gas cooler form an integrated heat exchanger. There are double containment features at joints in pressure boundaries throughout both recuperator and gas cooler. The accumulator, which is the major part of the gas management system, is located along side of the BRU. The functions of the two heat exchangers and the accumulator are described in the section on principles of operation. Control equipment located in the electrical equipment assembly (EEA) controls the BRU speed, alternator output voltage, power level, and start-stop functions. Electric power produced by the BRU which is not delivered to the power distribution system because of low demand is passed to the parasitic load radiator (PLR), a resistive load which radiates the excess load as heat to space. The PLR also absorbs and radiates transient power excess during system load changes to maintain the proper BRU speed. Lastly, the PLR, together with the controls, regulates the steady state speed of the BRU. The PCU is described in greater detail in Ref. [3]. The total mass of the various components and assemblies which make up the PCU is expected to be about 800 kg (1760 lb). Heat Rejection Assembly. The heat rejection assembly consists of a pumped liquid loop which collects the waste heat from the thermodynamic cycle and electrical components and transfers it to a deployable radiator, and the radiator itself. Fig. 11 shows the dominant part of this assembly, the radiator which is designed to reject about 100 kW of thermal power to space. The radiator is a deployable structure consisting of eight 8.7 m (26.4 ft) by 2.5 m (7.5 ft) panels connected together by flexible fluid-carrying
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