Closed Brayton cycle schematic

In the closed cycle, the heat is added to the fluid in a heat exchanger from an external heat source, such as a nuclear reactor, and the fluid is cooled in another heat exchanger after it leaves the turbine and before it enters the compressor. A schematic diagram of a closed Brayton cycle is shown in Fig. 4.3. 

Figure 3 contains the schematic of one of the two RELAP5-3D input models of the closed Brayton Cycle (CBC) system. The parallel system is identical. Each of these systems contains a turbine, recuperator, a gas cooler, a compressor, and a shaft connecting the compressor, alternator, and turbine. The gas cooler transfers excess etrergy to a heat rejection system (HRS) which contains NaK as its working fltrid and radiates the energy to space. 

The gas turbine cycle may be either closed or open. The more common cycle is the open one, in which atmospheric air is continuously drawn into the compressor, heat is added to the air by the combustion of fuel in the combustion chamber, and the working fluid expands through the turbine and exhausts to the atmosphere. A schematic diagram of an open Brayton cycle, which is assumed to operate steadily as an open system, is shown in Fig. 4.2. 

A RELAP5-3D model has been developed to analyze both steady-state and dynamic behavior of a reactor coupled to a parallel pair of closed-loop Brayton-cycle systems. Figures 2 and 3 contain schematics of the input model. A brief description of this model and some steady state and transient results are described. If the design effort had continued, it is judged that RELAP5-3D with the appropriate input procedure could have been used to answer mar of the Gas-Brayton design and operational questions. 

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