Path: Thermal/Brayton
% Brayton Cycle
d.r is the pressure ratio of the compressor. Higher r means higher thermal
efficiency but more mass. Typical closed-loop Brayton cycles for space
applications have r = 2. The default working fluid is a 70/30 (molar ratio)
mixture of Helium and Xenon.
The function draws a heat engine diagram with pressures and temperatures
labeled, if there are no outputs or the doPlot flag is true.
Type Brayton for a demo.
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Form:
d = Brayton( d )
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Inputs
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d (.) Input data structure
.T3 (1,1) Turbine Inlet temperature (deg-K)
.T1 (1,1) Compressor Inlet Temp temperature (deg-K)
.P1 (1,1) Compressor Inlet Pressure (Atm)
.pHeat (1,1) Heat input (kW)
.r (1,1) Pressure ratio of compressor
.name (1,:) Name of gas or mixture
.nc (1,1) Compressor efficiency
.nt (1,1) Turbine efficiency
.nPX (1,1) Exchanger pressure drop an empirically-determined factor
.gamma (1,1) Specific heat ratio
.cP (1,1) Specific heat (J/kg-K)
.molWt (1,1) Molecular Weight of the mixture in (g/mol)
.image (1,1) Image for diagram, default BraytonCycle.png
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Outputs
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d (.) Data structure additions
.P2 (1,1) Compressor outlet (Pa)
.T2 (1,1) Compressor outlet (deg-K)
.P3 (1,1) Heat exchanger inlet (Pa)
.T3 (1,1) Heat exchanger inlet (deg-K)
.P3 (1,1) Turbine inlet (Pa)
.P4 (1,1) Gas cooler inlet (Pa)
.T4 (1,1) Gas cooler inlet (deg-K)
.n (1,1) Brayton cycle efficiency.
.mDot (1,1) Mass flow (kg/s)
.wC (1,1) Compressor work (kW)
.wT (1,1) Turbine work (kW)
.wNet (1,1) Net work (kW)
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References: Barrett and Reid, "System Mass Variation and Entropy"
Generation (2003). MIT Pebble-bed reactor.
Wright, Lipinski, Vernon, and Sanchez, "Closed Brayton
Cycle Power Conversion Systems" (2006).
Wilson and Korakianitis, "The Design of High-Efficiency
Turbomachinery and Gas Turbines," Second Edition, (2014).
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Thermal: ThermalData/BraytonCycleSimple Common: Graphics/NewFig
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