Brayton Cycle Simulator

This program can be to analyze the performance of a closed-cycle gas turbine power conversion system. Power conversion systems that utilize gas as a working fluid typically follow a thermodynamic cycle called the Brayton cycle, after George Brayton who developed it.

In this simulation, the user can vary the input parameters to the Brayton cycle, and calculate important results, such as the efficiency of the cycle and the net work.

Graphical Controls
Turbine Inlet Temperature	Turbine inlet temperature represents the highest temperature in the Brayton cycle. It is controlled by left-clicking and dragging the red arrow on the left-hand side of the temperature-entropy (T-S) diagram up and down.
Compressor Inlet Temperature	Compressor inlet temperature represents the lowest temperature in the Brayton cycle. It is controlled by left-clicking and dragging the blue arrow on the left-hand side of the temperature-entropy (T-S) diagram up and down.
Resize T-S Diagram	Clicking on the white square in the upper right-hand corner will reset the temperature range and entropy range of the T-S diagram. Especially useful when the user has changed working fluids (which have very different entropies) or when the user has moved the high or low temperature arrows too far.
Overall Cycle Control Definitions
Preset Cycles	A pull-down menu of preset Brayton cycles. Choosing any one of these changes all of the settings of the other controls to conform to this cycle. In this way, the user can explore a variety of different cycle options without altering all parameters manually. Once a new cycle has been loaded, the user can then alter the individual parameters to see the effect of altering the cycle. The preset cycles include: ideal simple cycle: a single compression and expansion stage, no regeneration, perfect efficiencies and no pressure loss. ideal regenerated cycle: a single compression and expansion stage with regeneration, perfect efficiencies and no pressure loss. ideal triple reheat: three turbomachines, each with a single compressor and turbine, with intercooling and reheat between turbomachines and regeneration. Perfect efficiencies and no pressure loss. realistic triple reheat: three turbomachines, each with a single compressor and turbine, with intercooling and reheat between turbomachines and regeneration. 85% efficiencies for compression and expansion, 95% effective regenerator, and pressure losses. This is representative of an attractive helium gas turbine cycle for a liquid-fluoride reactor. GT-MHGTR: an attempt to model the General Atomics Modular Helium Gas Turbine Reactor. The MHTGR is a 228 MWe gas-cooled reactor, thus it has a single heating stage (the reactor itself). It has two compressors with a stage of intercooling and significant regeneration. Compressor efficiency is 90% and turbine efficiency is 92%. The regenerator is 95% effective and pressure losses are calculated.
Initial Pressure	The pressure at the inlet of the first compressor, and the lowest pressure in the overall cycle.
Total Pressure Ratio	The ratio between the pressure at the outlet of the last compressor and the inlet of the first compressor. The total pressure ratio has a strong effect on cycle efficiency and the net work produced by the cycle. As a general rule, cycles that are not regenerated tend to benefit from increased pressure ratio, whereas cycles that are regenerated may or may not benefit, depending on intercooling and reheat.
Turbomachinery Control Definitions
Turbomachinery Configuration	This pull-down menu lets the user choose the number and configuration of the turbomachines. Each turbomachine consists of a turbine, one or more compressors, and an electrical generator. Between each turbomachine is a heating or reheating stage. Between each compressor is an intercooling stage. Changes in turbomachine configuration can be seen both in the OpenGL graphical display and in their effect on the temperature- entropy (T-S) diagram.
Compressor Efficiency	The adiabatic efficiency of the compressor stages. The "adiabatic" assumption means that there is no heat transfer into or out of the compressor during the compression process. The efficiency then is a measurement of how much compression work is actually converted into an increase in the enthalpy of the flow. Typical compressor efficiencies range from 80-90%.
Turbine Efficiency	The adiabatic efficiency of the turbine stage. The "adiabatic" assumption means that there is no heat transfer into or out of the turbine during the expansion process. The efficiency is a measurement of how much of the enthalpy decrease of the expansion is actually converted into work. Typical turbine efficiencies range from 85-95%.
Intercooling Per Reheat	Each turbomachine has at least one compressor. By choosing one intercooling stage, the compression work is divided between two compressors with an intercooling stage between them. This reduces the overall amount of compression work since temperature increase during compression is reduced by using intercooling. Intercooling between turbomachines is implicitly assumed.
Use Regeneration	This checkbox should be selected if regeneration is desired in the cycle. Regeneration is possible if the exhaust temperature of the last turbine stage is greater than the exhaust temperature of the last compression stage. In some cases, regeneration can have a dramatic effect on cycle efficiency, depending on compression ratio and temperature limits. If turbine exhaust is cooler than compressor exhaust, then no regeneration will take place even if "Use Regeneration" is checked.
Regen Effectiveness	The effectiveness of the regenerator, which is a ratio of how much enthalpy is transferred from the low-pressure turbine exhaust to the high-pressure compressor exhaust. Note that this is not equivalent to pressure drop in the regenerator! Typical regenerator effectivenesses range from 90% to 97%. A "perfect" regenerator would have an infinitesimal temperature differential and would be infinitely large!
Include Pressure Losses	A checkbox that allows the user to simulate the effect of pressure losses across the precooler, intercoolers, regenerator, preheater, and reheaters in the cycle.
Design Performance Control Definitions
Electrical Power	The desired electrical power production of the turbomachines. Changing the electrical power has little effect on the cycle, but rather determines the mass flow rate necessary to generate that power within the cycle.
Generator Efficiency	The efficiency of the generator in converting shaft (mechanical) power into electrical power. Typical generator efficiencies range from 95-98%.
Display Units	The pulldown menu lets the user change the units in which data is displayed.
Step-Size Increment	This pulldown menu changes the "step-size" in each "spinner" control. The default setting is medium. Coarse steps are 2x as large, very coarse are 5x as large. Fine steps are 1/10th the size, very fine are 1/100th, and hyper-fine are 1/1000th.

Revision history:

2006/12/22: Updated with OpenGL turbomachine visualization and HTML control description.
2006/09/12: Released on energyfromthorium.com