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Recent content by gtsim

  1. gtsim

    Fuel Gas Composition

    If you have a change in the inerts (CO2, N2, etc) there will be a noticeable change in LHV, performance and NOx emissions.
  2. gtsim

    Fuel Gas Composition

    Higher the methane (CH4) content, which also increases the lower heating value (LHV) of the fuel, increases the GT power output and reduces heat rate. Also, NOx emissions decrease. The higher the CH4 content, greater is the water vapour in the products of combustion. This improves the engine...
  3. gtsim

    gas turbine combustor pressure loss

    You can try Gas Turbine Combustion by Lefebvre or Gas Turbine Theory BY Saravanamutoo, Rogers and Cohen. They cover it quite well.
  4. gtsim

    GAs turbine performance calculation -Doubst, i need some help.

    Also have a look at this thread thread1036-173075
  5. gtsim

    Moliere diagram

    If you only want the enthalpy of moist air you can use the formula: h = (1.007t – 0.026) + w (2501 + 1.84t) Where t is ambient temperature in C and w is specific or absolute humidity. h is specific enthalpy kJ/kg. This equation is valid between 0 and 60C.
  6. gtsim

    Air flow off the Turbo compressor map

    The increase in flow through the compressor will result in the expander/turbine imposing an increased back pressure on the compressor. This results in an increase in compressor pressure ratio and speed. Imagine this running line on the compressor map, which is approximately parallel to the surge...
  7. gtsim

    Air flow off the Turbo compressor map

    As you are aware, compressor maps are normally plotted with pressure ratio VS non-dimensional air or mass flow (W(RT/Gamma)^0.5))/AP) for a series of non-dimensional speeds ND/((GammaRT)^0.5). W = mass flow rate R = gas constant Gamma = cp/cv (ratio of specific heats) T = absolute temperature...
  8. gtsim

    Gas Turbine Compressor efficiency?

    Strictly speaking yes. If you want a ball park figure then constant gamma gives an answer to withing 3% of the actual efficiency.
  9. gtsim

    Gas Turbine Compressor efficiency?

    Yep, Thats right. gtsim
  10. gtsim

    Gas Turbine Compressor efficiency?

    p1 = 14.7 (atmospheric pressure) p2 = 230 psi (compressor discharge pressure) Pressure Ratio = 230/14.7 = 15.646 t1 = 75 deg F = 23.89 deg C = 23.89 + 273 =296.89 = 535 R t2 = 650 deg F = 343.33 = 243.33 + 273 = 616.33K = 1110R Gamma = cp/cv for air (approximately 1.4) C-1=...
  11. gtsim

    Gas Turbine Compressor efficiency?

    What are your temperature units - degrees F I think? Whatever units you use it should be in absolute (R or K). The efficiency should be bewteen 0.85(85%) to 0.9(90%). There is something wrong in your data. It gives 100% efficiency (assuming F for temperature)??? Where did you get these...
  12. gtsim

    Gas Turbine Compressor efficiency?

    To determine the (isentropic) efficiency of a gas turbine compressor, such as the Frame 7 the airflow is not needed. The compressor efficiency can be calculated via: Eff= (C-1)/(T2/T1-1) Where C= Pr^((Gamma-1)/Gamma) Eff is the isentropic efficiency, which is the same as adiabatic Pr is the...
  13. gtsim

    relative humidity calculation

    Relative Humidity (RH)=p/ps, where p is the vapour pressure at 37 deg C and ps is the saturated vapour pressure at 37 deg C. From steam tables we can calculate ps at 37 deg C. Therefore vapour pressure, p = RH x ps. Specific Humidity (SH) = 18/MW x p/(P-p), where P is the pressure of the gas...
  14. gtsim

    premix and diffusion

    Briefly, in conventional (diffusion flame) combustors, as saludos says, the fuel/air mixture in the primary zone, where the fuel is burnt, is heterogeneous or stratified. Therefore the fuel/air ratio varies a great deal from lean to near stoichiometric. Thus high flame temperatures result in the...
  15. gtsim

    Compressor MAP Ideality

    There isn’t one. The adiabatic efficiency depends on where on the map you are operating. For example, if the operating point moves from the current position to the left on the characteristic at a constant pressure ratio the adiabatic efficiency will increase (i.e. a decrease in corrected flow)...
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