GAs turbine performance calculation -Doubst, i need some help.
GAs turbine performance calculation -Doubst, i need some help.
(OP)
Dearl All,
I am trying to calculate the performance charactersitic of a LM 2500 gas turbine in our gas plants. But i have some doubts regarding to collect data, ( i ma taking data from MARK V, system control). For example the temperture T5.4 is valid to consider the combustion gases temperature???,
In my case we have a T5.4 = 744ºC (i think that is low)
Other doubts, i have T1(inlet compressor temperature=24.3ºC ambient) and at discharge compressor (16 stages) P2=13,2 and T2=413ºC, so if you use the theory to corroborate the date is not working.(T2=T1*Rc^(k-1/k))
Rc=Ratio compressor in this moment 13.2 and k (adiabtic coeficient)and our real temperature at discharge is 413ºC
so 413 is not equal to 24.3ºC*13.2^(1.4-1/1.4)
What is happening ,i know that i have to use n(politropic) but even in this way is very different the results.
Best regards
Fernando
I am trying to calculate the performance charactersitic of a LM 2500 gas turbine in our gas plants. But i have some doubts regarding to collect data, ( i ma taking data from MARK V, system control). For example the temperture T5.4 is valid to consider the combustion gases temperature???,
In my case we have a T5.4 = 744ºC (i think that is low)
Other doubts, i have T1(inlet compressor temperature=24.3ºC ambient) and at discharge compressor (16 stages) P2=13,2 and T2=413ºC, so if you use the theory to corroborate the date is not working.(T2=T1*Rc^(k-1/k))
Rc=Ratio compressor in this moment 13.2 and k (adiabtic coeficient)and our real temperature at discharge is 413ºC
so 413 is not equal to 24.3ºC*13.2^(1.4-1/1.4)
What is happening ,i know that i have to use n(politropic) but even in this way is very different the results.
Best regards
Fernando





RE: GAs turbine performance calculation -Doubst, i need some help.
T2=T1(p2/p1)^(n-1)/n
n = polytropic index, usually between 1,45 and 1,7.
T1 = Air inlet ABSOLUTE temperature (ºR or ºK)
T2 = Compressed air outlet ABSOLUTE temperature (ºR or ºK)
p1 = Air inlet ABSOLUTE pressure (PSIA or bara)
p2 = Compressed air outlet pressure (PSIA or bara)
Try once again !
RE: GAs turbine performance calculation -Doubst, i need some help.
thanks for your time, is working better using absolute values. But, how i know the real value of n(1,45-1,7) is a great difference. where i can get a good aproximation for n.
Best regards
RE: GAs turbine performance calculation -Doubst, i need some help.
The value of the polytropic index "n" has a strong relationship with the refrigeration of the compressed air. Usually, it is determined experimentally.
According to Emden´s equation, n = 1/(k-1).
If you do not have available information of your compressor, you could ask for the test run report, performed on the manufacturer´s workshop or, calculate "n" as a bench mark using the commissioning values obtained during the start up of your power plant.
RE: GAs turbine performance calculation -Doubst, i need some help.
thread1036-173075: Gas Turbine Compressor efficiency?
RE: GAs turbine performance calculation -Doubst, i need some help.
If you have suction and discharge Temperature and Pressure, you calculate real "n" and you know "k" you calculate whatever you want...
RE: GAs turbine performance calculation -Doubst, i need some help.
You might be able to do it using an energy balance around the combustor with the compressor discharge temperature/flow/pressure and the fuel heating value and flow as inputs and assuming an adiabatic combustor.