In a gas turbine experiment air enters the compressor at 77 degree F and 0.2 psi
ID: 1841785 • Letter: I
Question
In a gas turbine experiment air enters the compressor at 77 degree F and 0.2 psig and leaves the compressor at 300 degree F and 21.5 psig, then enters the Turbine at 1290 degree F and 21.3 psig and leaves the Turbine at 1040 degree F and 0.6 psig. The atmospheric pressure is measured as 14.7 psia Determine: The specific work of the compressor The specific heat added to the air through the combustion process The specific work of the turbine The engine actual efficiency Pressure ratio and the Brayton cycle efficiency Turbine isentropic efficiencyExplanation / Answer
1) pressure ratio is calculated. total pressure at inlet 1.027 bar, at outlet 2.496 bar
from gas relations T02'/To1 = (2.496/1.027) ^(k-1/k)
get To2'/To1 = 1.288
outlet temp (actual) is 231.65 F = 110.9C
inlet T=25C
DT = 85.9
Cp DT =work (specific) /kg = 1KJ/Kg K*85.9 = 85.9 KJ/kg
2)Specific heat add to the air thru combustion.
the change in temperature is (1290-300) F = 990F = 550 C=550 K since difference
work done per Kg 550*1 =550 KJ/kg
c) sp work of turbine ,
similar calculation gives T'/T = .783
where inlet temp is 1290F =699C
outlet temp .783*(699+273) = .783*972 =761K
Work CpDT= 1*211 = 211KJ/kg
d) engine actual efficiency. Use actual temps and work and get the ratio
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