Direction: In a simple Brayton cycle, the pressure ratio is 8 and temperature at the entrance of compressor and turbine are 300 K and 1400 K, respectively. Both compressor and gas turbine have isentropic efficiencies equal to 80%. For the gas, assume a constant value of cp (specific heat at constant pressure) equal to 1 kJ/kgK and ratio of specific heats as 1.4. Neglect changes in kinetic and potential energies.
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The power required by the compressor in kW/ kg of gas flow are is
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- 194.7
- 243.4
- 304.3
- 378.5
Correct Option: C
T2 = 543.43 K
| ηc = | T2' - T1 |
ηc = ηT = 0.8
rp = 8
T1 = 300 K
T3 = 1400 K
| ηc = | T2' - 300 |
| 0.8 = | T2' - 300 |
T2' = 604.3K
| ρc = mCp(T2' - T1) = Cp(T2' - T1) | kg |
= 1 (604.3 - 300)
| = 304.3 | kg |
