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In an ideal Brayton cycle, atmospheric air (ratio of specific heats, cρ /cv = 1.4, specific heat at constant pressure = 1.005 kJ/kgK) at 1 bar and 300 K is compressed to 8 bar. The maximum temperature in the cycle is limited to 1280 K. If the heat is supplied at the rate of 80 MW, the mass flow rate (in kg/s) of air required in the cycle is _________.
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- m = 18.07 kg/s.
- m = 108.07 kg/s.
- m = 1007 kg/s.
- m = 108kg/s.
Correct Option: B
Given:
γ = 1.4,
cρ = 1.005 kJ/kg.k
P1 = 1 bar,
P2 = 8 bar
T1 = 300 K,
T3 = 1280 K
| r = | = 8 | |
| P1 |
Qin = 80000 kW.
(1-2) isentropic process
| = (rρ)γ-(1/γ) | |
| P1 |
T2 = 300 × (8)1.4 - 1/1.4
= 543.43 k
Qin = mcp × (T3 - T2)
80,000 = m × 1.005 (1280 – 300)
m = 108.07 kg/s.
