Project ForgeThermodynamics
First Law of Thermodynamics
GATE 2016
Expert
Consider a simple gas turbine (Brayton) cycle and a gas turbine cycle with perfect regeneration. In both cycles the pressure ratio is 6 and the ratio of specific heats of the working medium is 1.4. The ratio of minimum to maximum temperatures is 0.3 in the regenerative cycle. The ratio of the thermal efficiency of the simple cycle to that of the regenerative cycle is __________.
0.8(± 0.02 accepted)
Explanation
η_simple = 1-(1/rp)^((γ-1)/γ) = 1-6^(-0.2857) ≈ 1-0.5995=0.4005. For perfect regeneration, η_regen = 1-(Tmin/Tmax)·rp^((γ-1)/γ) = 1-0.3×1.6682 ≈ 1-0.5005=0.4995. Ratio η_simple/η_regen ≈ 0.4005/0.4995 ≈ 0.80.
Source: GATE ME 2016 Set-2 (2016)
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