Question

A gas turbine operating on a simple Joule cycle has a pressure compression ratio of 8:1. The turbine has a thermal efficiency of 60% of the ideal. Determine the actual thermal efficiency.

Answer 1

$M_{therm(ideal)}=1-\frac{1}{\frac{g-1}{r^g}}$

$=1-\frac{1}{\frac{1.4-1}{8^{1.4}}}$

$=0.4479$

Actual efficiency of the gas turbine.

$M_{therm(actual)}=0.6\times\eta_{therm(ideal)}$

$=0.6 \times 0.4479$

$=0.2687$

$\eta_{therm(actual)}=26.87$ %