Question

A Carnot engine receives 100 kJ of heat at 600 K. Heat is rejected at 300 K. the displacement volume is 0.2 m³. The mean effective pressure is
1. 2 bar
2. 2.5 bar
3. 3 bar
4. 3.5 bar

Answer 1

Correct Answer - Option 2 : 2.5 bar

Concept:

The Carnot engine is a reversible engine. For reversible system, according to second law of thermodynamics

\(\frac{{dQ}}{T} = 0\)

Calculation:

\(\frac{{100}}{{600}} + \frac{{ - {Q_2}}}{{300}} = 0\)

Q₂ = 50 KJ

Work done = heat supplied – heat rejected

Work done = 100 – 50

Work done = 50 kJ                      

Also work done is given by

Work done = mean effective pressure × swept volume

∴ 50 = mean effective pressure × 0.2

∴ Mean effective pressure = 250 kPa = 2.5 bar