An idealised thermodynamic cycle of a heat engine involves several distinct stages.
Explain what is meant by an adiabatic process.
During the compression stroke of an ideal diesel engine cycle, air is compressed adiabatically from an initial pressure of 1.0 × 105 Pa and volume V1 V_1\,V1 to a final pressure of 75 × 105 Pa and volume V2V_2V2. Taking the adiabatic index γ \gamma\,γ for air to be 1.4, calculate the compression ratio V1V2\displaystyle \frac{V_1}{V_2}V2V1.
Explain why a diesel engine requires a much higher compression ratio than a standard petrol engine.
