Question

A sports car engine delivers 150 kW to the driveshaft with a thermal efficiency of 20%. The fuel has a heating value of 35 000 kJ/kg. Find the rate of fuel consumption and the combined power rejected through the radiator and exhaust.

Answer 1

Answer:600 kW

Step-by-step explanation:

Given

Power delivered
`P=150 kW`

Fuel heating value
`q=35,000 kJ/kg`

thermal Efficiency
`\eta =(Power)/(Heat)`

`0.2=\frac{150}{35,000* \dot{m}}`

where,
`\dot{m} =mass\ flow\ rate\ of\ fuel`

`\dot{m}=(150)/(35,000* 0.2)`

`\dot{m}=0.0214 kg/s`

For an Engine

`q\dot{m}=P+Q_r , where Q_r=heat\ rejected`

`Q_r=q\dot{m}-P`

`Q_r=750-150=600 kW`