Answer ALL parts (a)-(c). A van is powered by a 2.3 litre diesel engine, which has a compression ratio, r = 8, the temperature just after combustion is 1250 K and air is drawn into the engine at 300 K at a pressure of 101 kPa. At 2500 rpm the engine produces 85 kW of power. You may assume that the working fluid in the engine is an ideal gas and that R 0.287 kJ/kg/K and y = 1.4. (a) Determine the cut-off ratio, re, the thermal efficiency and the specific heat addition for the engine. (b) A turbocharger is connected to the air intake for the engine and at 2500 rpm, it increases the air pressure at the intake by a factor of 2.8. Assume that this is an adiabatic compression, and that the specific heat addition and (c) compression ratio of the engine remains unchanged. Determine the engine power with the turbocharger. Explain why diesel engines tend to have higher thermal efficiencies than petrol engines and why do diesel engines experience less engine wear than petrol engines.

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Answer ALL parts (a)-(c).
A van is powered by a 2.3 litre diesel engine, which has a compression ratio, r = 8,
the temperature just after combustion is 1250 K and air is drawn into the engine at
300 K at a pressure of 101 kPa. At 2500 rpm the engine produces 85 kW of power.
You may assume that the working fluid in the engine is an ideal gas and that R, =
0.287 kJ/kg/K and y = 1.4.
(a)
Determine the cut-off ratio, re, the thermal efficiency and the specific heat
addition for the engine.
(b)
A turbocharger is connected to the air intake for the engine and at 2500 rpm,
it increases the air pressure at the intake by a factor of 2.8. Assume that this
is an adiabatic compression, and that the specific heat addition and
compression ratio of the engine remains unchanged. Determine the engine
power with the turbocharger.
(c)
Explain why diesel engines tend to have higher thermal efficiencies than
petrol engines and why do diesel engines experience less engine wear than
petrol engines.
Transcribed Image Text:A2 Answer ALL parts (a)-(c). A van is powered by a 2.3 litre diesel engine, which has a compression ratio, r = 8, the temperature just after combustion is 1250 K and air is drawn into the engine at 300 K at a pressure of 101 kPa. At 2500 rpm the engine produces 85 kW of power. You may assume that the working fluid in the engine is an ideal gas and that R, = 0.287 kJ/kg/K and y = 1.4. (a) Determine the cut-off ratio, re, the thermal efficiency and the specific heat addition for the engine. (b) A turbocharger is connected to the air intake for the engine and at 2500 rpm, it increases the air pressure at the intake by a factor of 2.8. Assume that this is an adiabatic compression, and that the specific heat addition and compression ratio of the engine remains unchanged. Determine the engine power with the turbocharger. (c) Explain why diesel engines tend to have higher thermal efficiencies than petrol engines and why do diesel engines experience less engine wear than petrol engines.
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