27 real IC Engines & Power Plants questions from the Mechanical Core bank, as asked in Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd — free to start.
1. What is Compression ratio?
Junior
A.fuel energy input per unit of electrical output in kJ/kWh, around 8,500 for a supercritical coal unit and above 10,000 for an old subcritical unit
B.spontaneous auto-ignition of the end gas ahead of the flame front in a petrol engine, producing pressure waves heard as knock
C.a diesel fuel's ignition quality expressed as shortness of ignition delay, with higher values giving smoother combustion
D.ratio of total cylinder volume at BDC to clearance volume at TDC, about 8–12 for petrol and 16–22 for diesel engines
A.Compression ratio — hypothetical constant pressure that would produce the cycle's net work over one power stroke, used to compare engines of different sizes
B.Compression ratio — steam is reheated between the high- and low-pressure turbines to raise efficiency and keep exhaust dryness above about 88%
C.Compression ratio — spontaneous auto-ignition of the end gas ahead of the flame front in a petrol engine, producing pressure waves heard as knock
D.Compression ratio — ratio of total cylinder volume at BDC to clearance volume at TDC, about 8–12 for petrol and 16–22 for diesel engines
A.Cetane number — ratio of total cylinder volume at BDC to clearance volume at TDC, about 8–12 for petrol and 16–22 for diesel engines
B.Cetane number — steam is reheated between the high- and low-pressure turbines to raise efficiency and keep exhaust dryness above about 88%
C.Cetane number — a diesel fuel's ignition quality expressed as shortness of ignition delay, with higher values giving smoother combustion
D.Cetane number — fuel energy input per unit of electrical output in kJ/kWh, around 8,500 for a supercritical coal unit and above 10,000 for an old subcritical unit
A.Brake specific fuel consumption — fuel mass consumed per unit brake power per hour, the standard measure of an engine's fuel economy
B.Brake specific fuel consumption — spontaneous auto-ignition of the end gas ahead of the flame front in a petrol engine, producing pressure waves heard as knock
C.Brake specific fuel consumption — hypothetical constant pressure that would produce the cycle's net work over one power stroke, used to compare engines of different sizes
D.Brake specific fuel consumption — ratio of air mass actually inducted to the mass that would fill the swept volume at ambient conditions, improved by turbocharging
14. Which term means: "ratio of air mass actually inducted to the mass that would fill the swept volume at ambient conditions, improved by turbocharging"?
A.Volumetric efficiency — ratio of total cylinder volume at BDC to clearance volume at TDC, about 8–12 for petrol and 16–22 for diesel engines
B.Volumetric efficiency — fuel mass consumed per unit brake power per hour, the standard measure of an engine's fuel economy
C.Volumetric efficiency — ratio of air mass actually inducted to the mass that would fill the swept volume at ambient conditions, improved by turbocharging
D.Volumetric efficiency — hypothetical constant pressure that would produce the cycle's net work over one power stroke, used to compare engines of different sizes
17. Which term means: "hypothetical constant pressure that would produce the cycle's net work over one power stroke, used to compare engines of different sizes"?
A.Mean effective pressure — fuel mass consumed per unit brake power per hour, the standard measure of an engine's fuel economy
B.Mean effective pressure — ratio of total cylinder volume at BDC to clearance volume at TDC, about 8–12 for petrol and 16–22 for diesel engines
C.Mean effective pressure — a diesel fuel's ignition quality expressed as shortness of ignition delay, with higher values giving smoother combustion
D.Mean effective pressure — hypothetical constant pressure that would produce the cycle's net work over one power stroke, used to compare engines of different sizes
A.Reheat cycle — steam is reheated between the high- and low-pressure turbines to raise efficiency and keep exhaust dryness above about 88%
B.Reheat cycle — a diesel fuel's ignition quality expressed as shortness of ignition delay, with higher values giving smoother combustion
C.Reheat cycle — spontaneous auto-ignition of the end gas ahead of the flame front in a petrol engine, producing pressure waves heard as knock
D.Reheat cycle — fuel energy input per unit of electrical output in kJ/kWh, around 8,500 for a supercritical coal unit and above 10,000 for an old subcritical unit
26. Which term means: "fuel energy input per unit of electrical output in kJ/kWh, around 8,500 for a supercritical coal unit and above 10,000 for an old subcritical unit"?
A.Heat rate — ratio of air mass actually inducted to the mass that would fill the swept volume at ambient conditions, improved by turbocharging
B.Heat rate — fuel energy input per unit of electrical output in kJ/kWh, around 8,500 for a supercritical coal unit and above 10,000 for an old subcritical unit
C.Heat rate — ratio of total cylinder volume at BDC to clearance volume at TDC, about 8–12 for petrol and 16–22 for diesel engines
D.Heat rate — a diesel fuel's ignition quality expressed as shortness of ignition delay, with higher values giving smoother combustion
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