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The air standard efficiency of an Otto cycle is given by

where r = Compression ratio and

γ = Ratio of specific heats.

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  1. 1 - rγ-1
  2. 1 + rγ-1

Answer (Detailed Solution Below)

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Detailed Solution

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Concept:

Otto cycle

The air-standard-Otto cycle is the idealized cycle for spark-ignition internal combustion engines.

The Otto cycle 1-2-3-4 consists of the following four processes:

  • Process 1-2: Reversible adiabatic compression of air
  • Process 2-3: Heat addition at constant volume
  • Process 3-4: Reversible adiabatic expansion of air
  • Process 4-1: Heat rejection at constant volume

The thermal efficiency of the Otto Cycle:

Compression ratio: r = v1/v2

The air standard efficiency of an Otto cycle is  

Important Points

The air standard efficiency of a Diesel cycle is 

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More Otto Cycle Questions

Q1.In an ideal four-stroke petrol engine, the assumption made about the burning process during the power stroke i.e. after compression is:
Q2.An engine is assumed to be working on ideal Otto cycle with the temperatures at the beginning and end of compression as 27 °C and 327 °C. The air-standard efficiency of the engine is:
Q3.Which of the following is the assumption of Air Standard Cycles?
Q4.Identify the cycle on the basis of the T-S diagram shown below.
Q5.In the given T-S diagram of Otto cycle, which of the following processes is a heat addition process? 
Q6.The air standard efficiency of the Otto cycle is:
Q7.A four-stroke petrol engine theoretically operates on
Q8.The compression ratio of petrol engine usually in the range of
Q9.In an engine working on an ideal Otto cycle, the temperature at the beginning and at the end of the compression are 27°C and 327°C. What will be the compression ratio? (Assume constant specific heat and its ratio γ = 1.4)
Q10.The pressure and temperature of air at the beginning of compression in an Otto cycle is 100 kPa and 300 K, respectively. The heat added per kg of air is 1436 kJ. The compression ratio is 8. What will be the maximum temperature of the cycle? [Ratio of specific heat = 1.4; 80.4 = 2.3; Cv = 0.718 KJ/kg-K.]  

More IC Engine Cycles Questions

Q1.In an ideal four-stroke petrol engine, the assumption made about the burning process during the power stroke i.e. after compression is:
Q2.An engine is assumed to be working on ideal Otto cycle with the temperatures at the beginning and end of compression as 27 °C and 327 °C. The air-standard efficiency of the engine is:
Q3.The primary reason for diesel engines having more efficiency than gasoline engines is they _______________.
Q4.In four-stroke diesel engine, which valves are closed during the expansion stroke?
Q5.The heat rejection in Stirling cycle takes place at: 
Q6.Which of the following is the assumption of Air Standard Cycles?
Q7.Identify the cycle on the basis of the T-S diagram shown below.
Q8.A Carnot cycle runs between _______ adiabatic and _______ isothermal processes.
Q9.A diesel engine has a compression ratio of 15 and heat addition at a constant pressure takes place at 6% of stroke. Find the air standard efficiency of the diesel engine. (Take γ for air = 1.4.)
Q10.In two-stroke petrol engine, the air Fuel mixture is prepared 
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More Internal Combustion Engine Questions

Q1.In an ideal four-stroke petrol engine, the assumption made about the burning process during the power stroke i.e. after compression is:
Q2.An engine is assumed to be working on ideal Otto cycle with the temperatures at the beginning and end of compression as 27 °C and 327 °C. The air-standard efficiency of the engine is:
Q3.Frictional power in an engine is calculated as:
Q4.The primary reason for diesel engines having more efficiency than gasoline engines is they _______________.
Q5.In a two-stroke petrol engine, the primary function of the crankcase is to:
Q6.In most of the SI engines, the intake valve opens a few degrees before the TDC on the exhaust stroke to:
Q7.What does specific fuel consumption (SFC) measure in an internal combustion engine?
Q8.In which type of engine is a mist lubricating system most commonly used?
Q9.The intake valve closes at _____ for a low-speed engine and at _____ for high-speed four-stroke petrol engines.
Q10.Which statement best compares battery and magneto ignition systems in internal combustion engines?
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