Thermodynamics I

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Otto Cycle

• Air working fluid ideal gas
• Approach variable specific heats
• Approach constant specific heats

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Otto Cycle

• Compression ratio r
• mep

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Otto Cycle

• Thermal efficiency
• ? 1 (1 / rk-1)
• ONLY with constant specific heats

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Otto Cycle

• r 9.5
• Start of compression
• 100 kPa
• 35oC
• ? 600cc

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Practice problem

• A 4-cylinder, 4-stroke internal combustion engine
  has a bore of 2.55 inches and a stroke of 2.10
  inches. The clearance volume is 12 of the
  cylinder volume at BDC. The crankshaft rotates
  at 3600rpm. At the beginning of the compression
  stroke, air is at 14.6psi 100oF. The maximum
  cycle temperature is 5200oR.
• Find the net work per cycle (Btu) and the power
  developed by the engine (HP).