A diesel engine with a compression ratio equal to 20 is modeled using air. The compression...

 

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A diesel engine with a compression ratio equal to 20 is modeled using air. The compression process can be modeled as adiabatic and reversible and the expansion processes can be modeled as a process with polytropic exponent equal to 1.35. The compression process starts at P₁ = 95 kPa and T₁ = 20°C. If the maximum temperature of the cycle should not exceed 1827°C, answer the following. a. Sketch the cycle on a P-v and T-s diagrams. b. Determine the cutoff ratio. Show your relations in literal form prior to any calculations. c. Derive an expression to compute the thermal efficiency using symbols only that represent heat transfer and work processes. d. Use your expression in (c) to compute the thermal efficiency. e. Compute the mean effective pressure. A diesel engine with a compression ratio equal to 20 is modeled using air. The compression process can be modeled as adiabatic and reversible and the expansion processes can be modeled as a process with polytropic exponent equal to 1.35. The compression process starts at P₁ = 95 kPa and T₁ = 20°C. If the maximum temperature of the cycle should not exceed 1827°C, answer the following. a. Sketch the cycle on a P-v and T-s diagrams. b. Determine the cutoff ratio. Show your relations in literal form prior to any calculations. c. Derive an expression to compute the thermal efficiency using symbols only that represent heat transfer and work processes. d. Use your expression in (c) to compute the thermal efficiency. e. Compute the mean effective pressure.