Internal Combustion Engines Air Standard Cycles ME 429

Otto Cycle Derivation:

Otto Cycle Derivation

The Four Stroke Otto Cycle:

The Four Stroke Otto Cycle

Otto Cycle P-V & T-s Diagrams:

Otto Cycle P-V & T-s Diagrams Pressure-Volume Temperature-Entropy

Otto Cycle Derivation:

Otto Cycle Derivation Thermal Efficiency: For a constant volume heat addition (and rejection) process; Assuming constant specific heat: Otto Cycle Derivation

Otto Cycle Derivation:

For an isentropic compression (and expansion) process: where: γ = C p /C v Then, by transposing, Otto Cycle Derivation Leading to

Otto Cycle Derivation:

The compression ratio (r v ) is a volume ratio and is equal to the expansion ratio in an otto cycle engine. Compression Ratio where Compression ratio is defined as Otto Cycle Derivation

Otto Cycle Derivation:

Then by substitution, The air standard thermal efficiency of the Otto cycle then becomes: Otto Cycle Derivation

Otto Cycle Derivation:

Summarizing where and then Isentropic behavior Otto Cycle Derivation

Otto Cycle Derivation:

Heat addition (Q) is accomplished through fuel combustion Q = Lower Heat Value (LHV) BTU/lb, kJ/kg Otto Cycle Derivation also

Otto Cycle Analysis:

Otto Cycle Analysis

Otto Cycle P & T Prediction:

Determine the temperatures and pressures at each point in the Otto Cycle. Compression Ratio = 9.5:1 T 1 temperature = 25 o C = 298 o K P 1 pressure = 100 kPa Otto Cycle P & T Prediction

Diesel Cycle Derivation:

Diesel Cycle Derivation

Diesel Cycle P-V & T-s Diagrams:

Diesel Cycle P-V & T-s Diagrams

Diesel Cycle Derivation:

Diesel Cycle Derivation Thermal Efficiency (Diesel): For a constant pressure heat addition process; For a constant volume heat rejection process; Assuming constant specific heat: where: γ = C p /C v

Diesel Cycle Derivation:

For an isentropic compression (and expansion) process: However, in a Diesel The compression ratio (r v ) is a volume ratio and, in a diesel, is equal to the product of the constant pressure expansion and the expansion from cut-off. Diesel Cycle Derivation

Diesel Cycle Derivation:

Compression Ratio Then by substitution, Diesel Cycle Derivation

Diesel Cycle Analysis:

Diesel Cycle Analysis

Diesel Cycle P & T Prediction:

Determine the temperatures and pressures at each point in the Diesel Cycle. Compression Ratio = 20:1 T 1 temperature = 25 o C = 298 o K P 1 pressure = 100 kPa Diesel Cycle P & T Prediction

Otto-Diesel Cycle Comparison :

Otto-Diesel Cycle Comparison

PowerPoint Presentation:

Dual Cycle P-V Diagrams:

Dual Cycle Efficiency :

Dual Cycle Thermal Efficiency Dual Cycle Efficiency where: γ = C p /C v

Diesel Cycle Derivation:

Critical Relationships in the process include Diesel Cycle Derivation

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