Chapter 1 Gas Power Cycle

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Intake valve Bore Air-Standard Assumption � The working fluid is air which continuously circulated in a close loop and behave as an ideal gas � All the processes are internally reversible � The combustion process is replaced by a heated-addition process from the external source � The exhaust process is replaced by a heat rejection process which restores the working fluid to its initial state Over View on Reciprocating Engines Exhaust valve Stroke TDC BDC Top Dead Center (TDC) : Position of the piston when it forms the smallest volume in diameter Bottom Dead Center (BDC) : Position of the piston when it forms the largest volume in diameter Stroke : Length of piston travel Bore : Diameter of the cylinder Clearance Volume (Vc ) : minimum volume formed in the cylinder when the piston is at TDC Displacement Volume (Vd ) :Swept Volume (Vmax-Vmin ) Source: Assoc.Prof.Dr.Sommai Prepream Compression Ratio (r v ) = (V max /V min ) = (V BDC /V TDC ) Mean Effective Pressure (MEP) : Fictious pressure that acted on the piston during the entire power stoke Net Work during the actual cycle (Wnet ): Wnet = (MEP) x (Piston Area) x (Stroke) = (MEP) x (Displacement Volume)
P Mean Effective Pressure, MEP Concept Actual Processes v min W net Equivalent v max TDC BDC Source: Assoc.Prof.Dr.Sommai Prepream Four Stroke Engine v P MEP Equivalent by MEP v min W net v max Wnet = (MEP) x (Displacement Volume) = (MEP) x (Vmax-Vmin ) Intake Compression <strong>Power</strong> Exhaust 1. Intake Stroke piston moves from TDC to BDC, drawing in fresh air-fuel mixture. 2. Compression Stroke piston moves from BDC to TDC, compress air-fuel mixture. 3. <strong>Power</strong> Stroke piston at TDC, spark plug ignite the air-fuel mixture. the combustion occur very fast that, in theory, the piston still at TDC. After that the piston is pushed to BDC. 4. Exhaust Stroke piston moves from BDC to TDC, pushes the combustion gases out. v
Page 1 and 2: Chapter 1 Gas Power Cycle Content:
Page 3: Example 8.1 Show that the thermal e
Page 7 and 8: P Air Standard Otto Cycle Ideal Ott
Page 9 and 10: Example 8.2 An ideal Otto cycle has
Page 11 and 12: 1st law : closed system Ideal gas:
Page 13 and 14: Ideal Brayton Cycle Brayton Cycle c

Chapter 1 Gas Power Cycle

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