Work and heat transfer in internal combustion engine

AI Thread Summary
The discussion focuses on calculating the power absorbed during the compression stroke of a two-cylinder internal combustion engine, given specific parameters and a compression law of PV^1.2 = const. A participant is struggling to match their calculated power output with the provided answer of 17.95 kW, suspecting a potential error in the compression law, possibly suggesting it should be PV^1.4 instead. Another contributor clarifies that the correct approach involves understanding the volume swept by the piston, indicating a misunderstanding in the initial calculations. The conversation highlights the importance of accurate application of formulas and understanding the physical principles involved in engine compression. The correct solution emphasizes the need to properly calculate the volume swept by the piston to achieve the expected results.
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Homework Statement

: [/B]At the beginning of the compression stroke of a two-cylinder internal combustion engine the air is at a pressure of 101.325 kPa. Compression redeuces the volume to 1/5 of its original volume, and the law of compression is given by PV^1.2 = const. If the bore and stroke of each cylinder is 0.15 m and 0.25 m , respectively, determine the power absorbed in kW by compression strokes when the engine speed is such that each cylinder undergoes 500 compression strokes per minute.

The answer is given as : 17.95 kW

2. Homework Equations : I hv written all formulas in the solution (attachment).

The Attempt at a Solution

:[/B] I hv attached the solution I hv done. Please rectify my mistake... where I am doing wrong..my ans is not matching with the given one.
 

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Suman_babai said:
given by PV^1.2 = const.
Are yo usure this is not pV^1.4 ?
 
Replusz said:
Are yo usure this is not pV^1.4 ?
that could be a printing mstake... thanks... this book is just full of calculation errors.
 
And if you calculate it with 1.4? do you get the right answer? (it is 1.4 because for adiabatic expressions pV^(1+2/f)=const. and f=5 for air. )
 
Replusz said:
And if you calculate it with 1.4? do you get the right answer? (it is 1.4 because for adiabatic expressions pV^(1+2/f)=const. and f=5 for air. )
no.. it is coming around 16.(something)... may be the question is wrong.. thanks anyway.
 
Suman_babai said:

Homework Statement

: [/B]At the beginning of the compression stroke of a two-cylinder internal combustion engine the air is at a pressure of 101.325 kPa. Compression redeuces the volume to 1/5 of its original volume, and the law of compression is given by PV^1.2 = const. If the bore and stroke of each cylinder is 0.15 m and 0.25 m , respectively, determine the power absorbed in kW by compression strokes when the engine speed is such that each cylinder undergoes 500 compression strokes per minute.

The answer is given as : 17.95 kW

2. Homework Equations : I hv written all formulas in the solution (attachment).

The Attempt at a Solution

:[/B] I hv attached the solution I hv done. Please rectify my mistake... where I am doing wrong..my ans is not matching with the given one.
Here is correct solution bro. V1-V2= Volume swept by piston.
Volume swept by piston not equal to v1, where you went wrong.
 

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