# Diesel Engines - Power question

1. Jan 17, 2008

### cabellos6

1. The problem statement, all variables and given/known data
Please can someone help me with this....
I have a question on a four stroke diesel engine. I have been given the stroke length of 500mm and the bore size of 300mm. The compression ratio as 18/1 and the speed of revolution of 600rpm. Also the ambient air conditions are assumed to be 20C at 1 bar. Max cylinder pressure = 100 bar and exhaust gas temperature = 480C

It asks to calculate the power developed per cylinder using the air conditions at the start of the cycle?

2. Relevant equations

3. The attempt at a solution

Now i have answerd the previous question which was to calculate the thermal efficiency of the cylce. So as this is a Dual Cycle i have drawn it and calculated all the temperature points and worked out the efficiency which was 67%. Correct

It says calculate the power from the initial air conditions but i have tried to do this by using Power = Work done x cycles per second

I have worked out the Work done as Qin - Qout and multiplied this by 5 cycles per second (as 600 rpm is 10 rps and there are 2 revolutions in one cycle as it is 4 stroke).

i am not getting the correct answer which is supposed to be 153KW.

Why??

Thanks

Last edited: Jan 18, 2008