1. Jan 20, 2016

### Rx7man

1. The problem statement, all variables and given/known data
I am working on creating a spreadsheet where you can input the parameters of an engine at a given rotational speed such as volumetric efficiency, boost pressure, atmospheric pressure and temperature, and compressor efficiency... It's been a very long time since I've done thermodynamics, and have forgotten too much of it to derive all the equations.

The online calculators I found require the volumes to be known, not the pressures

2. Relevant equations
Working with an initial volume of 1 m3 at atmospheric conditions

P initial = 101,000 pa
T initial = 300K
V initial = 1
Calculate n from ideal gas law: PV = nRT, (n= PV/RT), n = (101000*1)/(8.314*300), n = 40.5

We know n inital = n final

Pfinal = 303,000 pa (3:1 pressure ratio)
Work = ?
T final =?
V final =?

3. The attempt at a solution
I was trying to work out the solution with the help of this site but I'm not getting too far with it

When I get there, I will factor in the compressor efficiency as a function of extra work added to the system... So if a perfect system would require 10J, a 50% efficient system would require 20J, raising the temperature and volume, but keeping the pressure the same (since the pressure is what I measure and control)

Thanks for the help... My mind has turned to mush looking at this for a couple hours

2. Jan 21, 2016

### Nidum

I'm a bit confused by your terminology - what type of engine are you trying to develop the spreadsheet for ??

3. Jan 21, 2016

### Rx7man

Cummins 5.9L diesel. the engine isn't terribly important until you want to know the flow...

Where I mention V initial I just choose 1 m^3, which would be the volume of air before the turbocharger, and V final is the volume after the turbocharger, They are just a ratio, not an absolute amount.. I know the pressure ratio (3), but am looking for the volumetric ratio which will NOT be 1/3 because of a lot of added heat, and that's where I run into problems