At what point on the PV diagram can we find the exhaust temperature.

[Miteshshetty]

Hello,
Im doing a project on simulation of Hatz 1b20 diesel engine and will be plotting the pv diagram of the Otto cycle using the compression ratio of this engine.
I dont have the mass flow rate of air nor do have the various engine temperature but I do have mass flow rate of fuel and exhaust temperature.
If I can use the exhaust temperature to predict the temperature of the inlet point then I could calculate the mass flow rate of air. Can I do this?

 

[BrianPetersen]

How do you expect the exhaust temperature to even remotely predict the inlet temperature? Sure, the residual gases in the cylinder at the end of the exhaust stroke will affect it, but the intake air temperature will dominate.

If you are doing the simulation, why isn't the simulation software telling you what the mass flow rates are? It's rather fundamentally basic information ...

And in any case, just knowing the temperatures isn't going to tell you the volumetric efficiency.

Give us more details on what you are trying to do and why.

 

[Miteshshetty]

I'm having the engine Specification with me i.e CR and displacement,
experimental data i.e speed, fuel consumption, torque, temperature at the exhaust.

I want to design an ideal Otto cycle for this engine.

Taking following two assumptions,
1) pressure P1= atmospheric pressure
2) heat addition to the cycle = the heat content of the amount of fuel added each cycle,
I have worked out the pressure and volume at each point on the PV diagram.

Lets consider the volumetric efficiency to be 100%,
are there any correlation or assumption that can help me to find the temperature? if not accurate then at least close by.

 

[BrianPetersen]

No one in the real world tries to fit an ideal model to reality in such a manner. It won't work.

Measure the thing you are actually looking for. If that is not possible, measure the closest proxy for what you are actually looking for. The further removed that the measurement is from the actual thing that you are looking for, the more you are dealing with a guess rather than a measurement. If someone is trying to figure out the mass flow rate and they measured the exhaust temperature, they measured the wrong thing. Tell them to go back and do the experiment again, this time measuring the right thing.

Besides, in the idealized model, the mass of air taken into the engine is a simple function of the displacement, revs, and density, which is a no-brainer to figure out. There are millions of cars and motorcycles out there on the road with no mass-airflow sensors, and which infer the amount of air going into the engine from revs, displacement, and intake manifold pressure. (Come to think of it, all of the fuel-injected vehicles that I currently own are like that.) The revs are easy to measure with extreme accuracy, the displacement is a simple constant to the engine control ECU, and the intake pressure and temperature is a close enough proxy that the flow rate can be readily calculated.

Is this a school project?

 

[dgallup]

I would not map an Otto Cycle to a Diesel engine.

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[Miteshshetty]

Im not trying to map otto cycle to a diesel engine but trying to compare both of them with same compression ratio and initial volume(V1)
And ya mass flow rate for ideal cycle is simply volume*density, thanks!