Main Question or Discussion Point
I have been working on a series of questions dealing with gas expansion and temperature change for my PE exam.
sorry having trouble with the latex thing so im just going to type it out,I have been working on a series of questions dealing with gas expansion and temperature change for my PE exam.
Vr generally stands for Reduced Volume (i.e. The ratio of the specific volume of a substance to its critical volume). Not sure without seeing the book you are reading though.I am kinda working the thermal expansion of methanol in tandum with joule thompson expansion. I am studying for my PE right now (along with doing that thermal expansion of methanol at work) and I am having the same set of problems dealing with air, I attempted to use joule thompson to model rapid expansion of gas (the calcs under methanol expansion actually apply more to joule thompson rather than liquid expansion). If you view the work I did attached to thermal expansion of methanol (and I will also attach the mathcad and updated hand calcs) you will see that you get temperature trends opposite of what is expected and after going through the first law derivation and a bernoulli differential equation its pretty frustrating because it should be correct for the rapid expansion of a gas, I was doing this in order to develop an equation for T2 in terms of pressure change using a vander walls equation of state.
All that being said I need to progress with my PE study so I have just been using the air tables at the back of the PE book but I am not sure what Vr actually is. In an otto cycle in the constant volume expansion V is constant from D to A but Vr is not what exactly is Vr, we never used air tables in college and while I can crank out the PE problems using the methods in the book I would really like to know what it is im doing.
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I have the updated joule thompson calcs worked out using the bernoulli differential equation (the roots of the methodology of solving first order non seperable differential equations will have to wait another day in a different section, but what is up with the integrating factor and why can you assume the constant of integration goes away, among other questions) and I will post them as soon as I can consolidate my work and scan everything in.
It is the chemical engineering PE exam book by professional publications. I have attached my final calcs, it would not allow me to attach xmcd files but this should be enough. The A was put there by another engineer that was looking at it at my desk while I was away from my desk and he was waiting to go to lunch with me, this was just for the first sheet deriving the joule thompson relationship.Vr generally stands for Reduced Volume (i.e. The ratio of the specific volume of a substance to its critical volume). Not sure without seeing the book you are reading though.