Engineering Thermodynamics

[khansisters]

a system consisting of 1.2 kg of an ideal gas at 4.8 bar pressure and 0.02 m^3 volume executes a cyclic process comprising of (a)reversible expansion to 0.08 m^3 , 1.6 bar & presuming pressure to be a linear function of volume(b) reversible cooling at constant pressure(c)reversible hyperbolic compression according to the law PV=constant.this brings the gas back to the initial condition.(1)sketch the cycle on P-V diagram(2)calculate work done in each process stating whether it is done on or by the system(3)evaluate the net work done & heat transfer.

[Flonska]

Reported

[Captain2]

We'll have the full exam paper soon.
Are you taking note of the comments on your other threads?

[Flonska]

Many years ago a boy at our school was asked by the "Careers" Master what he thought he should study at Uni. He answered, "I appear to have a choice between "Thermonuclearfusion or Folk Singing!"

[IJKLM]

Hi KhanSisters

As one of the resident engineers here, I can probably help. Thing is that it will take me an hour or so to refresh my kmnowledge of this subject, and I was not sure of the terminology, such as "reversible hyperbolic compression"

I have a couple of questions - have you already spent an hour or so trying to solve this one (because I really don't want to spent that time to help you, if you have not already put some effort in.

The other is, have done a very simple search?

I tried putting "reversible hyperbolic compression" into a well-known search engine. It came upwith this link (below), which essentially tells you how to do it.

So to save us all a lot of time, do you think you could do the same?



https://books.google.co.uk/books?id=65gxCX2dC84C&pg=PA203&lpg=PA203&dq=reversible+hyperbolic+compression&source=bl&ots=sJkdPZkkO5&sig=nYKLvsBYXc4sjoaIgllR_oz-Dpw&;hl=en&sa=X&ved=2ahUKEwjro6yHgLvdAhXHKMAKHSIPCyoQ6AEwE3oECAEQAQ#v=onepage&q=reversible%20hyperbolic%20compression&f=false

[Mamyalynne]

IJLKM - the OP is suspended, probably been reported for overposting.

Maybe check back tomorrow to see if that changes.

[Peter Pedant]

o come on come on
a is a straight line with neg gradient at const temp so use P1V1=P2V2

b) is const P so is a straight line parallel to the X axis

c) PV=const is hypernolic

the triangle is (.02, 5) then (.08, 1.6) for a
b is parallel line at y=1.6
c is PV =const from (02,5) to p2, 1.6) ( this allows you to calc p2)
and so you now know the intercept for the straight line....

a does work b looks as tho it does work c work done on it

honestly you read the chapter in your textbook
and then do the problems as they do in examples .....

and no please dont post again - two thermodynamic problems for an OAP are quite enough, but thanks

[Mamyalynne]

I'm off to practise my alphabet.

[Sqad]

These answers make me feel like "Trigger" in Only Fools and Horses.

[rowanwitch]

Could be a recipe for an exotic cheesecake for all I can tell

[sandyRoe]

Come, come, Sqad, could any of these people whip out an appendix while ogling an attractive theatre nurse?
I think not. :-))

[Sqad]

LOL^^^ never thought of that.

[Peter Pedant]

IJKLM
reversible hyperbolic compression
as a cambridge physiologist is
PiVi = constant
looks like a hyperbola to me

a thought this was gonna be a carnot cycle
but a is a straight line
b is parallel to the x axis - but you need to find the intercept
c is pv=const - and will give you the intercept as the P is known

oh I cant work out if the parallel x axis is "work done on"
or "work done by" - o it is work done on

so the PV diagram looks like a leany over triangle.... obscene or whatever it is called

honestly this is all in
Fundamentals of Engineering thermodynamics
Morgan and Shapiro

he has to read this and not me

I thought this was a spoof - but he may be under the impression that we are a free gratis essay mill .....
rather than the rum mix we are

[IJKLM]

PP
Thanks for that. Reversible compression is obvious, but it was the hyperbolic bit that I had not seen before.
I figured it was that the adiabatic compression follows a hyperbolic path on the P-V diagram.
Most steam tables (P-Volume and P-enthalpy) are drawn from measurements.
I figure that the problem approximates the heuristically-derived chart to a hyperbola in an effort to make the integration easier.

But I did not spend the hour trying to understand exactly what is going on, so I might be wrong.

If I am, I'm sure you'll let me know, but to be honest, I'm very glad that I don't have to do that stuff any more and quite relaxed about being wrong.

[Peter Pedant]

yeah - no, nice to speak to an engineer
I thought it was one student going 'eek'

but instead a lazy tike with a c/p capability - and a belief that if he gets s/o else to do the problems he will do really well in engineering

Hey whilst you're here - have you got a model for Hurrican Florence?
I worked out that over the sea it can get worse from a cycle point of view from the rain/evap cycle - all driven by heat from the warmish water
but that on land, there is no sea to evaporate so the cycle is interrupted ... so the storm intensity decreases after land fall

but I hadnt got much further than that ....

( the equations for storm surge were worked out in 1913 no less)

[fbg40]

If it takes a man and a half to lay a lawn and a half, how many eggs in a butcher's dozen ?? QED.
FBG40

[Peter Pedant]

ah foo!
I thought some one would eventually let the lunatics in

[fbg40]

Thanks PP, just trying to "lighten the atmosphere" a bit - apologies.
FBG40