How Do You Determine Heat Transfer and Work in a Thermodynamic Cycle?

[kdinser]

I'm having problems getting started on this one.

A gas undergoes a thermodynamic cycle consisting of 3 processes

process 1-2 compression with pressure(p)*volume(V) = constant, from
p_{1} = 1 bar
V_{1} = 1.6m^3
to
p_{2} = ?
V_{1} = .2m^3

U_{2}-U_{1}=0

process 2-3
Constant pressure to V_{3}=V_{1}

process 3-1
Constant Volume, U_{1}-U_{3} = -3549kJ

There are no significant changes in kinetic or potential energy.
Determine the heat transfer and work for process 2-3 in kJ.

I don't have any problems findingp_{2} or the work needed to compress the gas, but I'm not really sure where to go from there.

p_2=\frac{p_1V_1}{V_2}

W=\int p dV

When I work these out, I end up with 333kJ for W and 8 bar for p2.

If someone could give me a quick push in the right direction, that would be great.

 

[quantumdude]

Sorry for the late reply. In case you're still interested, here are some questions for you to think about. If you answer them in order, you'll be led straight to the solution.

* What is the net change in internal energy for the entire cycle?
* What is the net change in internal energy for the process 2\rightarrow 3?
* What is the work done for the process 2 \rightarrow 3?
* Now use the First Law to get the heat transferred in the process 2 \rightarrow 3.