# I need help calculating the maximum pressure

1. Aug 11, 2006

### xto

I've serach for almost a day now ,
just to search the formula to calculate the maximum pressure in the cycle
A very big thank you and appreciate for the help

2. Aug 11, 2006

### Staff: Mentor

What cycle specifically are you referring to, xto? Could you please provide a more complete problem description, and show us what you have tried so far?

3. Aug 12, 2006

### xto

i)isothermal compresssion from state 1 through a volumetric compression ration of 6 to state 2
ii) isobaric expansion from state 2 back to the initial volume thus reaching state 3
iii) isochoric cooling from state 3 back to the original pressure to reach state

it ask for the mass of air present and the maximum pressure in the cycle

Given
R=0.287 kj/kg K
Cp=1.005 Kj/KG K

i have done
pv=nrt
t=303K
p=1.2x0.9869
=1.1832
V=2.2x1000
=2.2x10^3

so (1.1832atm)(2.2x10^3L)
-----------------------
(1.005) (303K)

which the ans is 247.90g Air

then i use this formula
vm=(Qp/4 x Z)
so (2.2x10^3)(1.005)/4x(0.287)
which get
1925.958

i'm not sure if it's rite or not