Chapter 2 : Review of basic concepts

Example 2.1 Page No : 29

In [3]:
import math

# Variables
R = 8.314;			 #universal gas constant in J/molK
t1 = 300.;			 #initial temperature of gas in K
p1 = 0.1;			 #initial pressure of the gas in MPa
p2 = 0.5;			 #pressure of gas after heating in MPa
p3 = 0.1;			 #pressure of gas after expansion in MPa
n = 1.; 			 #number of moles of gas in mole

# Calculations
w1 = 0*n;       			 # Calculations of work done by the gas during heating in kJ (since dv = 0)
t2 = t1*(p2/p1);			 # Calculations of temperature of gas after heating in K
t3 = t2;		        	 # Calculations of temperature of gas after expansion in K (constant temperature expansion)
volume2 = p2/p3;			 # Calculations of  ratio of volume of gas after expansion to the volume of gas after heating (no unit)
w2 = (R*t2*math.log(volume2)*n)/1000
volume3 =  t3/t1;		
w3 = (R*t1*(1-volume3)*n)/1000
work_net = w1+w2+w3;			 # Calculations of net work done by the gas for the process in kJ

# Results
print ' Work done during heating process:Work from 1-2 =  %d kJ '%(w1);
print ' Work done during constant temperature expansion: Work from 2-3 =  %.3f kJ '%(w2);
print ' Work done during constant pressure compression: Work from 3-1 =  %.3f kJ '%(w3);
print ' Net work done by the gas during the process =  %.3f kJ '%(work_net);
 Work done during heating process:Work from 1-2 =  0 kJ 
 Work done during constant temperature expansion: Work from 2-3 =  20.071 kJ 
 Work done during constant pressure compression: Work from 3-1 =  -9.977 kJ 
 Net work done by the gas during the process =  10.095 kJ 

Example 2.2 Page No : 30

In [4]:
# Variables
v1 = 0.1;			 #volume of gas initially present in the cylinder in m**3
p1 = 0.1;			 #initial pressure of gas in MPa
p_atm = 0.1;		 #atmospheric pressure acting on the piston in MPa
v2 = 0.3;			 #volume of gas after heating in m**3
p2 = 0.6;			 #pressure of gas after heating in MPa

# Calculations
work = ((p1+p2)*(v2-v1)*10**6)/(2*1000);			 # Calculations of work done by the gas in kJ 

# Results
print ' The work done by the gas  =  %d kJ'%(work);
 The work done by the gas  =  70 kJ