Example:

Given: T=16.85_°C, P=1_atm, V=25_1, MW=36_g/gmol.

Solution: n=1.0506_gmol, m=3.7820E-2_kg.

Ideal Gas State Change (5, 2)

Equation:

Pf ⋅ Vf Pi ⋅ Vi

---------------- = ---------------

Tf Ti

Example:

Given: Pi=1.5_kPa, Pf=1.5kPa, Vi=2_l, Ti=100_°C, Tf=373.15_K.

Solution: Vf=2_1.

Isothermal Expansion (5, 3)

These equations apply to an ideal gas.

Equations:

Vf

m = n ⋅ MW

W = n ⋅ R ⋅ T ⋅ LN------

Vi

 

Example:

Given: Vi=2_l, Vf=125_l, T=300_°C, n=0.25_gmol, MW=64_g/gmol.

Solution: W=4926.4942_J, M=0.016_kg.

Polytropic Processes (5, 4)

These equations describe a reversible pressure-volume change of an ideal gas such that P ∗Vn is constant. Special cases include isothermal processes (n=1), isentropic processes (n=k, the specific heat ratio), and constant-pressure processes (n=0).

Equations:

 

 

 

 

 

n – 1

 

 

Vf –n

 

 

-----------

Pf

=

Tf

=

Pf n

-----

------

-----

-----

Pi

 

Vi

Ti

 

Pi

Example:

Given: Pi=15_psi, Pf=35_psi, Vi=1_ft^3, Vf=0.50_ft^3, Ti=75_°F.

Solution: n=1.2224, Tf=164.1117_°F.

Isentropic Flow (5, 5)

The calculation differs at velocities below and above Mach 1. The Mach number is based on the speed of sound in the compressible fluid.

5-26 Equation Reference