CITY GAS DISTRIBUTION (Energy that creates a better path): Gas Discharge To The Atmosphere Calculation

Tuesday, February 16, 2021

Gas Discharge To The Atmosphere Calculation

 

Gas Discharge To The Atmosphere 
From A Pressure Source:
 

When the gas velocity is choked, the equation for the mass flow rate is:



or this equivalent form:

[ It is important to note that although the gas velocity reaches a maximum and becomed choked, the mass flow rate is not choked.  The mass flow rate can still be increased if the source pressure is increased. ]

Whenever the ratio of the absolute source pressure to the absolute downstream ambient pressure is less than [ ( k + 1 ) / 2 ] k / ( k - 1 ), then the gas velocity is non-choked (i.e., sub-sonic) and the equation for the mass flow rate is:


or this equivalent form:



where: 
 
  
  
  
 
  
  
 
  

Q
C
A
 
gc
 
k
 

Rho
P
 
PA
 
M
R
T
Z

=  mass flow rate, lb / s 
=  discharge coefficient     (dimensionless, usually about 0.72)
 
=  discharge hole area, ft
 2 
=  gravitational conversion factor of  32.17 ft / s
 2 
=  cp
 / cv  of the gas
=  (specific heat at constant pressure) / (specific heat at constant volume)
=  real gas density, lb / ft
 3 at P and T 
=  absolute source or upstream pressure, lb / ft
 2 
=  absolute ambient or downstream pressure, lb / ft
 2 
=  gas molecular weight
=  the Universal Gas Law Constant  =  1545.3 ft-lb / ( lbmol · °R )
=  gas temperature, °R
=  the gas compressibility factor at P and T     (dimensionless)


Damage line Gas  Loss calculation


https://drive.google.com/file/d/1eorVzInCN3csoSwYMm8duU4M-bS8iW96/view?usp=sharing

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