Hi Guys
I am trying to put together a spreadsheet, whereby a volumetric flow rate can be input, along with the properties of the fluid (IE Molecular Weight, Compressibilty and Specific Heat Ratio) and the process conditions (IE Temperature and Pressure), then this can be converted into mass flow rate of the fluid.
I am trying to do this for Nm3/hr, Sm/hr and mmSCFD and guess what the required mass flow is in kg/hr.
Obviously i have read up on conversions and the conditions for the measurement of the Nm3/hr and Sm3/hr been important. I would say that the Nm3/hr was at 0degC and the standard at 15degC.
The various conversions i have looked at on my travels are giving me a much higher value for the mass flow rate than for the volumetric one. However i am trying to calculate the Cv of a valve (whereby this is calculated in either Nm3/hr or in Kg/hr).
I know that Cv = Q / (2.12E3 x p1 x Y ) * (SQRT (( M x T1 x Z)/ X)
Y is the expansion factor of the gas and is calculated by:
1 - ( X / 3Fy x XT ) (XT is constant set by manufacturer in this case 0.8) (Fy is the specific heat ratio factor which is the specific heat ratio of the gas / 1.4)
M is molecular weight
T1 is inlet temp in Deg K
X is ratio of pressure differential to inlet pressure (delta p / p1 )
Q = Nm3/hr
There is also a seperate equation for calculating Cv if the flow rate is in kg/hr:
Cv = ( W / ( 94.8 x p1 x Y )) * SQRT((T1 x Z)/ (X x M))
The calculated Cv should be the same if i convert the mass flow into vol flow or vice versa... however it isn't working that way.. Thus i need some help.
The example i am working is, is 10000 Sm3/hr, Z=0.96, M=18, and Specific heat Ratio of 1.33.
p1=30bara , p2=15bara and T1 = 523K.
W=kg/hr
I would appreciate any input.
Cheers Folks
Matt
I am trying to put together a spreadsheet, whereby a volumetric flow rate can be input, along with the properties of the fluid (IE Molecular Weight, Compressibilty and Specific Heat Ratio) and the process conditions (IE Temperature and Pressure), then this can be converted into mass flow rate of the fluid.
I am trying to do this for Nm3/hr, Sm/hr and mmSCFD and guess what the required mass flow is in kg/hr.
Obviously i have read up on conversions and the conditions for the measurement of the Nm3/hr and Sm3/hr been important. I would say that the Nm3/hr was at 0degC and the standard at 15degC.
The various conversions i have looked at on my travels are giving me a much higher value for the mass flow rate than for the volumetric one. However i am trying to calculate the Cv of a valve (whereby this is calculated in either Nm3/hr or in Kg/hr).
I know that Cv = Q / (2.12E3 x p1 x Y ) * (SQRT (( M x T1 x Z)/ X)
Y is the expansion factor of the gas and is calculated by:
1 - ( X / 3Fy x XT ) (XT is constant set by manufacturer in this case 0.8) (Fy is the specific heat ratio factor which is the specific heat ratio of the gas / 1.4)
M is molecular weight
T1 is inlet temp in Deg K
X is ratio of pressure differential to inlet pressure (delta p / p1 )
Q = Nm3/hr
There is also a seperate equation for calculating Cv if the flow rate is in kg/hr:
Cv = ( W / ( 94.8 x p1 x Y )) * SQRT((T1 x Z)/ (X x M))
The calculated Cv should be the same if i convert the mass flow into vol flow or vice versa... however it isn't working that way.. Thus i need some help.
The example i am working is, is 10000 Sm3/hr, Z=0.96, M=18, and Specific heat Ratio of 1.33.
p1=30bara , p2=15bara and T1 = 523K.
W=kg/hr
I would appreciate any input.
Cheers Folks
Matt
