air pressure drop calculation misleading

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adam24
Posts: 1
Joined: Thu Jun 13, 2013 6:02 pm

air pressure drop calculation misleading

Post by adam24 »

Hi admin,
I believe the air pressure drop calculation is a bit misleading. The input I selected was -calculate for Pressure drop, pressure on the pipe start, volumetric flow rate at normal conditions.

If I specify the volume flow, the mass flow is calculated based on 1 bar pressure density. While the density should be calculated from inlet pressure since the inlet pressure is one of the inputs.

It can be simply checked:
qn=0.1 m3/s
w=0.1293 kg/s ( this does not vary whatever is the p1)

In fact originally I thought I found an error, but perhaps it was meant to be like that.
What do you think?

Best regards,
Adam
admin
Site Admin
Posts: 375
Joined: Mon Feb 08, 2010 7:47 pm

Re: air pressure drop calculation misleading

Post by admin »

Hi Adam,
As you can see in calculator flow rate has symbol of - qn and it is for normal conditions (p=101325 Pa, T=0) so density is also at that condition.
I can also add option to enter flow at p1 or p2 but I think it is not very convenient way for calculation - I think much more often you will not know the flow at p1 but flow at normal condition?
Pipe flow calculations - since 2000
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