volumetric flow and mass flow

[김진수]

In order to see the chimney effect,

the inside temperature of the shaft was set higher than the outside temperature,

and the outlet of the chimney was set at a position higher than the inlet.

The simulation result shows the same inlet and outlet volume flow rates.

Since the inlet air flow is of outside temperature and the outlet air flow is of inside temperature,

shouldn't the volumetric flows be different each other when the mass flows are same?

 

Thank you in advance.

Jin soo

[Stuart Dols]

ContamW only displays mass flow rates.

It does not display volumetric flow rates.

Some airflow units may appear to be volumetric, e.g., sm3/s, but these are actually mass flow units based on standard conditions.
You can convert them to volumetric flows using the upstream air temperature and standard density of 1.2041 kg/m3 at 293.15 K.

- Stuart

[ehsan alam]

Hello Stuart,

Does this mean sm3/s is the same as kg/s ?

I am working on a prj file in which one of the supply airflow rates shows 0.825 sm3/s. 

Could you please convert this to mass flow rate or volumetric (at 21 degree Celsius) so that I can confirm my calculation?

I am using the following formula from CONTAM user guide:

Thank you for your help

Ehsan

[William Dols]

RHOstd = 1.2041 kg/m3 for CONTAM at 20 C

RHO21C = RHOstd * (Tstd/(273.15 + 21)) = 1.2000 kg/m3

Mass Flow = 0.825 sm3/s * RHOstd = 0.9934 kg/s

Volumetric Flow = 0.9934 kg/s / 1.2 kg/m3 = 0.8278 m3/s 

In my previous message, Vdot is volumetric flow in units of m3/s.

- Stuart