[esp-r] Re: CO2 unit

[Aizaz Samuel]

Ehsan,

Concentration reporting in the thesis is in PPM by mass. Units of volume have 
not been used anywhere in the code or the thesis because the analysis is 
based on conservation of mass but no conservation of volume exists. 

Furthermore I have not investigated mechanisms to convert PPM by mass to PPM 
by volume, it probably includes scaling by relative gram formula masses (air 
being 28 approximately and CO2 being 44) So one can convert: 1000ppm mass = 
1g CO2 per 1000g air = 1/44 mole CO2 per 1000/28 mole air = (1/44)*24 litre 
CO2 per (1000/28)*24 litre air = 0.636 lit CO2 / 1000 lit air = 636ppm volume

The above assumes a molar volume of 24 lit/mol for both gases. There might by 
other considerations in the above simple calculation so do check against some 
reference text.

Regards,
Aizaz Samuel


On Monday 18 January 2010 18:57, Ehsan Asadi wrote:
> Dear all,
>
> I have done a room simulation with esp-r and defined the contaminant and
> network flow as well. I was wondering the result in CO2 graph are reported
> in g/kg or not. As I could see it has written beside the axes g/kg of CO2.
> I do not know how can I convert the values to PPM unit. Usually 1000(g/kg)
> of CO2 is considered as PPM (MASS) and to transfer that to the PPM(Volume)
> it is necessary to times the value by 0.667. But in ESP-r documents(Samuel
> thesis) he just cross the values of CO2 in g/kg by 1000 and report the
> result. If someone knows something in this matter, please help me.:)
>
> Regards
> Ehsan