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Dew Point Calculation in a Gas Mixture

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Dew Point Calculation in a Gas Mixture fac 03-19-2008
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Posted by fac on March 21, 2008, 5:57 am
I have a heated mixture of:
O2: 12%
H2O: 13%
N2: 70%
CO2: 5%


Temperature: is around 200ēC.

Somebody is asking me about the dew point. I know how to calculate the dew
point if it were H2O in air (using psicometric ASHRAE diagrams) but I am not
able to calculate it in this mixture.

Does anybody knows any standar o procedure to calculate this?

Thanks


> I don't know what are you trying to get or do
> water contents in gases are measured in parts per million
> and the dew point temperature varies with temperature
> of particulars gas/refrigerant lower the Temp. the lower the dew
> point, example while 10 parts per million maybe ok for R-134A
> it is not good for R-508B which it needs to be 7 parts per million
> or lower, there for dew point will be much lower.
> if you are looking for formulas sorry can't help you.
> In another process you can dry air what you are breathing
> to 100 below zero dew point or lower using chemical reactivation.
> which I am sure you are not looking for that.
> Tony
>
> > Does anybody knows where to find information to calculate the Dew Point
> > temperature of water in a gas mixture.
> >
> > In air it is stated in ASHRAE, but what happens with water in different
> > gases (for example a mixture of H20, Ar, N2 .......)
> >
> >
> >
> > Thanks
> >
> >
>
>



Posted by on March 21, 2008, 9:45 am

>I have a heated mixture of:
>O2: 12%
>H2O: 13%
>N2: 70%
>CO2: 5%

        No, you don't. No way do you have that much water vapor.

        What is the compositoin of the gas BEFORE you add water to
it ? It looks similar to air ( not exact ).

        

>
>
>Temperature: is around 200ēC.
>
>Somebody is asking me about the dew point. I know how to calculate the dew
>point if it were H2O in air (using psicometric ASHRAE diagrams) but I am not
>able to calculate it in this mixture.
>
>Does anybody knows any standar o procedure to calculate this?
>
>Thanks
>
>
>> I don't know what are you trying to get or do
>> water contents in gases are measured in parts per million
>> and the dew point temperature varies with temperature
>> of particulars gas/refrigerant lower the Temp. the lower the dew
>> point, example while 10 parts per million maybe ok for R-134A
>> it is not good for R-508B which it needs to be 7 parts per million
>> or lower, there for dew point will be much lower.
>> if you are looking for formulas sorry can't help you.
>> In another process you can dry air what you are breathing
>> to 100 below zero dew point or lower using chemical reactivation.
>> which I am sure you are not looking for that.
>> Tony
>>
>> > Does anybody knows where to find information to calculate the Dew Point
>> > temperature of water in a gas mixture.
>> >
>> > In air it is stated in ASHRAE, but what happens with water in different
>> > gases (for example a mixture of H20, Ar, N2 .......)
>> >
>> >
>> >
>> > Thanks
>> >
>> >
>>
>>
>

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Posted by -zero on March 21, 2008, 12:33 pm

>I have a heated mixture of:
> O2: 12%
> H2O: 13%
> N2: 70%
> CO2: 5%
>
>
> Temperature: is around 200ēC.
>
> Somebody is asking me about the dew point. I know how to calculate the dew
> point if it were H2O in air (using psicometric ASHRAE diagrams) but I am
> not
> able to calculate it in this mixture.

That would be a flue-gas mixture, not a fuel-gas mixture. It will
condense according to the environment the flue is discharged into.
To keep it from condensing inside the pipe, insulate the pipe
to keep it above 250° Fahrenheit.

-zero



Posted by Zyp on March 21, 2008, 12:40 pm
-zero wrote:
>> I have a heated mixture of:
>> O2: 12%
>> H2O: 13%
>> N2: 70%
>> CO2: 5%
>>
>>
>> Temperature: is around 200ēC.
>>
>> Somebody is asking me about the dew point. I know how to calculate
>> the dew point if it were H2O in air (using psicometric ASHRAE
>> diagrams) but I am not
>> able to calculate it in this mixture.
>
> That would be a flue-gas mixture, not a fuel-gas mixture. It will
> condense according to the environment the flue is discharged into.
> To keep it from condensing inside the pipe, insulate the pipe
> to keep it above 250° Fahrenheit.
>
> -zero

Well there ya go... see, I didn't see the writing on the wall :)

--
Zyp



Posted by -zero on March 21, 2008, 6:37 pm

> -zero wrote:
>>> I have a heated mixture of:
>>> O2: 12%
>>> H2O: 13%
>>> N2: 70%
>>> CO2: 5%
>>>
>>>
>>> Temperature: is around 200ēC.
>>>
>>> Somebody is asking me about the dew point. I know how to calculate
>>> the dew point if it were H2O in air (using psicometric ASHRAE
>>> diagrams) but I am not
>>> able to calculate it in this mixture.
>>
>> That would be a flue-gas mixture, not a fuel-gas mixture. It will
>> condense according to the environment the flue is discharged into.
>> To keep it from condensing inside the pipe, insulate the pipe
>> to keep it above 250° Fahrenheit.
>>
>> -zero
>
> Well there ya go... see, I didn't see the writing on the wall :)

Well,,, sniffing too much flue gas will do that to ya. ;o)


> Zyp
>




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