Will condensation occur? 1

[afa13]

Hey guys,
Supposedly there is a space with the following properties:
T1=23 C
Td1= 14 C
RH= 55 %
Where,
T1 is the room temperature,
Td1 is the room dew point temperature
RH is the relative humidity.
Let us say that there is an exhaust fan moving the air from the room to the surrounding outdoor with the following properties:
T2=50 C
Td2= 39 C
RH= 55 %
Where,
T2 is the outdoor temperature,
Td2 is the outdoor dew point temperature
RH is the relative humidity.

Will condensation occur at the end of the exhaust duct where room air gets pushed outside?

 

[berkshire]

As long as the end of the duct is designed properly with a downward slope or a gooseneck, it does not matter.
Since you, cannot, always control the outside air conditions, you must presume that the exhaust duct will, get condensation in it if you are exhausting warm room air to outside if you have no insulation at the end of the duct. If this is a student question go back to your books and charts and do the math.
B.E.

You are judged not by what you know, but by what you can do.

 

[RandomUserName]

Water condense out of the air onto any surface whose temperature is lower than the room air dewpoint: 14 C (such as a cold coke can from the fridge).

As your air moves through the exhaust and outside (where it is 50 C outdoors), I see no reason why water will condense out of the air.

 

[afa13]

RandomUserName,
the air coming out from the room is the coke taken out from the fridge in your example, right?
the room's air dew temperature is lover than the outdoor's temp meaning it should condense 23<39

 

[IRstuff]

"the room's air dew temperature is lover than the outdoor's temp meaning it should condense 23<39"

Perhaps there's a language issue here. The air that comes from room will itself not condense, because it's drier than the external air, which is why it has a low dewpoint. Only the external air can be condensed, but only if it gets sufficiently cooled by the exhaust air. And only if there's sufficient air mass in the exhaust air. Now, the duct could get cooled by the exhaust air sufficiently that when the exhaust air stops and the outside air mixes in, there might be some momentarily condensation until the duct warms up and the cycle resumes.

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[afa13]

IRstuff,
The fan will be constantly running.
Supposedly it won’t, I think a backdraft damper would resolve the issue, don’t u?
And r u saying that condensation has a low probability of happening?

 

[IRstuff]

The outside surface of the duct will have condensation

TTFN
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[afa13]

IRstuff,
would 50 mm of insulation resolve it?

 

[IRstuff]

Do you really care if it's on the outside? Wouldn't you get dew?

TTFN
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homework forum: //

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[afa13]

IRstuff,
I am just asking out of curiosity