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fresh air load calculation
2

fresh air load calculation

fresh air load calculation

(OP)
hai to all,
I am new to this site and I have one doubt please help me..
Imagine a non-conditioned room, and I am supplying 1000cfm of fresh air at 18 degrre.
I want to know how much heat load will take that fresh air ?

RE: fresh air load calculation

it depends on room temperature and humidity. For example if your room is 18°C, you don't cool anything with 18°C air. You may remove some moisture (Latent load) if your fresh air contains less water.

read some fundamentals.

RE: fresh air load calculation

how much heat load will take that fresh air ?

? How much heat load that fresh air has to be removed?

What dew point do you have to what do you want at what temperature to end up with; as in first reply...?

RE: fresh air load calculation

Smart question

RE: fresh air load calculation

(OP)
thanks to all for the response, my problem still existing..
let me make it more clear. I know it is depended to lot of if's and but's.
I have a kitchen. the total heat load calculated for that room is say 10 ton.
the thermostat set point taken as 24 degree. Now I am supplying 1000 cfm of fresh air @ 18 degree.
I think it much more clear now. I want to know is there is any direct calculation for finding out the load taken by the fresh air?

RE: fresh air load calculation

I take it you're the only "senior engineer" at your company even though you only have 1-year experience (if that).
Basically, you don't have a clue about HVAC and you want us to design you a solution.

RE: fresh air load calculation

Here's how you calculate:
q: heat transfer rate, Btu/h
Trt: Room temperature, F
Tst: Supply Air temperature, F
V: Air flow rate, ft3/m
q= 1.085 x V x (Trt - Tst)

Metric form:
q: Watts
V: L/s
Trt, Tst: C
q = 1.2 x V x (Trt - Tst)

Note this calculation is based on sensible heat and it is used for dry bulb temperature while not taking into consideration the latent loads or moisture sources.

RE: fresh air load calculation

(OP)
Dear Foreiner,

Thank you for your valuable information. it is clear now.

RE: fresh air load calculation

(OP)
Dear Cry22,

For me it is a part of my learning curve. I believe that I will be always junior when it comes studies.
And I prefer continuous learning until my last breath.

RE: fresh air load calculation

That formula applies only to sensible load calc, and you cannot know whether there is only sensible load removal until you know relative humidities and find dew point temperature.

There is no bypass to basic learning, which in this case means - psychrometrics.

RE: fresh air load calculation

It almost feels as if you don't know what you are doing, and that feeling doesn't make clients feel good. Your client might realize that you have no business designing hvac if you are making these kind of fundamental questions, and end up hiring someone else.

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