Can I Calculate the Maximum Air Flow for Maintaining Room Temperature Below 36C?

In summary: Thanks for your time.In summary, if you have a room with a size of 3x7x3.5 meters, and a blower fan that is putting out 4 kilowatts of power, you need to make sure that the air in the room is well mixed, and that you provide an opening where the air can exit the room. If you want to maintain the room temperature below 36 degrees Celsius, you will need to calculate the time it will take for the room to reach steady state.
  • #1
yeswan
3
0
Hi all,

I have a question here. If I have a room with size of 3m x 7m x 3.5m with equipment of heat dissipation of 4kW. A blower fan is installed in the room to draw in the ambient air into the room to reduce the room temperature. At extreme condition the ambient temperature is around 33C. What is the calculation of the maximum air flow is if we want to maintain the room temperature below 36C?

Thanks.
 
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  • #2
Welcome to physics forums.

You need to make sure that the air in the room is well mixed. Then,

[itex]WC_p(T - T_{amb}) = 4 [/itex] kilowatts
 
  • #3
Hi! Thanks for your reply in advance!

By the way, how to consider the room is well mixed?

And for your formula, what is the W and Cp stand for?

Since this is related to a room volume, doesn't it the room volume have to be considered as well??
 
  • #4
yeswan said:
Hi! Thanks for your reply in advance!

By the way, how to consider the room is well mixed?

And for your formula, what is the W and Cp stand for?

Since this is related to a room volume, doesn't it the room volume have to be considered as well??

Well, you have a fan blowing air in, so that does some mixing, but the room is pretty big. Maybe another fan would help. You also need to provide an opening where the air can exit the room, and, by supplying the mixing, you want to make sure that the intake air does not channel directly to the exhaust fan so that it avoids mixing with the other air in the room. You can check to see if more mixing is needed by moving a thermometer around the room.

In the formula, W is the mass rate of flow of air through the fan and exit port, and Cp is the heat capacity of air.

The room volume only has to be considered if you are trying to estimate how long it takes for the system to reach steady state. That amount of time will be on the order of the room volume divided by the volume rate of flow of air through the room.
 
  • #5
Mmm... What is the unit for heat capacity? How do we know that the heat capacity is? Is it get from Psychometric chart or there actually is a constant?

If we also want to calculate the time to steady the room temperature, what is the formula like?

Thanks.
 
  • #6
It is close enough to constant. You can google specific heat capacity of air...
 
  • #7
yeswan said:
Mmm... What is the unit for heat capacity? How do we know that the heat capacity is? Is it get from Psychometric chart or there actually is a constant?

If we also want to calculate the time to steady the room temperature, what is the formula like?

Thanks.

I'm beginning to get the feeling that you are not so much interested in learning Physics as you are in getting some free consultation on a specific system you are dealing with. If you want some consultation, many of us can accommodate you, but not for free.
 

1. What is air mixture calculation?

Air mixture calculation is the process of determining the composition of gases that make up the air around us. It involves measuring the amount of different gases, such as oxygen, nitrogen, and carbon dioxide, and calculating their proportions.

2. Why is air mixture calculation important?

Air mixture calculation is important for many reasons. It helps us understand the quality of air in a specific location, such as in a laboratory or industrial setting. It also allows us to monitor changes in air composition over time, which can provide valuable information about the environment and potential health risks.

3. How is air mixture calculation performed?

Air mixture calculation can be performed using various methods, such as gas chromatography or mass spectrometry. These techniques involve separating the different gases in a sample and then measuring their concentrations. Other simpler methods, such as using gas sensors, are also commonly used.

4. What factors can affect air mixture calculation?

There are several factors that can affect air mixture calculation, including temperature, pressure, and humidity. These variables can impact the behavior and concentration of gases in the air, and therefore must be taken into account during the calculation process.

5. What are the applications of air mixture calculation?

Air mixture calculation has many applications, including air quality monitoring, environmental studies, and industrial processes. It is also used in medical and scientific research to understand the effects of different gas compositions on human health and other living organisms.

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