Temperature/Humidity Reduction in Semi-Closed Centrifugal Fan Set-up

[resilientsoma]

Hello All,

I'm new, but have been browsing your forums for quite some time. Please point me in the correct direction with my current problem:

In my plant we use a water-cooling system which generates a lot of heat. I have proposed to use a centrifugal blower to pull this moisture/humidity out of this area which is mostly enclosed. Before hand, it was making the surrounding areas very hot and humid. Making the area more enclosed and having a blower pulling out the moisture/humidity, is there a calculation to use to determine the reduction in temperature and humidity?

The information I have is temperature for the enclosed area (water cooling system), temperature/RH/dewpoint of surrounding areas, CFM and SP of blower.

Basically trying to figure out if there is a reduction calculation or only assume ambient effects being enclosed. The enclosed area is a stainless steel housing with a canvas roof.

I'm sorry for not being more specific, your help is greatly appreciated. Thank you!

 

[resilientsoma]

 

[KiwiMace]

Generally when you consider such a problem, you draw a circle around your room and consider what is coming out of the circle and what is going in.

You have a room in which the climate is influenced by a number of factors such as solar load, conduction, infiltration of air etc, and a humid steam bath in the middle of the room. You now have a situation in which you have ducted this high latent load out of the circle.

What is important is not just the one process you are changing, but the effect on what is going in/out of the circle. The load calc for the room needs to be looked at.

One thing that won't change is the radiant heat coming off the surface of the process housing. It might be cooler and less humid in the room, but it still might feel hot due to this.

 

[sprinkler1000]

You should use a psycrometric chart to establish enthalpy differences between exhausted air and incoming air, wich I assume is from outdoors.
Also this air changes in the room should take care of humidity, as long as your climate is not very humid.
As Kiwimace said the radiant heat is an issue, but exhausting the air with the vapor heat output is a must.

You have to design not only the exhaust fan but the intake fan. Otherwise the air may be drawn from adyacent rooms.

BR

 

[resilientsoma]

I agree to your posts Kiwi & Sprinkler. What great insight! I made an error, the CFM calculated is 40,000 not 40.

This would only operate in the summer months, so doors would be open bringing in air. I agree there will be ambient temperature effects, but should be minimum. Being the cooling chamber is mostly enclosed and exhausting the moisture/steam from the process, should I assume only ambient & radiant effects?

I heard about psycrometric charts. I'm new with this kind of mindset engineering, but I'm trying. This leads me in a good direction for sure though. The moisture is created from water hitting the red-hot product and steam being created. This will exhaust out, and condensate created will drain into a tank. During the summer months, we cannot make the inside air conditions better than the outdoor air conditions (industry obviously). As far as an inlet fan, this was not considered. Only 1 centrifugal fan. Enclosing the cooling chamber will direct the steam to the ducts (assumed). I am trying to stick with this design, but need to know if I can match the indoor air quality (T, RH, DEWP) with the outdoor since when this cooling chamber is running with the process, it brings the humidity and moisture content up in the surrounding areas. So I'm trying to take this moisture away to make the conditions better for the workers in the surrounding areas. Sorry to ramble.

 

[sprinkler1000]

40,000 cfm is a large flow rate. Certainly the indoor conditions will be much like outdoor since this air is coming through windows. I don't know how many people work there but if you want to control temperature and humidity for this air flow rate you will need to install a makeup air unit. In summer the internal load plus the outdoor heat can make the space very uncomfortable.

 

[willard3]

You should either find or hire an Engineer to help you with this, it is not a simple problem.

 

[resilientsoma]

There is make-up air units in the plant. The cooling chamber when running raises the temperature/humidity/dew point. If I ventilate this to the outside, assuming the cooling chamber is enclosed, will I only experience radiant heat effects? Or is there some formula(s) where I can find the change in the surrounding area's T/RH/DEWP with the centrifugal blower installed exhausting the moisture outside? I am sorry if I'm not including enough detail; as you can tell I'm quite new at this. I'm just trying to be pointed in the right direction.

 

[resilientsoma]

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[IRstuff]

The bottom line is that there is no "simple" answer. Much depends on extremely precise details about your proposed configuration. This would generally need to be fed into a software package designed for this type of application.

Nonetheless, assuming adequate insulation on the enclosure, there should be minimal impact to the outside, e.g., think about a refrigeration with a separately ducted heat exchanger on the back. There is only a small amount of heat transferred between the cold space and the exterior, as intended by the design.

TTFN
faq731-376

 

[317069]

"The cooling chamber when running raises the temperature/humidity/dew point."
Can you help to understand how cooling chamber raise humidity?

 

[resilientsoma]

Thank you so much for your responses;

I was assuming only radiant/ambient effects being an enclosed cooling chamber, assuming the chamber is well insulated. I was just wondering if there would be any formulas that I was not aware of... maybe as something simple as TEMP1 of body will increase room temperature? Seems simple enough...

@ 317069 : the cooling chamber produces humidity/moisture and increases temperature because it is cooling a product at 1200F as pictured above. It uses water to cool the product, creating a lot of steam and moisture; that's why I need to enclose the area more and ventilate it outside.

 

[resilientsoma]

Alright guys,
I'm going to assume that this is only radiant heat effects in the surrounding areas. If the cooling chamber is to become enclosed, doesn't seem like it will make the surrounding area much more hotter/more humid. I will assume it to be negligible, only a couple degrees of ambient temperature increase. Thanks for the insights.