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Lc_shi
22-02-2006, 08:45 AM
Hi Sirs,
I need to set a test room(higher precision) for air cooling and heating coils heat transfer measurement. I check ASHRAE 33-1978 is for it. But I don't have it on hand. Who have similar experience to test air cooling coils to give me some suggestions:
I want the test system can automatically check and keep the temp/humidity/presure etc data in PC. i'm new to this tech. pls offer me a hand:)


best regards
LC

US Iceman
22-02-2006, 04:40 PM
LC,

Here are some sources for you to review.

http://www.ni.com/dataacquisition/

and,

http://www.ni.com/labview/

One of the problems which I think you will find is the area of providing uniform air velocity over the coil face. This will require some investigation of duct work losses and system effects to provide a uniform face velocity.

Here are some links for fan system effects.

http://www.greenheck.com/technical/files/engineering/00apr_eng.pdf

http://www.greenheck.com/technical/tech_detail.php?display=files/Product_guide/system_eff

http://ateam.lbl.gov/design-guide/DGHtm/ductworksystemeffect.htm


I once looked at this problem for air cooling coils in refrigeration use. The links for the data acquisition hardware/software above are from the company I investigated for this purpose.

I wanted to record the live data into a computer program and have the program do all of the calculations to improve the validity of the data and calculated performance of the cooling coils.

Unfortunately, the project did not develop since it was not important enough and would cost money.:(

frank
22-02-2006, 05:18 PM
One of the problems which I think you will find is the area of providing uniform air velocity over the coil face. This will require some investigation of duct work losses and system effects to provide a uniform face velocity.

You could always use an equalising grid - the problem here though is selecting one to give an acceptable pressure loss

Peter_1
22-02-2006, 06:48 PM
I scanned this information for you, coming from a very old Kuba catalog.

You just have to switch page 1 and 2, I scanned it not the right way and you will also need to turn sometimes a page.

I hope it's usefull for you.

For the registration and logging of all the parameters you describe, we use the loggers form Picotech (UK)
They're cheap, very reliable and extremely fast.

Have once a look at www.picotech.com

Their software is for free, including all the updates.

Litlle problem while scanning the Kuba papers and typing this message: file is to big to post (+/- 220 K) unless Dez can allow for once a larger upload.
There was last a suggestion to download it from another location.
PLease help.

US Iceman
22-02-2006, 07:15 PM
Frank,

I am showing my ignorance here, but what is an equalizing grid? The air side of the system is not my strongest area.

Thanks

frank
22-02-2006, 08:28 PM
Frank,

I am showing my ignorance here, but what is an equalizing grid? The air side of the system is not my strongest area.

Thanks
Iceman

An equalizing grid is a sheet (for want of a better word) of perforated metal that sits across the duct, coil, grille etc. As the air volume hits the sheet the air is forced or drawn through the small regular holes. It acts to "eqalize" the flow across an area.

If you select a sheet with really small holes then the equalization is increased but the resistance is also increased. If you choose a sheet with larger regular holes then the air has less resistance to the flow and the effect is somewhat less efficient.

We used a perforated sheet with holes of 8.5mm on a pitch of 18mm recently in an aidiabatic cooler where the air flow was 4.5m3/s. The air was delivered into the cooler in a 900 dia duct by a square to round transition on to a wetted cell 1800 high x 1500 wide. The equalizing sheet allowed the air volume to be spread quite evenly over the whole wetted surface and not just through the middle section.

Try typing equalization grid into Google. Most of the hits refer to grilles or louvres but you'll get the idea.

US Iceman
22-02-2006, 08:33 PM
Thank you for the answer Frank. I have seen these before on a built-up central station air handler I used for an egg breaking plant.

I'll be darned if I can remember the name of thing, but after I read your description I immediately knew what your were describing.

Thanks for the excellent answer.

frank
22-02-2006, 08:35 PM
My pleasure :)

Lc_shi
23-02-2006, 01:15 AM
I wanted to record the live data into a computer program and have the program do all of the calculations to improve the validity of the data and calculated performance of the cooling coils.

Unfortunately, the project did not develop since it was not important enough and would cost money.
I understand:). All the boss like their staff do more things and spend no money:p

For the registration and logging of all the parameters you describe, we use the loggers form Picotech (UK)
They're cheap, very reliable and extremely fast.
Peter,I'll check if it has sale agent in our place.

I'm deep grateful for all of your kind help.:)

best regards
LC