Radiators performance with air flow

cougem · 06-12-2004, 06:35 AM

Hi, how does a heater cores performance vary with air flow? I mean is it proportional?

If I had a 70-80 CFM 120mm fan, pretty low but it's nice and quiet, would I get a huge increase with a 100+ CFM screamer, or does performance seem to level out as it raises?

Thing is I haven't been able to find any experiments on how CFM of fans is linked to cooling ability.

Just for information, I have 2 heatercores, each with a 79CFM fan on it, with shrouds.

Groth · 06-12-2004, 06:53 AM

Some of Billa's old work: http://thermal-management-testing.co...esting%201.htm

cougem · 06-12-2004, 07:01 AM

Ugh, I'm not at home ATM and this really **** proxy is telling me ACCESS DENIED! (though it lets me access these forums?!) so what's the basic jist of that site?

Sorry to be a bother....

cougem · 06-12-2004, 07:50 AM

Hmm OK I've managed to get onto the site but I can't seem to find anything relevant? The only graph against coolant flow was backpressure.

Unless of course by coolant flow he means air flow, but it's in GPM which makes me think it's water....

Any help?

Groth · 06-12-2004, 08:01 AM

You have to turn the page. Follow the link to part2, and be sure to look at the corrected graphs linked at the top of page 1.

cougem · 06-12-2004, 08:42 AM

Is this the graph I'm looking for?

Is the coolant flow rate the air flow rate then, in grams per minute (x axis)? And then the different lines the different water flow rates?

So basically it shows that after a certain air flow rate it levels off? Trouble is I don't work in gpms, most people work in CFM, so could I get a ballpark figure of when performance starts to taper off?

Or have i got the completely wrong idea?

Groth · 06-12-2004, 09:07 AM

The coolant is the water, flowing at whatever gallons per minute. The different lines are different amounts of air pressure (measured in inches of water) pushing air through the rad. Check for another graph that show how much air is going through the various rad at the different air pressures.

arterius · 06-12-2004, 09:08 AM

A havn't completly read the article but I will do it tonight. What kind of air pressure do you think can a 8" rotor fan which is 3 1/4" in height produce? I know it is a lot more powerful than an axial fan but by how much? The reason i ask is because the manufacturer doesn't produce my fan anymore and i can't find data on it.

Groth · 06-12-2004, 09:10 AM

I haven't a clue as to what your fan will do. You might try searching for a similar model that has spec's available.

Pug · 06-12-2004, 09:42 AM

From what I gather, if you look at all the graphs on that page, you'll see that yes, performance varies with airflow, the more the better.
Conversely, if you look at chart 5 you'll see it indicates that in some cases, rads can suffer performance loss with higher coolant flow and according to chart 6, some rads may even have a sweet spot at a particular liquid flow rate (unlike the airflow factor).

arterius · 06-12-2004, 09:44 AM

There are two problems with your advice. Similar fans have a three times higher power consumption and will do 550cfm.The second problem is that google only spits out similar ebay auctions with the same description.Also the data on ebay could be wrong. Here is a pdf with a fan of similar size. I guess i shouldn't have bothered you with this question. I will soon find out how powerful they really are when they arrive at my doorstep.With only 5$ a fan you really can't go wrong.

pdf doc

06-12-2004, 06:35 AM	#1
cougem Cooling Savant Join Date: May 2004 Location: Cambridge Uni Posts: 176	Radiators performance with air flow Hi, how does a heater cores performance vary with air flow? I mean is it proportional? If I had a 70-80 CFM 120mm fan, pretty low but it's nice and quiet, would I get a huge increase with a 100+ CFM screamer, or does performance seem to level out as it raises? Thing is I haven't been able to find any experiments on how CFM of fans is linked to cooling ability. Just for information, I have 2 heatercores, each with a 79CFM fan on it, with shrouds.

06-12-2004, 09:42 AM	#10
Pug Cooling Neophyte Join Date: Jun 2002 Location: UK Posts: 80	From what I gather, if you look at all the graphs on that page, you'll see that yes, performance varies with airflow, the more the better. Conversely, if you look at chart 5 you'll see it indicates that in some cases, rads can suffer performance loss with higher coolant flow and according to chart 6, some rads may even have a sweet spot at a particular liquid flow rate (unlike the airflow factor). __________________ Owner: Wizard Designs :: WizDforums :

06-12-2004, 06:53 AM	#2
Groth Cooling Savant Join Date: Mar 2003 Location: MO Posts: 781	Some of Billa's old work: http://thermal-management-testing.co...esting%201.htm

06-12-2004, 07:01 AM	#3
cougem Cooling Savant Join Date: May 2004 Location: Cambridge Uni Posts: 176	Ugh, I'm not at home ATM and this really **** proxy is telling me ACCESS DENIED! (though it lets me access these forums?!) so what's the basic jist of that site? Sorry to be a bother....

06-12-2004, 07:50 AM	#4
cougem Cooling Savant Join Date: May 2004 Location: Cambridge Uni Posts: 176	Hmm OK I've managed to get onto the site but I can't seem to find anything relevant? The only graph against coolant flow was backpressure. Unless of course by coolant flow he means air flow, but it's in GPM which makes me think it's water.... Any help?

06-12-2004, 08:01 AM	#5
Groth Cooling Savant Join Date: Mar 2003 Location: MO Posts: 781	You have to turn the page. Follow the link to part2, and be sure to look at the corrected graphs linked at the top of page 1.

06-12-2004, 08:42 AM	#6
cougem Cooling Savant Join Date: May 2004 Location: Cambridge Uni Posts: 176	Is this the graph I'm looking for? Is the coolant flow rate the air flow rate then, in grams per minute (x axis)? And then the different lines the different water flow rates? So basically it shows that after a certain air flow rate it levels off? Trouble is I don't work in gpms, most people work in CFM, so could I get a ballpark figure of when performance starts to taper off? Or have i got the completely wrong idea?

06-12-2004, 09:07 AM	#7
Groth Cooling Savant Join Date: Mar 2003 Location: MO Posts: 781	The coolant is the water, flowing at whatever gallons per minute. The different lines are different amounts of air pressure (measured in inches of water) pushing air through the rad. Check for another graph that show how much air is going through the various rad at the different air pressures.

06-12-2004, 09:08 AM	#8
arterius Cooling Neophyte Join Date: Aug 2003 Location: europe Posts: 18	A havn't completly read the article but I will do it tonight. What kind of air pressure do you think can a 8" rotor fan which is 3 1/4" in height produce? I know it is a lot more powerful than an axial fan but by how much? The reason i ask is because the manufacturer doesn't produce my fan anymore and i can't find data on it.

06-12-2004, 09:10 AM	#9
Groth Cooling Savant Join Date: Mar 2003 Location: MO Posts: 781	I haven't a clue as to what your fan will do. You might try searching for a similar model that has spec's available.

06-12-2004, 09:44 AM	#11
arterius Cooling Neophyte Join Date: Aug 2003 Location: europe Posts: 18	There are two problems with your advice. Similar fans have a three times higher power consumption and will do 550cfm.The second problem is that google only spits out similar ebay auctions with the same description.Also the data on ebay could be wrong. Here is a pdf with a fan of similar size. I guess i shouldn't have bothered you with this question. I will soon find out how powerful they really are when they arrive at my doorstep.With only 5$ a fan you really can't go wrong. pdf doc

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