EcoRenovator  

Go Back   EcoRenovator > Improvements > Geothermal & Heat Pumps
Advanced Search
 


Blog Register 60+ Home Energy Saving Tips Recent Posts Search Today's Posts Mark Forums Read


Reply
 
Thread Tools Display Modes
Old 07-02-15, 03:22 AM   #1
Acuario
Apprentice EcoRenovator
 
Join Date: May 2011
Location: Tortosa, Spain
Posts: 217
Thanks: 2
Thanked 70 Times in 42 Posts
Question Best configuration for double panel hx

Hi,

I'm after some advice.

I have what is effectively a double panel air to water heat exchanger that is used to heat/cool a house via air ducts. The unit has a fan that draws air through the exchanger and blows it from the room vents.

What is the best direction for water vs air flow - the uncooled air passing through the coldest panel first, then the warmer panel or the reverse?

Acuario

Acuario is offline   Reply With Quote
Old 07-02-15, 08:40 AM   #2
stevehull
Steve Hull
 
Join Date: Dec 2012
Location: hilly, tree covered Arcadia, OK USA
Posts: 829
Thanks: 241
Thanked 165 Times in 123 Posts
Default

If the temperature differences are not large, either way will work.

Steve
__________________
consulting on geothermal heating/cooling & rational energy use since 1990
stevehull is offline   Reply With Quote
Old 07-02-15, 10:28 PM   #3
NiHaoMike
Supreme EcoRenovator
 
NiHaoMike's Avatar
 
Join Date: Oct 2008
Location: Austin, TX
Posts: 1,126
Thanks: 15
Thanked 247 Times in 233 Posts
Default

Counterflow if possible.
__________________
To my surprise, shortly after Naomi Wu gave me a bit of fame for making good use of solar power, Allie Moore got really jealous of her...
NiHaoMike is offline   Reply With Quote
Old 07-03-15, 07:28 AM   #4
stevehull
Steve Hull
 
Join Date: Dec 2012
Location: hilly, tree covered Arcadia, OK USA
Posts: 829
Thanks: 241
Thanked 165 Times in 123 Posts
Default

NiHao is correct, but the efficiency difference may be small. Try it both ways and see. The greatest heat flow (Q) is proportional to dt (delta t - temperature difference). So a counter flow system maximizes this with the coldest return air being exchanged for the warmest outflow water. There are many equations that model this, which is why I put in those terms above. You can find them in books on thermodynamics and also on the internet.

But you may have physical constraints that limit which pipe goes where. I suggest hooking it up as easily as possible (counter flow is best) and see how it works.

Let us know.

Steve
__________________
consulting on geothermal heating/cooling & rational energy use since 1990
stevehull is offline   Reply With Quote
The Following User Says Thank You to stevehull For This Useful Post:
AC_Hacker (07-03-15)
Old 07-06-15, 06:57 AM   #5
Mikesolar
Master EcoRenovator
 
Mikesolar's Avatar
 
Join Date: Aug 2012
Location: Toronto
Posts: 958
Thanks: 40
Thanked 158 Times in 150 Posts
Default

It depends on the temp drop in each direction but in general counterflow wins out every time. You will get the highest heat transfer. Flow rate is not that important for watts transferred as it is either going to be a high flow at low temp rise or vise versa. That said, the flow rate is determined by the desired output temp (and supply temp). If you need 35C, go slow and save fan/pump power but if you want 25C you may need to spend a bit more energy to do it.

Mikesolar is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 02:31 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Ad Management by RedTyger
Inactive Reminders By Icora Web Design