DIY ventilation heat exchanger

Fornax · 12-11-12, 02:09 PM

Mikesolar,

Indeed, given enough coroplast the efficiency might be high enough.
When just rotating whole plates 90 degrees you'll have surfaces that are not totaly flat pressed against eachother thus making a lousy contact with eachother. Not only will you have a double amount of coroplast between the cold and warm airstreams, they are separated with a thin layer of insulating air, this is not ideal.

A while back I wondered why use coroplast at all? To me plastics aren't known for their great transfer of heat. But of course if it's a thin sheet with a large surface this is hardly a problem.
Actual numbers: Coroplast 0.20W/m*K, Aluminum 237W/m*K
I found a study where a HRV is build and tested with Coroplast, along with calculations.
I replaced the value for coroplast with the one for aluminum in one of the formulas for -that- heatexchanger-core and the result changed from 12.7 W/m2*K to 13.2 W/m2*K, which is only about 4% higher for aluminum (if used in -that- specific HX).
Link: http://www.ewp.rpi.edu/hartford/user...0Exchanger.pdf

12-11-12, 02:09 PM	#11
Fornax Helper EcoRenovator Join Date: Oct 2012 Location: Beuningen (Gld), the Netherlands Posts: 64 Thanks: 4 Thanked 19 Times in 16 Posts	Mikesolar, Indeed, given enough coroplast the efficiency might be high enough. When just rotating whole plates 90 degrees you'll have surfaces that are not totaly flat pressed against eachother thus making a lousy contact with eachother. Not only will you have a double amount of coroplast between the cold and warm airstreams, they are separated with a thin layer of insulating air, this is not ideal. A while back I wondered why use coroplast at all? To me plastics aren't known for their great transfer of heat. But of course if it's a thin sheet with a large surface this is hardly a problem. Actual numbers: Coroplast 0.20W/mK, Aluminum 237W/mK I found a study where a HRV is build and tested with Coroplast, along with calculations. I replaced the value for coroplast with the one for aluminum in one of the formulas for -that- heatexchanger-core and the result changed from 12.7 W/m2K to 13.2 W/m2K, which is only about 4% higher for aluminum (if used in -that- specific HX). Link: http://www.ewp.rpi.edu/hartford/user...0Exchanger.pdf Last edited by Fornax; 12-13-12 at 03:24 AM..