Baffle and plate spacing for 4X8 glazed air collector?
Question:
Does anyone have a good reference for proper spacing of the plate and baffles for a 4X8 air collector? Planning to take air in at one bottom corner and out at the other bottom corner. Plate spaced 2" from back of unit for airflow, 1" spacing between plate and glazing. One main baffle up middle splitting the 4′ width and then a cross baffle every 2′ up the sides, with an 8" opening into next chamber.
Response:
Here are two baffle design ideas. One is just using foam baffles in the air flow. The other uses aluminum angle iron attached to the collector plate. Was thinking this would both act as a baffle and also provide for better heat transfer to the air. Any thought? http://www.corl.ca/drawing1.jpg http://www.corl.ca/drawing2.jpg
– Hide quoted text — Show quoted text -> Does anyone have a good reference for proper spacing of the plate and > baffles for a 4X8 air collector? > Planning to take air in at one bottom corner and out at the other bottom > corner. Plate spaced 2" from back of unit for airflow, 1" spacing between > plate and glazing. One main baffle up middle splitting the 4′ width and > then a cross baffle every 2′ up the sides, with an 8" opening into next > chamber.
Response:
| Here are two baffle design ideas. One is just using foam baffles | in the air flow. The other uses aluminum angle iron attached to | the collector plate. Was thinking this would both act as a baffle | and also provide for better heat transfer to the air. | | Any thought? A bit… It’s probably worth pointing out that the objective is to get heat out of the panel rather than achieve the highest possible temperature inside the panel. Since warm air wants to rise, you’re planning to use electrical power to overcome what mother nature would’ve given you as a gift. High temperatures inside the panel promote losses. Lower temperatures yield higher efficiencies. Baffles aren’t the friends you seem to think they are – seek to maximize the cross-sectional areas of your plenum(s). Angle iron/aluminum is (thermally) massy. If you want to use aluminum as an absorber/heat exchanger, look for minimal thermal mass and high surface area – and try to impede airflow as little as possible. Warning: this is a non-trivial balancing act; but worth the effort to achieve the balance. A lot of experimentation went into the designs at the link below – perhaps you’ll find an idea or two you can use. — Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto/collectors.html
Response:
Ideally yes I would take heat put at the top, but where this needs to be mounted that is not an option. I want to have the heat returned into the ground floor and thus need to have the out at bottom. Thanks for the info. The baffles were meant to help disrupt airflow over the flat panel, otherwise I assume it would be too smooth a flow and not extract enough heat. Using the angle iron or flanges was to help again in heat transfer from the plate, not to hold the heat.
– Hide quoted text — Show quoted text – > | Here are two baffle design ideas. One is just using foam baffles > | in the air flow. The other uses aluminum angle iron attached to > | the collector plate. Was thinking this would both act as a baffle > | and also provide for better heat transfer to the air. > | > | Any thought? > A bit… > It’s probably worth pointing out that the objective is to get heat out > of the panel rather than achieve the highest possible temperature > inside the panel. Since warm air wants to rise, you’re planning to use > electrical power to overcome what mother nature would’ve given you as > a gift. > High temperatures inside the panel promote losses. Lower temperatures > yield higher efficiencies. Baffles aren’t the friends you seem to > think they are – seek to maximize the cross-sectional areas of your > plenum(s). > Angle iron/aluminum is (thermally) massy. If you want to use aluminum > as an absorber/heat exchanger, look for minimal thermal mass and high > surface area – and try to impede airflow as little as possible. > Warning: this is a non-trivial balancing act; but worth the effort to > achieve the balance. > A lot of experimentation went into the designs at the link below – > perhaps you’ll find an idea or two you can use. > — > Morris Dovey > DeSoto Solar > DeSoto, Iowa USA > http://www.iedu.com/DeSoto/collectors.html
Response:
> Does anyone have a good reference for proper spacing of the plate and > baffles for a 4X8 air collector? > Planning to take air in at one bottom corner and out at the other bottom > corner. Plate spaced 2" from back of unit for airflow, 1" spacing between > plate and glazing. One main baffle up middle splitting the 4′ width and > then a cross baffle every 2′ up the sides, with an 8" opening into next > chamber.
Hi, You might take a look here: http://www.builditsolar.com/Projects/SpaceHeating/SolAirHtSysBook/Sol… While this dates back a ways, these guys built many, many air collectors, and learned and refined a lot as they went along. Gary www.BuildItSolar.com "Build It Yourself" Solar Projects —-== Posted via Newsfeeds.Com – Unlimited-Unrestricted-Secure Usenet News==—- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups —-= East and West-Coast Server Farms – Total Privacy via Encryption =—-
Response:
> Ideally yes I would take heat put at the top, but where this needs to be > mounted that is not an option. I want to have the heat returned into the > ground floor and thus need to have the out at bottom.
I don’t have any experience with this, so this is just a "thought experiment" observation. If you have to have the intake and outlet at the bottom, I think you’d do better to have a straight shot from the top down to the outlet. In drawing 1, move your vertical divider to the left, so that 85% (wild ass guess) of the collector’s area is to the right. All of your baffles should be in that right-side region. Does that make sense?
Response:
Thanks Gary. I’ll check the link for some info on baffling. In general do you think the tabs/angle iron would be a better option over baffles to both improve heat exchange and provide the baffling?
Response:
Related Posts