Welcome to the Solar Collector
Brainstorming and Development Page!


 

Home

Hot Air Collector

Hot Water Project 1

Hot Water & Space Heating

Solar Electric

Solar Construction 101

FAQs

Best Collectors

Simply Solar
Register Calendar Latest Topics
 
 
 


Reply
  Author   Comment   Page 5 of 6     «   Prev   2   3   4   5   6   Next
solardan1959

Avatar / Picture

Registered:
Posts: 1,845
Reply with quote  #41 
Scott,
   As an example,

Solar Web Page > Forums > Links

First pinned topic would be:  Topic Guidelines
                  
                                           This is an area to post your favorite links, please post links you feel are of interest to the Solar Community or provide relevant information that may be useful to other members.
Post your link in a current topic that is related to your link or if unrelated to any current topics, feel free to add a new topic along with a header that describes your subject link.

Here is an example from the links section:


[image]

Something similar could be done in each section such as solar hot air collectors, with examples of a couple of different type air collector etc.
Dan

Scott Davis

Avatar / Picture

Super Moderator
Registered:
Posts: 697
Reply with quote  #42 
Done, great job Dan!
__________________
Take care, Scott MD
SolarInterested

Avatar / Picture

Spam Stomper
Registered:
Posts: 1,028
Reply with quote  #43 
Looks good Scott and Dan.
__________________
Both temperature rise and airflow are integral to comparing hot air collectors
Scott Davis

Avatar / Picture

Super Moderator
Registered:
Posts: 697
Reply with quote  #44 
Thanks for your thoughts G_H!  I think we will stick with General Discussion for now, but we will see what develops...
__________________
Take care, Scott MD
gmpoulos50

Registered:
Posts: 5
Reply with quote  #45 
Question: has anyone tried pulling a vacuum either inside the entire collector or possibly betweem two layers of glazing? Would there be a way to predict the results? I was thinking about using 6mm twin wall and pulling a vacuum between the layers. Anyone wanna guess what combination of temp and vacuum would turn it into single wall poly?
Thanks everyone
george
gbwillson

Avatar / Picture

Registered:
Posts: 2,249
Reply with quote  #46 
Hi gmpoulos50-

What would you think the advantage might be with a vacuum?  Are you thinking of an energy efficient window that has a vacuum between the panes to reduce heat loss? If so, I would imagine it might help a small bit. Any dead air space between the cold outside air and the hot collector box would be an improvement. But my experience with twin-walled glazing is that it is somewhat difficult to seal both ends and not get condensation/freezing between the layers. Drawing a vacuum in each slot and sealing would prove even more difficult. I have thought of using 2 single layers of glazing with a dead air space in between the two layers. And it sure would be easier to add a slight vacuum than each slot of twin-walled glazing. Not sure I understand your last sentence. 

Greg in MN[wave]
Garage_Hermit

Avatar / Picture

Registered:
Posts: 2,240
Reply with quote  #47 
Hi, gmpoulos,

FWIW, my understanding is that most double glazing these days does not in any event "contain" a vacuum between the panes, but rather an *inert gas*.

The reason is, pulling a vacuum is more expensive in the industrial process (and in particular requires a tougher glass...).

However, some DG does employ vaccum, and research into vacuum-based double glazing continues (in Northern Ireand, I believe), using needles to withstand the external positive pressure and prevent the unit imploding...

==========
In addition, "tryng to pull a vacuum in the entire collector" would defeat the object somewhat, since the aim of an air collector -- a pneumatic device -- (by definition, running on air...) is to VENTILATE the house, via the collector, by pulling "cool" *air* through the latter, while warming it over a solar absorber.  Whence the sticking point: the AIR is the vehicle for moving the heat...  By definition "vacuum" or "partial vacuum" implies LESS AIR, so the arguments start to wane pretty quick...  In any event, maintaining a collector "vacuum" would require a monumental differential pressure to be created over the collector, which in turn would require expenditure of power (a prime mover) (pump, compressor etc.) & this would rapidly negate any benefits as regards energy savings provided by the collector in the first place...

(translation: better to use that energy for heating the living volume...)

In any event, the collcector would still not be "under vaccum", it would just be "at low pressure" (cf. "depression", in meteorology).  This in turn would have negative impacts on the viability of the living volume... (like pulling books off shelves or upsetting one's budgerigars or the mother-in-law's hairstyle...).

Apologies for wrecking your plan !

G_H

__________________
(1)  "Heat goes from hot to cold, there is no directional bias"
(2) It's wrote, "voilĂ " unless talking musical instruments...
stmbtwle

Avatar / Picture

Registered:
Posts: 2,748
Reply with quote  #48 

To be honest I don't think it would be that difficult to pull a partial vacuum on twinwall.  You'd need a "D" channel to cover the end, sealed on the surface but letting the individual channels open into the "D".  Seal off the other end of the pane with another D channel.  Put a hose fitting on one end of one D and seal the other ends.  Then pull your vacuum.

I'm not sure how effective it would be, though, 'cause you'll still have the 'webs' between the channels in the pane, which will still conduct some heat.

Trying to evacuate an air collector would be counterproductive, even if it didn't collapse under the external pressure.  It makes sense with a WATER collector though, and you can buy evacuated tube hot water collectors.  Then pump the hot water to a heat exchanger in the living space.  Probably been done already, and it opens up a lot of opportunities for energy storage.


__________________
Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
gmpoulos50

Registered:
Posts: 5
Reply with quote  #49 
So then could you assume that.a big change in elevation would have the same effect? At ten thousand feet you would have one third less air pressure(approx) so does that mean that the wind has only two thirds the effect on the collector or is the real world difference much smaller? I ordered sone 6mm twin wall to cover a 4x8 pex collector and the vacuum pump i have laving around says it. Will pull 16hg. I live at 7000ft. So if all goes well i will happily melt the pex tubing with all the xtra btu's.
Thanks for the reply stmbtwle
george
gmpoulos50

Registered:
Posts: 5
Reply with quote  #50 
Ok garage hermit i have noticed you using math that is way over my head so give this a try. . . If i pulled a 16hg vacuum in a 6mm glazing how much would it increase the rvalue. For that matter i cant even find a solid number for 6mm poly in the first place. I am sure i can seal it well enough to get it done.the pump i have shuts off reliably at 16hg. There would still be ordinary 7000 ft air in the collector. I want to build it like Scott's except use two runs of pex. The pump shouldnt have to run that long to create the vacuum and then it would just cycle when nesseccry to maintain. Not sure if the combo of vacuum and heat would flatten the glazing. Not sure if 16hg is enough vacuum to have an effect on rvalue... I am sure i can do it just want you to take a shot at predicting the outcome.
Thanks
george
Previous Topic | Next Topic
Print
Reply

Quick Navigation:

Easily create a Forum Website with Website Toolbox.

 

web statistics