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
Sign up Calendar Latest Topics
 
 
 


Reply
  Author   Comment   Page 2 of 2      Prev   1   2
Bert

Avatar / Picture

Registered:
Posts: 532
Reply with quote  #11 
If they had the same charge, then maybe that would keep the air inside the screens. The air pressure would still push it through.

If they had opposite charges them they would be pulled to the screen?

Not really sure how that would work though. 

__________________
Bert K.
Michigan

https://www.youtube.com/user/1thinkhealthy/playlists

mocars2

Registered:
Posts: 173
Reply with quote  #12 
In my adjusted Berts design - it would have 4 screens - 2 individual frames - both with ZP slots. The question is would the bottom frame get enough sun to warm the 2 layers of screen.

Greg - I also thought about 7/8" space. You said you had some thought - And what would your thoughts be?
gbwillson

Avatar / Picture

Registered:
Posts: 2,293
Reply with quote  #13 
mocars2-

My only thought is the use of such a large screen gaps at lower velocities. Also, with 2" of insulation on the back I'd consider a much smaller space between the back of the collector and screen since most of your heat loss will be via the glazing. I do agree that little sun will warm the 4th screen, so maybe a 1" screen gap with an intermediate screen. So you would have 3 screens ½" apart. This would allow you to possibly have a thinner, lighter collector or have a much larger space between the glazing and the 1st screen. My ZP has only the ¾" frame between the glazing and the 1st screen, but even with the air being is such close proximity to the glazing, I must be doing something right as I'm not hurting my performance.

Greg
mocars2

Registered:
Posts: 173
Reply with quote  #14 
Greg - what does this mean - "My only thought is the use of such a large screen gaps at lower velocities."
I was thinking of the 3/4" gap between the top and bottom screen in each of the 2 ZP frame ( I used his drawing and didn't catch the larger 7/8 gap between the 3 screens). Is that what you mean by large screen gaps  - you mean Berts 7/8"?


The 2" backing was what Bert was thinking of - I'd probably go with 1" unless I had 2" lying around

. BUT the 4th screen is a good question. How much warmth would the 2nd ZP 3/4" spacing produce?
Previously you mentioned a 3RD screen just lying on the absorber (below the ZP run)- brings up a good question. If the 4th screen would see little sun to warm it - wouldn't that be the same for your 3rd screen and even less sun on the foil absorber? If so then is it worth it?
But if the 3rd screen on the absorber does help and increases performance - the 2nd ZP run might also increase performance
Bert

Avatar / Picture

Registered:
Posts: 532
Reply with quote  #15 
The first drawing I posted was just a cross section of the spacing and screens. I was trying to figure out how Greg made his.
I couldn't find a complete diagram or details, so I posted that to ask him how close it was to his design.

I'm trying to get some ideas for future builds.

These projects keep changing, so I know it's not easy to get exact details.

__________________
Bert K.
Michigan

https://www.youtube.com/user/1thinkhealthy/playlists
gbwillson

Avatar / Picture

Registered:
Posts: 2,293
Reply with quote  #16 
Mocars2-

Yes, I was referring to the ⅞" screen gap. Nothing wrong with the ⅞" gap itself as I'm using 1". But that is why I asked about the size of the collector and the volume of air that was expected to be used. Also, with all of the gaps and spaces inside the collector being exactly ⅞" it didn't take long to realize Bert built the the inside of the collector to fit the space. 

As far as using 2" of insulation for the collector box I think it is overkill if the collector is protected from the wind such as being mounted to the side of the house. And at higher velocities, the air is only inside the collector for less than one second. I made my current 4x16 ZP in two pieces using 3 ½" stud track to save weight.  And although it is less than half the weight of my previous ZP, it is still too heavy for me to carry by myself. So the next collector will likely use 2" of insulation, since the ¼" plywood back weighs as much as the rest of the collector.

I don't see a need for a separate 2nd channel of air, as the second channel has three layers of screen between it and the sun. But I think if the air gap between two screens is too large for the air being passed between, the screens may not heat the air as effectively as they could as the heated screens will radiate heat only so far. So a lot depends on how fast the air is passing through the screen gap. That is why as I was contemplating a middle layer of screen to keep the air from being too far from a heated screen. 

When I was conceptualizing my double-pass ZP I thought about maybe laying the back-most layer of screen directly upon the divider plate to not only help scrub heat from the flow, but to save space. I recall Dan building his DP/ZP and it was thought the front air channel would cool the back channel too much. That could be true, but my tests so far show the air at higher velocities staying between the screens quite well. So if the screens are either laying directly on the divider plate or just above may not matter.

I don't know...yet

Greg

Previous Topic | Next Topic
Print
Reply

Quick Navigation:

Easily create a Forum Website with Website Toolbox.

 

web statistics