A couple questions popped up as I start teaching this..

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gbwillson

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Posts: 2,274

Posted 1515712212	Reply with quote #21

The only reason I could see the need for ducts is a short 12'"-18" stub at the exhaust so the air velocity can be more accurately measured. With 4 collectors, one should always be an empty box, while the other 3 units can try out various configurations to achieve the best BTU output. So the students will have to understand that there will be a tradeoff for having a long path through the collect. A longer path leads to higher output temps, at the cost of lower CFM/BTU output. I know you only have each group for a few weeks so time is limited, but once the group has discovered a design that gives the best BTU output, you might challenge them with the task of comparing that unit to other designs such as backpass, can or tube, and various matrix or screen type collectors. I know as a student at their age I loved classes such as yours. I remember learning about middle rockets by building and launching them during class time. Greg in MN

stmbtwle

Registered:1388591029
Posts: 2,784

Posted 1515721048	Reply with quote #22

A length of flex might be good for demonstrating the effect duct resistance has on the collector, if you want to go that far. __________________ Solar is like the wind. It may be free, but putting it to work isn't! Willie, Tampa Bay

Gordy

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Posts: 137

Posted 1515725612	Reply with quote #23

I did not realize he only had them for a short time. So prolonged duct testing may not be possible, it does at least needs to be discussed as part of optimizing a successful solar collector build. __________________ Gordy, Minnesota

matlocc

Registered:1420920295
Posts: 66

Posted 1515768147	Reply with quote #24

I actually have 8 collectors. When this is the total focus of the class I can do all of that. Currently, I am easing this into the class. The regular class the students choose any topic that they want to learn about (within reason) and have seven weeks to learn the history, economic /environmental effects, how it has moved about the planet and provide a visual demonstration and or perform experiments. Then present a 10 minute presentation on their topic. Some of the topics that have been covered and were neat: catapults, solar panels, solar cookers, soap, dolls, shoes, makeup, chewing gum, crystal growth and (All of the previous the kids made their own to demonstrate) also the effect of air pressure in a basketball and how it affects shooting.

Gordy

Registered:1362754383
Posts: 137

Posted 1515780268	Reply with quote #25

Sounds like a neat class. Should take away some of the boredom of the forced / mandatory curriculum. __________________ Gordy, Minnesota

stmbtwle

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Posts: 2,784

Posted 1515794699 · Edited	Reply with quote #26

As solar is a growing industry, you might suggest that the school consider some more advanced courses in solar, as electives. __________________ Solar is like the wind. It may be free, but putting it to work isn't! Willie, Tampa Bay

matlocc

Registered:1420920295
Posts: 66

Posted 1516639098	Reply with quote #27

Well the kids started with their ideas for baffles. A couple days of testing the designs and refining them, then we will get into the fans. Attached Images 20180119_110943.jpg (775.18 KB, 9 views) 20180119_110953.jpg (703.43 KB, 9 views) 20180119_111027.jpg (703.81 KB, 8 views) 20180119_145219.jpg (841.50 KB, 9 views)

Gordy

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Posts: 137

Posted 1516642618	Reply with quote #28

Good job, look's like you got them thinking and engaged. It might be interesting for them to test the baffles as is, then paint them black. And see what kind of difference it makes. Also use a permanent marker on the blue tape. __________________ Gordy, Minnesota

stmbtwle

Registered:1388591029
Posts: 2,784

Posted 1516654069	Reply with quote #29

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

gbwillson

Registered:1352981942
Posts: 2,274

Posted 1516663258	Reply with quote #30

I find it very interesting seeing how the students are thinking through the problem. If the tape is to help the baffles upright, the velcro isn't strong enough, or is weakening from the constant pulling. A suggestion for a future build might be to place a thin sheet of galvanized flashing on the back. And instead of velcro, attach 2 or 3 thin rare earth magnets to the bottom. The magnets are strong and will allow the baffles can be moved easily while firmly holding them in place. The grip won't weaken over time. https://www.amazon.com/X-bet-MAGNET-100-Ceramic-Magnets/dp/B018ITTFDM/ref=sr_1_9?ie=UTF8&qid=1516662865&sr=8-9&keywords=rare+earth+magnets Greg in MN

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