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Silly project, day two

Posted by admin on Apr 10th, 2008
Apr 10

I took the mini solar oven to work today and unfortunately found a problem right away. The way the building is situated, the mid-morning sun doesn’t start to hit the window I’m using until around 10:30am. As the sun crept into the box I started taking temperature measurements at semi-regular intervals. Here’s what I recorded, it’s a bit disappointing:

10:30 = 75
11:15 = 85
12:30 = 95 – start of full sun in the box
1:30 = 102
2:30 = 98 – moved to the western window which caused the drop in temp
3:15 = 105
4:30 = 109

As you can see, the highest it got was 109 degrees but I was really hoping for around 150. I attribute this mostly to a tint on the windows and a slight haze in the sky. It was a bright sunny day, but I’m guessing there was about a 10% haze.

I’m going to give it another try tomorrow. I’ve added a 15″x15″ reflector panel to the lid to amplify the amount of sun being collected (I’ll take pictures later this week). I know that the reflector will help considerably and the lack of having one on the prototype I built for the backyard last summer was part of the problem with it’s inability to go higher than about 200 degrees.

I’m going to bring home the mini solar oven this weekend and test it outside to see how much of a difference the windows at work make.

Check back tomorrow!

Silly project, just for fun

Posted by admin on Apr 10th, 2008
Apr 10

I was at work today, heating up my lunch (which I bring every day, thanks to my awesome wife) in the microwave when I got a moment of inspiration. To hopefully help this all make a bit more sense, let’s start with a little back history to explain the basis of the project you’re about to read about. Last summer I built a solar oven which worked…okay, I guess. We did cook a pot of beans in it one day so I guess it works well enough. I’ve been meaning to revamp it and have been thinking about that more and more lately, which is probably the reason for my lunchtime epiphany today.

My idea was to build a small solar oven to heat my lunch in. I sit in an office on the south west corner of the building so I get decent light in the window by the time I get to work. I spent some time tonight building my contraption and I must say, I think it turned out pretty well. It’s in prototype rough mode but I think it’s actually going to work. I used two old cardboard boxes, used tinfoil, duct tape (new, unfortunately), and a piece of plexi-glass I used for a water heating experiment last summer. It’s probably about one cubic foot of interior space. Here’s a picture –

mini solar oven for the office

I’m going to take it to work tomorrow and test it out. I’ll report on what I find tomorrow night.

If you’re so inclined, this would be a great project to do with kids. I just started with a small box, made sure it was deep enough for a container, the back of it was high enough to accomodate for a 30-45 degree angle, then just started putting it together. One note is that I did double layers of cardboard for insulation, otherwise it wouldn’t realize it’s full heat retention potential 🙂