May 152008

I wanted to see if I could get a solid stream of steam. If not steam, at least a good flow of hot water. Perhaps a insanely large tea maker. My hope was that if I could get steam, I can turn a small turbine. I looked again at the feed horn. I decided to pull off all the stuff that might melt. It was a actually a rather nice looking piece of machined aluminum. If I wasn’t so intent on making this solar thingmabob, I could see it being a very Star Wars candle holder or wine goblet. Since this piece fits perfectly into the holder (as it was sort of designed to be there), it will be used as the mount for my steam chamber. My thought is this, if I can get the water to flow slowly enough, and get a tube hot enough, once the water hits it, it will flash to steam. I bought some 1/4 in coper tubing, some brass fittiings and a 6 inch 1/2 in. diameter metal pipe. I made a coil with the brass tubing that flows in a spiral towards the center of cone on the horn. The idea being that the cool water starts on the outside and warms up as it moves towards the center. Then water is then directed up into the larger metal pipe. The pipe will is in the focal point, so it should be the hottest object on there. Man this is hard to write as nothing has a real name.

The pain here was coiling the tubing without kinking it. All in all I did pretty well, I only ended up with one kink. Once the coil was finished, I fitted it to the horn and attached the pipe. I pushed the coil down into the horn so it followed the contour of the piece. With everything in place it held together remarkably well. I then spray painted the thing with black grill paint. I don’t know if it will get grill hot or not, but if it was how enough to boil water, I figured I should use something a little more robust than standard spray paint.

I took everything over to the dish and screwed it on and got it attached to the hose. I had an interesting problem. I had a hard time getting a gentle steady stream. Even at a low flow it was almost too fast. I figured that I could use 2 taps for the flow adjustment. I wanted to use one for the coarse adjustment, then one for the fine. I really had not thought this through I guess, but once the water built up between the first and second tap, it had the same force through the contraption. There was too much pressure from the house I suppose. They say electronics is like water flowing through a pipe. I suppose I could have just built a water divider and send  the rest to um… the ground (via a sprinkler).

Once I got the stream slow enough I aimed the dish towards the sun. My method for testing the tempature was highly scientific. I did not have a thermometer for the metal so I would occasionally touch it (Bio temp sensor). Once it got hotter than I wanted to touch I knew it was on the right track. The water that was coming out was getting warmer and warmer. It too eventually got hotter than I wanted to touch. I let it go for a while.  I turned off the water and after a couple of minutes it started to sputter and dribble, then I got steam. I turned the water back on. While there was steam coming off of the water, I never got just a jet of steam. I think that this is mainly due to the pressure of the water. I will do more testing at some point in the future. This is a fun experimenters toy.

In the future I will sand out all the texture that was built into the dish. I think that the combination of the texture and the somewhat sloppy job of  putting the aluminum on is softening the focus of the dish. Also, the dish was designed to allow a wide vertical capture area. This means that the focus point  is more of an oval than a round point.

 Posted by at 5:26 pm
May 112008

With the success of the first tests on the collector, I decided to do more. Really, it is an excuse to go outside and melt stuff. I expanded the holder so I could hold a can. My goal… Boil a can of water. Like the bottle, I spray painted the can black. I grabbed a thermometer out of the kitchen. I got it all hooked up and pulled the dish out into the sun. The thermometer was reading about 82° (ambient) when I put it in the can. The temp dropped to about 73° due to the water. I tried to check on it fairly often. I wanted to check every 5 minutes, but I get distracted fairly easily, and lets just say it didn’t happen. Fortunately digital cameras embed the time of the shots.

I put the can out at about 3:10pm. The temperature came up slower that I had hoped for. But it was a little cloudy, so I was not getting constant heat. At around 3:52 it hit a light boil (205°). So in about 40 minutes the temperature went up 132°. Not bad. I am concerned that the texture that is on the dish may be dispersing some of the light as the foil conformed to it. Also being that the foil is not completely flat from when I glued it down. This is also probably causing a little bit of loss as well. Lastly, the paint I used was a satin, so it had a little bit of a sheen. This probably caused a little bit of loss due to reflection. But again this is an experiment, and why do we experiment?

82° at 3:09pm 78° at 3:15pm 145° at 3:27pm
190° at 3:35pm 201° at 3:40pm 205° at 3:52pm
 Posted by at 10:50 pm
May 042008

One night I stumbled on the subject of solar collectors. The guy was using several mirrors to bounce sun light to a single spot. The result was obviously the combined power if all the mirrors. He was aiming it at a solar panel and was able to increase the output fairly significantly. I started looking around for anyone who had done similar experiments. I found so many cool tributary ideas. The range included “death rays”, cookers, ovens, air heaters, water heaters, stirling power.

I have always been interested in solar, but my scope was limited to electrical panels. I have been in the process of bulding my own solar panel, but it has been slow going, and met with a few setbacks. I suppose in hind sight that it makes sense, but there is so many uses for solar energy. The more I learn, the more I am shocked that solar is not playing more of an important role in this energy crisis we find ourselves in. One of the things I was really intrigued by were solar collectors. Using a parabolic reflective surface to focus the light to a single point for maximum power. I like the dish idea because it is a fairly controlled experiment surface. Using a set of mirrors presents a danger of shooting somewhere untended… catching something on fire.

I work at a TV station and there is a small yard full of “obsolete” satellite dishes. I talked to our engineer and he said I could take one. I took one of the smaller ones, a 1.8 meter dish. Once I got it home I cleaned it as it was covered in years of crud. I took the feedhorn off as it was not necessary. I got a roll of heavy duty aluminum foil and some spray adhesive. I covered the inside of the dish with the foil shiny side out. It became immediately obvious that the reflection idea was working. In just garage light, the focus spot was very bright. I used a piece of PVC pipe in the feedhorn holder hole to hold my test subjects I covered the holder with foil to keep it from melting.

I started with a piece of paper as I figured that it would be an easy thing to get lit. I wadded it up and stuck it in the end of the PCV tube. I pulled the dish outside and aimed it at the sun. I kept a wrench in my pocket at I was constantly having to adjust the angle of the dish. I got it aimed and angled and was very excited. I waited…and waited… but nothing was happening. I was scratching my head. This thing should have been lit already. I put my hand near the holder and could feel heat. Then the reality smacked me. Duh! White paper is highly reflective. I replaced the paper with a piece of cardboard. As soon as I got it set it started smoking. It smoked more and more and finally ignited. Muahhh ahhh ahhh ahhhhhh!!! I have the power… Yes,  you bet I was excited.

My neighbor came over to see what I was doing. He was concerned that it would hit his house and catch it on fire. I assured him that, no, it was focused to a point that was sort of restricted by the shape of the dish. I am not sure that he believed me.

My next experiment… water. I grabbed a coat hanger and fashioned a holder. I got a water bottle from the recycle bin. Having learned from the paper, I spray painted the bottom of the bottle black. I filled the bottle about a third of the way up with water I shoved the hanger bottle holder into the PVC tube and watched. Rather quickly I started to see condensation inside the bottle. I figured the bottle would be a safe thing based on the concept where one can boil water in a leaf. It did start to melt above the water line so I covered the top with foil. Within minutes the water started to bubble, and soon after it was at a fairly strong boil.

 Posted by at 5:45 pm