How much heat such DIY solar heaters give us
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- čas přidán 12. 10. 2019
- I made these solar heaters only to measure their energy parameters, and first I made this variant from a cheap polyethylene pipe. Then I measured the energy parameters of this 2nd variant which is characterized in that its pipes lie on a black surface. This is my 3rd variant which is similar to the 1st variant, but with large gaps between adjacent pipes. Then I tested this 4th variant, and we see large gaps between its pipes, like the 3rd variant, but the pipes lie on a black surface, and its north side has thermal insulation.
The main results of my tests are described by these graphs and tables which will be explained during this video.
This is my measurement of the energy parameters of my four variants of the cheap solar heaters. However I want to clarify that I used such cheap polyethylene pipe with an outer diameter of 16 mm and a wall thickness of almost 2 mm. The Ukrainian prices of this cheapest pipe are about 15 American cents per meter, and we can calculate that complete covering each square meter by this pipe is about 10 dollars.
In addition, I painted my pipes, and now this half of the solar heater is already covered in black paint which increases the efficiency of the heater and protects the plastic from ultraviolet solar radiation.
So, a square meter of our solar heaters is several times cheaper than these traditional pool heaters, but we can see that their energy parameters noticeably better than our solar heaters. That is why our square meter will produce significantly less heat, and this is due to the fact that our black pipes do not cover the whole surface of the heaters.
For example, the pipes cover only 66 % of the surface of my 2nd variant because we see small gaps between adjacent pipes. In addition, these areas are not covered by the pipes, and I want to clarify that the coverage area is the multiplication of the pipe length by its outer diameter.
The length of the pipes of my 4th variant is even 2 times smaller, and they cover only 33 % of the surface of the heater.
My 1st variant is covered with pipes by 73 % if we think that this square is the area of the heater, and this is a fair idea if we remember how neighboring heaters are placed.
The area of the 3rd variant of my heater is covered with the pipes only by 37 %.
This table shows the heat production of one square meter of my four variants of the heaters during an absolutely sunny day in Europe, the United States and India. These are cases where the solar heaters must heat swimming pool water with a temperature of 30 ºC.
It is interesting to compare our heat production with these more durable and expensive solar pool heaters. We see that one square meter of expensive heaters produce significantly more heat, but our square meter is several times cheaper. That is why our heaters can make economic sense if we do not have a deficit of space for the location of our solar heaters.
In addition, we can remember that such heaters are sometimes used for a primitive shower. Now we see that the sun has heated the water inside the black pipes of my heater to 67 ºC when the temperature of the ambient air was 28 ºC.
This graph describes the heating capacity of one meter of my black pipe for my four variants for different temperature differences between the heater water and ambient air.
So, we see that our 3rd variant is the most inefficient use of our black pipe. Now I show one of my experiments with the 3rd variant, and this pump moves the water of this tank through our black pipe which has already heated the water to 45 ºC. But on the other hand, our 3rd variant is the best if the water temperature is noticeably less than the ambient temperature, and it can be a case of heating a pool immediately after replacing its water.
Our 1st variant is similar to the 3rd, but the gaps between the pipes are minimal. This experiment shows how my 1st variant heated 27 liters of water from a temperature of 22 ºC to a temperature of 52 ºC for 2 hours. We see that our 1st variant uses the pipes more efficiently than the 3rd because the large gap between the pipes of the 3rd variant increases their heat exchange with the ambient air, especially during wind. - Věda a technologie
Thank you so much for conducting these tests and sharing the results!
Thank you for sharing your knowledge about these different heaters. I will be putting it to use.
Great job with the tests and the presentation of the data!!!
Congratulations on the data acquisition and explantation. Thank you for all the work on it. I will be building one for sure. I`ll use a solar panel and a solar pump so it will heat my pond proportional to the sun intensity.
Awesome experiment for practical purposes of heating the water using varying models
excellent scientific approach to an important subject..I feel you have made a great contribution to the understanding of solar heat conversion 5 *****
great pojects, love it!
Great job man, really helps a lot for newcomers like me. Greetings from Brasil.
Nice video comparing things !!
Great video thank you.
if coverage is your problem, you should look at different patterns in which to "wind" your pipes. Fractal curve patterns like gosper curves, Peano curve or Hilbert curve were designed to fill a complete square, rectangular or hexagonal surface evenly.
It might be a bit challenging to create them, but the cover much more of the surface with a single, continuous line than a spiral.
Sergei, you have made many experiments now, is it soon time for a home build with all the information and data you have gathered? I’d like to see your choice and build and heat returns, thanks as always
I wonder if you placed a clear plastic sheet over the black painted coil if that would decrease the heat loss to the air significantly. I would like to see the breakdown of the cost for the variants of these heaters.
I think people should try to understand the limitations of these systems. A general rule of thumb, if you live in a sunny climate, is that the power coming from the sun is about 1 kW per square meter. That's if the square meter is presented "straight on" to the sun, there's no cloud cover, etc. Obviously this varies throughout the day because the amount of atmosphere the sunlight has to penetrate changes. Consider it a "noon value," and at any rate it's good for calculations.
Ok, now say your pool contains G gallons of water. A gallon is about 3.8 liters, and a liter is a thousand cubic centimeters. It requires 1 calorie (not a food calorie - that's actually a thousand calories) to raise one cubic centimeter of water one degree C. A calorie is 4.184 joules of energy, and a watt is a joule per second. Putting this all together, one square meter of sunlight, if you capture it completely, can raise one gallon of your pool water one degree C in about 15.8 seconds.
So, if you want to raise the temperature of your G gallon pool by T degrees C, then you need 15.8*G*T seconds of full sunlight to do that with a one square meter collector. For my 19,000 gallon pool and a desired temperature rise of, say, eight degrees C, that means I need 2.4 million seconds. That's a little under 28 days. And don't forget that the pool will loose heat during nights, and you're going to have an inefficiency factor in there too.
The take-away here is that if you have a big pool, you just can't expect a small collector like the ones I see in a lot of these DIY videos (most of them I've seen are around a square meter) to work magic on your situation. There is a reason your gas pool heater costs a lot to operate.
On the other hand, if you're using this square meter collector to warm up, say, a five-gallon container of water, then you can bring it up a degree ever 5*15.8 = 79 seconds. If your collector and your water container or well insulated, you'll be able to get it quite hot - potentially even hot enough to cook stuff in.
A general formula for the above calculation would be that seconds = 15.8*gallons*temp_change / collector_area. Or you could rearrange this to collector_area = 15.8*gallons*temp_change / seconds; this one lets you put in how long you want it to take. Let's say I wanted my 8 degree C temp change in 10 hours (one good sunny day). For my 19,000 gallon pool I'd need collector_area = 66.7 square meters. I haven't see a DIY project for that. ;-) By the way, that would be about 22 collectors each four feet wide and eight feet long.
For me to really have any sort of hope with my pool, I need to learn more about how it cools down overnight and hope that I might be able to heat over a period of many days and gradually build up to the temperature I wanted. Try to do a "two steps forward during the day, one step back during the night" sort of thing. And I'd *still* need to be willing to build a fairly large collector.
Niiice 👍🏻 Where can I find a video of the more advanced versions please?
very good.
I laid out asphalt shingles that retain and radiate intense heat compared to my heater similar to you spaced out variants. the painted pipe never felt hot to the touch but with the Black asphalt shingles loosely laid flat over the coil the coil was warm and the asphalt was so hot you could burn yourself. even after the sun goes down the asphalt continues to radiate heat. You can just use this method without needing to paint.
So you put asphalt shingles on top of the black irrigation pipes?
How did it hold together?
Very fare and interesting video Only heat exchange equations are left in order to compare the heat exchange coefficients
I like your project, but I would make one suggestion. You're losing a lot of heat energy because of the reflectivity of the tubing. I'd use a flat, or matte, black paint for better heat absorption.
Or scuff the tubing?
I have just built one of these which is kind of like his 1st variant combined with the 2nd, however i have not painted my tubing, is this necessary?
My experience shows flat works best, matte reduces heat absorption a LOT, similar to glossy in fact. Flat black spray paint, cheap, has the best results with by far the lowest cost. Thermal absorbing 'ultra-black' paint does not, in fact, perform noticeably any better.
The best material I could find was aluminium, coated black.
@@janglur when you say flat, do you mean satin?
So your saying satin is better for heat absorption (such as when painted on black irrigation tubing or copper pipes) then both Matt and gloss (be it spray or brush) paint?
Thanks
Sergiy, great experiment, I am working on my solar collector to maximize its heat exchange potential. I have found the rate in which water flows through the solar collector pipe is a very important variable. To big a pump (powerful) the water flows to fast and doesn't have time to pick up heat from the pipes. Example, I would prefer the water to come out of the collector at 100 degrees with a flow rate 500 GPH rather than 1600 GPH at 50 degrees. My collector is 4'x8' using 300' of 1/2" poly pipe. I have a lexan sheet covering it. I installed an oven thermometer and the internal box tem. has gone to 165 degrees on a 80 degree day I am heating a 16,800 gallon pool. I think the trick will be to find a timer to cycle the pump off for 15 mins. and on for 10 mins. this will give the water time to fully pick up heat from the hot tubing. Love the think tank and sharing of ideas!
less speed isn't always better
, for pool would be better to have higher speed and smaller temperature difference. it mixes water
(upper layers are warmer)
high temperature and low speed hot water doesn't mix water in pool and just cools down quickly
I agree with Руслан. Energy in= energy out so I dont think the rate of water is that critical if the goal is to actual heat the 16,000 gal pool. Eventually the water coming into the system will be warmer and warmer and you will raise the temp of the pool. My question with all these is how possible is it to actually heat a pool this size without loosing the heat gains to the ground and air before you can enjoy them or the sun goes down?
Hi all,
Do you know if a thinner PE tube, collects and transfers faster than a thicker one?
half inch PE tube with a 2mm wall vs 1.2 mm wall, Nominal pressure 16 vs a Nominal pressure 6 bars.
Which is best? Thank you
Very good experiments. I would like to see a build of your best version. I have built a 48" square box with 0.75" x 3.5" walls with foil coated 25mm foam on base painted flat black sitting on 0.75" supports using 16mm x 30m held by wire ties with corrugated polycarbonate with edges sealed with foam.
Great stuff! What are you using it for?
@@ronrover6594 18'x48" pool heating
I am just getting started with my project. What are the most important pieces.
I currently have a 48” square box.
Should I do one row of tubing or two.
@@tdhoeffel I got two 50 foot rolls of 0.7 inch, for each 48" box.
This worked really well for a year until it started to leak. Got a second one straight away.
How much water was it able to heat?
Why did number 2 not have plexiglass or similar covering to trap heat?
So gloss black collects better than flat black?
sergiy this system is the water in the winter if the water is 10 c ,how many degrees the water l want to do my istanbul
where is the future video ?
whith policarbonate sheat?
I think the missing point is not the gap but overall length of tubing through which the water travels. The dens 73% probably has 2x the length. Meaning more opportunity to exchange heat.
Yes use 50 m for all
Indeed.
Did you actually take your heaters to Munich, Phoenix and Mumbay for a test? Oh, I see, (calculation, not experiment). But - can these heaters be used in winter (freezing overnight)?
These heaters cannot be used in winter because you can not remove the water from the pipes (only with antifreeze)
Hi Sergy,
Do you know if a thinner PE tube, collects and transfers faster than a thicker one?
half inch PE tube with a 2mm wall vs 1.2 mm wall, Nominal pressure 16 vs a Nominal pressure 6 psi.
Which is best? Thank you
Please Sergiy, if you can advise or anyone?
Do you think efficiency would increase if you filled frame 4 with clear epoxy? This would allow better heat transfer between the back material and the tubing.
Try use 2 suns by add a mirror on the ground or a polished stainles steel plate.
Can the heater provide constant water temperature? or if you turn on the water after the hot water inside is flushed out you will have to wait some time to be heated again?
Run that supply into a water heater that way it is constant and the water heater barely runs
what about chemicals leaking into water?
where can i find the pex piping that everyone uses, pplease provide a link
Google irrigation pipes
Irrigation tubing. They sell them in different lengths at Lowe's or Home depot. I got 3 100 1/2" tubing for my project.
what if inside the case (covered with glass) you put water, or even oil, or even black colored oil, and the pipers are copper?
Anyways, my problem with these is that if there are clouds.. its all useless.
Instead. of covering it with polycarbonate, why don't you cover it with glass, since the transparence is better. And glass does not degrade bcos of UV.
UV adds a lot of heat energy I’d say? Was thinking this myself and thought poly carbonate or similar would be best.
Glass allows more light in (so more heat energy in) but also allows more heat loss. It’s the net gain or loss that determines the choice of material and cost too, that comes at the end.
Polycarbonate has much thinner plastic then glass, and also an air gap. The thinner plastic allows plenty of light in or even more then glass, as it’s 0.2mm of plastic vs 4mm glass.
Polycarbonate at 4mm has 61% light transmission for both sides and the air gap. And U value of ~3.8-3.9
4mm glass has about 89%. With u value of ~5.8-5.9.
The lower the u value the batter for insulation.
Thin flexible plastic(such as used for greenhouses for example, which naturally is made to resist UV damage) seems likely to be efficient and cost effective, along with being safer in cases of possible impact.
Oh thanks for the data. Looks like it isnt good for me for my 18ft pool (8300 gallons US). To get1 degree celcius I would need 20KWh. In Canada this mean probbaly needs half to 3/4 of the pool superficy in heating to get something decent. I already got an heat pump and works great, but for the fun of it and get free energy I looked at this. But would not make sence for me finally.
A floating solar heater on the pool itself seems likely to be more effective, and won't take up space on the ground.
Borat?
This guy is nuts 🥜
Wish I could understand your accent.
You have interesting content but your English is so poor that it is too difficult to understand.
The full English text is in the description.
You need a better narrator. Can hardly understand you
That's what closed captions in English are for.
He speaks at least two languages & I only understand English. I could understand you just fine my friend. Thanks for sharing your work/results/data. Some people will not even lift their hands to their mouths to feed them selves. Here you are feeding us & some feel the need to comment on the meal you prepared. It was a beautifully prepared feast & I enjoyed it. Thank you sir.
Perhaps *you* need more exposure to different accents, I had no problem understanding him.
Besides, he doesn't owe the viewer anything.