germicidal use for solar concentrators?

Respected Sir, Hope you will be fine. I am a university student in Turkey and doing MS Environmental Engineering. I am interested in designing and application of Concentrator Parabolic Panels as a reactor in waste water treatment. In this technology my basic purpose will be to use UV portion of sun light in degradation of water pollutants. I need your kind guidance in this project. Please guide me with what strategy I should precede and which areas are still needed to be studied, improved or discovered on which an academic research should be carried on.

Waiting for kind response..
Best Regards
Muhammad T
Fatih University Istanbul Turkey.

Hello Muhammad and thank you for writing to me.

I had thought also about using UV in concentrated sunlight for such a purpose. I am interested in your ideas about this.

The big problem is that the UV required for germicidal irradiation is UV-C (100-290 nm). According to the US EPA:[UV-C is] completely absorbed by the ozone layer and atmosphere. This is a good thing for us humans. There is such a small amount that even when concentrated, it may not be effective. Even at the concentration of my parabolic trough solar concentrator (about 18:1), the heat produced from the rest of the spectrum might boil the water before any UV-C sterilizes the microorganisms?

en.wikipedia.org/wiki/Ultraviolet

The glass of the reactor must be of a type clear to UV-C (quartz glass).

The water to be treated must already be very clear since particulates shield the UV-C. The water must be filtered to a high level (reverse osmosis?) before irradiation.

A correct exposure time must be determined for the radiation to be effective.

Successful operation of the system needs a test that the organisms are sterile and cannot reproduce since the UV-C does not kill them. Looking with a microscope, they will still be moving.

Do you plan to build a model?

Would boiling or distilling the water with concentrated sunlight be a better project? There is much heat available this way which can effectively kill all organisms, even in sludge. The UV-C is difficult.

George Plhak

hi george, I came across your plans ...

while searching for ways to build my own solar panels for heating water. I believe I saw that you were using the parabolic system to heat pool water. I'm wondering, could this be used in a residential application? I was hoping to use this for heating our home's water for showers, sinks, etc. How would I determine how many panels I need? We're a family of 5, 7 during the summer. Two bathrooms plus all the other normal household water applications (dishwasher, washing machine). Our electric water heater prevents us from running two showers at the same time and we must wait at least 20 minutes between showers to suit everyone. Also, we have a farm. I'd love to be able to utilize this for an outdoor shower system if possible. I guess we'd need some sort of storage tank. Am I correct? Eventually, the use of it on pools may be desired but for now the kids don't mind the cold water! Any guidance you could provide would be greatly appreciated! The price of your plans seems very reasonable!

Thanks in advance,
Tracy

Hello Tracy and thanks for your note.

I am using my collector to heat a swimming pool because that is what I needed. But the hot water produced could be used anywhere.

Depending on where you live some changes would need to be made for my system to operate well in the winter. Here near Toronto, winter can be quite severe. Changes like insulated collectors and piping. I do not yet have a reliable all season version. You will see some of my attempts to create an insulated concentrator at my blog.

You have system type questions and you are asking a guy who is focused almost exclusively on only one part, the heater. I encourage you to keep looking to get your questions answered and to find the approach that you want to take. There is a lot of information on the web. There are many do-it-yourself DIY solar heater approaches being tried, some of them quite excellently done. Good places to look around are:
www.builditsolar.com
and the SimplySolar and SolarHeatgroups at groups.yahoo.com (Yahoo sign-on required I think).

I wrote about what I have learned about my own parabolic trough heater approach at two websites:
www.ffwdm.com/solar/solar-index.htm
georgesworkshop.blogspot.com

If I haven't written about it, it is probably because I haven't tried it. Being an engineer, I don't like to speculate too publicly on my work in progress. I am also not a solar thermal installer who has more of a systems perspective. There are many considerations to reliable domestic hot water which I can conveniently ignore while heating a pool.

My system is admittedly more of an experimental approach to the heater itself and I wrote about it that way hoping to interest people in my book who have a similar outlook and the skills to carry it out. I am not trying to sell anything other than the book. Maybe you will be able to use my ideas for your situation, I am not sure. The book is very thorough and I did price it to hopefully be not out of reach.

I hope that I answered your questions.

George Plhak

More info at https://georgesworkshop.blogspot.com/2015/08/pool-heating-2.html

Reader questions and answers

Hello Carlos and thank you for your interest in my book. My answers are below:

On 12/14/2011 08:06 PM, carlos e wrote:

Hello Mr George,how you doing?
I see that you have a great job on this things,congratulations.

Thank you.

I brougth from you the plans to make my own unit...but I need to get some awnsers first.
Did you have some problem with acrilyc durabitity?

At first yes but it was a problem of my own causing. I let the concentrated light that was not properly focused at the collector tube hit the back of the sheet in front and the sheets were deformed by back heating. This damage occurred when the unit was OFF and not following the sun under control of the sensor. This was solved by painting the backs of the acrylic sheets white and when not using the array, parking it horizontally. The current acrylic is on the third year of use here. It needs a good cleaning in the spring, but it is fine. You can read more about that here:
http://georgesworkshop.blogspot.com/2009/07/mirror-distortion-is-due-to-back.html

Did you tested some others interesting materials?

I did. In the book on page 30-33 I talk about MIRO IV polished aluminum, Galvanized steel (no joke), aluminum roof flashing, reflective film and acrylic mirror. I did not try polished stainless steel since I could not find it locally but others like this material. I would like to review the situation again since many different kind of materials can be used.

I am thinking about making some examples and sell it to some people but you know,I am a serious person I dont want to sell a bunch of problems to my friends..in case that they need to change the reflector in a short time!

I suggest you make one for yourself first to get experience and to adjust for local materials and situation. You should do your own life testing. Maybe your acrylic is different from mine but we don't know that until you use it for a while.

How long is your device working?

I started six years ago. The current "production" array which heats the swimming pool is essentially the same for three years. I am now replacing some worn parts and poor manufacturing (my own fault).

You did not refer in your plans,the size of your pool,how much litters or gallons do you heat with your unit?
Can you hit wich temperature increase in one day?

The pool size is about 50,000 gal, I talk about that here:
http://georgesworkshop.blogspot.com/2010/03/what-size-of-pool-heater-do-i-need.html

what about trying 2 axis track in your model..it seems to be easy to do,do you think it will get some important increase of power?

Please tell me how to do it easily. The seasonable adjustment seems like a small benefit. The big operators in the desert do not do this. But reader Andrew Gray wants to try to do this also:
http://georgesworkshop.blogspot.com/2011/09/reader-projects.html

And about the ribs,do you think for example 10mm acrilyc it will be good to use instead of wood?
probably it will last more and no need to repair

I think it will depend on your conditions. Here there is winter cold (not good for most plastics) and wind but we do not get hurricanes, nor really heavy hail like they do in Texas. The wood highway sign material (MDO) is turning out to be very durable here but the edges must be sealed. The baltic plywood is my favorite, to be cut with a water-jet. But please try the acrylic. Check that it is UV stable. Use a lightweight material, like the wood laminate or plastic or you will be re-balancing the reflectors.

thank you so much.

ps. about mylar film can you share your experience with me too?

I did not use it. I thought it would be difficult to apply smoothly in small quantities and I was concerned about the durability. Others have used it with success. The manufacturer of Reflectech film recommends a purpose built "application machine" but I can't afford one of those nor could most of us, I thought.

Sorry if I am making a lot of questions but you seems to be a helpfull person and I really need your help!
My inglish is not very good,sorry for that...

Your English is GREAT! Thank you for your questions.


George