Aluminum Tubing for Solar Heating Application

I would consider black anodizing or even flat black paint; probably way cheaper, even if not theoretically as good (relative comparison probably 95% or better vs 100%).

Thanks but I'd already tried flat black spray paint AND the kind used on wood stoves - still very reflective.

Anodizing? The last time I used THAT (on optical instruments) it rubbed off.

Hello Larry,

I can assure you that I'm not building a list of any type.....it's for my security.

I see that you're down in Middletown. Actually, you're not too far from me. I'm up in Red Hook near Rhinebeck in the northeastern corner of Dutchess County. Howdy Neighbor!!!! **WAVING**

Okay, you look legit, so just PM my mailbox with the Prof's name and email and I'llsee what I can do for you back channels @ RIT, okay?

I don't know if you're going to get any blacker/less reflectivity than flat black paint and still be economical.....

BTW, I just had solar PV installed on the roof here....7.56 KW worth......Also, I have designed and am starting to build my solar thermal/DHW system for heating the house via the existing hydronic system...using 52 ex-NASA solar evacuated glass tube collectors.

Glad to see another tinkerer in here living nearby!!!!

Pretty soon the DIRT racing will be starting at Orange County Speedway there. Are you a fan?

Please have a great sunny day, (well hopefully soon anyhow!!!!) ****LOL****

Talk with you later,

Captmoosie (Mark)

Red Hook, NY

Hey Larry,

I checked out the URL link that you provided. That prof, is at the University of Rochester, not at RIT. the two universities are not affiliated with one another, so my RIT contacts will be of no use in contacting the guy whatsoever.

BTW, the base metal the Prof is using is Titanium! Very expensive and very difficult to work with in any metal machine shop. Knowing what I know if titanium from the aerospace industry, it will most likely be uneconomical for you to use it in your panels. Getting one of those specialized lasers may be another story in of itself. On top of everything, it appears that this process is more experimental than anything else and then as a developing technology there will be expensive and time consuming growth pains to mature it for any manufacturing endeavor.

May I suggest that you build the panels with a high quality optical glass that'll admit the radiant heat yet not allow it to escape. To increase your gain on the radiant energy may I suggest that you install either flat or curved plastic linear Fresnel lenses......flat ones made in Japan whereas the curved ones made in the UK.

I can supply to you the URLs for both companies if you are interested. I plan on installing the thin film ones from the UK above my evacuated tube collectors...you may be able to have anywhere from 8 Suns to 15 Suns gain, all depending on the final optics configuration, etc.

Beers & Cheers!

Yea, I'm not too far away. But no - I don't care for the dirt track racing. Can't see the fun driving in circles. F1 and Road Rally more to my liking. (Paris to Dakar) Takes me back to my own driving to school in PA so many years ago and during that recent blizzard.

Thanks for the correction - recalled incorrectly the Uni. but hoped the GizMag link would lead you to the Prof ID.

Fresnel? Yea, thanks. Please send me those URLs. I was hoping to use those myself but could only find flat ones. My concern is that I don't incinerate the collector. If I defocus the spot I'll still have a lot of heat but not enough to burn - right?

Vacuum evacuated tubes? I've seen those advertised by Chinese firms and CHEAP - but for the shipping costs.

As for the Ti surface - I read other articles which claim he can treat other metals as well. And I HAVE found webpages which tout using Femtosecond lasers in the same process by other people. I'll send them when I have more time.

Trapped at work by flood waters and still exhausted by my search for a safe route TO work. Wish I'd still had that 1960s VW Bug. (Herbie?) Then I could skim across the water. Remember those old VW commercials? :-)

Hey Larry,

I guess you have to grow up with DIRT modified racing to really appreciate it....I'm sort of dating myself here!*LOL*

I used to do SCCA-sponsored Road Rally events when I was going to college. One of my friends had an old BMW 2002 which we did fairly well in every time we went out. I even entered my old '69 Pontiac Trans-Am several times, but the cost of gas usage really killed me.....boy, that engine sure liked to slurp down the gas on those back roads in southern Albany, Schoharie and Columbia Counties. There were several times where I thought we'd never get to a gas station.....running out of gas that is! Anyhow, it was loads of fun!

Here's the URL's for those two Fresnel lense companies that I wrote to you about:

Nihon Tokushu Kogaku Jushi Co, Ltd. (NTKJ), Japan, maker of flat Fresnel lenses on PMMA.

http://www.ntkj.co.jp/index_en.html

Microsharp Corp., Ltd., in the UK, maker of several types of fresnel lenses including flat and curved linear on PMMA.

http://microsharpsolar.com/home

I wrote to both companies requesting pricing and both responded that they'd be willing to sell to me direct. The fresnel lens itself is manufactured acrylic thin film technology which both companies bond to a PMMA (acrylic) backing sheet. I found that Microsharps' prices somewhat lower (but not too much) than the Japanese firm and they also mentioned that they'd sell the film to me directly since I was going to conduct pilot testing with the Fresnel lenses.....it'd still cost me over $1K for the film and buying my own PMMA sheets and gluing the film to it myself.....that to make 52 curved linear fresnel lenses of my own making 12" x 45" long......not too bad, but not in this years tinkering budget either!

Forget the cheap Chinese evacuated tubes as they're crappola and not worth a damn...most come DOA with the vaccum lost between the inner and outter tubes! Buyer beware!!!!!

I bought mine from a guy on Ebay who is down in Richmond VA. He also happens to have some tubes stockpiled up here in a Buffalo warehouse as well. The ones that I bought from him are NASA and USDOE surplus and made by Owings-Illinois, costing the Fed's $250 apiece when new,,,they are state of the art having a thin gold bonded film coating fused on the inner tube surface. I was able to buy them at an average cost of $22.50 apiece, and he even delivered them to me himself. Usually, you have to arrange courier or pick them up yourself. The seller even verified by testing that each tube had vacuum present. I still have to fabricate the copper heat tube pieces that go inside the evacuated glass tube collector, but that's fairly easy to do!

If you want to know about active solar thermal like my system, just give a yell and I'd be happy to help you out!

Now, back to your "convection oven" solar system panels. If you use the Fresnel lenses you may have a problem of burning-off any old flat black paint that you'd be applying to the base metal of choice. I suggest that you try a black black engine paint specifically made for high temps.....check out Ebay or Eastman's online. You may even be able to find the high temp paint (for service over 500 F) in Walmarts or your local auto parts store.

Have you thought of using copper sheets and tubing instead of aluminum? It would conduct heat much better than aluminum...

>Have you thought of using copper sheets and tubing instead of aluminum? It would conduct heat much better than aluminum...

Yea, I HAD originally thought of using Cu but for the cost. I know someone who claims to have a roll of 0.5" Cu tubing but I want the tubes larger OD (2" - 2.5") and absolutely straight and parallel.

I even price checked some aero-gel blanket and pellets through Cabot for insulation. The cost per sq ft and liter aren't all that high but they set minimum orders which take it into the thousands of dollars. Maybe Aspen Aero-gels?

I did manage to spot a firm in the UK which makes aero-gel refractory blankets - 1 square meter for around 70 pounds. Three pieces should suffice for a 6'x4'x6" box I think.

Haven't found any links to an Eastman with metal blackening. Will keep checking though.

$1000 for plastic Fresnel film!?

I certainly would like to get my hands of some of those vacuum insulated tubes though! How long are they?

Any ideas on a low-head water turbine/generator? We have a stream outside and all winter it roars like Niagara Falls.

Trouble is - NYS has no 'Net Metering' scheme for hydro-power just solar and wind - according to Kingston's Kevin Cahill (Chairman of the Assembly Energy Committee) and HE won't explain why.

I wanted to attend some energy conference at SUNY New Paltz Saturday in the hope of putting this issue to whomever was in-charge but I couldn't get out of work (surrounded by flood waters).

Just look a a topographical map of NYS. It's blanketed by valleys which have water-ways. Most of those could probably be used to generate electric via some 'micro-generation' set-up but no one is going to invest if they can't sell off the excess wattage.

Hello Larry,

You posted a ton of questions, so I copied and paste your posting here, and tried to answer them as best as I could.......

yea, I HAD originally thought of using Cu but for the cost. I know someone who claims to have a roll of 0.5" Cu tubing but I want the tubes larger OD (2" - 2.5") and absolutely straight and parallel.

>>>>>I just wonder why you're set on tubes instead of a thin copper sheet to capture the Sun's radiant energy. You can then use a thin galvanized sheet steel and a 1/2-inch air space between the two sheets.....copper pipe/tubing prices are out of sight and rising by the day. The more open cross sectional opening you provide the better and you'll not achieve optimum area using tubing.

I even price checked some aero-gel blanket and pellets through Cabot for insulation. The cost per sq ft and liter aren't all that high but they set minimum orders which take it into the thousands of dollars. Maybe Aspen Aero-gels?

I did manage to spot a firm in the UK which makes aero-gel refractory blankets - 1 square meter for around 70 pounds. Three pieces should suffice for a 6'x4'x6" box I think.

>>>I don't even know what aero-gel is!!! LOL If you want an efficient insulation, why not instead insulation board on the backside of the steel plate I suggested to use, or use "mineral wool"/"rock wool" you can buy at any lumber store? both are cheap as hell and easy to cut and work with.

Haven't found any links to an Eastman with metal blackening. Will keep checking though.

>>>>Oppssss, my BAD. SORRY!!!!!! It's Eastwoods, not Eastman, and they're located in PA and on the web as well as Ebay.

$1000 for plastic Fresnel film!?

>>>The price was for the optically clear acrylic Fresnel lens film and the 4'x8' sheets of very good grade acrylic sheets that I'd have to cut up. Anything to do with Acrylics and other plastic this day and age is expensive every since the oil price hikes of nearly 2 years ago, but plastic has hardly budged downwards in price like crude oil did.

I certainly would like to get my hands of some of those vacuum insulated tubes though! How long are they?

>>>my tubes are 2 1/8" O.D. x nearly 48' length. I'll try to find the Seller's name again (on Ebay)...something like "fossilfreedom" and he's located in Richmond VA. You do understand that the tubes are for an active solar collector, and you will need to build the entire system of copper piping incl. heat headers, insulation, valves, flow control valves, flowmeters, circulation pumps, controller, thermal couples, heat exchangers, and hot water storage tank(s). If you have any Mechanical Engineering behind you or even a thermodynamics course or two, then you're half way there.

>>>Do you have an oil-fired or NG-fired existing boiler and Hydronic system to heat your house, or do you have a forced air system? If its the former type system, then you can tie in your solar thermal collection system to the Hydronic system and augment tour boiler-made heat, though not entirely supplant it. I could talk you through the design of my system, but if you have a forced air you have to do some more work on your own....I can recommend some design manuals that you can purchase in Ebay or Amazon.com fairly cheaply.

>>>Before anything, you need to conduct a heating audit on your house and identify where the insulation weaknesses are and what needs to be fix or replaced or augmented to limit your heat losses...ditto with cooling losses. You must also determine you heating demand for the entire house, after the fixes. You could do it for the house's current state, but the end result will be a more larger solar system which can get costly. I have references how to do this as well. there are several free online software programs that can do the number crunching for you.....

Any ideas on a low-head water turbine/generator? We have a stream outside and all winter it roars like Niagara Falls.

>>> the key to successful hydro generation is the vertical drop from the penstock inlet elevation to the turbine tailwater elevation....the larger the drop the electrical power you can generate. Caution here!!!! If the stream you're located on is a NYS Regulated stream (NYS ENCON) is involved don't even try it by drawing water off the upstream side of turbine and then discharging it back into the stream...all without permitting, unless you want to be dragged into court, pay massive environmental disturbance fines, and sit rotting in a jail for a few years. First, see if the stream is "CLASSIFIED" If you only have a few feet of head, it just isn't worth the cost of the turbine and generator.....turning potential energy into kinetic energy is key here!!!!

>>>I've been involved with designing large and small hydro dams when I was with the USACE and latter in private practice. The key is regulatory statutes and knowing them, and then knowing how to engineering the dam, the penstocks, bar gates, tailwaters, the turbine itself, gates and valves,,,there's a ton to know how to design because there's potential for dam collapses and resulting downstream property damage and life issues....then there is the environmental issues such as water volumes drawn and then released plus fish-kill issues....and the list goes on and on. And if you build it and don't get permitted by ENCON and later get caught, then the games up! You really need to hire a NYS LPE (like myself) who knows the ropes.

>>>>I know you're near Middletown, but are you located within either the NYS Catskill Forest Preserve boundary or the NYCDEP West of the Hudson Watershed Boundary????? If you are and the answer is yet, good freaking luck! DEP will stonewall you to death with Regulatory constraints and paperwork up the kazoo, and you won't get anywhere in the next century!

Trouble is - NYS has no 'Net Metering' scheme for hydro-power just solar and wind - according to Kingston's Kevin Cahill (Chairman of the Assembly Energy Committee) and HE won't explain why.

>>>>ENVIRONMENTAL ISSUES & STATUTES,,,,,ELECTRICAL GENERATION & REGULATION....see what I wrote above! After nearly 40 years of environmental progress cleaning up the watersheds and streams/creeks lakes and rivers they're (the Feds and states) not going to let just anyone build a turbine generator in a dam anywhere they want, no matter who they are and how much they have or how much politic pull they have.... also,those already on the grid providing power aren't going to let new small potato's and johnny be latelys just jump on board to the gravy train and share a piece of the pie.....The Environmental groups and activists over the years have placed tremendous political pressure on the state legislators, who in turn put pressure on the power companies to accept the solar, wind and geothermal credits and that took a lot of teeth pulling!!! be lucky we even have that...well, until 2016 at least....heck they could repeal it all tomorrow if they wanted too!

I wanted to attend some energy conference at SUNY New Paltz Saturday in the hope of putting this issue to whomever was in-charge but I couldn't get out of work (surrounded by flood waters).

>>>They're held at all of the community colleges across the state...if you go, talk to Besty from Sundogsolar (Catha NY...518-392-4000)....and another big one is coming up at the Dutchess County Fair soon...I think in either April or May....check the fair website for additional info. BTW, Sundogsolar is the company that installed my solar PV system, all 7.58 kW of it!!!

Just look a a topographical map of NYS. It's blanketed by valleys which have water-ways. Most of those could probably be used to generate electric via some 'micro-generation' set-up but no one is going to invest if they can't sell off the excess wattage.

>>>see my comments above.....The typical time for a NEW hydro micro-plant to get online is between 10 and 15 years,,,,from start of the permitting and regulatory compliance process to the end of construction process. its not for the fair at hearted and those without deep deep pockets and having Friends in Washington as well as Albany.....and really forget it if the US Army Corps of Engineers is involved...meaning you're along a navigable water way or a major water course that feeds into one.

>>>Can I ask if you have any engineering background or education?

Hello Larry,

Who is the Professor at RIT? I assume he's in the ME Dept. or Materials Dept., correct?

I'm a RIT Alumni (Class of '83) and have lots of connections there. I could give a whirl for you, if you like?

One caution though: His work may be in the process of either being patented (or has been granted a patent or patents for this body of work) or the entire process may belong to the US government as there are several Federal agencies funding R&D programs at RIT, least of which are the DOE, DOD, CIA, DIA, HLS, and the NSA for starters, hence it may be Classified or NEED TO KNOW.

Where did you hear about this work??????? If you're not a US Citizen, I will not be obtaining an information on your behalf, so where are you located? Please provide your full name, email addie, physical addie and most importantly, your IP address for verification to my Mailbox..... I am not willing to go to US Federal prison on charges of espionage, industrial or otherwise if you know what I mean. Also, I do not want to jeopardize my security clearances.......

Thanks for the offer and I'll appreciate any help you can provide but -

Requiring all THAT information I have to assume you're building an mailing list - NOT for security purposes.

Here is a link to the article which led me to the professor.

http://www.gizmag.com/t-rays-detected-black-metal/13555/

Larry Pines, PO Box 643, Middletown NY 10940

If it turns out to cost money, the return on the investment may not make it attractive anyway......so if he does get in touch, test a small piece and see how much better it is than other cheaper methods......it may not be worthwhile!!

I am assuming that you want as much heat as possible for as little tubing as possible and that may require a different solution that just trying to capture more heat via a process that may not be economically advantageous. What working solution are you using? As I am sure you are aware, different heat carriers do better jobs than others. Work is being done on MOHC's ( metal organic heat carriers) that can increase the heat carrying capabilities of working fluids by 20 to 30%. Without more information it is impossible to say what solution is best for your application. With the proper heat carrier, you can have an inefficient tubing and still get improved heat carrying performance.

For the present I'm using atmosphere - air. It's a solar air heater folks - just to heat a house from sunlight. If the design works out - it MAY go commercial for houses, highrises (roof, window, wall or balcony installations) and businesses.

Very good efforts you are doing there on the solar energy front. It is always fruitfull when researching efficiency of materials in energy conversion systems.

I have used a number of lasers in my career to machine all sorts of features on metals, insulators wood, plastic, anything really.

Going through the article it seams to me that this is another laser fluke that is attempted to be comercialised. Good attempt, but perhaps not suitable for your purposes.
Prof Guo is trying to make a far-far IR sensor device at a size that would marginally reach a surface of 100mm x 100 mm. Most likely these laser blackened devices will be needed with an area of 10 x 10 mm.

Unfortunately there is no description of the surface structure that was achieved, neither of the processing speed or method.

There you can see that a 30 micro-metre focussed beam is scanned over the target at a speed of 10mm/s. At a speed of 1KHz 3 pulses are being overlapped per line, and I would guess that the same overlapping would be necessary between the lines. In otherwords, you might need about 30s to process a 10mm x 10mm patch of your material, single scan. Better surface porosities are achieved at 50 to 70 overscans.
Higher fluence/irradiance gave more blackenned and absorbing surface finnish.

Looking at the suface finish, similar effects can be achieved by black anodising of aluminium. The pitting will not be as consistent as this, but the loss in absorption will never justify the use of a relatively slow scanning laser.
Bare in mind that anodising can be scalable, and longer lasting anodising treatments will return greater pitting depth and frequency. Thus quick and chep anodising will rub off easier than a more persistent, still relatively economic treatment.

Electroplating will probably do exactly the same job as these femptosecond lasers, giving you a more durable surface treatment. More expensive than chemical anodising, still much less expensive, and faster than a femptosecond laser.

Some of the most efficient small area absorbers known are stacks of razorblades. For the very same reasons really, that consecutive reflections between the sides of the blades will result in full absorption of impinging light.

A quick summary of the laser and its running costs will get you to a $300 to $500 K easily for your laser. And running costs of $500 to $1500 per day for such a process.
These are not highly industrial systems like the YAGs or CO2 lasers that last for years before refurbishing. They will need more frequent refurbishment when put into continuous use, somewhere in the scale of 3 to 6 months. Kepp in mind that you have three tuned resonators in there.

Another example I would like to bring to your attention is when I rented a bangalow in the mediteranean for hollidays a few years back.
The guy wanted to save on electricity bills and since he was renting these during the hot summers, what he did to provide customers with hot water wa this.

He covered glavanised steel tanks with petroleum tar on the outside. About 2 to 3 cubic metres for each house was available, exposed in direct sunlight. Galvanised steel is not the best heat conductive material. The water was burning hot even when I was showering at 1 after midnight. Tar is resistant to rain, water (and lets say self repairing to scratches but I wont stretch that point too much). Costs are in the $100 limit per unit.

All I am trying to say here is that there is probably a more cost effective way of achieving similar results.
However, I would be tempted to send another email to the professor and ask if he thinks the technique renders feasible the treatment of a few square metres. Just to test his ingenuity!

Interesting post, your points tend to support my own (completely untested) theories......

I also feel that one can achieve such things without great cost (as you appear to have done!) and even if the efficiency is only say 50% of an expensive system, I just say "then build it twice as large!"

Many thanks.

Larry, I have to agree with the other guys, you aren't going to get much better (from an economics perspective) than either flat black paint or a good anodizing job. I can tell you this much, if it rubbed off, you got screwed! Somebody painted it and tried to pass it off as anodized. There are different types and quality levels of anodizing, make sure you chose the correct type and make sure you deal with a reputable company that isn't going to screw you. Laser etching the tubing is going to be really cost prohibitive I suspect. Especially in small quantities. Also look at powder coatings, which are applied electrostatically as fine powder and then baked on. Depending on the kind of powder coating you choose (polyester vs epoxy vs hybrid) you can get an EXTREMELY long lasting coating that will resist fading quite well, and will be far more protective from the elements than anodizing or laser etching ever will be. You have to ask yourself will this coating process result in a matte black that will last for a long time or will atmosphere and moisture turn it white in short order? What works in the lab often does not work well in the real world.

Just remember, perfect is the enemy of good. You can spend a buttload of money trying to squeeze another 2% out of the system, but if the ROI isn't there, you are wasting your time and money. This has been the downfall of many tinkerers that refuse to acknowledge that most of the time "good enough" is better than "perfect" in the grand scheme of things.

So thats how M.Jackson got such a light coloured skin!!! He stayed in the sun too long!!