/diy/ - Do It Yourself

The idea that I've been playing around with involves using synthetic oil as a heat transfer fluid and collecting said heat in a large bank of hot bricks. The heat will then be used to flash boil water for use in a turbine. My first question is what brand of oil you would recommend. I need something that is relatively cheap, but resistant to high temperatures (200-400°C)

The bricks that I'm planning on using would be the kind with holes in them so I can snake the copper tubes for both the heated oil and water to be boiled through them. I'll probably need about a half a tonne.

>>263869
That doesn't sound possible.

Maybe scale it down a lot and do a proof of concept first?

>>263875
Doesn't sound possible how? Please go into detail

>>263879
well you have too many heat transfers. Oil to brick to water, through piping is going to loose too much heat; its incredibly inefficient.

Solar is usually either photovoltaic cells, or parabolic mirrors focused on steam generators or sterling engines. I don't see how you gain any advantages from this oil/brick contraption.

The turbine I am planning on using will be of the Tesla variety. There are more efficient designs, but this one would be the simplest to construct. Also, they operate very well at high-rpm s (20-60,000)

>>263881
hes got a point, and since its solar you wont have a terrible amount of energy to start with anyways.

>>263882
teslas a good start, but they warp like a fucker, thats the only reason they never went commercial.

in like 5 uses the blades became warped and unusable

The brick is to retain heat over night, allowing for continuous power generation once the system is running. The heat can also be stored for a short period of time, such as in a molten salt storage unit in a large-scale power plant, like this one.

>>263885
they have really high rpm, but almost no torque. using them for any kind of power generation is a nonstarter because even mild resistance from a motor grinds them to a stop.

>>263891
Good thing for three-phase AC motors then.

>I asked for advice, please give some while critiquing the flaws

>>263886
but why generate power at night?

If you are going to be completely disconnected from a grid, a much better system would be to create a bank of air tanks and use excess power during the day to fill them with pressurized air and use that to power generators at night.

heat storage like what your talking about is incredibly inefficient.

>>263893
don't be impetuous about advice freely given. It's poor form.

>>263894
Hmm, pressurizing air. How would one go about such wizardry without generating power/torque/mechanical energy.

>I don't wish to sound impetuous

>>263896
You simply have an air compressor kick on when you are generating more power than you are using. A system of release valves and pressure gauges will fill the tanks up in order. When you are generating less power than you are using you have a separate system in the same line turn on and use the air to power a tesla turbine.

The whole thing could be automated and connected to whatever solar system you decide on. Its a little inefficient because your using the compressor to store the energy before retrieving it, but it's nothing compared to the heat loss the brick system would suffer from ambient air.

>>263899
Sounds good, but then there's the cash limit thing. A bank of batteries and fine controlling units wouldn't be too costly, but the compressor and tanks would probably cost more and be less reliable/efficient than bricks. Also, I've read that a 3HP turbine consumes about 90cfm of air @90psi. Water is much more feasible of a working fluid, especially since exhaust steam can be used to preheat the incoming flow.

>>263902
If your system doesn't work ALL the money is wasted. That's why I said test it with a small scale trial first.

To be honest I'm not sure how extensive of a system you could build for 2k anyways. Have you priced copper tubing lately?

>>263907

$170 for 100 ft of 1/2 inch of type L tubing. Probably going to need at least 200 ft.

All of the components listed only have a total of two moving parts. The idea isn't just about cost-effectiveness, it's also about reliability.

Let's assume this is for a house, and let's wildly assume he can convert 10% of the sun's energy into electricity.

We're talking like 70 watts per square meter of mirrors.

If he builds a 10 square meter collector, he could generate 700 watts during peak sunlight. Let's just say he gets on average 8 hours a day, so he gets 5.6 kWh/day of electricity. This would conceivably be enough to power a small home.

You'd need to have enough storage for half of that, so 2.8 kWh of storage, or roughly 10,000 BTU

>Google "sopogy"

These guys use a similar system which runs at no more than 300 C (let's call that 500F to make a nice whole number).

To flash steam, you'd need the bricks to get no cooler than about 350 degrees, so you'll have 150-200 degrees of delta T to work with.

The specific heat of a brick is .22 BTU/(lb*F)

10000 = 0.22 x [mass of bricks] x 150 degrees

>tl;dr, you need 300 pounds of bricks which are properly contained to go from 350 to 500 degrees daily

There are purpose-engineered "Heat-transfer fluids" and specialty oils for specifically this kind of thing (well, not exactly, but in the ballpark). They are not cheap, and the associated tech is also bulky to get into.

iirc you will find a company called Radco that makes some of these, but they are geared towards industrial users.

you Might be able to find a common synthetic engine oil that can handle those temps. The trick would be long life, but at least if you used standard engine oil you could probably incorporate standard filters and pumps.

>i still think this concept is a little clunky. or a lot clunky.
>direct steam creation feeding turbine, with waste steam-heat being used to pre-heat water for the system or even for a home, storing energy in a battery bank for surplus seems the most reliable method.

>>263866
honestly, why don't you use a stirling engine instead of a turbine? Otherwise you have to make a really really large array of panels! also you could try working "twodimensionally". check out archimedes project: you don't need a supercomplex structure that can orient your dish in two directions, you have only one axis with very minor loss at the end. the power output depends on how long you make it.

>>263949
Thanks for the info, that's good stats to know.
>>263966
you've re-stated what i've already said here >>263869 and here >>263899

>>264049
Sorry, I meant here>>263886

>>264002
I have an idea about how to orient the array that would use more parabolic reflectors focused on paraffin-filled copper tubing. It would use the expanding properties of the heated parrafin to drive two pistons for each axis. Simple, reliable and efficient.

>the reason I've decided to use a dishvrather than troughs is because of the area required for a trough is realitively large. I also live on a mountian, so finding large stretches of even ground would be kind of difficult.

Thanks for the input.

I like the idea of solar-thermal but I think this is going about a bit wrong. There should be a good heat transfer between the oil and water. A simple heat storage would be an insulated tank. A water heater tank might work, those are cheap as balls and you can get more as you expand.

>>264055
oh right, sorry!

Any way you do it, it will cost you about the same amount of energy to drive a car all day as it costs to keep a living space comfortable all day.

It's a good "rule of thumb" way to pre-plan for your power needs.

Bump

Bump

Bump

>>263866
Check out this setup, OP.

>STEAM ENGINE 12KW GENERATOR Solar Mirror Array Death Ray
http://www.youtube.com/watch?v=jTvAL7ty53M

>>263875
Oil would be far better than water. Since the oil is being directly heated, you won't have expansion like you would with water. This means you can attain extreme temperatures. Even massive solar power plants use molten salt to capture the energy and transfer it to water to create steam. The blocks would help hold a great deal of heat for a long time during bad weather and over night It would be far longer than what water could hold because you can heat the bricks and oil up far hotter. Molten salt is normally stored underground as a "battery" backup for when the sun isn't shining for large-scale solar power plants. These methods are standardized.

OP here

>>265507.
Thank you very much for the vid link and the blackup

Okay, so I've been contemplating just using two used turbochargers in sequence instead of a bladeless turbine. This is because:

• I wouldn't have to build them from scratch

2. They have less risk of cautostrophic failure (turbine explosion= shrapnel, potential loss of life and limb.)

C. they have higher starting torque

IV. The power output is more easily predicted

The only problem is that I can't find much material on other successful turbo/steam conversions. Sure there's plenty of info on diy jets, but that's not what I'm looking for. Can anyone point me in the right direction? Thanks guys, I'm really looking forward to your input.

>>266671
bumping so i can look it up too later

Bump

>>263869
OIL? ARE YOU FUCKING CRAZY? Solar concentrators get stuff hot, and I MEAN REALLY HOT! Any exposure to oxygen will ignite the oil. You might even get hot enough to break down the oil...

One of my friends built a concentrated solar stirling engine that ended up melting down the stirling into slag.

I for one would recommend what they use in pro solar concentrators, molten salts like potassium nitrate, lithium nitrate, and sodium nitrate. These chemicals aren't that hard to obtain. Now you can also use molten salts for thermal storage...

Try using the molten salt composition described in this paper:
www1.eere.energy.gov/solar/pdfs/csp_prm2010_alabama.pdf

>>267010
Oil is not all that crazy as a heat transfer fluid. The idea is to collect the thermal energy BEFORE you reach spontaneous ignition. In fact, most small-scale thermal collectors use some form of oil as a collecting medium, and there are even synthetic oils designed specifically for that purpose. see here:

> http://www.radcoind.com/TechTips2.html

The thing is, I'm working with a limited budget and molten salt storage would be prohibitively expensive, for obvious reasons. Thanks for the concern and the input, but I already mentioned your suggestion here:>>263886

>>267218
>>267010
Mineral oil is used to cool high voltage transformers around the world. It would be a fine medium for heat transfer from solar to steam. The system should be set up so that excess heat never builds up past the needed temperatures. This can be done with a redundant thermally controlled heat exchanger system that shunts the heat off when the main heat exchanger either gets too hot, the focal point gets too hot, or the rest of the system is not circulating and heat starts to build in the focal point. Essentially, it is like the electrical heat shunt you would use in a normal solar PV system, only this would still be liquid based like the rest of your system.

There's no danger of an oil fire if things are done correctly. People doing this sort of thing are normally very smart, research well, and don't give in to knee jerk reactionary fears.

>>267383
Oh, and the cheapest source of mineral oil is bulk purchasing baby oil.

>>267010
>OIL? ARE YOU FUCKING CRAZY? Car Engines get stuff hot, and I MEAN REALLY HOT! Any exposure to oxygen will ignite the oil. You might even get hot enough to break down the oil...

Motor oil has a typical temperature range of around 320F in gas and 600F in diesel engines at max. Water boils at 212F creating steam. That alone gives you a wide range of temperature.

>>267399
>>267383

Thank you for clarifying that for me.

>>267384

Could you point me I'm the right direction for where I can find bulk mineral oil? I've been looking at food-grade stuff (which is the highest quality,) but it's pretty expensive. Walmart sells it in 1 gallon jugs for $25 a piece, which isn't all that big of an investment in the long run, but I'll need a lot.
Thanks a lot guys.

>>267414
Food grade is low grade actually. So is baby oil. High grade is transformer oil. You can get it from ham radio suppliers like,

http://www.hamradio.com/detail.cfm?pid=H0-008727

It's effing expensive stuff.

Best pricing for real bulk ordering is,

http://www.alibaba.com/showroom/baby-oil-in-bulk.html

And you really do need to buy in BULK for those prices. My suggestion is to make a far small prototype solar steam unit first. Work out all the bugs in it. Then scale it up. That way the expenses will be next to nothing the first time around.

>>267477
Thanks, I was incorrect to assume that what (might) go into our food would be of the highest quality. I have also discovered that transformer-grade isn't necessary.
>I've found some retailers for oil of varying grades and purposes. Which supplier should I go with?

https://store.steoil.com/ (food and transformer grade)

http://www.natural-formulations.com/Products/MineralOils/MineralOil.htm (cosmetic-grade)

http://www.clarionlubricants.com/ProductList.do
(food-grade machine oil)


Any input would be appreciated.

OP I think there is a lot of potential here.

The very first thing you need to do, before you actually build anything, is to do some really basic math.

1) Determine how much power you'll need.
2) Determine the efficiency of a particular motor.
3) Determine how much water you'd need to pass through as steam in order to generate the desired power.
4) Determine how much heat energy is required to be added to ambient-temperature water to generate that power.

Only at this point (once you've got an idea of the actual amount of thermal energy needed and over what timecourse the energy must be transferred into the water) can you begin to plan out your method of energy harvest and heat transfer in a meaningful, productive way.

Best of luck to you. I'm looking forward to seeing pictures and details of your final rig!!

Bump while at work

>>267614
uh, thanks for the advice, but most of what you've said has already been covered. On that note, does anyone know where I can find some sort of chart or list of energy potential for steam at different temperatures/pressures? Equations would do, for I rather enjoy math and am quite bored at the moment.

>>264002
nice didn't even know we had a DIY board

I'd also suggest Stirling engines.

also in the process of making a solar array, heliostats
Its very simple, even if it doesn't appear so..

its a turntable like.. for trains.. but smaller
on top is a square frame same width and length
ontop of that is 5 rods evenly spaced
that turn on their length axis
each rod has a bunch of mirrors fixed

the mirrors fixed to the rods are parapolicly focused
the whole assembly turns to keep the rods perpendicular to the sun, then each rod turns to keep the mirrors at a bisector angle to the sun/focus point

this way you only have to actuate the turntable and the 5 rods and you get perfect focus.

use more rods with more, smaller mirrors to get their focus to a much smaller area for much more heat.
same energy just higher temp/smaller area

The cold side could be your working fluid, oil.

If you use this hot oil coming off the cold side of the stirling engine, then you get a CHP

Combined heating and Power system.
aka shaft power=electricity
hot oil= hot water tank preheater/thermal mass.

or feed that same oil into a rankine cycle engine and use your tesla turbine anyways for a double scoop of the thermal power.


probably not the direction you were going but..
some food for thought.

>>268551
Um, yeah. I dig the suggestions, but see this:>>263866-> My build costs will be about $1500-2,000 USD over the next 6-8 months.
And here: >>264055

Once again, thanks and any (new) input would be appreciated .

Well, so you're set in the dish, fair enough..

You are on a mountain.. Ok that may or may not make salvaging parts to cut costs possible..

My suggestion is if you are going to use oil...
get used hot water tanks, fill them with bricks... Be clever about their positioning and plywood a enclosure around the tanks and use the space filler cans of foam to pimp dat insulation R factor

That's the best low-cost thermal mass for oil I can think of and the copper tubes for flashing the steam, the oil would use the cold/hot connectors on the top of the tank
The water is thru the copper, you'll have to mcgyver that into the tank

Ps telsa's turbines are not quiet, and you want to switch to turbos to avoid shrapnel??

>>269133
That's to say to deal with the noise you would either be really far away or bury that fucker under ground either way you shouldn't be finding yourself in a position to be worrying about shrapnel...

And ofc you'll want to salvage hot water tanks as you wouldn't buy new ones to cut them open on the chance the whole idea might work

The money really isn't as important as having the right tools for the job

Also don't be retarded like that one guy who melted an aluminum stirling engine on a parabolic dish

G8 work to that guy, really if you've focused to a small enough point you'd be able to burn through a wall of pure carbon, so your point is invalid use your head instead of spouting hearsay

>>269133
>foam

No, the temperatures to make steam are too high for the foam. It'll melt. Dry sand is actually a better insulator with higher temps like this. A 6 inch thick layer of dry sand all around the tank. Use a few layers of plywood to hold the sand THEN use foam on the outside of it. Although, foam board insulation will be cheaper, unless you get someone to come in and spray foam for you. The stuff in the cans doesn't go very far and becomes extremely expensive very quickly. The sand will also act as thermal mass. To pit off with white paint (black paint allows heat to escape faster and white allows the least amount to escape which is why the heat exchanger coils of a fridge/freezer are black.)

>>269133
>>269136
the point of using a turbo would be the increased starting/operating torque. It would also simplify things a bit since I wouldn't have to make a turbine myself. As for reliability, just about all diesel engines nowadays use turbos and they go over 300,000 miles operating at much higher temperatures without critical failure.

>>269172
Thanks for the suggestion. I was considering mineral wool as an insulation myself, but the whole cost thing is a pretty big deal. A few hundred pounds of sand on the other hand would be pretty cheap and readily available. I'm not too keen on the whole water heater thing because I'm trying to do this with as little tools and as simple materials as possible (I know a turbine isn't that common, but finding one at a scrapyard shouldn't be too hard.)

>>269216
>I'm not too keen on the whole water heater thing because I'm trying to do this with as little tools and as simple materials as possible (I know a turbine isn't that common, but finding one at a scrapyard shouldn't be too hard.)

>I'm trying to do this with as little tools and as simple materials as possible

Wait. You're bullshitting us then. You aren't actually going to be doing this project are you? You just had the idea and are really getting off on the possibilities of the design phase, but when you come down to the actual work required you'll just be sitting there in your computer chair not doing it and eventually moving onto the next project idea. This is more like a zombie apocalypse thread than an actual DIY thread because this will never happen for you.

Dang it, OP!

>>269695
Not at all. I just lack the tools and experiencd necessary to build a molten salt storage container, a(reliable) turbine, cut through water tanks and construct large-scale pneumatic storage systems. Sand, mineral oil, copper tubing, pipe tools, bricks, brushless motors, Mylar, plywood, paraffin and turbochargers are all relatively common and fairly cheap pre-manufactured materials to work with. I will build this for several reasons. This project is to prove to myself that I can accomplish what I set my mind on. It is so my will have reliable, off grid power without breaking the bank. It is to increase awareness that larger-scale DIY green power is fesiable for the average person. I will make an instructable for others to benefit from as well. Hopefully it will be featured and maby even win some prizes. This project might also draw some attention from schools and potential investors so I can contribute more to the green-power movement. It would also be pretty badass to be able to say: "yeah, I built a solar-powered steam turbine plant from scratch without any prior knowledge" (+10 swagger.) Don't understimate the force. I find your lack of faith disturbing.

>>269714
*family*

>>269714
>$1500-2,000 USD over the next 6-8 months

This amount will get you the tools and materials you need to do this job (oil-based, not salt-based) for a solar-steam-powered generator.

Unlike what "most" have stated ITT, this is a rather simple thing to accomplish (see video in >>265507 ). It is merely several small things and skills rolled into one project (like most projects). ITT you get a lot of opinions from people that obviously don't know much about the subjects involved.

I say, make a prototype on a very small scale. Like the entire system and setup small enough to fit into a 2'x2' area, excluding the solar collector which can be as big as you want. Work out some of the bugs in design like,

-Are all parts easily accessible and replaceable if needed?
-When reaching into X place will I need safety gear or will I get burned and should I place Z near Y to prevent this type of problem?
-How is the thermal flow; is the heat that is going up being sapped by something being too close or in the wrong place in relation to top/bottom?
-What hot parts need shielding to protect you?
-Where do you stand when observing or showing off the device and is this place safe if there is a blowout?
-Is the design safe for kids and pets or will the entire thing be fenced off completely to prevent their access?
-Is there a chance a bird might land/fly into a focal point and burst into flames? (it has happened before, fyi)
-Of the parts you are using, are they off-the-shelf and readily available for replacement? (they should be)

You can even make a mockup that doesn't use the real parts. Literally, using wooden blocks, legos, cardboard, etc to make it. This can help immensely in the design phase. Many DIYers well do a CAD mockup, but not a physical mockup. Make one and get your hands on it. That will tell you lots.

Bump

>>269823
Thanks for the advice. I've doodled it on paper to solidify my thoughts and I have a very vivid imagination to work with, so I don't think I really need a physical mock-up. Pets and kids? Yes, they have been a consideration and will have to be kept away from the station. Incinerating birds¿-didn't think about that one.

>I think all productive contribution has ceased for this thread, so I believe it is time to retire it. HTML will be saved for foture reference. Thanks everybody for the input.

Saving awesome thread from page 12 :)

>>271508
Alright then, one more bump.

OP here
I have an idea for the turbo turbines that would be similar to the diy jets seen all over thr internet. Rather than just pumping lots of steam in, I intend to use a two-stage heating process where "cold" steam is pumped in through the intake, which is then mixed with superheated steam and further heated in a reactor chamber. The superheated steam is then introduced to the "hot" side of the turbine and exhausted. I'll try to post some drawings of the design, but my artistic skills are somewhat lacking. At the very least, I will post a flow chart.

>>271615
I'd like OP to know that this board has an archive:
https://archive.installgentoo.net/diy/thread/S263866

Bump for more design time

interesting read...

i would advise you to avoid 2000-era ford turbos they don't make it to 300k

Also feel like this is a bit of a solar version of a arm chair commando zombie apocalypse thread...

The money makes almost all those suggestions easily possible

If it's going to come down to waxing and waining over making the reflective surface out of aluminium foil instead of Mylar so pennies pinched here cab be spent there, then pennies pinched there go somewhere else, that paradime is just a confab we can give you choices but you have to make them yourself, just seems like a lot of "what If's" and "but that's to costly"

Really out of wood and aluminumfoil 6 servo's and a arudino 5kw of sunlight for 100bux

Pipes, oil, storage and turbine $1850? Buy a metal lathe and a 200usd plasma cutter and a welder and learn the skills

>>272348
The idea is to use as few tools as possible to create a simple but efficient system.


So, here's the flow chart I promised.

The Ranque-Hilsch vortex tube is incorporated inline before the steam is injected into the compressor turbine and the superheater. The reason for this is to help keep the apparatus relatively cool while supplying the superheater with a higher-density fluid to expand. This would make the turbine operate similarly to a turbojet, but without combustion. The operation would be more akin to that of a rocket than a turbojet since no outside gas is used for combustion.

>Ranque-Hilsch vortex tube here:

http://en.m.wikipedia.org/wiki/Vortex_tube
http://m.instructables.com/id/The-Hilsch-vortex-tube/
http://www.pdbuchan.com/ranque-hilsch/assembly.html

>>272384
I found a DIY video of how to make one of those. It's a 2-parter, bu the rest of this guy's channel is also enlightening.
http://www.youtube.com/watch?v=fcqFb5kSMxc

Bump to draw interest.

Don't get me wrong I love steam engines, super chargers and generators but what if you just used a couple peltier coolers, they aren't even that expensive at 10$ for 200 watts give or take

>>272655
>10$ for 200 watts

>>272719
>You looked up vortex heating I see

>>272655
Peltier coolers are really neat, but obtainable is what I'm looking for. Sure you can buy them online, but can you find them in a scrapyard in a third-world country?
A 1m2 area recieves about 700 watts of solar power. I'm building a 20m2 parobolic collector. While the lowest price/100 watt listed in the screencap is about $20, I would need about ten of these for the dish I'm building-that's $450, a signifigant portion of my build costs. I can buy the turbine, make the boiler and build the dish for that amount. Each Peltier device takes up about 60 cm2- ten would take up .6 of a meter-this would be fairly unweildy and reduce the sunlight falling on the dish. Not to mention the extreme heat these devices would be subjected to-some collectors can even melt metal! I'm thinking of going the el-cheapo way and using about four cored 10-hole bricks painted with stove black. Copper piping with mineral oil circulating through the bricks would serve as the transfer fluid to remove the heat.

>does anybody know where I can find a high-speed (10,000rpm) 20hp brushless motor? A 10:1 reduction ratio for turbine gearing wouldn't be too much of a stretch, would it?

>thanks again for any input

>>272837
> can you find them in a scrapyard in a third-world country?
Nope.

>Not to mention the extreme heat these devices would be subjected to-some collectors can even melt metal!
You wouldn't shine the light on the Peltier cells, you'd heat the oil, which would go through several of those thermoelectric units before looping back for re-heating, while water flowed through the cooling side of each unit.
>rough idea attatched
For variable heat control, you could have a thermometer measuring the oil temperature rigged to mechanically to drop a piece of quality steel/rock in front of the heating area of the pipe, to be raised when it detects the temperature to be at a reasonable level.

If you look in the attached image, you can see that you can get to some pretty high heat tolerances of up to 200 degrees Celsius.

These units do generate DC current, so you'll still need an inverter to create an AC current and a transformer to step up the voltage and drop the amperage to a more tolerable level.

>>272837
>high-speed (10,000rpm) 20hp brushless motor
I found this
http://industrialmotorresource.com/companies/met-motors-675.html
http://www.metmotors.com/products/bldc/48-series-specs/
>attached

>>272857
the cost is still about $20/100 Watts

>For variable heat control, you could have a thermometer measuring the oil temperature rigged to mechanically to drop a piece of quality steel/rock in front of the heating area of the pipe, to be raised when it detects the temperature to be at a reasonable level.
>more circuitry and possible catastrophic breakdown

Also this:
>"Thermoelectric generators (also called thermogenerators) are devices which convert heat (temperature differences) directly into electrical energy, using a phenomenon called the "Seebeck effect" (or "thermoelectric effect"). Their typical efficiencies are around 5-10%."
> http://en.m.wikipedia.org/wiki/Thermoelectric_generator

>>272869
Thanks for the link, that's just what I need

>>272897
yeah I know peltier units are terrible for the budget.
I only addressed that just to present an idea of how they could be used.
>>more circuitry and possible catastrophic breakdown
very true, if the machinery jams and you overheat your units, you're toast. Mechanically though, it's still a good way to 'turn off' the heating of your oil, just having something in between the pipe and the light.

>>272719
Go on ebay they are a 1/4 of the price. even less if you buy bulk used units

Bump

No more contriboot?

Find a derelict C-band dish, cover it in mylar foil.

>>275036

>>275036
>C-band dish

I know where one is. the black metal screened kind. Had I the room I would have gotten it long long long ago. :/

I'd helostat it and it'd be boss.

>>275036
Wow, I didn't even think of that. Do you think I could easily find one of those in a scrapyard?

>>275186
Try freecycle and craigslist while your at it. If you are not familiar with freecycle, you go to the website, search the yahoo group nearest you then join that group and read the rules. Everything is free on it. Put up a wanted add and avoid using the word "need".

>>derelict C-band dish

Instead of mylar, use the hexagon mirrors at IKEA that are 12" or so in a 6-pack. Get dozens of these, they only cost like $5 each and cover the inside of the antenna.

Done right the focal point should be hot enough to melt steel.

Pic: Markus Kayser using a simple fresnel lens 3D print melted sand.

>>275547
I can buy 200 sq feet of mylar for $30 and positioning it would be as simple as cut and paste.

>The 3d-printed sand is quite intriguing

>>275809
Mylar isn't that good for this sort of purpose. There is a great deal of loss. Rigid reflective surface are better, even though you'll be applying the Mylar to a rigid surface, it is not the same.

Thin bathroom mirrors from a dollar store are very cheap and you can easily cut them with a typical glass cutter.

FYI, there's a guy that has already used both foil and mirror on one of those big old C-ban satellite dishes.

Here the 12 feet diameter one,

>light sharpener
http://www.cockeyed.com/incredible/solardish/dish01.shtml

There's several pages to that link above, each link to the next page is at the bottom of the pages.

A quick google search gives me this one I'd not seen before with those small dishes (I have one of these types of dishes I'll be doing this with),

http://www.dailymail.co.uk/sciencetech/article-1351935/Eric-Jacqmain-invented-Death-ray-dish-intensi
ty-5-000-suns.html

Video for it,
http://hacknmod.com/hack/diy-solar-death-ray-using-a-satellite-dish/

FYI, Mylar and foil are best used for non-parabola solar collecting like solar box cookers. The out of focus reflecting helps more evenly heat the inside of the box allowing the ambient temperatures to raise faster and more evenly for cooking purposes.

>>275547
>fresnel lens
You can get free ones/cheap ones of massive size if you look online for old box TV's.
http://www.youtube.com/watch?v=p7dvd959wfg
There are also different types of fresnel lenses with different performances.
http://www.youtube.com/watch?v=xExXjXm0YV0

Bump

ITT: tl;dr

Probably been said before but dawg, two things.

Start small. Don't be that guy.

Look into STIRLING ENGINES. They are used commercially in parabolic solar dishes. Use helium as your conducting gas. (says my experience with Stirling and Fluidyne fucks.)

>>276733
>start small
>helium

Hurr-durr

>>276733
See:
>>263866

Fresnel Lens with Stirling Engine!!!! Use Hydrogen to transfer heat!!

>>277489
>hydrogen
No.
I may be in favor of using hydrogen as a lifting gas, but that much energy in one place with a flammable gas is asking for trouble.