Solar thermal power - Fathers Day gift

BWhite · 2005-06-10 15:10:03

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A few months ago I told my wife I might want a http://www.cleardomesolar.com/]solar thermal oven for Father's Day. She called me at work today looking for some links on where to get one. (This guy has weird web navigation, the link takes you to a home page yet the solar oven page has the same URL - - so, just click the "oven" link at the top of the page)

Anyway, after reading about it we mutually decided that with children 900 degrees was just a little too dangerous.

The guy who makes these things said that with two 24 inch parabolic disks set to focus both mirrors on the target he melted an industrial thermometer that was rated to 1800 degrees F - - he estimates the furnace hit 2000 degrees F.

These would be awesome for the Moon if you added a Sterling cycle engine. No atmosphere and in the shadows temperatures approach, well very very cold. Those Sterling engiens should just whir right aloing if you can dispose of the waste heat fast enough.

Edited By BWhite on 1118438072

Fledi · 2005-06-10 16:00:12

Nice idea, do you know how far they can go down with the thickness of the reflectors? One way to dispose of the heat could be by also using the reflectors as radiators (maybe the back side of them), after running the steam through the Stirling.
Would also be nice to know if the reflection efficiency decreases in space, and if yes by what rate.

C M Edwards · 2005-06-11 07:36:27

I had a professor who was involved with a prototype for a solar powered stirling engine generator for remote use. The design employed sheets of flat mylar a few microns thick, with a reflective coating, for the mirrors. The mirrors were shaped and focused by stretching them drum tight across a manifold with a suction pump on the other end. The suction would pull the mylar membrane into a curved shape, making a spherical mirror that required no polishing and could be as large as you could find mylar for.

Fledi · 2005-06-11 16:37:52

Any idea why this is not used and advertised as much as solar cells?

dicktice · 2005-06-11 18:16:49

Well, for one thing, space is already a vacuum . . . oh, sorry, you mean on Earth. Brilliant: The double acting hand pump could simultaneously inflate a narrow torus-like rim, while sucking parabolas on both sides, to form a rigid collector pegged to the ground by the tripod supporting the cooking pot, etc. If damaged, just unroll and inflate/evacuate a new one, they cost so little, plus a hand-pump and tripod per camel.

Fledi · 2005-06-12 05:34:34

In space it is also a weight isue, how rigid a support grid (to which the mylar is attached in some other way than suction) must be to keep everything focused.
But for Earth applications it's surprising to see all the solar cells on top of buildings and nothing like that. Maybe it's because this supposedly has to stay pointed at the sun more precisely?

dicktice · 2005-06-12 09:49:05

Undoutably, and building demands being so large, structural rigidity as well as all day use (as opposed to noontime water heating in the desert, say) needing tracking machinery.

C M Edwards · 2005-06-13 09:37:29

But for Earth applications it's surprising to see all the solar cells on top of buildings and nothing like that. Maybe it's because this supposedly has to stay pointed at the sun more precisely?

Exactly. Solar thermal powerplants are seen as less reliable than photovoltaic powerplants.

People forget that solar thermal powerplants can operate at night, producing two to three times the peak power output of photovoltaics - at half the initial price, with equivalent maintenance costs.

But the spectre of the repair man looms too large...

C M Edwards · 2005-06-13 09:52:10

Oh, BTW, before anybody asks, I did write "solar thermal powerplants can operate at night". Solar thermal powerplants need the heat, not the light. Anything that will release heat back to the generator will keep it running at night.

A ton of molten lithium can soak up enough heat during the day to keep a kilowatt generator going for hours after dark.

BWhite · 2005-06-13 11:17:47

Oh, BTW, before anybody asks, I did write "solar thermal powerplants can operate at night". Solar thermal powerplants need the heat, not the light. Anything that will release heat back to the generator will keep it running at night.
A ton of molten lithium can soak up enough heat during the day to keep a kilowatt generator going for hours after dark.

Build a solar chimney in a desert region and supplement with solar thermal powered Sterling-engines using a liquid metal heat sink as you propose. Put the heat sink underneath the outer umbrella of the chimney and heat with reflected sunlight harvested from even farther out.

Some of the heat not captured by the Sterlings can be captured by the chimney.

Kinda like a turbo-charger to prime the pump and accelerate air flow up the chimney.

Fledi · 2005-06-14 09:17:21

Now that reminds me of the thermic wind turbine project in Australia. Only that they simply build a glass top over a huge surface with a mile high chimney in the middle. It also can be made to work at night by covering parts of the surface with water that stores heat during the day and releases it at night.
It has a somewhat higher investment cost per Watt than coal plants, but is more cost effective on the long run.

BWhite · 2005-06-14 17:03:35

Now that reminds me of the thermic wind turbine project in Australia. Only that they simply build a glass top over a huge surface with a mile high chimney in the middle. It also can be made to work at night by covering parts of the surface with water that stores heat during the day and releases it at night.
It has a somewhat higher investment cost per Watt than coal plants, but is more cost effective on the long run.

That's the exact project I have in mind. We discussed it at length here a few months/years ago.

Add heat sinks and large solar reflectors outside the perimeter and it seems to me you can turbo-charge the thing. .

SpaceNut · 2005-06-15 05:35:18

Yup you memory did not fail you, here are the other threads:
Solar chimeys, Feasible?

solar power towers on mars, km-high vertical wind tunnel turbo-elec

SpaceNut · 2015-08-12 22:21:33

Wow I had made the last post back then and the shifting problem was not there back then...but its all fixed now...

Interesting topic of solar concentration, Sterling engines and power long after the sun goes down with a solar chimney....

SpaceNut · 2018-12-20 21:22:28

bump for co2 collection

SpaceNut · 2019-12-11 07:13:45

Solar thermal via concentrating the suns energy but how hot will the target spot be for mars or Earth use.
Another topic we have here Solar thermal power

https://en.wikipedia.org/wiki/Parabolic_trough

SpaceNut · 2021-02-09 18:22:33

Another application to heat molten salt for longer daily power making.

SpaceNut · 2021-04-07 19:48:52

We have been talking about the use of "a 60% sodium nitrate/40% potassium nitrate molten salt" to allow for heat to be used in a co2 dry ice to pressure machine. A schematic of a molten salt power tower system during operation, has a cold (285°C) molten salt tank that keeps it from turning hard where it is pumped from the cold salt tank through the receiver in a tower. Where it is heated to 565°C or more depending on reflective mirror count and reciever tank area size. It then flows by gravity to the hot salt tank, where it is stored until needed for generation of steam to power the turbine. At that time, it is pumped through the steam generator, producing 512°C steam for the electric power generation system before being routed back to the cold tank to begin the cycle again.

https://www.energy.gov/sites/prod/files … _reddy.pdf

https://ir.ua.edu/bitstream/handle/1234 … sAllowed=y

https://www.bia.gov/sites/bia.gov/files … 021596.pdf

SpaceNut · 2021-12-04 12:51:32

A Unique Heat Storage Technology Gathers Steam

Argonne’s TESS is a form of latent heat storage, where the energy is contained within a phase-change material such as molten salt. While such materials are good at retaining heat, they are typically poor conductors, so it takes too long for them to absorb and release energy. Researchers have demonstrated the TESS to operate in temperatures over 700° Celsius (1,292° Fahrenheit). Its high energy density makes it smaller and more flexible than commonly used sensible heat storage systems, which rely on raising and lowering a material’s temperature. The technology won a 2019 R&D 100 award, and researchers are now working to integrate it within CHP systems from Capstone Turbine Corporation to boost heat recovery

60% of the energy is lost as heat

Single-tank thermocline systems store thermal energy in a solid medium—most commonly, silica sand—located in a single tank.

photo_termocline_test.gif?itok=UHRiKhBh

https://newscenter.lbl.gov/2021/11/18/t … buildings/

In the United States, buildings account for 40% of total energy consumption. Of that, almost half goes toward thermal loads, which includes space heating and cooling as well as water heating and refrigeration.

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#1 2005-06-10 15:10:03

Re: Solar thermal power - Fathers Day gift

#2 2005-06-10 16:00:12

Re: Solar thermal power - Fathers Day gift

#3 2005-06-11 07:36:27

Re: Solar thermal power - Fathers Day gift

#4 2005-06-11 16:37:52

Re: Solar thermal power - Fathers Day gift

#5 2005-06-11 18:16:49

Re: Solar thermal power - Fathers Day gift

#6 2005-06-12 05:34:34

Re: Solar thermal power - Fathers Day gift

#7 2005-06-12 09:49:05

Re: Solar thermal power - Fathers Day gift

#8 2005-06-13 09:37:29

Re: Solar thermal power - Fathers Day gift

#9 2005-06-13 09:52:10

Re: Solar thermal power - Fathers Day gift

#10 2005-06-13 11:17:47

Re: Solar thermal power - Fathers Day gift

#11 2005-06-14 09:17:21

Re: Solar thermal power - Fathers Day gift

#12 2005-06-14 17:03:35

Re: Solar thermal power - Fathers Day gift

#13 2005-06-15 05:35:18

Re: Solar thermal power - Fathers Day gift

#14 2015-08-12 22:21:33

Re: Solar thermal power - Fathers Day gift

#15 2018-12-20 21:22:28

Re: Solar thermal power - Fathers Day gift

#16 2019-12-11 07:13:45

Re: Solar thermal power - Fathers Day gift

#17 2021-02-09 18:22:33

Re: Solar thermal power - Fathers Day gift

#18 2021-04-07 19:48:52

Re: Solar thermal power - Fathers Day gift

#19 2021-12-04 12:51:32

Re: Solar thermal power - Fathers Day gift

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