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#101 2023-04-19 13:37:02

kbd512
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Registered: 2015-01-02
Posts: 7,270

Re: Trough Solar Collector- Design- Construction- Operation- Maintenance

SpaceNut,

It would make more sense to use oil instead of water in places with extremely cold temperatures, or to use gases that don't freeze, such as air without humidity / pure Nitrogen / CO2.

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#102 2023-04-19 21:17:34

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 28,639

Re: Trough Solar Collector- Design- Construction- Operation- Maintenance

The oil would go to a heat exchanger for home use heating to keep oil quantity as low as possible. I seem to remember that oil circulates through a heat exchanger, turning a refrigerant into steam, which drives a turbine that, in turn, drives a generator. Here it is...How To Build a Solar Generator, Affordable solar power using auto parts could make this electricity source far more available.

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#103 2023-04-23 13:47:31

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 28,639

Re: Trough Solar Collector- Design- Construction- Operation- Maintenance

Heat engines and how to make use of temperature difference to achieve the goal.
4de213ad34c355197c666cc33e780c8a11f097fe

The Organic Rankine Cycle (ORC) converts thermal energy into electricity.how-it-works.svg

https://www.geothermal-energy.org/pdf/I … _Final.pdf
DESIGN AND BUILD OF A 1 KILOWATT ORGANIC RANKINE CYCLE POWER GENERATOR

https://www.popularmechanics.com/scienc … 0/4232571/

A group of recent graduates and grad students from MIT is reconfiguring parts from old cars to create a simple turbine that runs on the heat of the sun instead of the oil drum. They hope to make it available in off-the-grid regions such as remote parts of the African country of Lesotho--where they recently completed a prototype (pictured above)--as a clean, inexpensive source of electricity, hot water and even refrigeration. The team was co-founded by former Peace Corps volunteer Matt Orosz, who was inspired by a locally made parabolic solar bread cooker during his stint in the country.

The solar turbine has three main parts: an array of shiny parabolic troughs that track the sun, an organic Rankine cycle (ORC) engine and an electrical control system. Rather than converting light to electricity using photovoltaics, this system employs solar heat: The four large troughs focus sunlight onto a continuous loop of pipes. Circulating through the pipes is a thermal absorption fluid, such as glycol, the anti-freeze fluid used in car radiators. Reaching temperatures up to 300 degrees F, the glycol passes through a heat exchanger, where it transfers its heat to a working fluid--a refrigerant, such as the R134 found in a car's air conditioner--which vaporizes and spins turbines in the ORC. The turbines generate enough juice (about 1000 watts) to charge a bank of batteries, while the excess steam heats water for domestic use. Add an absorption chiller, and you've got refrigeration as well, rounding out the typical range of energy needs: heating, cooling and electricity.

They kept prices low by using junk auto parts. The ORC's turbines are made from a salvaged turbo charger, which is coupled to an alternator to create electricity.

Organic Rankine cycle engines are not new. In large power plants, they're currently used to convert energy from low-grade, second-stage steam heat. And some very large solar-thermal power plants rely on ORCs, including the recently completed Nevada One, capable of generating 64 mW of power (enough for 40,000 homes). The Solar Turbine Group (STG) is taking an entirely different approach, scaling its equipment way down so that it can be installed in remote locations. Orosz and three partners recently spent a year in the Lesotho mountains working with locals to install a prototype solar turbine at a remote girls' school.

https://www.osti.gov/etdeweb/servlets/purl/894040

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#104 2023-05-31 20:05:52

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 28,639

Re: Trough Solar Collector- Design- Construction- Operation- Maintenance

Here are the 4 troughs that create 10kw hot water and 1 kw of power with crude auto parts.

200908311112324199_0.jpg?itok=hmHFySQn

Here is another view of the troughs collecting heat energy
200908311113506346_0.jpg?itok=HZAUSjaB

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#105 2024-01-30 09:00:40

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 3,285

Re: Trough Solar Collector- Design- Construction- Operation- Maintenance

I wonder if building these devices could be made easier by eliminating electronic control systems that track the sun?  For a large plant, a human operator can adjust reflector angle manually.  All of the mirrors could be simulateously adjusted using a chain link.

The use of organic fluids within the power cycle has the advantage that a fluid like butane has high molecular weight and high gas phase density.  This allows the turbine to be more compact, which improves power density.  The use of oil as the primary heat transfer fluid is difficult to get away from because of the overwhelming advantages it offers as a coolant.  It is non-corrosive and has low vapour pressure even at temperatures exceeding 300°C.  The low vapour pressure means that trough tubes don't need to be pressurised.  The only other cooling fluid candidates that meet those requirement are liquid metals like sodium.  Sodium doesn't boil until 800°C, so a sodium cooled trough collector could operate at much higher temperature than oil.  But sodium leaks would be dangerous, as liquid sodium burns spontaneously in air.  Then again, there is a high chance that oil leaks would ignite in air at 400°C.

Liquid sodium operating at temperatures of 550°C, would generate much higher quality steam.  This is important, because it increases the pressure ratio and power density of the turbine in addition to improving the amount of electric power yielded per square metre of reflector area, as generating efficiency increases.  This would improve the economics of the system, as improved efficiency increases the whole system power density.  But dealing with safety issues of hot sodium would impose its own set of costs.  Swings and roundabouts.

Low temperature systems (<200°C) could generate power through direct cycles.  By this we mean the trough tubes containing pressurised water rather than oil.  Hot water would flow into a steam seperator.  This type of system would work best in combined heat and power mode, as efficiency would be low.  Economic performance depends upon putting the waste heat to work.  This sort of system might be useful for supporting district heating schemes in Europe.  For much of the year, sunlight is too weak to be put to work generating steam.  But warm water, in the 30 - 100°C range, would be valuable for district heating.

Last edited by Calliban (2024-01-30 09:12:21)


"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

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#106 2024-01-30 13:12:29

tahanson43206
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Registered: 2018-04-27
Posts: 16,473

Re: Trough Solar Collector- Design- Construction- Operation- Maintenance

For Calliban re human attention to equipment ....

I am reminded of a video about English history.  There are still huge fire places in (some) English castles, equipped with metal beams upon which giant roasts were mounted for slow cooking over a timber fire.  A surf (probably a younger person) was assigned the duty of turning the spit slowly, from a position off to the side but never-the-less plenty close to the fire.

That person had a mind numbing job.  The chief cook used a human for what a simple control circuit could do, because the chief cook had the surf available (a) and (b) because this was a time when such automation was out of the question.

I would invite you to consider the duty your vision would impose upon some hapless human being, if the society you are thinking about has descended so far into the abyss.

All those troughs could be chained together, and turned from a single crank.  A simple water wheel could turn the crank, if the society you are considering still has enough wits to make one.

(th)

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#107 2024-02-07 09:01:31

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 3,285

Re: Trough Solar Collector- Design- Construction- Operation- Maintenance

On Mars, solar thermal power generation and production of synthetic fuels has some advantages over an Earth based operation.  Sunlight intensity is only half that of Earth, but the atmosphere is so thin that there is far less cloud cover.  It is mostly sunny, outside of dust storms.

The thin, dry, CO2-dominated atmosphere has some advantages as well.  Steel structures will not corrode, provided we keep them away from brine in the soil.  The cold is a problem for carbon steels, but they may still be acceptable in low stress situations.  On Mars, we can use liquid sodium as the heat transfer fluid within the trough collectors.  If we do get a sodium leak on Mars, it will do little more than smolder in the thin CO2 atmosphere.  Using sodium allows coolant temperatures exceeding 550°C.  This allows superheated steam to be raised or even an S-CO2 cycle to be used on the power generation side.  This allows power to be generated at 40% efficiency, rather than the 20-30% that we are stuck with using oil as our primary coolant and saturated steam power cycles.  So this partially compensates for lower sunlight intensity.  The low atmospheric density would make it easier to engineer structures against wind loading.

On Earth, if we want CO2 to make fuel, we must extract it from air or seawater.  The second option is better, because CO2 is more soluble than other atmospheric gases.  But the CO2 still needs to be seperated from other gases.  On Mars, the atmosphere is 95% CO2.  And it is cold enough to compress it down to liquid, probably without intercooling.  An axial compressor could produce a steady stream of liquid CO2.  So solar synfuel production may be simpler on Mars.

Using point focus collectors, it is possible to generate heat at high enough temperature for thermochemical hydrogen production.  This is potentially cheaper than electrolysis if done at large scale.  The problem with this that I can see is that the sulphur-iodine cycle which is generally considered most promissing, involves decomposition of sulphuric acid at temperatures above 800°C.  Sulphuric is always corrosive.  But dealing with H2SO4 and SO2 at temperatures that high is going to be a real materials challenge.  Specialty stainless steels and nickel alloys probably.  Coating are possible.  Ceramic coatings will resist corrosion, but would be vulnerable to cracking.  This is something that needs a lot of thought.

Last edited by Calliban (2024-02-07 09:20:48)


"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

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#108 2024-02-07 11:43:01

Void
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Registered: 2011-12-29
Posts: 6,860

Re: Trough Solar Collector- Design- Construction- Operation- Maintenance

Your work looks very useful to me.  A hypersaline lake could serve as a heat sink, and technically a thermal storage at say 20 to 90 degrees C.

Then using some type of suitable fluid, I hope maybe a hydrocarbon, the heat of the lake can drive a turbine system with solar panels or mirrors doubling as radiators to take advantage of the deep cold that Mars can provide.

Done


Done.

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#109 2024-02-22 18:47:43

tahanson43206
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Registered: 2018-04-27
Posts: 16,473

Re: Trough Solar Collector- Design- Construction- Operation- Maintenance

The article at the link below is about a hybrid of a trough collector and solar cells...

https://www.msn.com/en-us/news/technolo … 5c2&ei=105

Research team develops parabolic trough solar module for hybrid electricity and heat generation
Story by Science X staff • 9h

The parabolic trough collector is manufactured using industrial production methods such as injection molding. Credit: EMS–TU Graz
© Provided by Tech Xplore

Solar rays focused on concentrator photovoltaic cells using parabolic mirrors not only supply electricity, but also thermal energy for industrial processes, heating or cooling. Three technological innovations significantly reduce costs.

An international team led by Armin Buchroithner from the Institute of Electrical Measurement and Sensor Systems at Graz University of Technology (TU Graz) has developed a parabolic trough collector with cost-effective photovoltaic cells that can be used to generate solar power and thermal energy at the same time.

The solar module developed consists of a trough-shaped concave mirror that focuses the sun's rays onto the photovoltaic cells arranged in the focal line. The waste heat from the solar cells is transferred to a heat transfer fluid that flows along the back of the cells in a system of pipes. The thermal and electrical energy generated in this way can, for instance, be used for climate-neutral heating and cooling of buildings or for various industrial purposes, e.g., in the food or textile industry.

The idea of generating electricity and heat from solar radiation at the same time has been around since the 1970s, but has not been successful due to high costs and technological problems. This could now change, as Buchroithner's team has succeeded in developing several technological innovations in the course of the ECOSun—Economic COgeneration by Efficiently COncentrated SUNlight research project.

Related video: New Solar Panel Concept Could Help Drive the Transition to Renewable Energy (Dailymotion)

Solar radiation is amplified 60- to 120-fold

In cooperation with the partner IMK Solarmirrotec, the parabolic trough collectors were manufactured much more efficiently using industrial production methods such as injection molding technology. The silicon solar cells developed with the Turkish research center GÜNAM are cost-effective and robust, so that they can withstand the high temperatures of concentrated sunlight.

This is an important factor, since the parabolic trough mirrors amplify the solar irradiation by a factor of 60 to 120. The researchers were also able to optimize the cooling of the solar cells, making the waste heat more usable for further applications.

"This approach has the potential to make a significant contribution to the energy transition," says Armin Buchroithner. So far, parabolic trough solar power plants have been located almost exclusively in particularly sunny regions such as Spain or the Persian Gulf.

"However, our tests have shown that it can also be useful here in Austria or other regions to replace fossil fuels in industrial processes," says Buchroithner. "Given the rising energy prices and the desire for energy independence, the importance of independent, efficient, and cost-effective solutions for the supply of electricity and heat is increasing."

Provided by Graz University of Technology

This story was originally published on Tech Xplore. Subscribe to our newsletter for the latest sci-tech news updates.

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#110 2024-02-22 18:56:38

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 28,639

Re: Trough Solar Collector- Design- Construction- Operation- Maintenance

Solar cells breakdown and drop in power output as the temperature of them rise.. These must be a high temperature cell that is a differeent product.

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#111 2024-02-22 19:12:36

tahanson43206
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Registered: 2018-04-27
Posts: 16,473

Re: Trough Solar Collector- Design- Construction- Operation- Maintenance

For SpaceNut re #110...

Thanks for noting the work done with a hybrid trough and solar cell system... You are absolutely right ... according to the article, the solar cells are robust to handle heating, but they are also cooled by circulating fluid, which is itself a source of thermal energy to be used elsewhere.

I hope our members will search for additional information about the new system.

(th)

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