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Cooking With Light How do parabolic solar cookers work?

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Parabolic solar cookers

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for subtopics, how-tos, project pages, designs, organization pages and more.

A parabolic solar cooker is essentially a solar thermal collector used to cook food or pasteurize water. Parabolic designs have been used for centuries. The idea to concentrate light using curved mirrors was developed by the Greeks, Aztecs, Incas, Romans and Chinese. The Incas used bronze and gold for their mirrors and they built structures that were several stories high. This technology seems to have appeared around the same time for each of the civilizations.

There are many designs and models for parabolic solar cookers. Some are made with locally gathered scrap materials while others are manufactured using highly machined, durable but more expensive materials. Here are links to and photos of a number of parabolic solar cooker designs.

  • Some Parabolic Solar Cookers
  • Fig1: Grilling meat with Parabolic Solar Cooker

  • FIG 2: Boiling water with an aluminum foil covered umbrella

  • Fig 3: Boiling water in the Himalayas

  • Fig 4: Sunbrella

  • Fig 5: Stadium Light Solar Cookers

  • Fig 6: SCRAP Humboldt solar wax melter with 3D printed molds

  • Fig 7: Papasan Chair Solar Cooker

  • Fig 8: Parabolic basket and tin can solar cooker

  • Fig 9: Aleiha’s parabolic solar cooker

  • Fig 10: Some parabolic solar cookers from Humboldt State University

Contents

  • 1 Danger from concentrated sunlight
  • 2 Notes
  • 3 See also
  • 4 External links

Danger from concentrated sunlight[ edit ]

A parabolic cooker concentrates sunlight. Ordinary sunlight is already dangerous (if the sun is viewed directly without protection) so concentrated sunlight can be much more so. (There is a story that someone in the USA damaged their eyes in this way.[ verification needed ])

The larger the parabola, the greater the danger.

Ways of reducing the danger include:

  • Safety rules. [1]
  • Design. Note that these mostly reduce the danger rather than eliminate it:
    • Putting the focal point inside the parabola (deep dish focus), so someone would have to put their head inside to expose themselves to danger. (There is still a danger if someone unwisely checks a problem or tries to do maintenance while the parabola is pointed towards the sun, or if children are playing.)
    • Using a physical barrier to prevent people going near the danger point.
    • A table to protect the cook from burns and dazzles. [2] (How does this work? It obviously can’t block too much, or it will block the sun from the doing its work.)
    • Keeping the parabola small.
    • Designing the parabola to avoid a small sharp focal point. This requires that the cooking vessel have a relatively large surface area to catch the reflected rays. This would make it more likely for someone to be struck by the focused rays, but less damaging if it actually happened. [3]
    • Maximizing the efficiency of absorption by the cooking vessel (it would be expected that making it matt black is the most important thing)
    • Four design methods to improve saftey are described at Wikia:Solarcooking:Satellite dish .

The risk can be reduced but not eliminated. Other solar cooker designs have much less risk, and are probably a better option in situations where they can provide enough heat.[ verification needed ] Alternatively, integrated cooking and improved cookstoves with fuels from waste biomass may be safer options which use only modest amounts of resources.

Are there other solar cooker designs that can provide comparable high levels of heat but more safely, without being too expensive? [Suggested project] I made a pseudo compound parabolic dish that concentrates the light down at the bottom of the dish and gives a bit longer cook time than a parabolic dish. It worked well.
I tested a winston w dish in software and that indicates MUCH longer cook time with good concentration amd a soft focus.

Notes[ edit ]

  1. E.g. Safety Rules (from the AMSI Solar Cooker Project)
  2. http://solarcooking.org/images/gallery-para.htm Parabolic Cookers] (The Solar Cooking Archive)
  3. This is just my ( Chriswaterguy ‘s) idea. When testing the parabola, it should not create an intense bright spot, but rather a slightly diffuse bright spot (but still significantly smaller than the smallest cooking vessel which will be used).

See also[ edit ]

  • Aleiha’s parabolic solar cooker
  • Parabolic Basket Solar Cooker – Engineering 305
  • Compound parabolic concentrator
  • Focus-balanced paraboloid

External links[ edit ]

  • Free and Easy DIY Parabolic Solar Concentrator Plan
  • How to harness Sun’s energy by making a solar concentrator
  • Build a Solar Cooker – plans at The Solar Cooking Archive (solarcooking.org).
  • A Parabolic Solar Cooker for Unattended Cooking at The Solar Cooking Archive.
  • Paraboloid Solar Cooker: Solar Cooker from recycled light fixture
  • Extensive descriptions of parabolic cookers from Solarcooking.wikia.com.

v    d    e

Solar topics ( Category )

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General
Composting greenhouse provides hot water  · Construction of an Affordable Greenhouse  · Humboldt greenhouse gallery
Tools
Kiva’s straw bale greenhouse  · Sequatchie Valley Institute cobb houses  · Sunny Brae Middle School Garden  · Greenhouse waste heat exchange
Passive solar
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Direct gain  · Parras passive solar design gallery  · Thermal mass  · Thermosiphon  · Passive annual heat storage
Tools
Trombe wall
  Photovoltaics
General
ASHRAE PVT  · Amorphous silicon PVT  · An open source simulation of photovoltic yield for Southeastern Ontario  · CCAT PV system energy analysis  · Combined photovoltaic solar thermal systems (PVT) – literature review  · Deployment of Renewable Energy Technologies to Mitigate Climate Change Literature Review  · Distributed generation  · Diverting indirect subsidies from the nuclear to the photovoltaic industry: Energy and financial returns  · Effects of Substrate Temperature on Indium Gallium Nitride Nanocolumn Crystal Growth  · Effects of low concentration planer concentrators on array-scale solar photovoltaic systems performance  · Effects of snow on photovoltaic performance  · Electrical wiring and switching  · Estimating the rooftop PV potential of a large-scale geographical region  · Extracting data from the ILC  · Government Investment and PV Manufacturing – Lit. Review  · Government PV Manufacturing Policy Lit Review  · Government support of photovoltaic manufacturing  · Green Building Pre-Apprenticeship Program/Solar PV Installation and Design Principles  · Grid connection  · Holographic solar  · Humboldt photovoltaic gallery  · InGaN Solar Cells Literature Review  · Industrial symbiosis in photovoltaic manufacturing  · LCA of silicon PV panels  · Levelised Cost of Electricity Literature Review  · Leveraging solar photovoltaic technology for sustainable development in Ontario’s aboriginal communities  · Lifespan and Reliability of Solar Photovoltaics – Literature Review  · Low level concentration for PV applications  · Lunar Solar Power Generation  · MECH820  · Maintenance of your Solar Electric System  · Modeling shading for PV system  · Open Solar Outdoors Test Field  · PV and CHP Literature review  · PV and CHP hybrid systems  · PV penetration level Literature review  · Parras solar gallery  · Peer to Peer Lending and Microfinance for Solar – Lit. Review  · Photovoltaic system at St. Jude’s church  · Producer responsibility and recycling solar photovoltaic modules  · Programming a CR1000 Datalogger  · Queen’s Innovation Park Test Site  · Refrigeration for developing countries  · Regional Rooftop Solar Photovoltaic Potential Literature Review  · Renewable powered desalination in coastal Central and southern Vietnam  · Rural lighting  · SEARC OSOTF Design and Operations Manual  · Solar (PV) Refrigeration of Vaccines  · Solar (PV) water-pumping  · Solar Photovoltaic (PV) Energy  · Solar Photovoltaic Cells for the Kingston Home FAQ  · Solar Photovoltaic Open Lectures  · Solar Radiation Maps  · Solar powered Internet cafe in Nairobi  · Spectral Selective Coatings Literature Review  · Spectral selective coatings – equipment  · The solar resource  · Tienda Hernandez photovoltaic feasibility study  · Transport PV – Lit Review  · Understanding Solar Cells
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How to calculate how much PV you need to cover your electrical needs  · PVTOM Operation Instructions  · Solar resource measurement for PV applications  · Troubleshooting a PV System/Literature Review  · Troubleshooting a Photovoltaic System  · Using Solid State Lighting
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Analysis of a solar box cooker with inclined window  · Solar cooking and development of solar cookers  · Harnessing Solar Power  · Solar Cooking and Health
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Locally Delicious School Solar Oven  · Parabolic cookers: Aleiha’s  · Focus-balanced paraboloid  · Papasan Chair  · Parabolic basket and tin can  · Stadium Light  · Sunbrella
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Food Drying with Superheated Steam  · Solar drying in Uganda
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AEF food dehydrator  · Chris’s ENGR305 Solar Food Dehydrator  · Locally Delicious school solar dehydrator instructions  · Locally Delicious solar dehydrator for kids with adult supervision
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Amorphous silicon PVT  · Concentrated solar power  · Open Solar Outdoors Test Field  · PVT  · Preliminary Review of Geothermal Solar Assisted Heat Pumps  · Smart windows  · Solar energy conversion system  · Solar Lighting  · Sun related calculations  · The solar resource  · P2P financing of solar  · PV+battery+CHP systems
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ASHRAE PVT  · DIY solar thermal collectors  · Solar Hot Water Installation and Design Principles  · Solar hot water – system types
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      Science
      HowStuffWorks
      Science

      1. HowStuffWorks

      2. Science

      3. Environmental Science

      4. Green Science

      How Solar Cooking Works

      by

      Julia Layton


      Cooking With Light

        Prev

      NEXT  

      ­

      ­Using stoves and ovens, we can cook foods like meat, vegetables, beans, rice, bread and fruit in just about any way. We can bake, stew, steam, fry and braise. Using a solar cooker, we can do the same things, but by using sunlight instead of gas or electricity .

      Sunlight isn’t hot in and of itself. It’s just radiation, or light waves — basically energy generated by fluctuating electric and magnetic fields. It feels warm on your skin, but that’s because of what happens when those light waves hit the molecules in your skin. This interaction is similar to the concept that makes one form of solar cooker, the box cooker, generate high temperatures from sunlight.

      At its simplest, the sunlight-to-heat conversion occurs when photons (particles of light) moving around within light waves interact with molecules moving around in a substance. The electromagnetic rays emitted by the sun have a lot of energy in them. When they strike matter, whether solid or liquid, all of this energy causes the molecules in that matter to vibrate. They get excited and start jumping around. This activity generates heat. Solar cookers use a couple of different methods to harness this heat.

      The box cooker is a simple type of solar cooker. At maybe 3 to 5 feet (1 to 1.5 meters) across, it’s essentially a sun-powered oven — an enclosed box that heats up and seals in that heat. At its most basic, the box cooker consists of an open-topped box that’s black on the inside, and a piece of glass or transparent plastic that sits on top. It often also has several reflectors (flat, metallic or mirrored surfaces) positioned outside the box to collect and direct additional sunlight onto the glass.

      ­To cook, you leave this box in the sun with a pot of food inside, the pot sitting on top of the black bottom of the box. When sunlight enters the box through the glass top, the light waves strike the bottom, making it scorching hot. Dark colors are better at absorbing heat, that’s why the inside is black. The molecules that make up the box get excited and generate more heat. The box traps the heat, and the oven gets hotter and hotter. The effect is the same as what goes on in a standard oven: The food cooks.

      Box cookers can reach up to 300 degrees F (150 degrees C) [source: SHEI ]. That’s hot enough to safely cook meat.


      HSW 2009

      ­­

      A parabolic cooker can get even hotter, up to 400 degrees F (204 degrees C), which is hot enough to fry food or bake bread. This slightly­ more complicated design uses curved, reflective surfaces to focus lots of sunlight into a small area. It works a lot like a stove, and it’s big, sometimes up to several feet across.

      A pot of food sits on an arm that holds it in the center of the curved reflectors, suspended slightly above the bottom point of the oven, where all the light is concentrated. This small point gets so hot — and the molecules vibrate so much — that the heat waves move upward in a steady stream to strike the bottom of the pot.

      Both parabolic and box cookers are quite large, making them difficult to carry around. And box cookers are heavy because of the glass. A panel cooker, which uses parabolic reflectors positioned above a box-type oven, tends to be smaller and lighter. The cooking pot goes in a plastic bag while it cooks, which acts as a heat trap (like the transparent top on a box cooker). People sometimes use these types of cookers in ­camping.

      Camping is something of a side job for solar cookers, though. The more central applications have to do poverty, hunger and disease.

      How can cooking with sunlight help?

      • 1
      • 2
      • 3
      • NEXT 

      Print |
      <a data-track-gtm="Byline" href="https://www.howstuffworks.com/about-author.htm#layton"> Julia Layton </a> "How Solar Cooking Works" 3 February 2009.<br />HowStuffWorks.com. &lt;https://science.howstuffworks.com/environmental/green-science/solar-cooking.htm&gt; 4 December 2018″ href=”#”>Citation & Date | Reprint

      Print |
      <a data-track-gtm="Byline" href="https://www.howstuffworks.com/about-author.htm#layton"> Julia Layton </a> "How Solar Cooking Works" 3 February 2009.<br />HowStuffWorks.com. &lt;https://science.howstuffworks.com/environmental/green-science/solar-cooking.htm&gt; 4 December 2018″ href=”#”>Citation & Date | Reprint

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      Science
      HowStuffWorks
      Science

      1. HowStuffWorks

      2. Science

      3. Environmental Science

      4. Green Science

      How Solar Cooking Works

      by

      Julia Layton


      Cooking With Light

        Prev

      NEXT  

      ­

      ­Using stoves and ovens, we can cook foods like meat, vegetables, beans, rice, bread and fruit in just about any way. We can bake, stew, steam, fry and braise. Using a solar cooker, we can do the same things, but by using sunlight instead of gas or electricity .

      Sunlight isn’t hot in and of itself. It’s just radiation, or light waves — basically energy generated by fluctuating electric and magnetic fields. It feels warm on your skin, but that’s because of what happens when those light waves hit the molecules in your skin. This interaction is similar to the concept that makes one form of solar cooker, the box cooker, generate high temperatures from sunlight.

      At its simplest, the sunlight-to-heat conversion occurs when photons (particles of light) moving around within light waves interact with molecules moving around in a substance. The electromagnetic rays emitted by the sun have a lot of energy in them. When they strike matter, whether solid or liquid, all of this energy causes the molecules in that matter to vibrate. They get excited and start jumping around. This activity generates heat. Solar cookers use a couple of different methods to harness this heat.

      The box cooker is a simple type of solar cooker. At maybe 3 to 5 feet (1 to 1.5 meters) across, it’s essentially a sun-powered oven — an enclosed box that heats up and seals in that heat. At its most basic, the box cooker consists of an open-topped box that’s black on the inside, and a piece of glass or transparent plastic that sits on top. It often also has several reflectors (flat, metallic or mirrored surfaces) positioned outside the box to collect and direct additional sunlight onto the glass.

      ­To cook, you leave this box in the sun with a pot of food inside, the pot sitting on top of the black bottom of the box. When sunlight enters the box through the glass top, the light waves strike the bottom, making it scorching hot. Dark colors are better at absorbing heat, that’s why the inside is black. The molecules that make up the box get excited and generate more heat. The box traps the heat, and the oven gets hotter and hotter. The effect is the same as what goes on in a standard oven: The food cooks.

      Box cookers can reach up to 300 degrees F (150 degrees C) [source: SHEI ]. That’s hot enough to safely cook meat.


      HSW 2009

      ­­

      A parabolic cooker can get even hotter, up to 400 degrees F (204 degrees C), which is hot enough to fry food or bake bread. This slightly­ more complicated design uses curved, reflective surfaces to focus lots of sunlight into a small area. It works a lot like a stove, and it’s big, sometimes up to several feet across.

      A pot of food sits on an arm that holds it in the center of the curved reflectors, suspended slightly above the bottom point of the oven, where all the light is concentrated. This small point gets so hot — and the molecules vibrate so much — that the heat waves move upward in a steady stream to strike the bottom of the pot.

      Both parabolic and box cookers are quite large, making them difficult to carry around. And box cookers are heavy because of the glass. A panel cooker, which uses parabolic reflectors positioned above a box-type oven, tends to be smaller and lighter. The cooking pot goes in a plastic bag while it cooks, which acts as a heat trap (like the transparent top on a box cooker). People sometimes use these types of cookers in ­camping.

      Camping is something of a side job for solar cookers, though. The more central applications have to do poverty, hunger and disease.

      How can cooking with sunlight help?

      • 1
      • 2
      • 3
      • NEXT 

      Print |
      <a data-track-gtm="Byline" href="https://www.howstuffworks.com/about-author.htm#layton"> Julia Layton </a> "How Solar Cooking Works" 3 February 2009.<br />HowStuffWorks.com. &lt;https://science.howstuffworks.com/environmental/green-science/solar-cooking.htm&gt; 4 December 2018″ href=”#”>Citation & Date | Reprint

      Print |
      <a data-track-gtm="Byline" href="https://www.howstuffworks.com/about-author.htm#layton"> Julia Layton </a> "How Solar Cooking Works" 3 February 2009.<br />HowStuffWorks.com. &lt;https://science.howstuffworks.com/environmental/green-science/solar-cooking.htm&gt; 4 December 2018″ href=”#”>Citation & Date | Reprint

      More to Explore


      Related


      Seeds of Worlds Rarest Trees and Crops Cant Be Banked


      Georgia Tech Using Campus Wastewater to Grow Veggies


      Temps in National Parks Increasing Much Faster Than Rest of U.S.


      Fungus-based Pesticides Might Be the Green Solution of the Future


      Male and Female Farmers Cope Differently with Climate Change


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