Experiment 4

Nature's Kitchen

Solar Box Cooker

Objective: After performing this experiment, you will be able to design an apparatus to cook food with energy from the sun.

Practical applications: These principles may be useful if you are camping or stranded in the wilderness without a Coleman stove.

Review of Scientific Principles:

Common fuel sources used for cooking include gas, electricity, microwaves, or wood. What if we ran out of all of these sources or if they were unavailable for use? What could we use instead? In this lab we will investigate how to use solar power as a cooking fuel.

The sun may shine all day, but is it warm enough to cook anything? Can we simply put the food outside in the sunshine to cook it? These questions should be considered as you build your solar cooker.

The idea is simple. If you have ever started anything on fire with a magnifying glass, you have used an uncontrolled solar cooker. The solar cooker you will build will concentrate the sun's rays in order to achieve a temperature suitable for cooking food. This heat from the sun must be stored or trapped, in order to reach cooking temperature. In order to trap the heat efficiently, reflectors, a glass or Plexiglas window, and insulation around the perimeter will be used. As you build your solar cooker, think about how it would fit into your lifestyle and how this technology could be used as an alternative fuel source.

Time: 1 class period to build

1-8 hours to cook


Safety Guidelines:


Materials and Supplies:

Procedure:

  1. Remove the flaps from the smaller box.
  2. Make four 4 cm high stacks (3 cm x 3 cm) from discarded flaps for bottom supports.
  3. Crumple newspaper into baseball size balls and cover bottom of large box with the supports.
  4. Use aluminum foil to cover:
    a. inside of small box.
    b. outside of small box.
    c. both sides of flaps on large box.
  5. Put the covered smaller box inside larger box on the newspaper balls and supports.
  6. Add newspaper balls between sides of the boxes.
  7. Cut black construction paper to fit inside smaller box.
  8. Cut flaps of larger box to fit inside the smaller box and cover the space between both boxes. Tape in place.
  9. Make a snug fitting lid from the single piece of cardboard and tape (do not tape to large box).
  10. Cut three sides of a rectangle in the lid (the same size as the smaller box).
  11. Cut the Plexiglas 2 cm larger than the lid's rectangle.
  12. Center and tape Plexiglas in lid and put lid on the cooker.
  13. Bend the uncut side of the rectangle in the lid to open window and cover inside of the cardboard with aluminum foil.
  14. Tape a 10 cm piece of string to the rectangle to open the window.
  15. Use a stick to prop open the window to collect the sun's rays.

You are now ready to cook in your solar cooker.

Video Clip

Data and Calculations:

SampleTimeTemperature
   
   
   
   
   
   
   
   
   

Questions:


  1. Identify the collector, storage, and controls on your solar cooker.
    a. collector:


    b. storage:


    c. controls:

  2. How does the sunlight cook the food?

  3. What parts of the world would a solar cooker work the best? the worst?

  4. What are some disadvantages of using a solar cooker?

  5. What are some advantages of using a solar cooker?

  6. What are some health benefits of using a solar cooker in developing countries?

  7. How are solar cookers beneficial to the environment?

  8. What other types of materials could be used in the construction of a solar cooker? Would cost have to be a consideration?


Experiment 4: Teacher's Notes

Nature's Kitchen

Solar Box Cooker

Objective: After performing this experiment, you will be able to design an apparatus to cookfood with energy from the sun.

Practical applications: These principles may be useful if you are camping or stranded in the wilderness without a Coleman stove.

Time: 1 class period to build

1-8 hours to cook


Safety Guidelines:


Questions:

  1. Identify the collector, storage and controls on your solar cooker.
    a. collector: the glass cover that lets the sunlight in the cooker.
    b. storage: the newspaper insulation prevents heat from escaping and the food also will absorb the heat.
    c. controls: the reflectors direct the sun's rays into the cooking area.
  2. How does the sunlight cook the food?

    The sun's rays are absorbed by the cooker's inside surface and transformed into heat energy.

  3. What parts of the world would a solar cooker work the best? the worst?

    Areas that get lots of sunshine on a consistent basis would be the best. Areas where the sunlight is less intense such that it takes a long time to collect the same amount of energy as from a sunny place would be the worst.

  4. What are some disadvantages of using a solar cooker?

    Need a lengthy span of available sunlight, longer cooking times, smaller portions.

  5. What are some advantages of using a solar cooker?

    There isn't any waste product, and you can cook in the summer without heating the entire house.

  6. What are some health benefits of using a solar cooker in developing countries?

    a. temperatures can reach the point to purify water and to kill bacteria and dangerous diseases, but only on sunny days.

    b. eliminates disease caused by inhaling toxins common to food cooked over wood.

    c. decrease health problems related to constant exposure to smoke and fire.

    d. decrease malnutrition due to the decreased availability of firewood

  7. How could solar cookers be beneficial to the environment?

    They could reduce the need of fuel gathering (wood, coal, or gas) that can lead to the destruction of forest and agricultural lands. In addition, much of the waste products from burning fossil fuels would be reduced. However, remember that the majority of our energy is consumed for transportation, not cooking food.

  8. What other types of materials could be used in the construction of a solar cooker? Would cost have to be a consideration?

    Answers may vary. Materials should be capable of providing insulation, absorption, storage and reflection.

Teacher Notes

This lab may be done in groups or as an individual project for solar cooker design. Students could experiment with different insulation materials (do not use Styrofoam, they may emit toxic fumes at high temperatures), reflector angles, and general design materials. This could also be a good science fair project, or it might make a fun project for a class competition to see whose cooker can most completely cook a certain type of food in a given time.

Solar cooker should be preheated approximately one hour before using.

Observed Cooking Times

1-2 hours: rice, fruit, above-ground vegetables, pretzels

3-4 hours: potatoes, root vegetables, some beans, most bread

5-8 hours: most dried beans

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