Physics Solar Heating Model Proposal Group leader: Kwok Yan Lam 3A (15) Group member: Choi Ka Man 3A (8) Chung Ho Man 3A (9) Hung Hiu Ting 3A (12)

Content Introduction Material required Procedures Points need to be caution Pictures descriptions Disadvantages and limitations References

Introduction Solar energy is the primary source of energy for our planet. Increased utilization of the same would result in an all-round benefit, both in terms of cleaner environment and monetary gain, for the individual users as well as the nation. Use of solar energy would save a lot of time and money for the user and solar cooking is the simplest, safest, most convenient way to cook food without consuming fuels or heating up the kitchen.

Material required A box Black construction paper Extra-wide aluminum foil Plastic (plastic window covering from a hardware store works best) Glue Tape Scissors Ruler Marker String

Procedures 1.Tape foil to the inside bottom of the box. Cover the foil with black paper. Tape in place. 2.Put the box on the plastic. Draw the outline of the box on the plastic with the marker. Cut the plastic about 1/4 inch inside the marks. 3.On the top of the box, draw a line one inch from all sides. Cut along front and side lines but not along the back. This will be the hinge for the flap. Carefully fold open the flap.

Procedures 4.Cut a piece of foil the size of the flap. Glue it to the side of the flap that faces into the box. Flatten out all the winkles. Wipe glue smears off with a damp towel before they dry. 5.Tape the plastic to the inside of the box. Tape one side first, then the opposite side. Make it tight so it looks like glass. Tape the other edges. Seal tight so no air can get in. 6.Cut a piece of string as long as the box. Tape one end to the top of the flap. Push a small nail into the back of the box so you have a place to tie the string.

Points need to be caution A. Box size The size should allow for the largest amount of food commonly cooked. If the box needs to be moved often, it should not be so large that this task is difficult. The box design must accommodate the cookware that is available or commonly used. B.Solar collection area to box volume ratio Everything else being equal, the greater the solar collection area of the box relative to the heat loss area of the box, the higher the cooking temperatures will be. Given two boxes that have solar collection areas of equal size and proportion, the one that is of less depth will be hotter because it has less heat loss area.

Points need to be caution C.Solar box cooker proportion A solar box cooker facing the noon sun should be longer in the east/west dimension to make better use of the reflector over a cooking period of several hours. As the sun travels across the sky, this configuration results in a more consistent cooking temperature. With square cookers or ones having the longest dimension north/south, a greater percentage of the early morning and late afternoon sunlight is reflected from the reflector to the ground, missing the box collection area. D.Reflector One or more reflectors are employed to bounce additional light into the solar box in order to increase cooking temperatures.

Pictures Descriptions

Disadvantages and limitations  Solar energy is diffused, intermittent and the radiation is available.  Cooking has to be done according to sun time (preferably hours).  Cooking is not possible on cloudy/rainy days or at night. There has to be some alternative arrangements ready.  Quick cooking or cooking at short notice is not possible.  Cooking takes a comparatively longer time.  The suns rays must fall directly on the cooker throughout the day. Shadows on the cooker hinders cooking. It is okay if clouds move in and out, but that slows the process.

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