Solar Sterilizer - Group 5

During this week we spent the entire time solely working on the reflective wings surrounding the outside of the box. During the building, work was also put into creating the final presentation on our design. The wings were designed in a way in which they are able to be placed directly onto the box, without further attachment. We utilized pieces of cardboard and aluminum foil to create the wings. However, these pieces are only to be used in the prototype. Sturdier and more reflective pieces would be used in the final design. Several pieces of cardboard were cut using box cutters in specific measurements to create a forty five degree angle when placed around the box. Four side panels were made, along with four corner pieces to fill the gaps created when the sides were angled outwards. The wings are held together by a combination of tape on the bottom corners, and string to connect the pieces and hold them at the correct angle of forty five degrees. The basic outline and skeleton of t...

This week the team finished up the sterilizer. The reflective wings were finalized, the mechanism to angle the sterilizer was added and a paint job was done for appearance and practical applications. To represent the reflective wings that are added to the sterilizer to focus the light energy and add more area to the amount of light it absorbs, cardboard and tinfoil were used. These materials would not be used in for a working prototype because they would not be reflective enough and could catch on fire. Ideally, polished aluminum or tin would be used. The angle of the sun changes all day and in order to account for that, a mechanism was added to the bottom to change the angle throughout the day. This was a very simple design. A base and hinges were added to the bottom and a block can be used to prop up the main component of the sterilizer. This design is both simple, and effective without using many materials. It is an essential component of t...

During this week, we created the base of the reflective array for the sterilizer. We decided to use cardboard as the construction material for the array as it is low cost, easy to manipulate, and accessible. The reflective material has yet to be mounted to the cardboard, but the framework has been created. The base of the array consists of 8 pieces: 4 rectangles and 4 triangles. The bottom of which fit around the top of the box. These pieces will be 45 degrees from the ground. The array is broken into two halves that are tied together using string. We are currently working on a method of attaching the pieces to the body of the box so that they can be easily transported. The purpose of this array is to focus the necessary amount of light energy into the sterilizer. It stands at a 45-degree angle to aim the direct light perfectly downward. Although cardboard and tinfoil were used in the prototype, aluminum sheeting would be better because it is more reflective sturdier an...

This week during lab we continued work on constructing the lid and box. Four pieces of wood were set along its outer edge of the lid. These will serve as a mounting point for the reflective flaps later on. The Quikrete was set into the box as the insulator. A layer was added to the bottom of the box as well as on all four sides. We also worked to simplify the design of our adjustable base. The box will be connected to the ground plate by a hinge and the angle will be able to be adjusted by moving a hinged bar that is held in place on the opposite side of the base plate. The bar then attaches to the bottom of the sterilizer using thin divots that hold the bar in place depending on the angle.

After finalizing the design, the solar sterilizer is finally going into the building stage of the design process. We purchased a new sheet of glass that is a smaller size than the original, this way the prototype will be a lot easier to transport to and from our dorms. The lid of the solar sterilizer is being built today and the dimensions are based on the size of the glass, which is 12x16 inches. The frame will be constructed out of wood with a notch going around the entire interior edge of the wood pieces to create a channel for the glass to slide into. The wood will be then glued to the glass and it will act like a picture frame. This requires an accurate draft of the design so that the channel is the correct size that the glass can slide in and remain secure. This will be the lid of the box and will be attached to the box with hinges. We also constructed the main body of the box, the base of which is MDF as that was the material that was available to us. Other materials were purc...

After purchasing materials, including a large piece of glass, we realized that the size of the oven needs to be smaller for the conceptual design. The materials were too large to transport, so we are going to create an oven around the size of a shoebox (about 12x10) for the prototype instead. We considered using styrofoam, concrete, wood, or clay for the insulation materials. The melting point of styrofoam is too low to withstand the temperatures that this oven will reach so we had to consider other options. Concrete would have been difficult to work with and not very accessible, and wood would have absorbed a lot of the heat from the oven. After much contemplation and research, we decided on using clay as our insulation material because it will keep the heat in and is easily accessible just about everywhere.  For the reflective materials of the box, we have a lot of options. The interior of a juice box is reflective, so that is a possible reflective material for this desig...

Sketches of Expected Design:

This week the group discussed which materials we will use. Our biggest considerations were cost, availability, and practicality. These requirements must be met so that the design is achievable for both a small clinic and because the teams budget is very little. The Frame-  This outer wooden covering can really be made out of any type of lumber accessible. Drexel's Innovation Design Studio will supply all the lumber necessary for the Solar Sterilizer. In third world countries, wood unfinished wood is relatively cheap and not hard to find. Wood is a very appropriate material for the frame because it is sturdy and an insulator and will be safe to touch when the inside is hot. Insulation-  Insulation will help hold all as much of the heat in the oven as possible. Because this is powered solely by the sun it is going to require a lot of insulation to hold heat. If the oven is getting up to 300F the insulation has to be able to withstand that temper...