Week 9

       The results of our prototype were good and bad. Since none of our group members had previous knowledge or experience building solar stills, we were unable to make the box airtight. After testing, the group decided not to purchase a manual vacuum pump. However, if the box was airtight, the pump would be able to remove up to 13 PSI. This is very good information.

Figure 9.1: Graph of Evaporation Rate at Varying Pressures

      The reason is because at 160°F and with the removal of 10 PSI, the water would be boiling. Figure 9.1 shows this using Langmuir's Equation. This allows for very rapid evaporation of water and thus makes the solar still very efficient. Flaws arose while testing the box including bad positioning of the pipe and poorly sealed acrylic. However, the still was able to reach 160°F, as shown in Figure 9.2, which would boil the water if it was airtight and pressure was removed. With more time, experience, and planning, we would be able to make a much more efficient solar still at a fairly low cost.

Figure 9.2: Graph of Temperature Inside Box

Week 8

      The building of the solar still was completed this week. We sealed around the top of the box with epoxy, spray foam, caulking and weather stripping. Also, the acrylic was fitted to the top of the box. You can see the epoxy setting in Figure 8.1. 

Figure 8.1: Epoxy Setting with Clamps

       Once the epoxy set, we were able to screw down one of the acrylic sheets and fit the other onto the top frame. We used a band saw to shape each sheet and make a tight fit so that the box would be airtight. Figure 8.2 shows the finished product with both sheets attached.

Figure 8.2: The Completed Solar Still

    After the construction was complete, we decided to spray paint a Drexel dragon on the side of the box. A stencil was made and then taped to the side of our solar still. We are not art majors so it did not turn out too well. Figure 8.3 displays our attempt at school spirit.

Figure 8.3: Attempt at the Drexel Dragon

Week 7

      Our goals this week were to get the pipe in the box and fit the acrylic sheet on the top. The pipe had to be cut down and then cut in half. We used horizontal and vertical band saws to accomplish this. Holes had to be cut in the wood, insulation, and steel in order to fit the pipe. Also, the acrylic was cut with a band saw in order to fit it to the top of the box. We used sheers to cut a hole the inner shell for the pipe which can be seen in Figure 7.2. The prototype after these steps were complete can be seen in Figures 7.1 and 7.3.

Figure 7.1: Box with Pipe and Acrylic 

Figure 7.2: Inner Shell Being Cut

Figure 7.3: Box with Pipe, Acrylic, and Inner Shell

      The wooden shell was spray painted and a second coat was applied to the inner shell. Before spray painting, we used silicone caulking to seal both shells. Figure 7.4 displays the outer shell after it had been painted. Handles were then added to the front and back of the box which makes it easier to carry.

Figure 7.4: Spray Painted Outer Wooden Shell

Week 6

      The most productive week has to be this one. We spent a few hours at the machine shop to get the outer wood shell constructed as well as the insulation board. You can see some team members hard at work planning and cutting pieces for the box in Figures 6.1 and 6.2. 

Figure 6.1: Team Member Laying Out Wood Shell

Figure 6.2: Team Member Cutting Insulation Board

      Once the insulation board and wood were cut into pieces, we could start putting it all together. The wood was attached to pieces of 2" x 4" at each corner. Insulation board was then fit into the space between the inner and outer shells. You can see this process in Figure 6.3.

Figure 6.3: Starting to Construct the Wood Shell

      After finishing up at the machine shop, we took everything back to the dorms and assembled the box. The assembled box can be seen in Figures 6.4 and 6.5. Now, the inner shell will be spray painted and the acrylic sheet will be attached on the top of the box. A PVC pipe is going to be cut in half and used to collect the water at the lower end of the box. It will then run out through a valve and into a bucket.

Figure 6.4: Isometric View of Box

Figure 6.5: Top View of Box

      The group recently purchased the rest of the materials. Next week, the box will be completed and hopefully testing will begin soon after. Figure 6.6 shows the supplies needed to finish up the box.

Figure 6.6: The Last of the Building Materials

Week 5

      This was a big week for our group. We started making the prototype and purchased more materials. The inner shell of the prototype was made in the machine shop at Drexel. The front and back sides will be attached with epoxy. Figures 5.1 and 5.2 show the inner shell of the prototype.

Figure 5.1: Inner Shell of Prototype

Figure 5.2: Inner Shell of Prototype

       This will be painted flat black in order to absorb the most heat. Insulation board and wood will be attached to the outside of the shell. They are being added to keep the heat in the box and support the thin metal. PVC pipe is going to attach to the front inside of the shell to collect the evaporated water. You can see the shell being epoxied below in Figure 5.3.

Figure 5.3: Inner Shell Being Epoxied

Week 4

      The goal this week was to decide which materials we still needed to purchase in order to complete the construction of the box. We determined that an acrylic sheet will be used to let sunlight pass throw it and into the box. This sheet will be purchased online and will be attached to the top of our box. Hinges will be attached so that the acrylic can be lifted and the box can then be cleaned. Figure 4.1 (TAP) shows what the acrylic sheet will look like.

Figure 4.1: Example of Acrylic Sheet Being Purchased

             A bucket will be attached to the box via a hose and fasteners to collect the clean water. Having a separate area for collection allows for more storage of dirty water and less contamination between clean and dirty water. An example of the connection between the bucket and hose can be seen below in Figure 4.2 (pragmaticproducts).The entire system will be sealed and pressurized in order to increase the evaporation rate of the water. All of the materials will be collected by next week and construction of the box is already in progress.

Figure 4.2: Example of Bucket and Hose Connection

1. TAP Plastics. Acrylic Sheet. Digital image. Tapplastics.com. N.p., n.d. Web.
2. Pragmaticproducts. Hose and Bucket. Digital image. Ebay.com. N.p., n.d. Web.

Week 3

      A lot of progress was made this week. Our group created a conceptual flowchart, three-dimensional (3D) model of the prototype and started purchasing materials for it. The flowchart, Figure 3.1, gives you a look at how our solar still is going to work. 

Figure 3.1: Conceptual Flowchart of Solar Still

      Creating a 3D model of the prototype allowed us to get a better understanding of how the materials will fit together and the dimensions of them. We decided that this should be done before purchasing materials. This way we knew how much of each material to get. Two views of the model can be seen below in Figures 3.2 and 3.3.

Figure 3.2: Overview of 3D Model of Prototype

Figure 3.3: Back View of 3D Model of Prototype

      Lastly this week, a group member was able to go to the store and pick up most of the materials for the solar still. As shown in the picture, SOB board, aluminum sheets, a 2" by 4", spray paint, a PVC pipe, and screws were purchased. Our group will begin constructing the solar still soon. The materials purchased so far can be seen in Figure 3.4. 

Figure 3.4. Materials are Being Purchased