Solar Water Heater for Uganda, Africa
Our problem statement is that we are wanting to help a boarding school in Uganda who spends hundreds of dollars every month heating up water for cooking. It would be beneficial and sustainable to have them start the cooking with already hot water.
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Our target audience is a boarding school Uganda, Africa. There, they spend $600 a month heating up water to cook beans in. With our cheap and simple design to heat up water, this will allow the people in Uganda to start with hot water, reducing their costs to around $300 a month.
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Our research has shown us many things. We have looked at Maddi Fleming’s project of insulated solar electric cook stove and how she made covered solar ponds that heat water to 60 degrees Celsius. We have decided that we want to recreate the covered solar ponds to heat water as our target project. Here is what we found, "“We built the solar water heater.. by digging a pool in the ground that was roughly 2.5’ wide by 8’ long by 0.5’ deep. We filled the earth pool with hay insulation and lined the inside with black plastic. We then filled with the pool with 10 cm deep of water and covered the top with clear plastic. The pool heater works by the black plastic underlining absorbing heat from the sun. The insulation and clear plastic on top of the water work to insulate and trap the absorbed heat so that the maximum amount of heat goes toward heating the water and is not lost to reflection or conduction. A crucial design component of the pool is the large surface area and shallow depth of the pool. This helps to maximize the area that is actively absorbing heat from the sun”.
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Rough Sketch of Our Project
Here we have a sketch of what we want our project to be. We have decided to make our solar pond a size of three meters by three meters. In our sketch, we have included a wood box to hold everything together. We may or may not actually go through with that, we may just use the hole in the ground. Since we have just decided on what our final project will be, we have not created anything for the project yet. Our plan is to have our supplies ready before lab on Monday, that way we can jump right into digging our hole and starting our solar pond.
Decision Matrix
Here is our decision matrix template!
First Prototype
Here is our first prototype!
For our first prototype we are trying to use an inflatable pool. We dug a little hole to place the inflatable pool in. We set up the pool with the clear and black plastic and filled the pool with water. As of now, we have not been back to check to see how well the water heated. We will update when we check on the pool and see how it works.
When we checked back, the pool did not heat so we immediately needed to add all the plastic to our pool to have a real solar water heater.
Second Prototype
This is our second update of our project!
As you can see in the pictures above, this is the process we have taken to set up our solar water heater. We used the inflatable pool as our base to hold everything. As for insulation, we added hay to keep our solar water heater nice and insulated. Next, we added our black plastic inside the pool. This black plastic will help to draw the sun in and is how our solar water heater will heat up. We added in our aluminum tubing, since aluminum has a high thermal conductivity, to heat our potable water. Lastly, we covered the entire kiddie pool with clear plastic to stop the water from completely evaporating and to keep the heat in the water.
We came back the following week to check on how our solar water heater was going. The temperature of the original water was 12.7 degrees Celsius. When we came back, the water inside the pool has heated up to 24.4 degrees Celsius That is about a 12 degree difference, so we saw this as a success that the water was actually being heated up by the sun. Although, we want the water to get to a higher temperature, so we realized a potential issue could be our "clear" plastic which is not actually clear, it is very cloudy. We came up with a new plan to replace this cloudy plastic which something new that the sun can shine through easier and heat up the water more quickly.
Third Prototype
This is our third update of our project.
Now time for our third prototype! We needed to add more water so our solar water heater could be completely full again. After that, took off the cloudy cover and added clear plastic Saran Wrap (BPA free!) to create a better cover for our water heater. We made sure to include some holes for our aluminum tubing could stick out for us to run our potable water through. We attached a funnel for a much easier way to run the potable water through, since we had some trouble with last time since the opening was very small. Since the aluminum tubing was already warm from sitting out in the sun for weeks, we decided to do a quick test and see how well the potable water would heat up in that short period of time. Since we added fresh water, it was not as high of a change as before but the water heater up an extra 10 degrees Celsius!
We went back and checked our solar water heater after a few days in the sun. The pool water got up to a temperature of 37.7 degrees Celsius. The water in the hose was 28 degrees Celsius. After running the potable water through the aluminum tubing, the water got up to a temperature of 37 degrees Celsius.
Conclusion
Although we did not get the results we were intending to receive, the water did heat up after being ran through the aluminum tubing. The goal was to reach 60 degrees
Celsius so our results were pretty far off. If we had longer than 10 weeks, we feel we could have made more prototypes
until we got to the results we wanted. We believe that this is a project worth looking more into as it would be a great and inexpensive alternative for the people at the boarding school in Uganda.
