Proposal to conceive, design,
prototype, and evaluate a Solar
Boiling Unit to heat water using solar
energy
Cody Coleman, Tshiamo Lechina, and Tatiana Mamaliga
Summary
In order to heat water using solar power in most effective way I propose to conceive, design,
prototype, and evaluate a Solar Boiling Unit. Our team met multiple times to brainstorm and discuss
several ideas to come up with a final design, which is using a parabolic shaped shiny surface to focus
the light rays onto a black metal object inside the water. Our Solar Boiling Unit should be able to direct
the solar energy towards the water and raise its temperature. These requirements are addressed by
positioning the black object at the focal point of our parabolic shaped shiny surface where all the light
rays will be focused. Through the reflectivity of the parabolic object we predict the efficiency of our
design. The risks of melting the materials due to the intense solar heat are addressed by using
aluminum as our main material, which has a very high melting point. When implemented, the Solar
Boiling Unit will contribute to the world economy by saving money on energy that could be used to
heat water.
Introduction
A Solar Boiling Unit is of significant importance to the world. It is commonly observed that every
household needs hot water, and normally electricity or gas is used to heat the water. However,
electricity and gas are nonrenewable sources of energy and they cost money, which affects both the
environment and the economy. To solve this problem, this project is to heat water using solar energy
which is free and renewable. In addition to the requirement that it heat water, this device should also
satisfy the following requirements:
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It should not expose anyone to undue hazards;
It should not occupy a large area;
It should not contaminate the water;
The product must have a small ecological footprint, both in terms of the materials
used to construct the product and the labor required to produce the product.
These requirements are weighted with the ultimate requirement that the object heat the water using
solar energy. For environmental and economic reasons the Solar Boiling Unit will be constructed
mainly of sheets of plywood, metal, and aluminum, which are widely available and considerably cheap.
If the Solar Boiling Unit is successful, it could be used in households across the world, save the energy
that is usually used for heating water, save the money spent on electricity and gas, and decrease the rate
at which gas is diminishing from our planet.
Background
Heating model
The Solar Boiling Unit will be used to direct the solar energy towards a heating element—the black
metal immersed in water, and heat the water inside the beaker.
The atmosphere receives between 1,353 and 1,395 Watts of energy per square meter
(http://almashriq.hiof.no/lebanon/600/610/614/solar-water/unesco/21-23.html), and about 30% reaches
the Earth. Considering that aluminum reflects about 88% of the light rays off its surface, and that a
parabolic shaped device focuses almost all of the rays towards the heating element, we estimate that the
water will receive about 363 Joules of Energy per second. However, some of this heat energy will be
radiated back into the atmosphere and will not reach our object. Nevertheless, we expect our parabolic
shaped device to reflect most of the heat that does reach the aluminum mylar to the water.
Safety analysis
When constructing a device to boil water using solar energy, as required by our project, one needs to
consider several factors. The device should prevent exposure to undue hazards. The water should not be
contaminated by any part of the device seeing that the water may be intended for household use. The
product must have a small ecological footprint, both in terms of the materials used to construct the
product and the labor required to produce the product. We regard these safety requirements with
highest priority when considering the Solar Boiling Unit, and we will take them into strong account.
Aesthetics and ergonomics
A device described by the functional parameters above should be compact and fit into a one cubic
meter. This constraint restricts the amount of space that one such device can use, and, therefore, the
amount of sunlight that such device would receive. This will ensure the same amount of sunlight for all
such devices during the time of testing. Given that even a small area of land receives a large amount of
solar energy, any addition to the allowed area would give great advantage to a specific device over
another. Not only does the space regulation pertain to testing, but the functionality in the real world
depends substantially on space and ease of use; a big, clunky device would be undesirable. The more
massive the device is, the more difficult it would be to store and transport. A one cubic meter limit is,
therefore, optimal for this application.
Materials and labor costs
The materials that we are going to use for the Solar Boiling Unit as well as the estimated corresponding
measurements and prices are:
-aluminum mylar—55in x 25ft x 1mil for $14.99 for three devices;
-plywood--23/32 In for $17.97 X 5=$89.85;
-adhesive material—about $5--10;
-wood studs—2 In. x 4 In. x 8 Ft for $2.29 X 10=$22.90;
-black paint;
-scrap metal;
-scrap wood;
We estimate that for three Solar Boiling Units we will spend about $137.75.
Methods
Design overview
The Solar Boiling Unit will consist of a parabolic shaped device constructed from plywood that will be
covered with shiny aluminum mylar in order to reflect the light rays onto our object. The object will be
suspended with wood studs above the parabolic shape, and will consist of a pyrex glass with a fixed
metal inside that will absorb heat and warm the water surrounding it.
Figure 1 illustrates the components of the Solar Boiling Unit.
Fig 1 Big picture overview of the _Coffee-Saver_ design
Table 1 Design FRDPARRC
Qualifications of primary investigators
As first year MIT students, this year, we have had the experience of building a device that keeps coffee
hot for two hours. Additionally, each of us has built several projects in high school, as part of the
curriculum as well as during summer programs and other extracurricular activities.