SAGICOR VISIONARIES CHALLENGE PROJECT PROPOSAL
TITLE OF PROJECT: The solar cooler
NAME OF SCHOOL: Dominica SDA Secondary School
ADDRESS: Glanvillia, Portsmouth
PHONE NUMBER:
NAME: Kithana Telemaque
TEACHER: Ernesta Burnette
2. Problem statement and significance of the problem
Presently at the Dominica S.D.A secondary school, we have extremely hot classrooms and a
computer lab where the air conditioning unit is quite problematic. Students always complain
about the heat because the windows normally have to be closed in order for students to see the
board properly. On any given day, though the windows may be opened, students still complain
about the heat. The problem gets worst after break and lunch times when students have to return
to class from playing and all the heat is radiated throughout the classroom. Students take a while
to get settled as a result and end up missing some quality time in the period.
In the computer lab, the air conditioning system is really poor as it takes so much time to actually
come on and cool down the room. In addition, the unit can’t be left running to keep the
computers cool because it uses up quite a bit of electricity to produce the cooling effect. Each
month the school has to face an unreasonably high electricity bill where an exorbitant amount is
contributed by the continued use of the air conditioning unit.
Hot classrooms are definitely not conducive to learning and could eventually lead to health
problems.
3. Objectives of the project
This project of the solar cooler seeks to fulfil the following objectives:
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To create cooler classrooms.
To improve the cooling effect in the computer lab at DSDASS allowing it to stay cool for
longer periods.
Reduction in the electricity bill at our school.
To use water as a refrigerant
To promote and strengthen a product that is cost- effective and based on renewable
energy use so that they could eventually be purchased for home use by people in the
Portsmouth community by extension, and throughout Dominica.
To use solar energy to create a sustainable method of cooling which is environmentally
friendly causing my school environment and the rest of Dominica to remain clean and
green!
4. Approach or proposed solution
I visualise a not to simple, but inexpensive, environmentally friendly and sustainable solar cooler
solution that will alleviate this heat problem from our school and by extension the community of
Portsmouth, thereby improving the health and comfort of children and even families. This will
harness the power of the sun to significantly reduce electricity bills.
The job of an air conditioner is move heat from inside the home or whichever building to the
outside, thereby cooling individuals and the building. Air conditioners blow cool air into the
building by pulling the heat out of that air. The air is cooled by blowing it over a set of cold pipes
called an evaporator coil. This works just like the cooling that happens when water evaporates
from the skin. The evaporator coil is filled with a special liquid called a refrigerant, which
changes from a liquid to a gas as it absorbs heat from the air. The refrigerant is pumped outside
the house to another coil where it gives up its heat and changes back into a liquid. This outside
coil is called the condenser because the refrigerant is condensing from a gas back to a fluid just
like moisture on a cold window. A pump, called a compressor, is used to move the refrigerant
between the two coils and to change the pressure of the refrigerant so that all the refrigerant
evaporates or condenses in the appropriate coils.
The energy to do all of this is used by the motor that runs the compressor. The entire system will
normally give about three times the cooling energy that the compressor uses. This happens
because the changing of refrigerant from a liquid to a gas and back again lets the system move
much more energy than the compressor uses.
DIAGRAM SHOWING HOW AIR CONDITIONERS WORK
Solar air conditioners take advantage of the sun at its brightest and use its energy to cool during
the hottest part of the day. The solar cooler will cool the air by blowing it over water. Solar
energy will be used to power the fan and motor. Solar cells which are basically formed into solar
panels will convert the energy from sunlight directly into electricity which will power the unit.
The refrigerant used in the system will be water it will be hooked up to a water line or water
storage tank.
The refrigerant can be sent through a solar energy collector before the fluid reaches the
compressor, and solar energy can do a portion of the work—heating up the refrigerant—that
would normally be accomplished by the compressor. This allows the compressor to run less, or
to operate at a lower speed, and thus use no electrical energy. The very hot refrigerant gas
leaving the compressor will flow into another coil - the condenser coil. This coil, like a car
radiator, will radiate heat from the hot refrigerant into the outside air as a fan pulls outside air
across the coil. This exhaust air should be hotter than the surrounding air. The refrigerant cools
as it moves through the condenser coil.
Once the room achieves the desired temperature, the condenser will turn off. The refrigerant will
continue to cycle until the room temperature deviates from the desired temperature. During this
process, pressure within the circulating refrigerant will gradually decrease, reducing the desired
temperature. When the pressure drops too low, the compressor will turn back on to re-pressurise
the refrigerant.
DIAGRAM OF THE OPERATION OF THE SOLAR COOLER
5. The Competition
The solar cooler idea has already been implemented in various areas around the world but I am
confident that my design is more efficient and affordable.
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Some of the existing air-conditioning systems using solar energy also use ammonia or
some other refrigerant such as R-134a. Ammonia can be very corrosive and though the
R-134a refrigerant does not release as much air contaminants as the others, it is still not
100% environmentally friendly.
Water is used as refrigerant which unlike Chlorofluorocarbon doesn't support
greenhouse effect.
Electricity is saved up to 50% or more, so efficient use of air conditioning system will
result in saving of money in hot days.
More cooling is required when sun shines brightly and that is time when solar panel will
work best, resulting in efficient working of solar air conditioner.
The Solar air conditioner is silent in nature and puts no load on electricity during the
time of summer.
6. Resources needed
Resources needed
Evaporator
Condenser
Compressor
Solar panels
Solar storage tanks
Solar pump
Any other parts
Price in $US
150
200
100
500
200
300
200
Contributors
PTA
Alumni association
Alumni association
School
Sponsors
Student body
PTA
7. Timetable
Students, parents, teachers, and individuals from the community will work together over a six
month period to get all parts ordered and the system set up and running. The school could also
form a partnership with companies like Kool air or Tonge refrigeration.
8. Use of Stem
The use of stem is quite evident thoughout this project. The science involved includes knowledge
and use of water as a refrigerant, due to the fact that water can change states from liquid to gas as
it heats up and then condenses so that the heat could be radiated. Technology is involved in the
project is solar panels and the use of a closed system for the unit. Engineering is involved in the
actual process of putting all the parts together. The evidence of maths is seen when the energy
input and output for the system will be calculated.
9. Community involvement and community impact
In order to have this project completed successfully with all objectives achieved, the school will
work in partnership with engineers from Kool air company which is actually located in the
Portsmouth area. The PTA, Alumni association, student body and staff will make contributions
to the project directly or through fund raising drives.
The project can then be established in our school’s community in the Portsmouth area as sessions
will be held at the community center to explain the way in which the system operates. They will
encouraged to purchase these units in small business places and even homes to keep them cool
without an increase in their electricity bills. At the same time they will be keeping the
environment clean and clear of contaminants.
10. References
https://www.ashrae.org/resources--publications/free-resources/top-ten-things-about-airconditioning
http://www.stateenergy.net/how-solar-air-conditioning-works/
http://www.machine-history.com/Solar%20Powered%20Air%20Conditioning
http://www.hotspotenergy.com/solar-air-conditioner/
http://www.solarpanelsplus.com/commercial/solar-cooling/
Modern Refrigeration and Air Conditioning (Modern Refridgeration and Air
Conditioning) by Andrew D. Althouse