Which Passive Solar Collector Absorbs the Most Heat?

Researched by Daniel W.
2000-01



PURPOSE

The purpose of this experiment was to determine which design of passive solar collectors absorbed the most heat.

I became interested in this idea when my grandparents used a passive solar collector to heat water for their pool.  They used water flowing through black plastic piping mounted on a roof.  The water was pumped from the pool and back into the pool.  The water was heated as it went through the pipe. 

The information gained from this experiment would help engineers using passive solar collectors to determine what design of passive solar collector would be the best for them.  It would also be helpful to consumers to determine which passive solar collector is best for them.


HYPOTHESIS

My hypothesis was that the direct gain passive solar collector would absorb the most heat compared to the indirect gain and isolated gain passive solar collectors.

I based my hypothesis on my research of various web sites that say that the direct gain passive solar was the most often used by consumers and because the sunlight directly travels into the passive solar collector.  In the other passive solar collectors, the air has to travel to get heated.


EXPERIMENT DESIGN

The constants in this study were: 

  • type of thermal mass
  • beginning temperature inside the passive solar collector
  • outside temperature
  • type of glass
  • type of sun lamp
  • the amount of light given off by the sun lamp
  • type of plywood


The manipulated variable was the design of passive solar collector. 

The responding variable was the temperature inside the passive solar collector.

To measure the responding variable I used a glass thermometer and measure in degrees Celsius.


MATERIALS
 
QUANTITY ITEM DESCRIPTION
1 Sunlamp
1 Celsius thermometer
1 box of nails
1 bottle of wood glue
1 90cm x 240cm Ply wood
1 40cm x 45cm glass sheets
10 Bricks


PROCEDURES

1. Build Direct Gain Passive Solar Collector:

  • Cut a plywood piece 45cm tall 45cm wide for the base.
  • Cut another piece 20cm tall 45cm wide for the back.
  • Glue and nail the back piece to the bottom on the right side to make it look like a back wards L.
  • Then cut 2 plywood pieces for the sides 40cm tall at the front and 20cm tall at the back and 45cm wide on the bottom and 50 cm on the top making the top diagonal.
  • Glue and nail the sides to the other two pieces with the small side in the back.  Glue and nail one to each side.
  • Lay bricks across the bottom and the back so that they are covered.
  • Cut another plywood piece 50cm tall and 45cm wide for the top.
  • Cut and glue the top on the top of it so only one side is left open.
  • Duck tape the 40cm tall and 45cm wide piece of glass in the open space left.
  • Drill a 1cm hole in the center near the back of the solar collector for the Celsius thermometer to fit through.
2. Build Indirect Gain Passive Solar Collector:
  • Take the Direct Gain Passive Solar Collector and take glass off.
  • Rearrange the bricks to be near the front all the way to the top and leave two spaces in the wall of bricks.  One near the top and one near the bottom.  Each of the spaces should be the size of two bricks laid beside each other.
3. Build the Isolated Gain Passive Solar Collector:
  • Take the Indirect Gain Passive Solar Collector and take the glass off.
  • Cut two pieces of plywood 40 cm wide and 20 cm long for the sides.
  • Cut two more piece 45 cm wide and 20 cm long for the base. 
  • Then Glue and nail them together with two sides open.
  • Then fit it on to the Indirect Passive Solar Collector and put the glass on. 
4. Gather all materials.
5. Take one of the passive solar collectors and set it in a dark room at approximately 70 degrees Fahrenheit.
6. Turn sunlamp on and let it heat up for 5 min.
7. Make the sun lamp shine the light directly into the center of the collector and have it about 60 cm away from the collector. 
8. Close the door and make sure no light enters into the room. 
9. Check temperature every 30 min.
  • Open the rooms door and take the Celsius thermometer and fit it through the hole near the back.
  • Then close the door and wait approximately 1 min.
  • Then go back in and check the temperature reading and record it.
10. Continue checking the temperature for 4 hrs.
11. Repeat steps 4-10 for each of the other passive solar collectors.


RESULTS

The original purpose of this experiment was to determine which design of passive solar collectors absorbed the most heat.
 

The results of the experiment were that the Direct Gain Passive Solar Collector absorbed more heat than the Indirect and Isolated Gain Passive Solar Collector.

See the table and graphs



CONCLUSION

My hypothesis was that the direct gain passive solar collector would absorb the most heat compared to the indirect gain and isolated gain passive solar collectors.

The results indicate that this hypothesis should be accepted.  The direct gain passive solar collector absorbed more heat than the other two passive solar collectors. 

These findings should useful to consumers and engineers to help them decide what to buy for a passive solar collector. 

Because of the results of this experiment, I wonder if the amount of light would effect the temperature inside the passive Solar Collector.  I also wonder if the size of the collector effected the temperature inside of it.  Would the amount of thermal mass affect the temperature inside the passive solar collector? 

If I were to conduct this project again I would also include more designs of passive solar collectors.  I would also include True sun light against artificial. 
 
RESEARCH REPORT
 

Introduction

 Energy is very important to people for things like heating homes.  Unfortunately, it costs a lot.  An alternative energy source to save money is passive solar collectors.  It doesnít have machinery inside so it doesnít cost much to use .  All  does is  transforms the sunís light into heat, store it, and release it when the heat is needed. 

Passive Solar Collector

 Passive solar collecting is the simplest way of collecting the sunís energy.  It is a solar collector that doesnít use any mechanical parts.  All passive solar collectors do three things: collect the sunís energy, store the sunís energy, and distribute of the sunís energy.  When sunlight travels through a passive solar collector, it converts into heat.  Then it is stored in the thermal mass.  When the heat is needed, the thermal mass releases the sunís energy. 
There are three designs of passive solar collectors.  They are direct, indirect, and isolated gain passive solar collectors.  The direct passive solar collector is a collector in which the sunlight directly travels into to it and is stored.  The indirect gain passive solar collector is when the sun light goes in, it heats the air in the air flow inside the collector and when the air loses its heat it gets heated up again by the sun light.  The isolated gain passive solar collector is basically like the indirect gain passive solar collector.  The only difference is that there is a bigger place in which the air is heated.  This place is called the sunspace.

Solar Energy

 Solar energy is electromagnetic radiation that comes from the sun.  It is a very important form of energy.  It is produced by nuclear reactions inside of the sun.  It can produce heat directly or be changed into electricity over time.  The sun provides lots of the earthís energy.  Through photosynthesis and other processes, solar energy has made fossil fuels and other things.  The most common ways of capturing solar energy are flat-plate solar collectors. 

The Sun

The sun is made up of 70% hydrogen 28% helium 2% of other things.  The sun gives off 170 trillion kilowatts to the earth.  Thirty percent of it is reflected back to space.  Forty-seven percent is coverted to heat the earth.  Twenty-three percent powers the water cycle.  The sun also produces wind.  People only use a little of what the sun gives out. It also helps provide other ways of making electricity, like
 the water cycle and dams.

Thermodynamics

Thermodynamics is two laws or principles.  The first law is that energy in a system cannot be destroyed.  It either coverts to another form or is transferred to another system.  The second law states that heat always goes from a hotter object to a colder object.  So if the air is cooler than the thermal mass in a passive solar, heat flows to the cooler air.

Summary

 Passive solar Collectors have been important all over the world.  A Passive Solar Collector is all some people can rely on for heat.  It also saves money for people that canít afford heating in their house.  The people donít even have to operate the Passive Solar Collector.  Thatís why they are so useful.
BIBLIOGRAPHY

Brown, Warren. Alternative Sources of Energy. New York: Chelsea House Publishers. 1994.pp.24-26 

Brook, Bob. Solar Energy. New York: Chelsea House Publishers, 1992

"Energy Fact Sheet"[Online] Available http://cites21.com/efacts/passive.htm, November 13, 2000

Kreider, Jan."Solar Energy" Academic American Encyclopedia.1998.vol.18.pp.41-47

"Passive Solar Energy"[Online] Available http://www4.ncsu.edu/eos/users/r/rapalmer/www/permaculture.html, October 31, 2000

"Solar Energy" World Book Encyclopedia.1998.vol.18. Pp. 576

"Solar Energy" Science Encyclopedia.1997.vol.19. Pp.1773 

"Thermodynamics" World Book Encyclopedia. 1998.vol.19. Pp.253
 

ACKNOWLEDGEMENTS

I would like to thank the following for helping make my project possible and successful.

  • First of all I would like to thank my parents for getting the materials for my experiment and encouraging me to go on.
  • I would also like to thank my teachers for providing  materials for my experiment and for helping my write parts of my experiment.
  • I would finally like to thank my classmates for supporting me and giving suggestions on what to do.
Thanks you for all your help.

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