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| A 72 degree Fahrenheit phase change material was filled into 5 ft. long, 1.25" PVC pipes and sealed. |
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Wooden supports were drilled into the cinder block wall and the PCM pipes were horizontally bound. Three rows with 72 and one row with 58; totaling 274 pipes. Each pipe holds approximately 5 lbs. of PCM 22P; amounting to 1370 pounds. This system provides 30 kWh of heat storage capacity. During the day (heat gain cycle), the PCM pipes absorb 30 kWh of heat, reducing it's cooling load by 30 kWh. Reversely, at night, during the heat loss cycle, the system will release the absorbed heat by the PCM, and reduce the heating load by 30 kWh. This provides 60 kWh of free energy within a 24 hour day.
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| The rows of pipe were framed with wood and attic fans (1300 CFM) attached beneath for thorough air circulation. |
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| Finally, the pipes are covered in 1/2 inch, extruded, polystyrene, insulation board, R-value-3. The fans pull the air from the upper levels of the gh, passes over the PCM pipes and releases at the bottom, circulating the air and stabilizing the temperature inside the greenhouse. More to come... |
A very big THANK YOU to Harshul and Andy for their hard work! Great job!
PCM 22P is made from hydrated salts and have large amounts of heat energy. This energy is stored in the form of latent heat which is absorbed or released when changing from a solid to a liquid or a liquid to a solid. Phase change materials retain their latent heat without change in physical or chemical properties for over thousands of cycles. Best of all, PCM 22P is non-toxic and non-flammable.
If you'd like to learn more about PCM pipes in greenhouses, please contact us at:
info@rgees.com
harshul@rgees.com
nina@rgees.com
elena@rgees.com
Very interesting! It is great to see what PCMs look like in a greenhouse as it can be hard to visualize how to incorporate them into a design. We are currently designing a greenhouse with a SHCS. The greenhouse will be an addition onto our house along with an expansion of our kitchen and dining area. I am wondering if there are ways of incorporating PCMs as another way of maintaining temperatures. A couple of thoughts:
ReplyDelete1. In the design, we have a stairwell that goes from our house down into the greenhouse. Could we use PCM pipes as spindles supporting the railing? Perhaps we could construct a railing with hollow spindles that are just big enough to put a PCM pipe inside.
2. What about in our kitchen? What if we put a PCM backsplash behind the stove?
3. For particularly sensitive fruit trees in our greenhouse, perhaps we could put individual pipes or spheres around it.
4. I am also wondering about some sort of window shade made of thing PCM pipes sort of like a bamboo shade.
None of these have a fan dedicated to circulating the heat around the PCMs but do you think it could help with cooling hot spots passively?
Thanks! I really enjoy your blog!
Leah
Hi Leah,
ReplyDeleteThanks so much for taking interest in my blog! The greenhouse sounds like a great addition to your house.
To answer your questions, regardless of where you place the PCM within your greenhouse and kitchen/dining area, it will absorb heat at the hot spots.
There are 2 important things to remember when employing PCMs.
1) The surrounding temperatures have to be high and low enough for a sufficient amount of time to melt and freeze the PCM. For example, if you’re using the PCM at 72 degrees F, the air around the PCM needs to reach above 75 F for long enough during the daytime to melt the PCM (say for heating at night). Reversely, if you’re wanting to cool during the day, the temperatures need to reach below 69/70 F at night to freeze the PCM. If there is a significant difference in outside temperatures between night and day, the PCM with melt and freeze passively, releasing heat and cold on its own. Hope this is clear and not confusing.
2) The better the air circulation, the more productive the phase change. Generally, as long as there is sufficient air flow in the overall space, it should work well. With an SHCS, do you use fans to circulate air?
The stair railing and kitchen back splash seem like great ideas. Also, since hot air rises, any ceiling application would work well. PCM in the greenhouse is practical and ideal especially if you’ve got good night and day temps.
We can also encapsulate the PCM into larger size PVC pipes. We also have flat bottles and flat panels (longer), and balls. I will upload photos of these next week onto my blog so you can see what they look like and make creative use of them. Also, for faster melting, you could color/paint the PCM encapsulation black or dark blue.
Please let me know if you need any more info and I’m excited about following your progress with this project!
Thanks for your interest and have a great weekend!
Nina
Would you describe this set up as a Trombe wall? Have you considered using a Solar Chimney design instead?
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