Use of phase change materials - anyone?
This link got me interested in "PCM" as a psuedo-energy storage method.
https://www.vikingcold.com/
Probably quite "off the wall" for this forum, however with the breadth of knowledge about energy, I got to wondering if anyone has actually tried using something like sodium sulfate decahydrate (spiked with sodium chloride) to retain/shift cooling with conventional air conditioning? The goal would be to "freeze" the PCM during cheap electricity (night/early morning) and "thaw" it during the peak electricity pricing during the day. I pay for actual ERCOT set energy costs - that went to $13/kWh (plus) recently for fairly extended times. No typo
Just curious - seems there are obstacles of refreezing, containment, heat transfer, economics, etc, but maybe someone has overcome??
https://www.vikingcold.com/
Probably quite "off the wall" for this forum, however with the breadth of knowledge about energy, I got to wondering if anyone has actually tried using something like sodium sulfate decahydrate (spiked with sodium chloride) to retain/shift cooling with conventional air conditioning? The goal would be to "freeze" the PCM during cheap electricity (night/early morning) and "thaw" it during the peak electricity pricing during the day. I pay for actual ERCOT set energy costs - that went to $13/kWh (plus) recently for fairly extended times. No typo

Just curious - seems there are obstacles of refreezing, containment, heat transfer, economics, etc, but maybe someone has overcome??
3850 watts - 14 - 275SW SolarWorld Panels, 4000 TL-US SMA Sunny Boy Grid tied inverter. 2760 Watts - 8 - 345XL Solar World Panels, 3000 TL-US SMA Sunny Boy GT inverter. 3000 watts SMA/SPS power. PV "switchable" to MidNite Classic 250ks based charging of Golf cart + spare battery array of 8 - 155 AH 12V Trojans with an APC SMT3000 - 48 volt DC=>120 Volt AC inverter for emergency off-grid. Also, "PriUPS" backup generator with APC SURT6000/SURT003 => 192 volt DC/240 volt split phase AC inverter.
Comments
https://pdfs.semanticscholar.org/0f08/258f19b88e6421fb309a824e314fd2f3d990.pdf
https://www.cedengineering.com/userfiles/Thermal%20Energy%20Storage.pdf
Since you can get air sourced mini-split heat pumps that get a COP of 4 down to something like 13F... These systems seem to have become the goto devices (inverter powered--VFD controlled compressors) for AC and Heating.
You start looking at other systems like ground source heat pumps--A fair amount of power and complexity is used to run the external buried heat exchangers (and expenses to install/maintain)--The simple and efficient mini-split systems have been amazing for many folks (inverter-VFD controls give almost no starting surges, and can be throttled back to very low power (Watts) usage.
And getting rid of heating ducts and their losses/extra insulation requirements vs mini-split point source cooling--Another advantage.
-Bill
I've been able to mitigate the stated $13/kWh energy costs by using my home as "storage" - ranging from pre-cooling to 72 and "float" to 80 degrees on days with extremely high energy costs. It has worked OK, but If there was a simple retro-fit to enhance the capacity to hold these pre-cooling temperatures longer, that is what attracted me to the "viking cold" concepts of simple "ice cubes" with a small amount of circulation. The sodium sulfate decahydrate spiked with sodium chloride "freezes" at 66 degrees (F), so it seems like a natural. I cannot think of such a simple analogy to the "viking cold" that would work to retrofit A/C homes in Texas, but that does not mean someone else has not - lots of pragmatic geniuses out there!
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
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I am not an A/C guy... But if you want 70F and 60% maximum relative humidity and use the solution for direct cooling (not heat pump energy source/sink), then from a dew point calculation:
https://www.calculator.net/dew-point-calculator.html?airtemperature=70&airtemperatureunit=fahrenheit&humidity=60&dewpoint=&dewpointunit=fahrenheit&x=73&y=12
You end up with 55.5F heat exchanger maximum temperature to even begin to control moisture/humidity. With a 67F heat exchanger temperature for a 70F room you are looking at 90% relative humidity. That would be pretty clammy, and give you major mold issues (you need to get to 60% relative humidity or lower at least once every three days to stop the mold/spore process).
-Bill
Tony
*****Thanks all*****
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