Thermal buffer: avoid surface evaporation of hot water with oil or other blocking product?
published: 16/08/21, 13:40
To avoid or greatly limit the evaporation of a mass of hot water from a solar thermal buffer (therefore not boiling), it is necessary to block the contact of the water with the air. I think a thin layer (2-3mm) of a liquid that doesn't evaporate and spread over the entire surface might do the trick. Kind of oil?
The goal is to optimize the internal evaporation of my solar thermal pad that I featured here years ago.
Solar-thermal / thermal-solar-buffer-optimization-and-repair-t4517.html
solar-thermal / cop-d-un-solar-thermal-with-drainage-de-20-ans-d-age-t8220.html
A rare photo from the time when the level had dropped a lot when I moved in (2007) ... I had it repaired and isolated Solar-thermal / thermal-solar-buffer-optimization-and-repair-t4517.html
Once I find the right product to add to the surface, I'll open it again ... 15 years later and dozens of MWhs in storage later to see what it is!
Indeed: even if the evaporated water condenses on the top slab of the thermal buffer, this creates a "heat pump" which causes the hot water to lose calories in the buffer ... For a swimming pool evaporation constitutes the main part of the heating losses! In the case of a thermal buffer, the air is quickly saturated the effect is less great BUT the temperature can be much higher suddenly there are necessarily losses all the same (I cut the heating of the buffer at 65 ° C because each ° C gained during the day above 65 ° C, will be lost the following night...)
So 2 questions:
a) what type of oil would be the most suitable over time and for health (in the case of an indoor tampon) Vegetable? Motor ? Hydraulic?
And what rank? The buffer varies from 20 to 70 ° C ...
If you know of other products that float in water and that prevent surface evaporation, this interests me ...
b) What thickness so what quantity needed to be sure that the layer occupies the entire surface homogeneously?
Knowing that once it's put on ... it will be very difficult to remove it! So I don't want to be wrong!
I don't have to worry about putting 30 or 50L of oil in it, but if you need 200 or 300L I'm not sure to do it!
No worries about testing "in glasses"!
Also read about thermal buffers:
heating-insulation / thermal-concrete-heat-storage-buffer-t6335.html
Solar-thermal / a-house-a-solar-thermal buffer-almost-self-t5233.html
Solar-thermal / solar-installation-the-wood-of-Tigger-with-buffer-thermal t5200.html
Edit: photos from 2021 here science-and-technology / thermal-buffer-to-avoid-surface-evaporation-of-hot-water-with-oil-or-another-blocker-t16964-70. html
Edit addition: start of the experiment here science-and-technology / thermal-buffer-to-prevent-surface-evaporation-of-hot-water-with-oil-or-another-blocker-t16964-100. html # p462217
Edit, after 18 months of experience, in January 2023, paraffin seems the best candidate:
The goal is to optimize the internal evaporation of my solar thermal pad that I featured here years ago.
Solar-thermal / thermal-solar-buffer-optimization-and-repair-t4517.html
solar-thermal / cop-d-un-solar-thermal-with-drainage-de-20-ans-d-age-t8220.html
A rare photo from the time when the level had dropped a lot when I moved in (2007) ... I had it repaired and isolated Solar-thermal / thermal-solar-buffer-optimization-and-repair-t4517.html
Once I find the right product to add to the surface, I'll open it again ... 15 years later and dozens of MWhs in storage later to see what it is!
Indeed: even if the evaporated water condenses on the top slab of the thermal buffer, this creates a "heat pump" which causes the hot water to lose calories in the buffer ... For a swimming pool evaporation constitutes the main part of the heating losses! In the case of a thermal buffer, the air is quickly saturated the effect is less great BUT the temperature can be much higher suddenly there are necessarily losses all the same (I cut the heating of the buffer at 65 ° C because each ° C gained during the day above 65 ° C, will be lost the following night...)
So 2 questions:
a) what type of oil would be the most suitable over time and for health (in the case of an indoor tampon) Vegetable? Motor ? Hydraulic?
And what rank? The buffer varies from 20 to 70 ° C ...
If you know of other products that float in water and that prevent surface evaporation, this interests me ...
b) What thickness so what quantity needed to be sure that the layer occupies the entire surface homogeneously?
Knowing that once it's put on ... it will be very difficult to remove it! So I don't want to be wrong!
I don't have to worry about putting 30 or 50L of oil in it, but if you need 200 or 300L I'm not sure to do it!
No worries about testing "in glasses"!
Also read about thermal buffers:
heating-insulation / thermal-concrete-heat-storage-buffer-t6335.html
Solar-thermal / a-house-a-solar-thermal buffer-almost-self-t5233.html
Solar-thermal / solar-installation-the-wood-of-Tigger-with-buffer-thermal t5200.html
Edit: photos from 2021 here science-and-technology / thermal-buffer-to-avoid-surface-evaporation-of-hot-water-with-oil-or-another-blocker-t16964-70. html
Edit addition: start of the experiment here science-and-technology / thermal-buffer-to-prevent-surface-evaporation-of-hot-water-with-oil-or-another-blocker-t16964-100. html # p462217
Edit, after 18 months of experience, in January 2023, paraffin seems the best candidate: