Thermal buffer: avoid surface evaporation of hot water with oil or other blocking product?

Obamot · by **Obamot** » 18/08/21, 12:49

No that's not possible, with the exchangers suspended as they are. Except to put them at the bottom of the pool (or even lay them on their side, that's why I asked for their dimensions, eh ...)

So yes, if there is enough water permanently ABOVE them, it may be possible to float extruded polystyrene panels of 10cm or of the desired thickness (the panels are welded very very well to each other tightly with polyurethane foam)

But obviously, that requires a surface free of obstacles at all times. And put a nylon sidewall vertically, all around and against the vertical wall of the pool, so that the floating insulation can easily slide ... (up and down a little, if necessary).

Because water is a solvent, and I do not see it being mixed with oil without taking the risk that depending on temperature and pressure fluctuations, this will create an emulsion during exchanges, and which there is a risk of being sucked in by various effects during the circulation of the fluid (in particular by the difference in speed of movement of the fluids in contact, a “lubricated” greasy emulsion circulating more quickly) and encroaching on the walls of the sensor tubes, which with a very hot sun could fix part of it in a film on the walls of the glass tubes of the collectors, impossible to remove afterwards, and lowering the efficiency.)

Christophe · by **Christophe** » 18/08/21, 15:00

Macro wrote:Having a hydrocarbon (vegetable or mineral oil) on the surface of your water will undoubtedly limit condensation ... but have you thought about odors? a mineral oil stinks, a vegetable it becomes rancid and above all ... It polymerizes ... It solidifies and becomes sticky ....

It is for these reasons that I made this Macro topic ... find the best oil or the best product to answer this problem!

Silicone oils are odorless ...

izentrop · by **izentrop** » 18/08/21, 15:06

Macro wrote:Having a hydrocarbon (vegetable or mineral oil) on the surface of your water will undoubtedly limit condensation ...

I doubt. You should already try in a jar with the lid just placed or in a glass casserole dish, obviously with a lid.
Let stand so that the oil is on the surface then heat to 60 °

Christophe · by **Christophe** » 18/08/21, 16:19

I wanted to run a comparative test in 4 plastic bottle bottoms with 50 cl of water and 5 ml of oil of different nature ... at room temperature on a window sill in the sun then on my stove during the heating season. .

Surface diameter 8 cm = 50 cm2 ...
1L = 1 mm / m2 = 10000 cm2

To have 1 mm by 50 cm2 you need 5 ml ... I have a 2 ml syringe ... perfect!

But my scale is kidding this afternoon! : Evil:

Ah, maybe I shouldn't have cut the bottles: we would have seen the possible condensation on the walls ... I have others ... : Cheesy:

sicetaitsimple · by **sicetaitsimple** » 18/08/21, 16:26

Christophe wrote:
It is for these reasons that I made this Macro topic ...

Well, you know my opinion, very few gains a priori.
But out of curiosity, even though you may have already explained it, what is your downstream heating system?

I think I understood that the storage was in open circuit on the panels: it pumps into storage, it passes and heats up in the panels, and it comes back to storage.
But then? There is a circuit that goes through the submerged exchangers, but this goes directly into the heating circuit of the house (underfloor heating, radiators?) Or is there a heat pump between the two?
And you mentioned a boiler. Is it somehow "integrated" from a process point of view into the heating system or does it take over when it is too cold by bypassing the solar part altogether?

Christophe · by **Christophe** » 18/08/21, 16:31

Direct heated floors ... no heat pump ... I had thought about it briefly but suddenly pumping (cost) hundreds of kWh of calories into the insulated envelope of the house that posed a moral problem for me lol and it was a building site profitable in 40 years is to say never ... I consume 2 cubic meters per year and a few tens of L of fuel oil ...

Why this question ?

sicetaitsimple · by **sicetaitsimple** » 18/08/21, 16:50

Christophe wrote:Direct heated floors ... no heat pump ... I had thought about it briefly but suddenly pumping (cost) hundreds of kWh of calories into the insulated envelope of the house that posed a moral problem for me lol and it was a building site profitable in 40 years is to say never ... I consume 2 cubic meters per year and a few tens of L of fuel oil ...

Why this question ?

I was thinking of a water-water heat pump between a loop supplied by the submerged exchangers and the heating circuit.
Brief 3 loops:
-storage with solar collectors
-a very simple loop with the submerged exchangers and the "primary" of a heat pump
-a heating loop with heated floors and the "secondary" of the heat pump.

Christophe · by **Christophe** » 18/08/21, 17:41

Yes simple, the idea is nice except that as I just said: REpumping with kWh from kWh that are already in the insulated envelope is a bit of bullshit!

I doubt the profitability of such a system both thermally over X years and economically ...

Well, I just opened it 14 years later ... it's not pretty pretty ... several m3 are missing and I have condensation on the outside of the inspection slab, I had put a roofing above the hatch.

Before touching anything, it tasted permanently ... like a drop every 2 or 3 seconds ...

The buffer is currently at 42 ° C the slab at 37-38 ° ...

All this confirms that evaporation must be prevented at the source!

Obamot · by **Obamot** » 18/08/21, 20:56

Christophe wrote:Yes simple, the idea is nice except that as I just said: REpumping with kWh from kWh that are already in the insulated envelope is a bit of bullshit!

I doubt the profitability of such a system both thermally over X years and economically ...

Well, I just opened it 14 years later ... it's not pretty pretty ... several m3 are missing and I have condensation on the outside of the inspection slab, I had put a roofing above the hatch.

Before touching anything, it tasted permanently ... like a drop every 2 or 3 seconds ...

The buffer is currently at 42 ° C the slab at 37-38 ° ...

All this confirms that evaporation must be prevented at the source!

You wouldn't want to give us the ratings of the interchanges and the Chrichri swimming pool :?:

izentrop · by **izentrop** » 18/08/21, 22:14

Christophe wrote:The buffer is currently at 42 ° C the slab at 37-38 ° ...

Condensation or not, this is normal with the 30 cm of insulation above.

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Thermal buffer: avoid surface evaporation of hot water with oil or other blocking product?

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