Quote:
Originally Posted by osolemio
Biproduct from sugar, sweet!
I see this is a European product, should make it even better for me. I saw that company also has another product which does boil around 105C, but it's stable up to 150 (without gelling up)
As I wrote before, I do intend to keep the system cooled off all the time, both for efficiency and to avoid overheating of PVs (it's a hybrid system) and the heat transfer liquid.
The only concern is what happens if - despite redundancies - the panels do overheat.
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Looking at your diagram, it seems to me you could put a condenser in pretty easy as a heat dump. It's real easy, and I'll quickly tell you now, a step-by-step procedure.
1. Pick a common midsize car. For me, this would be a toyota camry or a ford taurus. In europe, maybe bmw 3-series?
2. Go to junkyard and get a condenser with the electric fan(s) attached...they call it a radiator with fans. If you can, get the expansion tank also.
3. Plumb the condenser in place of the overpressure valve in your system. Install two tees in the loop. Orient both tees vertically with the center fittings facing horizontally, one above the other. The center fitting of the top tee should be connected to the outlet of your collector. The center fitting of the bottom tee connects to the lower radiator hose, the upper radiator hose connects to the upwards facing fitting on the top tee. The downwards facing on the lower tee connects to the plumbing going to the main heat exchanger.
4. If you also obtained the expansion tank, make it the high point of the outdoor loop. The filler cap will serve as the overpressure valve.
5. The condenser should be positioned so that it is normally mainly empty, and fills only during a distillation or boiling event. In case of an inferno, the electric fans can be activated via staged thermostats. The latent heat transfer capacity should be well within your 10kw maximum.
With this rig, the condenser will regulate the max loop temperature to that of the boiling point of the most volatile fraction of your heat transfer solution. I would recommend a methanol or ethanol mixture, as the distillation would begin around 90 degrees Celsius at atmospheric pressure. Maybe closer to 100 under some pressure.
If the condenser/fan unit can keep up with your generated heat, you will retain all your coolant. If your main heat exchanger has fully charged your heat store, and/or cannot keep up with your generated heat, the condenser radiator can be run either passively as a condenser or actively by adding a pump between somewhere and the upper radiator hose.
If the temperature rises enough, the alcohol will begin to separate from solution, carrying its latent heat at high volume to the condenser. As the alcohol boils off, the boiling point will rise, providing a small buffer. Adding an electrolyte to the solution will increase this effect due to the increased boiling point of the saltwater brine.
The coolant will not all boil out of this system. At a certain level, there will not be enough liquid in the loop to either heat sufficiently to boil or to pump constantly, depending on the plumbing configuration. At this point, your main heat exchanger will still be submerged. If an electrolyte was added, it will be concentrated in the remaining water and will serve as freeze protection.