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Ben_bai said it pretty well. water is good but it can cause rust, pressure, freeze, leak, etc. sand avoids most of this. the big thing is that sand can be heate
by gorpy7 3y ago
Ben_bai said it pretty well. water is good but it can cause rust, pressure, freeze, leak, etc. sand avoids most of this. the big thing is that sand can be heated much much hotter and this helps make up for its shortcomings relative to water. they likely charge and discharge with air blowing thru stainless steel network of pipes thru the sand. this would require special tuning. as someone else mentioned, the thing with water is that the temp is uniform everywhere because water transfers heat within its volume easily. sand doesn’t, so you need pipes spaced out right.
i’ve wondered about insulation but, i think you can step it out with refractory bricks first then a mineral insulation, then something like perlite or fiberglass. the hot air would interface with heat exchanger to transfer the heat to whichever fluid that would go on to heat the home/s. since the sand can be heated to 1700F or more, a kiln or quartz heating element that can exceed this temp is needed. last, a thermally isolated heat temp tolerance fan would be required. i guess a slew of sensors in the sand and at the exchanger unit and output, i can imagine wanting sensors everywhere for tuning sake.
- lancewiggs 3y agoMGA Thermal uses tiny aluminium droplets in carbon matrix material to do heat storage with 1: constant temperature storage and 2: at much higher temperatures and energy density that allows for steam generation etc.
- Valgrim 3y agoSome Youtube folks tried a much simpler approach: Take a large metal bucket or barrel. Put a heating element and a simple oven thermostat on the bottom. Fill with sand. Connect to a solar panel or other enrgy source. The air between the sand particles seem to actually provide a bit of convection and insulation. The thermostat turns the circuit off before getting too hot for the heating element. The heat accumulated during the day is slowly released over time directly through the metal.
- immibis 3y agoAny system that involves an electrical solar panel connected to a low-temperature electrical heater is likely to be better served with a solar hot water panel, by about a 10:1 ratio.
- mercutio2 3y agoAre you including the maintenance costs of the water panel in your estimate? I used to buy this argument, but then: A) PV panels got ridiculously cheap B) everyone I know with solar hot water has emptied their systems because the maintenance hassles were not worth dealing with Using high grade intermittent current to produce resistive heat isn’t high on my list of efficient things to do, but unfortunately neither is maintaining hot water panels.
- palmfacehn 3y agoThe most I've had to do is clear the dust from the tubes during the dry season.
- defrost 3y agoMight be a location thing; there are vast numbers of solar hot water systems here in W.Australia and typical maintainence is maybe just replace the tank outright and flush the lines every 20 years or so. How 'clean' of salts, etc. is the water being put through your panels? Hard water clogs up faster.
- mattclarkdotnet 3y agoAs you allude to, our water in WA is notably soft, maybe that helps? I mean it's full of iron but that mostly just seems to cause staining not clogging. That said, a heat pump running at 4:1 COP coupled to 20% efficient solar panels gets you right back to the same efficiency as solar thermal, with a lot more flexibility.
- defrost 3y agoI'd rather run both in parallel, and I do, as do most of the people here abouts. No single point of failure, sun heats the water directly and provides power, with a breakout box that accepts power in from the grid (if required), exports excess for points, hopefully that gets better over time, and accepts a local generator input if the PV panels are offline for some reason when there's a local grid power outage. This is pretty good for now, there's loose neighbourhood discussion about perhaps getting a local area battery in a sea container that can buffer ~200 standard homes to further secure the town's energy stability. Flexibility, in rural settings, is about having options not a single point of failure | dependency. Eg: Way up the hill it's good to have PV panels on the bore pumps and better to have these independant of the house circuits with cables in place to route power "in case" .. along with option to use a generator if needed.
- Dalewyn 3y agoFor some reason this description sounds exactly like a computer, and specifically the CPU/GPU, and I love it.
- kiney 3y agoThats just a regular storage heater...
- rkangel 3y agoThis is called a Storage heater (https://en.wikipedia.org/wiki/Storage_heater https://en.wikipedia.org/wiki/Storage_heater), usually referred to in the UK as a Night Storage Heater as it took advantage of cheap electricity at night to provide heat for a house. Fitting Night Storage radiators was a much cheaper way of fitting central heating than the normal boiler and plumbing approach, and when electricity was cheaper it made more sense. Now, it makes no sense and if you buy a house with it the first thing you have to do is put in "proper" central heating. But maybe with excess renewables that will swing back.
- prometheus76 3y agoI'm toying with the idea of building one of these to use as a pool heater. Has anyone here tried this?
- onlyrealcuzzo 3y agoWhy not just do solar heating?
- prometheus76 3y agoBecause I have sunlight for a solar panel year-round, whereas I only have solar heat for a limited time.
- samstave 3y agoSeems like according to everyone above - why not just use the water from your pool.