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Listeroid Engines / Re: 6/1 and generator setup
« on: October 02, 2006, 06:02:18 PM »One of the best ways I can think of to utilize engine and solar (and woodstove or geo) heat is to have a centrally located, well insulated, tank with three heat exchanger circuits. One circuit moves water through the solar panels to the central tank ONLY if the heat in the panels is greater than the heat in the storage tank. The second circuit does the same with the Lister coolant tank. If there's heat in the engine circuit greater than in the storage, the pump starts moving it to the central tank.. The third circuit feeds radiators or other heating devices where the heat is wanted.
The central tank can be plain water with an added biocide and in total darkness. The water never goes anywhere, it's only a heat sink....add lots of salt to raise the potential for storage. The circulating circuits can be antifreeze mix so the solar system doesn't have to be drained in the winter. None of that fluid ever leaves either.
It takes several thermostatically controlled valves, a couple of small circulator pumps, and a control board that controls the circulators and has the overrides to quit adding heat at a certain point and to dump (the unlikely) excess heat to an outside radiator by way of a diverter valve.
If everything is run from 12 or 24VDC the whole system could be run 24/7 off grid.
Great minds...
I can use the heat since it is free... Until I priced a suitable tank, then priced the time and effort involved in building a suitable tank... And this project may have to wait for development. Maybe I can use the free heat, but it's not really free and I don't need it that badly yet (after all it's warm outside )
Still... It is one of those "Because it's there" adventures and will eventually have to be worked out. Hotater you describe exactly the correct way to pump, store, and utilize waste or solar generated heat.
I had a water test performed on the well water I will be using until my cachement system is developed... It is extremely high in TDS and exceeds the county standards for dissolved magnesium sulfate... And explains why the local water gives me the runs (active ingrediant in many laxitives)... I also checked out a swamp cooler system a local guy was running with the same water... The mineral content is high enough the entire system has to be cleaned and purged weekly and it still looks like a salt water fish tank gone bad; salt creeping everywhere and all the steel that is not stainless, like the frame mount to the building, is heavily rusted. I plan on using a fountain for evaporative cooling, and salting is going to be a real problem with 50-60+ gallons a day evaporating in the summer.
Next up on my list of needed equipment is a whole house RO unit with sufficient capacity to supply the fountain with demineralized water and this brings me, in a roundabout way... Back to hot water and heat exchangers.
The byproduct of running a reverse osmosis membrane on the local well water is brine. The accepted practice locally is to drain this brine directly to the soil where these units are operated. This practice will eventually result in salt plumes developing sub-soil and it may hurt deeply rooted native desert plants, not to mention salting up the groundwater. Also I hate to see stuff like this go to waste; it's perfect for use in hot tubs, a bidet, pre-wetting in the shower, and for heat storage.
I think with a high enough salt concentration in some circuits of the heat exchanger system, given the local climate... I can get away with running the brine in my hot water solar panels. At the worse the fluid would get slushy on a few cold nights, I don't see the brine hard freezing since 20 degrees F is a rare and short lived phenomina. An interesting side note... The Fahrenheit scale is based on saturated brine... 0 degrees F is the freezing point of saturated brine.
I cannot see running brine thru an engine however... Especially since most of the minerals that came back with high TDS numbers are sulfates which would cause a great deal of corrosion potential... So I will run the engine on a glycol based coolant, and can sink the heat into the tank which is outside of my reach for the moment.
I am thinking that for this to be practical (hot water storage tank w/heat exchanger loops) the tank needs to carry some summer heat over into winter. This means a large tank. Ground temps locally drop to below 60*F when you dig down 9-10 feet or so... I talked to one guy that excavated down to 12 feet and installed air ducting to feed cool air to his off-grid place but there is a _lot_ of radon contamination with this type system (he ignored me when I pointed this out)... So a below ground tank installation is not suitable, the ground will sink too much heat. This means a large above ground tank with a lot of covering insulation... Like a hay stack sealed up with stucco or something of the sort. In order to store enough summer heat to warm a radiant floor in winter I am thinking it's not worth the hassle for anything smaller than 10,000 gallons of extremely well insulated above ground tanking... It's either a huge job, or a very expensive one to farm out.
I have already budgeted for construction of a 10,000 gallon tank for fresh water storage, sunk below ground, and plumbed for a fountain and plans for a gazebo with a ceiling fan for shade and air movement.