Oil in vacuum tubes

[WillyP]

I am in the design phase of my new home. I am hoping to find somebody as crazy as myself, or even slightly close.
To keep it simple (for now) I am thinking about using evacuated tubes (vacuum tubes solar collectors) to heat oil, instead of water. Has anybody done this?

I want to use the oil to heat large storage tanks buried underground. But that gets complicated.

 

[BiduleOhm]

Why oil? it has less heat capacity than water.

 

[WillyP]

evaporation, and boiling.

 

[BiduleOhm]

Ok, I see

Well I don't think it's that crazy, totally do-able.

 

[Picasso]

Solar is so cheap just use PV to heat direct

 

[Zil]

50/50 blend of water and glycol. Pressurized as in your automobile. Why reinvent the wheel? So less problem if leaks.

 

[WillyP]

if nobody reinvented the wheel we would all still be using wooden tires.

 

[RCinFLA]

Other then safety concerns, just look up specific heat of oil compared to antifreeze.

Oil can get pretty high viscosity at low temps making it hard to pump around.

 

[MisterSandals]

Other then safety concerns

Once you burry petroleum tanks, you need to jump thru a LOT of EPA hoops for containment and hazmat contingencies. Your disclosures when selling the property will make it not sellable without excavation and verifications. Trust me, these are all very expensive things to deal with.

 

[WillyP]

Once you burry petroleum tanks, you need to jump thru a LOT of EPA hoops for containment and hazmat contingencies. Your disclosures when selling the property will make it not sellable without excavation and verifications. Trust me, these are all very expensive things to deal with.

That is a great point. Although I do not plan on burying the oil tanks (only the water tanks). The environmental

Other then safety concerns, just look up specific heat of oil compared to antifreeze.

Oil can get pretty high viscosity at low temps making it hard to pump around.

while this is true, water gets pretty thick and hard to pump around, when it gets below 32°F. In fact that is the main reason I wanted to go with oil.

 

[WillyP]

Once you burry petroleum tanks, you need to jump thru a LOT of EPA hoops for containment and hazmat contingencies. Your disclosures when selling the property will make it not sellable without excavation and verifications. Trust me, these are all very expensive things to deal with.

Let's try again. for some reason my post got cut in half. The environmental issues are an important thing to be concerned with. I don't want some inspector labeling my home a superfund site. In fact that is the most legitimate reason for not using oil I have heard so far.

 

[ianganderton]

That is a great point. Although I do not plan on burying the oil tanks (only the water tanks). The environmental


while this is true, water gets pretty thick and hard to pump around, when it gets below 32°F. In fact that is the main reason I wanted to go with oil.

Isn’t that what the antifreeze is for?

 

[LanduytG]

Oil will be much harder to pump when it gets cold. To keep it move you would have to use a positive displacement pumped which is load and draws more current. At -20 water and glycol is still very easy to pump with a centrifugal pump.

Greg

 

[Ampster]

if nobody reinvented the wheel we would all still be using wooden tires.

It wasn't the wheel they reinvented. It was the availability of inexpensive rubber and the additional speed from the technology of the automobile that made the steel rimmed wheels obsolete.

Solar heated fluids have been around for some time so it is proven technology. The economics may have changed because of the technological advances of heat pump technology and photo voltaic technology coupled with battery storage technology.

I know very little about thermal storage except it is similar to lead acid batteries in that the stored energy is lost over time. Less so with Lithium Ion energy storage. Then there is grid energy storage that is technically 100% efficient but is economically dependent on favorable Net Metering policies.

So the hypothesis that would be interesting to test is whether one would spend less money on PV solar and a heat pump versus evacuated tubes and liquid storage of heat and the equipment to store and distributed that heat.

 

[WillyP]

Yes antifreeze would fix that.

It wasn't the wheel they reinvented. It was the availability of inexpensive rubber and the additional speed from the technology of the automobile that made the steel rimmed wheels obsolete.

Solar heated fluids have been around for some time so it is proven technology. The economics may have changed because of the technological advances of heat pump technology and photo voltaic technology coupled with battery storage technology.

I know very little about thermal storage except it is similar to lead acid batteries in that the stored energy is lost over time. Less so with Lithium Ion energy storage. Then there is grid energy storage that is technically 100% efficient but is economically dependent on favorable Net Metering policies.

So the hypothesis that would be interesting to test is whether one would spend less money on PV solar and a heat pump versus evacuated tubes and liquid storage of heat and the equipment to store and distributed that heat.

PV would probably be cheaper and easier to use. Except it is only available during the day and becomes less available as heat needs increase. Of course with a grid tied system, there always the possibility of building enough credit with the power company to get free electricity in the winter... But of course that depends on the power company being cooperative and not passing regulations to prevent that from happening.
I will be getting most of my electricity from PV. PV panels seem to get better every month in today's market.

As for heat loss. There is some loss with storage. But by building the whole system inside of a greenhouse, I hope to create a large enough heat sink to keep my water warm all winter.

 

[Zil]

keep asking. sooner or later you will get an answer you want.

 

[WillyP]

here is a diagram of the whole system. It occurs to me I never posted that to this board.

 

[WillyP]

keep asking. sooner or later you will get an answer you want.

LOL! I don't mean to come off like that. I am hoping somebody has tried it. I know the science. I just want to hear some practical results.

 

[Ampster]

PV would probably be cheaper and easier to use. Except it is only available during the day and becomes less available as heat needs increase.

PV energy and heat energy are both only capable of being produced when the sun is shining. The economics of your proposal will be greatly influenced by the factors you described. Heat loss is much more difficult to calculate that electrical energy loss because of influence of ambient temperatures and the ability to insulate the storage. Have you looked into a geothermal source of heat? Putting several hundred feet of pipe below the ground could be a source of heat 24/7 depending on your location. One day rental of a trencher may favorably compare with the cost of evacuated tubes.

 

[ianganderton]

Have you looked into a geothermal source of heat? Putting several hundred feet of pipe below the ground could be a source of heat 24/7 depending on your location. One day rental of a trencher may favorably compare with the cost of evacuated tubes.

I’m not sure why ground source heating isn’t used more. Friends of mine used it and it worked spectacularly well. The heat exchanger and pump should run easily off solar