h a l f b a k e r yExpensive, difficult, slightly dangerous, not particularly effective... I'm on a roll.
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This idea is a minor improvement in a relatively old
idea.
Basically, an earth tube system consists of a long buried
pipe, typically buried about 10 feet (3 meters)
underground. A fan forces air through this pipe, and
into a building.
For this idea, we'll first increase the depth to 20
feet,
and use an open loop system (fresh air coming from
outside the house, not recirculating), and calculate the
yearly average air temperature outdoors (and call this
temperature T).
Next (and this is the really important part), whenever
the air temperature outdoors is above T, we blow the
air through the pipe in one direction, and whenever the
outside temperature is below T, we blow the air
through the pipe in the opposite direction.
That's it!
It's using dirt in the ground for thermal mass, and it's a
regenerative heat exchanger. Thus, the name.
As with any regenerative heat exchanger, sending cold
air in results in hot air coming out, and sending hot air
in results in cold air coming out. So in summer, when
the air outside is hot, we will be getting (free!) cold air
for our building, and in winter, when the air outside is
cold, will will be getting (free!) hot air for our building.
[link]
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What aspect of this is the original invention? |
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No radioactive magma at all? Hardly working on bun accrual at all... |
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I think a few details are missing. Where's the input to the house ? |
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Air is a terrible heat conductor and I suspect 20 feet
is not a sufficient depth to extract a useful heating
source from the earth. Could be wrong! |
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I think I get it. You're setting up a temperature gradient in the pipe, right? I imagine you'll need a H shaped topology, where the horizontal represents the storage tube, the top halves of the verticals lead to the external air, and the bottom halves lead to the house. The part you've left out is that the house draws hot or cold air from these as required. Right? |
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In effect, in summer you're pumping heat into the
earth around the "hot" end (where it's stored for
winter), and extracting coolth from the cold end. |
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In winter, you're pumping coolth into the earth
around the "cold" end (where it's stored for
summer), and extracting warmth from the warm
end. |
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I think this makes sense; I'm not sure you need
the "H" geometry, if the length of the pipe is
sufficient. |
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The "H" would allow charging to be independent of consumption. Otherwise, heating or cooling of the house would be governed by the outside temperature - the tail would wag the dog. |
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"Geothermal" typically refers to pipes that
circulate a
conductive fluid from a climate controlled
environent
to some depth within the earth, using the earth's
ambient temperature as a source of relative cold
in
the summer and hot in the winter (Think: oceans).
There is no
need
for atmospheric exhaust. A simple loop topology
will do, unless I'm severely missing something. |
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If the depth of the tube is sufficient, there is no
need to change current directions as the idea
implies. And, air sucks at transferring heat. Again,
having trouble understanding the novelty here. |
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rcarty, the novel part of the idea is the switching
directions of air flow. |
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daseva, the word geothermal has at it's roots, geo
(meaning earth) and thermal (meaning heat). |
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There's no specific requirement that a closed loop
be used, or that the intake come from a climate
controlled environment -- while there are many
such systems, there also exist systems which have
an intake from the atmosphere outside of the
house. |
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Also, there's no specific requirement that the fluid
coming out of the system match the earth's
ambient temperature -- while existing systems aim
for this, my idea aims to do BETTER than that. |
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Existing systems get tepid fluid from the
geothermal system all year round -- in winter this
is warm //relative to the atmosphere//, and in
summer this is cold //relative to the
atmosphere//, but it's actually roughly the same
//absolute// temperature all of the time. |
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My idea, on the other hand would get actual
WARM (summer-like) air out of the system in
winter, and actual COLD (winter-like) air out of
the system in summer. |
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I'm not sure what you mean by "atmospheric
exhaust"... the system's "exhaust" is inside the
building. |
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As for the purpose of changing the direction of air
flow, spidermother and MB understood it
correctly. |
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The root idea here is a "ground loop" heat pump,
which is an absolutely standard way to get
extremely efficient climate control by using the
stable ground temperature. This substitutes for
the negatively correlated air temperature (hot
when you need cooling, cold when you need
heating). |
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It can have problems in an environment where the
majority of the system requirements are either
heating or cooling, as the ground temperature can
be affected. |
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This, however, turns it into a stored energy
version, which is also a known approach. The
problem is that the volume of earth needed is so
large that it is typically not viable to do it on a
seasonal basis. |
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Where it may be useable is to increase the heat
exchange with the environment in the above
mentioned unbalanced states, allowing the
ground loop version to be used in a wider range of
environments. |
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