/Sorry a heatpump (HP) cannot have a COP 30 or 60/
Sorry but they can, I gave you the links.
The math also supports this.
No, you are right that a regular small house-hold heatpumps operating
at 100% power over the rated temperature differential will top out
currently at about a heating COP of 5.5.
However is it is well made and can be powered at the ideal power level
the COP goes up and can be measured at 10+
And that is just the heat being counted, if we count the cold side
which is normally ignored when we are trying to heat we get a true COP
of 20+
But have you ever wondered who small house-hold heat pumps have a
higher COP than larger ones?
It is because the smaller heatpumps have everything (for the power
level they work at) size larger and closer to optimal.
But when operating on an inverter basis, the efficiency can go higher.
And the COP of a larger heatpump that isn't working hard out can
exceed the rated COP of a smaller heatpump and even outclass it
entirely, though there might also be a point of something being
oversized but I don't really think it's much of an issue when it is
inverter based and you know how inefficient it is to have the cold
side outside to have a hard time due to getting too cold and frosting
up too much...
Note: "A W10W35 water-to-water heat pump should have a coefficient of
performance (COP) of at least 5.5. COP"
AT LEAST! not at best.
I just asked a chatbot, apparently 12.8F might be a plausible range to
give a reading over: " 47°F (8.3°C) outdoor temperature and 70°F (21°C)"
So I ran with that and based on the heat engine efficiency numbers, at
that temp there is a 4.3% efficiency as a heat engine, and that would
seem to indicate an absolute max heatpump COP of 29.
But at a 2C difference it was a heat engine efficiency of 0.67% and a
COP as high as 148!
People report to have measured COP's of 11, and I gave you links to
very professional examples of COP's up to 30 and explain why 30 can be
seen as 60 when you utilize both sides.
In theory COP can with some tiny fraction of a C separation across
each heatpump go near infinite if ideal (no losses).
Of course if you were driving so many you would need to find a super
efficient way, but we don't need a COP of 148 even if it is
theoretically possible.
A COP of 5.5 even without doubling it is plenty, even without running
it across a more modest gradient...
Just run enough in series to get the efficiency of the heat engine to
about 50% while the COP is not much worse than 3 and you not only have
a proof of principle but something perhaps practical.
But we don't need to build it, the fact is that in theory you can move
ANY amount of heat up any hill as long as it is divided up by enough
heat pumps that have low frictional losses.
We don't need to build it (though we could) to prove that the
conservation of Energy is more of a rule of thumb but easily broken in
practice if you know how.
/Assume a COP of 5 for a single step HP as we have it today in a
reasonably good probe heat pump. (mine has 5.5 for heating)
/
Ok. Can do.
/You can neither simply multiply or add the COP's/
I did neither one, well I doubled which is valid (or approximately so)
in a single state if you just count the cold side, but generally I
didn't add or multiply COP's.
/as you must provide e.g. 20x the basic energy to fill the reservoir
for the next HP state./
There are probably only 2 Reservoirs (one on the extreme hot and
extreme cold ends), and even if there is a reservoir between each one
it only takes a moment to reach a steady state condition and then it
is as if it isn't there.
I am not sure really what you are talking about, what reservoir needs
20 times the energy? I think you have misunderstood something.
What we are proposing is very much like Carnot's proposal, 2
Reservoirs, one hot and one cold.
There is a high efficiency heat engine connected between two
reservoirs turning say with 64% efficiency of the thermal energy to
mechanical.
If we were to try and make this heat engine drive another identical
heat engine connected between the same 2 resivious to act as a
reatpump it would fail as each would be matched, even If it was
smaller and weaker but just as efficient as a heat engine then as a
heatpump over that temperature differential it would have a COP of
less than 1 if I'm not mistaken, but not good anyway.
However if we had multiple identical reversible heat engines, and one
goes between the hot and cold, and the others are placed with one on
one hot, one on the cold and other heat engines placed in between.
As such they would behave just like a series of resistors across a
voltage potential. If you measured the temperature between each one
it would ideally be a fraction of the total.
Each one by being over a tiny fraction of the full temperature
differential is only driven as a heat engine very weakly (low
efficiency) that can easily hit a percent or 2 or less. And a 2%
efficient heat engine when run as a heat pump has a huge COp.
I really don't understand what you are imagining "/20x the basic
energy to fill the reservoir for the next HP state" but I have been
veyy careful to be easily comprehensible./
/
/
So, I ran it by a LLM, it didn't understand you either.
more below...
Based on the statements provided, it seems there is some confusion or
lack of clarity in the explanation being given. Here are a few
observations:
1. The statement about needing to "provide 20x the basic energy to
fill the reservoir for the next HP state" is unclear. There
doesn't seem to be enough context to understand what is meant by
"HP state" or why a factor of 20 would be involved.
2. The example about heating 1000L of water from 10°C to 50°C and
needing 25,000L at 10°C if taking out 2°C appears to be referring
to the amount of heat energy required, but it's not clearly
connecting this to COP calculations.
3. The statements about the "base COP" going in with a factor of 20
and dividing 25 by 20 for a first second step don't have enough
explanatory context to make sense on their own.
4. The final statement "initial total COP = 5 + 25/20" seems to be
arbitrarily combining numbers without a clear derivation.
Without more context about what specific system is being analyzed and
what assumptions are being made, it's very difficult to decipher the
meaning behind these statements. They don't seem to follow any of the
standard analyses for calculating heat pump or heat engine COPs based
on temperatures and energy inputs.
It's possible there is some valid point being made, but the
explanation lacks crucial details and derivations to make the logic
clear and followable. More contextual information would be needed to
try to interpret these statements accurately.
/ To heat 1000l from 10 to 50C you need 25'000 Liter of water at 10C
if you take out 2C. /
I'm not going to challenge this claim, at least I understand what you
are saying, but it has no relevance.
The goal is not to have any net increase in temp, actually if all
things go as planned the heat pump would have potentially no actual
heat output and would just power itself and produce excess power for
the grid making the world a bit colder.
The idea is the heatpump moves heat from one reservoir to the other.
You can think of the heatpumps being like a chain of men passing
buckets of water to put out a fire, each heatpump moves every joule of
heat from one end as it passes it on to the next.
Each only moves the bucket of water a tiny distance (each only moves
the joule of heat up a tiny temperature gradient of 1-10 degrees C).
Water is moved from one reservoir and poured into the other (thermal
energy is removed from one revivior and put into the other).
One reservoir ends up hot, and one ends up cold, one reservoir is
overfull the other is very low.
A heat engine (steam turbine?) converts the thermal energy to
mechanical energy, enough to drive the heat pumps and more.
Or a water wheel converts the energy.
Done right the hot and cold reach an equilibrium with the load and the
heatpumps and with the apparent exception that I believe it is meant
to be colder, it will just output power, if not it would also break
the first law.
/So the base COP goes in with a factor 20 in the total COP equation./
/Thus you must divide 25 by 20 for a first second step. In average by
10. Thus initial total COP = 5 + 25/20!
/
So lost, no idea what you mean.
Each heatpump is doing the same job, or each heat engine is doing the
same job with total ignorance that there are other inline with it,
If a heatpump is operating over a temperature and power range in which
it's COP is 10, it's COP is 10 and it doesn't matter at all if the
heat is drawn away by another heat pump, or the cold side warmed up by
another heatpump, as long as it is within the range at which it
provides as 10 times more heat than you put in then that's what it does.
There is no modification needed of the COP, other than to realize that
heat pumps normally only count half the output at a time (hot OR Cold,
never both), and normally are not rated for their maximum COP, but a
reasonable average COP.
PERHAPS the MVR ones I mentioned were in fact talking about the both
outputs but I don't think so but can't be sure and whatever, it
doesn't change the validity of my argument and just how dead the
second law is.
Once that is accepted then practical engineering can be considered.
/Also the cooling does only count if you can use it. Normally in
winter you must heat. /
Sure, but I'm not talking about such conditions. I am talking about a
dedicated and initially theoretical device that makes a hot and cold
side and drives it's own heatpumps. As such the cold side is very
valuable as it hugely increases the efficiency, at least of the heat
engine.
/The optimal solution would be to combine the fridge with a heat pump
but a good fridge today uses only 300W/day..../
A fridge though ok is hardly optimal.
We want AS MANY stages as we can practically do, 5 is the low end, 20
would be perhaps a decent tradeoff, but if I was trying to do this
well and make it a bit custom I'd try and have 100 heatpumps in series.
This them means each one can have a 5C uplift (temperature
differential) and we can have at least a 500C difference between the
hot and cold side, this is actually like a heatpump with a 2.5C uplift
from ambient, so maybe 10C is doable for a 1000C difference, or maybe
if that much worked, what's another 100!,
I would not bother going for 1000 or anything even if it was some
custom solution, at least not unless it was clearly all best but I'd
think it overkill.
But the point is that the less each ones works to increase the
temperature the greater efficiency they do (whatever little they do
each) at, in theory to the point of infinitely many heatpumps in
series moving infinite energy with no power input (only, not quite
obviously).
Jonathan
On Fri, 10 May 2024 at 21:35, Jürg Wyttenbach <ju...@datamart.ch> wrote:
Sorry a heatpump (HP) cannot have a COP 30 or 60. Assume a COP of
5 for a single step HP as we have it today in a reasonably good
probe heat pump. (mine has 5.5 for heating)
You can neither simply multiply or add the COP's as you must
provide e.g. 20x the basic energy to fill the reservoir for the
next HP state. To heat 1000l from 10 to 50C you need 25'000 Liter
of water at 10C if you take out 2C.
So the base COP goes in with a factor 20 in the total COP equation.
Thus you must divide 25 by 20 for a first second step. In average
by 10. Thus initial total COP = 5 + 25/20!
Also the cooling does only count if you can use it. Normally in
winter you must heat. The optimal solution would be to combine the
fridge with a heat pump but a good fridge today uses only
300W/day....
J.W.
On 10.05.2024 03:49, Jonathan Berry wrote:
Not sure why but this isn't forming into proper paragraphs...
/
/
/"Youtube physics usually is self satisfaction of people that
have no clue of the simplest things. So I almost never watch this
garbage."/
The video is covering the work of a company cascading heat pumps.
As such the temperature differential over each heat pump is a
fraction of the total over all the heatpumps, there is a
potential feedback instability effect they have resolved.
But cascaded heatpumps are an accepted thing with improved COP
over a given total temperature difference and the video isn't
making claims about the second law, that's me, and well Carnot...
/
/
/"A heatpump is not a Carnot process as *you obviously supply
additional energy*!"/
It is a carnot process though and the carnot process gives us the
efficiency limit.
A reversible heat engine if you supply it with kinetic energy can
generate a temperature differential, this is why it is called
reversible, you don't get energy from it, you reverse it and put
energy in to move heat.
To do this you obviously need to supply it with energy just as we
do with a heat pump.
/"You must calculate in the Carnot conversion rate of energy
gained --> electricity to get the proper conversion factor as the
current for the heatpump must be produced too* and subtracted!"*/
Yes, however the COP of a heat pump (electrical power in .vs heat
energy gain on the hot side) over a low temperature differential
can be 5, 10, or 30 or potentially more if the temperature
differential is low enough.
Note that in a single stage heatpump we can actually double that
COP by just counting both the hot and cold outputs as both being
beneficial outputs!
If a heatpump can deliver four times more thermal energy than the
power going in (and for now assuming the heat from the input
power is not seeping inside) then wit has a COP of 4, but we
ignore the cooling COP of 4 on the other side, that is "free
cold" and in terms of a temperature differential to put a heat
engine on both are sources of energy, but between the hot and
cold sides is a higher conversion efficiency than between the hot
and ambient and the cold and ambient.
Which is the point I am making, if you divide the heat potential
the COP of the heat moving ability of a heat engine or heat pump
it improves relative to the energy it takes to drive it.
/"The best Carnot process (multi stage turbines) today delivers a
conversion rate of about 61% always target is current."/
61% is a fine conversion of heat to to energy since heatpumps can
manage a COP of 30!
https://www.sciencedirect.com/topics/engineering/recompression
COP 30 "typically COP of 10–30 can be achieved" with a MVR heatpump.
https://www.gea.com/en/assets/304829/ COP 20
You can have 30 times more heat energy moved and that's just
looking at the heat energy gain, ignoring the energy below
ambient on the cold side, so with that a COP of 60!...
Now granted my whole point is not that this if done with a single
heatpump it would not be efficient when you run steam
turbines over 1C, 10C or so, so it does not matter how well it
was design, because to gain efficiency for conversion of thermal
energy we need as great a temperature difference as possible, but
there is no reason we can't put multiple heat pumps in series
each working over a small temperature range just as we put
batteries in series.
And we can do the same with heat engines which are just Carnot
heat engines under a different name not designed to be reversible
but conceivably can be redesigned to be reversible.
And again, the point of this post is to point it out from the
other direction, according to Carnot if a reversible heat engine
can be made more or less efficient (while still not having
frictional losses, poor thermal insulation etc) then the second
law would fail.
And as putting two in series makes it less efficient (as Carnot
would himself assert if he had thought if it and apparently he
managed not to)... well then the second law fails, it CANNOT be
true if this is a reversible heat engine, AKA, a heat pump, as a
less efficient heat engine is a more efficient heat pump!
That is the message of Carnot's theorem, but another thing of
Carnot's is the equation that tells us the efficiency of a heat
engine.
η = 1 - Tc / Th
We take the cold temp in Kelvin, divide it by the hot temp and
then subtract the result from 1 then multiply by 100 to get our
efficiency in percent.
So at -200C on the cold side and -190C on the "hot' side we have,
after adding 273.15 K 73.15 K which we divide by 83.15 =
0.8797354179194227 subtracted from 1 gives us a 0.12 which we
multiply be 100 to get the percent: 12% efficiency.
Interestingly if we drop the cold side to 0.0001 K and the hot
side to 10 K we get 0.00001 which subtracted from 1 x 100 gives
us an efficiency of 99.99999%! At just 10C (K) difference!
Just why the cold side being almost perfectly cold skyrockets the
theoretical conversion efficiency... I am not clear on. And this
should be called into question at another time, but I wonder if
it is related to how hard it is to pump heat from something
almost at absolute zero looking at it in reverse? IDK, but whatever.
But if we have a more normal temp range for our 10C difference of
15C and 25C then...
25+273.15 = 298.15 and 15+273.15=288.15 So 288 / 298
= 0.9664429530201342 subtracted from 1 then x 100 = 3.4%
Ok, staying at a middle temp of 20C...
70C (343K) hot side and 100 C/K colder at -30C or 243 K then
243/343 then subtract from 1 and multiply by 100 for percent and
we get 29.15%
Ok, so by having 10 times more heat potential difference we have
close to 10 times more conversion efficiency at turning heat into
energy.
And by using 10 heat pumps each just contributing 10C difference
between their hot and cold side we have a COP that might be quite
high.
The heat pumps each feel a mechanical feedback at about the 3.4%
level (they have to input in theory 3.4% of the heat they move).
3.4 / 100 That is a COP of 29.
So once we have a COP of 29 and the other way we have a
conversion efficiency of 29%.
Even though this is the max theoretical conversion efficiency at
this temperature differential and not a real world value, the
potential is clear, we can put in 100W, get 2.9KW of heat and get
29% of that back so 841W out!
You can of course go further, but while for practical application
the maximum efficiency of a heat engine is important, and putting
too many heat pumps in series sounds absurd, we can just focus on
the undeniable fact.
That there is no way the second law of Thermodynamics is
consistent with what we know for an absolute fact.
That a heat engine and heat pump (heat engine run in reverse)
have VERY different and inverse efficiencies over large and small
temperature differences.
It is easy (in theory even if expensive) to put 2 or 200
(reversible) heat engines in series to make them less effective
as a heat engine and more efficient as heat pumps.
And you can still tap the difference between the hot and cold
sides to achieve a conversion efficiency in reality of above 50%
And as the COP from a heat pump can be VERY high (30 and higher)
it's only an issue of making this practical, not a question of if
it can be done both in practice and in theory.
/"But there have been some materials detected that can improve
this further like thermo (Peltier-) elements."/
Well it is an interesting point that between every heat pump in
the series you could actually put a heat engine (which a peltier
is really) and you could get a little energy out, it won't really
affect anything (a little heat will be turned into energy but in
this case it's not really lost, that which is transferred is
meant to be transfered.
This allows us to gain little bits of energy, but it is not worth
the bother unless there is a suitable difference in temp, if it
is 1C it's pointless (but then the max theoretical COP is 274!)
the energy from it is negligible.
Having said that there IS a way to do it, if you put a bunch of
heat pumps in series there is going to be on the hotter half of
the heatpumps, after the fluid giving up it's extra heat to the
hot side and expanded it is col, likely colder than the ambient.
So let’s say we have a hot revivor at 100C (+273.15 = 373 K) and
0C (0 + 273.15 K) so we 273/373 = 0.7319 subtracted from 1 =
0.268 x 100 = 26.8%
Ok so 26.8% efficient.
But from 100C to 50C we get an efficiency of 13.4%
From 50C to 0 C we get an efficiency of 15.4%
For an average of 14.43% with 2 heat pumps in series but 26.8 for 1.
This then means the only issue is how many you need given the
real world issues.
And I'm happy to discuss that, but first let's just basc in the
(ironic) warmth of entropy being reversible.
Heatpumps are reverse Carnot engines and have a much higher COP
in respect to heat gained but *not to current gained!!!!!!!*
Even more interesting are quantum level processes in nano
particles where one could achieve the doubling of IR photon
energy by suppressing some emission bands. This could be used in
solar panels.
J.W.
On Fri, 10 May 2024 at 01:20, Jürg Wyttenbach <ju...@datamart.ch>
wrote:
Youtube physics usually is self satisfaction of people that
have no clue of the simplest things. So I almost never watch
this garbage.
A heatpump is not a Carnot process as *you obviously supply
additional energy*! You must calculate in the Carnot
conversion rate of energy gained --> electricity to get the
proper conversion factor as the current for the heatpump must
be produced too*and subtracted! *
The best Carnot process (multi stage turbines) today delivers
a conversion rate of about 61% always target is current.
But there have been some materials detected that can improve
this further like thermo (Peltier-) elements.
Heatpumps are reverse Carnot engines and have a much higher
COP in respect to heat gained but *not to current gained!!!!!!!*
Even more interesting are quantum level processes in nano
particles where one could achieve the doubling of IR photon
energy by suppressing some emission bands. This could be used
in solar panels.
J.W.
On 09.05.2024 14:39, Jonathan Berry wrote:
After 200 years (1824) the second law of thermodynamics is
disproven.
https://en.wikipedia.org/wiki/Carnot%27s_theorem_(thermodynamics)
Simply Carnot argues that if the efficiency of a reversible
heat engine was variable based on how it is made or the
gases etc, then the second law of conservation would be broken.
"A heat engine *cannot* drive a less-efficient reversible
heat engine without _violating the second law of
thermodynamics_." (excerpt from the Wikipedia article below
the image)
So what happens when you take 2 reversible heat engines and
put them in series (one touches the hot side, one the cold
side and they join in the middle with potentially a small
thermal mass that is thermally equidistant to the hot and
cold side)???
Well, we know what happens, according to Carnot!
The lower the thermal potential the lower the efficiency at
turning heat into mechanical energy and therefore the less
mechanical energy is developed when driving heat (operating
the heat engine as a heat pump)...
Which is to say that with a lower temperature differential a
heatpump operates with more efficiency.
So a heat engine constructed to act like 2 or more
reversible heat engines will break the conservation of energy.
There is a company that is making cascading heatpumps which
can keep a high COP over a much larger temperature differential.
https://www.youtube.com/watch?v=wSgv5NwtByk
The point is that it is absolutely possible to turn uniform
ambient heat into electrical power and heating and or
cooling with current technology...
And it is easily explained in a way that cannot be denied,
clearly 2 heatpumps cascading have a higher COP, same as
saying clearly 2 reversible heat engines in series have a
lower conversion efficiency and therefor a higher COP as a
hatpump, precisely the scenario that made Carnot assert 200
years ago would destroy the second law of thermodynamics.
Jonathan
--
Jürg Wyttenbach
Bifangstr. 22
8910 Affoltern am Albis
+41 44 760 14 18
+41 79 246 36 06
--
Jürg Wyttenbach
Bifangstr. 22
8910 Affoltern am Albis
+41 44 760 14 18
+41 79 246 36 06