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On 04/11/2019 09:25, Klaus Kragelund wrote:
https://www.terma.com/media/177686/array_power_regulation_module.pdf
It finds the maximum power point within 0.3%, but the losses of the
DC-DC converter are up to 5%. To maximise the output power, it might
have been worthwhile putting more effort into the latter and less into
the former.
On Sat, 2 Nov 2019 16:08:21 -0700 (PDT), Rick C
gnuarm.deletethisbit@gmail.com> wrote:
On Saturday, November 2, 2019 at 4:25:01 PM UTC-4, Whoey Louie wrote:
On Saturday, November 2, 2019 at 2:40:55 PM UTC-4, Rick C wrote:
Basements are typically not insulated because being below ground they are close to the optimum temperature. Only above ground walls are insulated.
Only if you think ~55F is the optimum temperature.
Where is this that basement walls are a magic 55F?
On Monday, 4 November 2019 15:15:59 UTC+1, Jeroen Belleman wrote:
klaus.kragelund@gmail.com wrote:
[Snip!]
The accuracy of 0.3% is cheap, just takes some thought. As I wrote, much lower than 1 USD
Increasing efficiency of the converter is costly, cannot be compared
Cheers
Klaus
I don't understand that circuit very well. I see two comparators,
one comparing the SA voltage with a sampled fraction of same,
the other the SA current with a sampled fraction of that current.
The comparator outputs drive an SR FF, the crossed outputs of
which drive the S/H switches and an integrator. The integrator
controls the PWM input of the power converter.
How does this converge on the maximum power point? Does it rely
on the charge of the hold capacitors drifting in some specific
way?
When you look at the I/V curve for the solar array, you find that the maximum power point is at the curvature, where the slope is 45 degrees
To if you sample the voltage, let the converter ramp the current up linearly, until the voltage has decreased say 1%
You change direction on the 1% decrease, so now you sample current, ramp the current down, and change direction again at 1% degrease
You find that you are then operating in the MPPT point
The flipflop is just there to change the direction, and trigger the S/H circuit for either the voltage or current part
Cheers
Klaus
Cheers
Klaus
On Mon, 4 Nov 2019 06:59:29 -0800 (PST), klaus.kragelund@gmail.com
wrote:
On Monday, 4 November 2019 15:15:59 UTC+1, Jeroen Belleman wrote:
klaus.kragelund@gmail.com wrote:
[Snip!]
The accuracy of 0.3% is cheap, just takes some thought. As I wrote, much lower than 1 USD
Increasing efficiency of the converter is costly, cannot be compared
Cheers
Klaus
I don't understand that circuit very well. I see two comparators,
one comparing the SA voltage with a sampled fraction of same,
the other the SA current with a sampled fraction of that current.
The comparator outputs drive an SR FF, the crossed outputs of
which drive the S/H switches and an integrator. The integrator
controls the PWM input of the power converter.
How does this converge on the maximum power point? Does it rely
on the charge of the hold capacitors drifting in some specific
way?
When you look at the I/V curve for the solar array, you find that the maximum power point is at the curvature, where the slope is 45 degrees
To if you sample the voltage, let the converter ramp the current up linearly, until the voltage has decreased say 1%
You change direction on the 1% decrease, so now you sample current, ramp the current down, and change direction again at 1% degrease
You find that you are then operating in the MPPT point
The flipflop is just there to change the direction, and trigger the S/H circuit for either the voltage or current part
Cheers
Klaus
Cheers
Klaus
That is a pretty good way to track MPP... I suppose there is no such
think as partial shading in space ? Otherwise you have to work even
harder at it.
You can also find the max power point by measuring the Voc and then
running at a fixed percentage of that open circuit voltage. If not
THE MPP, it's a good starting point at least for non-shaded PV arrays.
Making the hardware efficient to within 99.7% is going to cost a lot
of money and be larger than wanted. It's easier to get high
efficiency with larger systems than anyone has talked about here on
SED. Besides, PV is inexpensive enough these days, just buy an extra
module or two. That will most likely be less expensive that trying to
find an MPPT controller that is greater than 99.5% efficiecent.
On Monday, 4 November 2019 23:17:18 UTC+1, boB wrote:
On Mon, 4 Nov 2019 06:59:29 -0800 (PST), klaus.kragelund@gmail.com
wrote:
On Monday, 4 November 2019 15:15:59 UTC+1, Jeroen Belleman wrote:
klaus.kragelund@gmail.com wrote:
[Snip!]
The accuracy of 0.3% is cheap, just takes some thought. As I wrote, much lower than 1 USD
Increasing efficiency of the converter is costly, cannot be compared
Cheers
Klaus
I don't understand that circuit very well. I see two comparators,
one comparing the SA voltage with a sampled fraction of same,
the other the SA current with a sampled fraction of that current.
The comparator outputs drive an SR FF, the crossed outputs of
which drive the S/H switches and an integrator. The integrator
controls the PWM input of the power converter.
How does this converge on the maximum power point? Does it rely
on the charge of the hold capacitors drifting in some specific
way?
When you look at the I/V curve for the solar array, you find that the maximum power point is at the curvature, where the slope is 45 degrees
To if you sample the voltage, let the converter ramp the current up linearly, until the voltage has decreased say 1%
You change direction on the 1% decrease, so now you sample current, ramp the current down, and change direction again at 1% degrease
You find that you are then operating in the MPPT point
The flipflop is just there to change the direction, and trigger the S/H circuit for either the voltage or current part
Cheers
Klaus
Cheers
Klaus
That is a pretty good way to track MPP... I suppose there is no such
think as partial shading in space ? Otherwise you have to work even
harder at it.
Correct, no shades in space, except for the odd alien
You can also find the max power point by measuring the Voc and then
running at a fixed percentage of that open circuit voltage. If not
THE MPP, it's a good starting point at least for non-shaded PV arrays.
That is an easy way, if you have a microcontroller and you can do periodic sweeps
Making the hardware efficient to within 99.7% is going to cost a lot
of money and be larger than wanted. It's easier to get high
efficiency with larger systems than anyone has talked about here on
SED. Besides, PV is inexpensive enough these days, just buy an extra
module or two. That will most likely be less expensive that trying to
find an MPPT controller that is greater than 99.5% efficiecent.
Correct. But in Denmark the cost of the arrays are about 10.000 USD for 6kW. If you make the MPPT 10% more efficient, that is 1000 USD saved
Cheers
Klaus
On Mon, 4 Nov 2019 06:59:29 -0800 (PST), klaus.kragelund@gmail.com
wrote:
On Monday, 4 November 2019 15:15:59 UTC+1, Jeroen Belleman wrote:
klaus.kragelund@gmail.com wrote:
[Snip!]
The accuracy of 0.3% is cheap, just takes some thought. As I wrote, much lower than 1 USD
Increasing efficiency of the converter is costly, cannot be compared
Cheers
Klaus
I don't understand that circuit very well. I see two comparators,
one comparing the SA voltage with a sampled fraction of same,
the other the SA current with a sampled fraction of that current.
The comparator outputs drive an SR FF, the crossed outputs of
which drive the S/H switches and an integrator. The integrator
controls the PWM input of the power converter.
How does this converge on the maximum power point? Does it rely
on the charge of the hold capacitors drifting in some specific
way?
When you look at the I/V curve for the solar array, you find that the maximum power point is at the curvature, where the slope is 45 degrees
To if you sample the voltage, let the converter ramp the current up linearly, until the voltage has decreased say 1%
You change direction on the 1% decrease, so now you sample current, ramp the current down, and change direction again at 1% degrease
You find that you are then operating in the MPPT point
The flipflop is just there to change the direction, and trigger the S/H circuit for either the voltage or current part
Cheers
Klaus
Cheers
Klaus
That is a pretty good way to track MPP... I suppose there is no such
think as partial shading in space ? Otherwise you have to work even
harder at it.
You can also find the max power point by measuring the Voc and then
running at a fixed percentage of that open circuit voltage. If not
THE MPP, it's a good starting point at least for non-shaded PV arrays.
Making the hardware efficient to within 99.7% is going to cost a lot
of money and be larger than wanted. It's easier to get high
efficiency with larger systems than anyone has talked about here on
SED. Besides, PV is inexpensive enough these days, just buy an extra
module or two. That will most likely be less expensive that trying to
find an MPPT controller that is greater than 99.5% efficiecent.
On 04/11/2019 13:55, dcaster@krl.org wrote:
On Monday, November 4, 2019 at 8:06:24 AM UTC-5, Martin Brown wrote:
The poor intrinsic efficiency of the PV cells means that
a well
insulated black painted flat radiator under glass perhaps
followed by a parabolic trough with a black pipe at the centre
will capture a far greater proportion of solar energy and
deliver it as hot water (or antifreeze mix). Kingspan, a pump
and mild steel radiators are cheaper.
Plenty of designs about usually for heating swimming pools or
bulk thermal stores.
I'm sure there are lots of ways to do this job more efficiently,
but?
really? You want the guy to run plumbing instead of wires for a
3 0 0 watt heater?
It is a way more appropriate solution to the problem than the DIY
solar PV approach and would be able to supply more heat than a puny
300W.
You are absolutely correct. But my problem with that approach is
that I never get around to building the better system. I may not get
around to making a PV system. but it seems like it would be a lot
less work. And I think a puny 300 watts for about 3 hours a day
would be enough to make the basement a pleasant place.
Maybe I should make a 300 watt heater and run it off a timers and
see if that is enough. ( or just use heater that I already have and
adjust the times so the heater provides one KWH per day.
You definitely should test it first. My guess is that a 300W heater
won't even be noticeable unless your basement is incredibly well
insulated. I'd guess you need at least 1kW and a few hours to make any
noticeable change. A 3kW fan heater would definitely make a difference.
Three 100W bulbs in an old empty oil drum will do it for a test.
As a ball park figure to get 1C rise every 10 minutes in our village
hall 12mx6mx3m requires about 16kW of active air heating. The walls are
solid Victorian engineering brick so not dissimilar to concrete.
On Monday, 4 November 2019 05:10:32 UTC, Bill Sloman wrote:
On Monday, November 4, 2019 at 1:15:30 PM UTC+11, tabby wrote:
On Monday, 4 November 2019 01:20:14 UTC, Bill Sloman wrote:
On Monday, November 4, 2019 at 3:48:17 AM UTC+11, tabby wrote:
On Saturday, 2 November 2019 22:27:17 UTC, John S wrote:
Heating the air does not remove the moisture. The water content in
the air stays constant, just the *relative* humidity goes down. To
remove the moisture you must cool the air to below the dew point.
You can then heat the air if needed.
some half truths there
But NT doesn't know, and can't tell us, which bits are less than perfectly accurate.
Sure I can. And for once I will reply despite your childishness.
I can't find anything wrong with either statement, so this looks more like NT not understanding what is being said and.
Dehumidifiers do cool the incoming air below it's dew point. The cold, dry air is then passed over the other end of the heat-pump circuit to warm it up again (and recondense the refrigerant that little bit faster).
Heating air doesn't directly change its moisture content, though it does lower its RH.
So NT agrees that this statement was entirely correct
But heated indoor air inevitably exchanges with outdoor air in domestic properties, which is on average lower in moisture content, and which then drops RH as it warms.
This is just irrelevant carping. Out-door air was be wetter or drier than indoor air, or warmer or cooler. Swapping air with the outside world is ventilation.
Exchange between heated indoor air & unheated outdoor air is the mechanism by which the great majority of houses are dehumidified.
It's an incidental feature of the more general process of ventilation. If you are getting worried by damp patches on the walls, dehumidifiers attack the problem directly. NT is in evasive mode here.
Dehumidifiers do cool the incoming air below it's dew point. The cold, To remove the moisture you must cool the air to below the dew point.
Not really, on both counts there are other options too. Desiccant wheel dehumidifiers don't use chilling at all. Nor do box-of-salt type ones, even though they're of minimal use.
I have seen both sorts of dehumidifier sold for domestic use. It's nuts, but some hardware stores cater for people with little money and even less sense. As NT admits, they don't work well enough to be of much use, and they certainly aren't cost effective.
Laboratory desiccators frequently used water absorbers which can be regenerated by heating, but strictly for tiny volumes of air.
I know from Bill's history here that any moment of sense from him is merely an invitation to enter into his spiral of madness. I'm not interested in doing so & don't care what he has to say.
There's no madness involved, if we exclude NT's inane enthusiasm for unhelpful pontification.
Lol. And desiccant wheel dehumidifiers work just fine.
On Friday, November 1, 2019 at 6:41:03 PM UTC-4, John Larkin wrote:
On Fri, 1 Nov 2019 15:24:21 -0700 (PDT), Phil Allison
pallison49@gmail.com> wrote:
John Larkin wrote:
------------------
Solar cells are inefficient, and resistive heaters are inefficient.
** Really ?
Other than heat, what do resistive heaters convert electricity into ?
Far IR light?
..... Phil
Some people claim that resistive heating is 100% efficient. Then a
heat pump must be 400% efficient.
They don't use efficiency, they use a measure called coefficient of performance, COP, which is ratio of useful heat output to totality of input energy required to produce it. Electric resistance heating actually has higher COP than the average fossil fuel burner, but the cost factor does the electric in.
https://en.wikipedia.org/wiki/Coefficient_of_performance
On Fri, 1 Nov 2019 15:24:21 -0700 (PDT), Phil Allison
pallison49@gmail.com> wrote:
John Larkin wrote:
------------------
Solar cells are inefficient, and resistive heaters are inefficient.
** Really ?
Other than heat, what do resistive heaters convert electricity into ?
Far IR light?
..... Phil
Some people claim that resistive heating is 100% efficient. Then a
heat pump must be 400% efficient.
--
John Larkin Highland Technology, Inc
picosecond timing precision measurement
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
boB wrote:
You can also find the max power point by measuring the Voc and then
running at a fixed percentage of that open circuit voltage. If not
the MPP, it's a good starting point at least for non-shaded PV arrays.
That is an easy way, if you have a microcontroller and you can do
periodic sweeps.
John S wrote...
tabbypurr wrote:
And desiccant wheel dehumidifiers work just fine.
And what do you do with the desiccant when it is
saturated with water?
Do they become humidifiers, when (if) the air
otherwise becomes dry again?
On Tuesday, November 5, 2019 at 1:14:59 AM UTC+11, tabby wrote:
On Monday, 4 November 2019 05:10:32 UTC, Bill Sloman wrote:
On Monday, November 4, 2019 at 1:15:30 PM UTC+11, tabby wrote:
On Monday, 4 November 2019 01:20:14 UTC, Bill Sloman wrote:
On Monday, November 4, 2019 at 3:48:17 AM UTC+11, tabby wrote:
On Saturday, 2 November 2019 22:27:17 UTC, John S wrote:
Heating the air does not remove the moisture. The water content in
the air stays constant, just the *relative* humidity goes down. To
remove the moisture you must cool the air to below the dew point.
You can then heat the air if needed.
some half truths there
But NT doesn't know, and can't tell us, which bits are less than perfectly accurate.
Sure I can. And for once I will reply despite your childishness.
I can't find anything wrong with either statement, so this looks more like NT not understanding what is being said and.
Dehumidifiers do cool the incoming air below it's dew point. The cold, dry air is then passed over the other end of the heat-pump circuit to warm it up again (and recondense the refrigerant that little bit faster).
Heating air doesn't directly change its moisture content, though it does lower its RH.
So NT agrees that this statement was entirely correct
But heated indoor air inevitably exchanges with outdoor air in domestic properties, which is on average lower in moisture content, and which then drops RH as it warms.
This is just irrelevant carping. Out-door air was be wetter or drier than indoor air, or warmer or cooler. Swapping air with the outside world is ventilation.
Exchange between heated indoor air & unheated outdoor air is the mechanism by which the great majority of houses are dehumidified.
It's an incidental feature of the more general process of ventilation.. If you are getting worried by damp patches on the walls, dehumidifiers attack the problem directly. NT is in evasive mode here.
Dehumidifiers do cool the incoming air below it's dew point. The cold, To remove the moisture you must cool the air to below the dew point..
Not really, on both counts there are other options too. Desiccant wheel dehumidifiers don't use chilling at all. Nor do box-of-salt type ones, even though they're of minimal use.
I have seen both sorts of dehumidifier sold for domestic use. It's nuts, but some hardware stores cater for people with little money and even less sense. As NT admits, they don't work well enough to be of much use, and they certainly aren't cost effective.
Laboratory desiccators frequently used water absorbers which can be regenerated by heating, but strictly for tiny volumes of air.
I know from Bill's history here that any moment of sense from him is merely an invitation to enter into his spiral of madness. I'm not interested in doing so & don't care what he has to say.
There's no madness involved, if we exclude NT's inane enthusiasm for unhelpful pontification.
Lol. And desiccant wheel dehumidifiers work just fine.
I've never seen one. What sort of volume are they used to desiccate?
Laboratory desiccators have a volume of a couple of litres, and silica gel works fine for them. Anything bigger and the approach gets impractical.
Ignoring dessicant wheel humidifiers is being less than comprehensive, but they wouldn't have been an option for Dan's basement and skipping any reference to them didn't make "To remove the moisture you must cool the air to below the dew point" any kind of half truth (which implies a deceitful omission, even if NT were is too dim to appreciate what he was saying).
noun: half-truth; plural noun: half-truths
a statement that conveys only part of the truth, especially one used deliberately in order to mislead someone.
"the nuclear industry has often resorted to half-truths and cover-ups"
klaus.kragelund@gmail.com wrote...
boB wrote:
You can also find the max power point by measuring the Voc and then
running at a fixed percentage of that open circuit voltage. If not
the MPP, it's a good starting point at least for non-shaded PV arrays.
That is an easy way, if you have a microcontroller and you can do
periodic sweeps.
That's exactly the approach I was using: set the buck converter's
UVLO setting to near the 45-degree edge of the IV curve, so that's
where it was always running. At low levels, a large electrolytic
saved up solar-panel energy in that region and extracted energy in
chunks whenever enough had built up. Other than the capacitor and
the ULVO setting resistors (assuming accurate hysteresis UVLO), no
other parts were required.
On Monday, 4 November 2019 14:54:48 UTC, Winfield Hill wrote:
John S wrote...
tabbypurr wrote:
And desiccant wheel dehumidifiers work just fine.
And what do you do with the desiccant when it is
saturated with water?
Do they become humidifiers, when (if) the air
otherwise becomes dry again?
The wheel slowly rotates, drying room air on one side, and drying the desiccant on the other. Pass hot air through it, which then circulates around a metal compartment. The metal is cooled by the room air, forming condensation thus removing damp from the compartment. Condensate drips into a container or down a pipe. These machines are ideal for unheated spaces, where compressor types become near useless.
On Tuesday, 5 November 2019 01:26:15 UTC, Bill Sloman wrote:
On Tuesday, November 5, 2019 at 1:14:59 AM UTC+11, tabby wrote:
On Monday, 4 November 2019 05:10:32 UTC, Bill Sloman wrote:
On Monday, November 4, 2019 at 1:15:30 PM UTC+11, tabby wrote:
On Monday, 4 November 2019 01:20:14 UTC, Bill Sloman wrote:
On Monday, November 4, 2019 at 3:48:17 AM UTC+11, tabby wrote:
On Saturday, 2 November 2019 22:27:17 UTC, John S wrote:
Heating the air does not remove the moisture. The water content in
the air stays constant, just the *relative* humidity goes down. To
remove the moisture you must cool the air to below the dew point.
You can then heat the air if needed.
some half truths there
But NT doesn't know, and can't tell us, which bits are less than perfectly accurate.
Sure I can. And for once I will reply despite your childishness.
I can't find anything wrong with either statement, so this looks more like NT not understanding what is being said and.
Dehumidifiers do cool the incoming air below it's dew point. The cold, dry air is then passed over the other end of the heat-pump circuit to warm it up again (and recondense the refrigerant that little bit faster).
Heating air doesn't directly change its moisture content, though it does lower its RH.
So NT agrees that this statement was entirely correct
But heated indoor air inevitably exchanges with outdoor air in domestic properties, which is on average lower in moisture content, and which then drops RH as it warms.
This is just irrelevant carping. Out-door air was be wetter or drier than indoor air, or warmer or cooler. Swapping air with the outside world is ventilation.
Exchange between heated indoor air & unheated outdoor air is the mechanism by which the great majority of houses are dehumidified.
It's an incidental feature of the more general process of ventilation. If you are getting worried by damp patches on the walls, dehumidifiers attack the problem directly. NT is in evasive mode here.
Dehumidifiers do cool the incoming air below it's dew point. The cold, To remove the moisture you must cool the air to below the dew point.
Not really, on both counts there are other options too. Desiccant wheel dehumidifiers don't use chilling at all. Nor do box-of-salt type ones, even though they're of minimal use.
I have seen both sorts of dehumidifier sold for domestic use. It's nuts, but some hardware stores cater for people with little money and even less sense. As NT admits, they don't work well enough to be of much use, and they certainly aren't cost effective.
Laboratory desiccators frequently used water absorbers which can be regenerated by heating, but strictly for tiny volumes of air.
I know from Bill's history here that any moment of sense from him is merely an invitation to enter into his spiral of madness. I'm not interested in doing so & don't care what he has to say.
There's no madness involved, if we exclude NT's inane enthusiasm for unhelpful pontification.
Lol. And desiccant wheel dehumidifiers work just fine.
I've never seen one. What sort of volume are they used to desiccate?
Laboratory desiccators have a volume of a couple of litres, and silica gel works fine for them. Anything bigger and the approach gets impractical.
Ignoring dessicant wheel humidifiers is being less than comprehensive, but they wouldn't have been an option for Dan's basement and skipping any reference to them didn't make "To remove the moisture you must cool the air to below the dew point" any kind of half truth (which implies a deceitful omission, even if NT were is too dim to appreciate what he was saying).
noun: half-truth; plural noun: half-truths
a statement that conveys only part of the truth, especially one used deliberately in order to mislead someone.
"the nuclear industry has often resorted to half-truths and cover-ups"
so when his ignorance has been shown he comes out with more ignorance & bs.
What's new.
On Monday, November 4, 2019 at 9:01:17 PM UTC-5, Winfield Hill wrote:
klaus.kragelund@gmail.com wrote...
boB wrote:
You can also find the max power point by measuring the Voc and then
running at a fixed percentage of that open circuit voltage. If not
the MPP, it's a good starting point at least for non-shaded PV arrays.
That is an easy way, if you have a microcontroller and you can do
periodic sweeps.
That's exactly the approach I was using: set the buck converter's
UVLO setting to near the 45-degree edge of the IV curve, so that's
where it was always running. At low levels, a large electrolytic
saved up solar-panel energy in that region and extracted energy in
chunks whenever enough had built up. Other than the capacitor and
the ULVO setting resistors (assuming accurate hysteresis UVLO), no
other parts were required.
You must know the 45 degree curve is a moving target. The constant current level will vary with insolation and the constant voltage portion of the curve will vary with the temperature. So you will give up significant efficiency area by not adapting to the the moving knee of the curve.
What your system is doing is essentially setting the voltage output of the solar cell to a constant level, a rather crude approximation to the MPP.
Yes, a fast autotuning is a lot faster than a periodic sweep
On 11/4/2019 8:14 AM, tabbypurr@gmail.com wrote:
On Monday, 4 November 2019 05:10:32 UTC, Bill Sloman wrote:
On Monday, November 4, 2019 at 1:15:30 PM UTC+11, tabby wrote:
On Monday, 4 November 2019 01:20:14 UTC, Bill Sloman wrote:
On Monday, November 4, 2019 at 3:48:17 AM UTC+11, tabby wrote:
On Saturday, 2 November 2019 22:27:17 UTC, John S wrote:
Heating the air does not remove the moisture. The water content in the
air stays constant, just the *relative* humidity goes down. To remove
the moisture you must cool the air to below the dew point. You can then
heat the air if needed.
some half truths there
But NT doesn't know, and can't tell us, which bits are less than perfectly accurate.
Sure I can. And for once I will reply despite your childishness.
I can't find anything wrong with either statement, so this looks more like NT not understanding what is being said and.
Dehumidifiers do cool the incoming air below it's dew point. The cold, dry air is then passed over the other end of the heat-pump circuit to warm it up again (and recondense the refrigerant that little bit faster).
Heating air doesn't directly change its moisture content, though it does lower its RH.
So NT agrees that this statement was entirely correct
But heated indoor air inevitably exchanges with outdoor air in domestic properties, which is on average lower in moisture content, and which then drops RH as it warms.
This is just irrelevant carping. Out-door air was be wetter or drier than indoor air, or warmer or cooler. Swapping air with the outside world is ventilation.
Exchange between heated indoor air & unheated outdoor air is the mechanism by which the great majority of houses are dehumidified.
It's an incidental feature of the more general process of ventilation. If you are getting worried by damp patches on the walls, dehumidifiers attack the problem directly. NT is in evasive mode here.
Dehumidifiers do cool the incoming air below it's dew point. The cold, dry
To remove
the moisture you must cool the air to below the dew point.
Not really, on both counts there are other options too. Desiccant wheel dehumidifiers don't use chilling at all. Nor do box-of-salt type ones, even though they're of minimal use.
I have seen both sorts of dehumidifier sold for domestic use. It's nuts, but some hardware stores cater for people with little money and even less sense. As NT admits, they don't work well enough to be of much use, and they certainly aren't cost effective.
Laboratory desiccators frequently used water absorbers which can be regenerated by heating, but strictly for tiny volumes of air.
I know from Bill's history here that any moment of sense from him is merely an invitation to enter into his spiral of madness. I'm not interested in doing so & don't care what he has to say.
There's no madness involved, if we exclude NT's inane enthusiasm for unhelpful pontification.
Lol. And desiccant wheel dehumidifiers work just fine.
And what do you do with the desiccant when it is saturated with water?
On 2019-11-04, John S <Sophi.2@invalid.org> wrote:
On 11/4/2019 8:14 AM, tabbypurr@gmail.com wrote:
On Monday, 4 November 2019 05:10:32 UTC, Bill Sloman wrote:
On Monday, November 4, 2019 at 1:15:30 PM UTC+11, tabby wrote:
On Monday, 4 November 2019 01:20:14 UTC, Bill Sloman wrote:
On Monday, November 4, 2019 at 3:48:17 AM UTC+11, tabby wrote:
On Saturday, 2 November 2019 22:27:17 UTC, John S wrote:
Heating the air does not remove the moisture. The water content in the
air stays constant, just the *relative* humidity goes down. To remove
the moisture you must cool the air to below the dew point. You can then
heat the air if needed.
some half truths there
But NT doesn't know, and can't tell us, which bits are less than perfectly accurate.
Sure I can. And for once I will reply despite your childishness.
I can't find anything wrong with either statement, so this looks more like NT not understanding what is being said and.
Dehumidifiers do cool the incoming air below it's dew point. The cold, dry air is then passed over the other end of the heat-pump circuit to warm it up again (and recondense the refrigerant that little bit faster).
Heating air doesn't directly change its moisture content, though it does lower its RH.
So NT agrees that this statement was entirely correct
But heated indoor air inevitably exchanges with outdoor air in domestic properties, which is on average lower in moisture content, and which then drops RH as it warms.
This is just irrelevant carping. Out-door air was be wetter or drier than indoor air, or warmer or cooler. Swapping air with the outside world is ventilation.
Exchange between heated indoor air & unheated outdoor air is the mechanism by which the great majority of houses are dehumidified.
It's an incidental feature of the more general process of ventilation.. If you are getting worried by damp patches on the walls, dehumidifiers attack the problem directly. NT is in evasive mode here.
Dehumidifiers do cool the incoming air below it's dew point. The cold, dry
To remove
the moisture you must cool the air to below the dew point.
Not really, on both counts there are other options too. Desiccant wheel dehumidifiers don't use chilling at all. Nor do box-of-salt type ones, even though they're of minimal use.
I have seen both sorts of dehumidifier sold for domestic use. It's nuts, but some hardware stores cater for people with little money and even less sense. As NT admits, they don't work well enough to be of much use, and they certainly aren't cost effective.
Laboratory desiccators frequently used water absorbers which can be regenerated by heating, but strictly for tiny volumes of air.
I know from Bill's history here that any moment of sense from him is merely an invitation to enter into his spiral of madness. I'm not interested in doing so & don't care what he has to say.
There's no madness involved, if we exclude NT's inane enthusiasm for unhelpful pontification.
Lol. And desiccant wheel dehumidifiers work just fine.
And what do you do with the desiccant when it is saturated with water?
You blow hot air over it until it dries, and the wheel rotates the
dessicant back into the damp air flow.
On Monday, November 4, 2019 at 8:06:24 AM UTC-5, Martin Brown wrote:
On 03/11/2019 17:15, Rick C wrote:
On Sunday, November 3, 2019 at 4:32:49 AM UTC-5, Martin Brown wrote:
Plenty of designs about usually for heating swimming pools or bulk
thermal stores.
I'm sure there are lots of ways to do this job more efficiently, but
really? You want the guy to run plumbing instead of wires for a 300
watt heater?
It is a way more appropriate solution to the problem than the DIY solar
PV approach and would be able to supply more heat than a puny 300W.
It's also a lot more work for a DIY project. A LOT more work.