Just wondering:
does it use more energy to dry my laundry in the drier, exhausting the
humidity outside, or to just hang them in the basement and let the
dehumidifier do the job, or is it the same? Assuming nice weather so
that you're not pumping out air you had to warm or cool, and that the
dehumidifier has enough excess capacity. I can't think of a basis to
differentiate.

z wrote:
Just wondering:
does it use more energy to dry my laundry in the drier, exhausting the
humidity outside, or to just hang them in the basement and let the
dehumidifier do the job, or is it the same? Assuming nice weather so
that you're not pumping out air you had to warm or cool, and that the
dehumidifier has enough excess capacity. I can't think of a basis to
differentiate.

Thermodynamically they should be the same, but since drier also ejects
hot air, the extra energy to just heat the air would favor drying in
the basement. Best thing to do is dry outside
Frank

It would always use more energy to use a clothes dryer. All the heat
blown out the vent is lost. Not to say air drying inside won't cost as
well. The heat of evaporization will cool the air in the winter. In
the summer, the dehumidifier will add heat.

I wonder why we bother using heated air to dry clothes. Instead, seal
the dryer and evacuate all the air. In a vacuum, the water will boil
out of the clothes at room temperature. There will be zero heat or
stress to the clothes. Only the energy necessary to cause the state
change of the water, plus some loss in the hardware, will be used.

-rev



z wrote:
Just wondering:
does it use more energy to dry my laundry in the drier, exhausting the
humidity outside, or to just hang them in the basement and let the
dehumidifier do the job, or is it the same? Assuming nice weather so
that you're not pumping out air you had to warm or cool, and that the
dehumidifier has enough excess capacity. I can't think of a basis to
differentiate.

The Reverend Natural Light wrote:
....
I wonder why we bother using heated air to dry clothes. Instead, seal
the dryer and evacuate all the air. ...

Because the cost of building/maintaing a high-volume vacuum pump would
exceed that of a conventional drier by far more than the energy
savings...

dpb wrote:

... the cost of building/maintaing a high-volume vacuum pump would
exceed that of a conventional drier by far more than the energy savings...

Would you have any evidence for this article of faith?

Suppose it removes 10 pounds of water in 1 hour...

Nick

wrote:
dpb wrote:

... the cost of building/maintaing a high-volume vacuum pump would
exceed that of a conventional drier by far more than the energy savings...

Would you have any evidence for this article of faith?

Suppose it removes 10 pounds of water in 1 hour...
....

Engineering judgement...

The problem I see is that in one instance you're making a pretty cheesy
mechanical system w/ cheap heat source, the other is (relatively) a
precision device to pull and maintain the necessary vacuum. While the
theoretical energy savings may be there, to me the practicalities would
negate them...

I find this area interesting and will run it by a buddy who is a
engineer tonight.

i have some vacuumn pumps sitting unused and may try it on a small
scale just out of curosity

Well, it is a grand idea, but there are more challenging obstacles in
the way than simple economics.

The first time a woman put her laundry into the VacuDry(tm) heatless
clothes dryer and pulled out a crusty mess of wrinkled clothes, it'd be
back to the drawing board. We depend on the fluff of the hot air
dryer.

But the concept would make for a very entertaining hair dryer.


-rev



wrote:
I find this area interesting and will run it by a buddy who is a
engineer tonight.

i have some vacuumn pumps sitting unused and may try it on a small
scale just out of curosity

dpb wrote:

... the cost of building/maintaing a high-volume vacuum pump would
exceed that of a conventional drier by far more than the energy savings...

Would you have any evidence for this article of faith?

Suppose it removes 10 pounds of water in 1 hour...
...

Engineering judgement...

Aha, bull**** :-)

Nick, engineer.

both use a fan, but the dryer heats as well. in the winter you need
more humidity anyway.

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z wrote:
Just wondering:
does it use more energy to dry my laundry in the drier, exhausting the
humidity outside, or to just hang them in the basement and let the
dehumidifier do the job, or is it the same? Assuming nice weather so
that you're not pumping out air you had to warm or cool, and that the
dehumidifier has enough excess capacity. I can't think of a basis to
differentiate.

z wrote:

Just wondering:
does it use more energy to dry my laundry in the drier, exhausting the
humidity outside, or to just hang them in the basement and let the
dehumidifier do the job, or is it the same? Assuming nice weather so
that you're not pumping out air you had to warm or cool, and that the
dehumidifier has enough excess capacity. I can't think of a basis to
differentiate.



Well, wad'ya know!

http://www.instructables.com/id/E3CZW45XVXEP2866YX/

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
"Rudeness is the weak man's imitation of strength."

z wrote:

Just wondering:
does it use more energy to dry my laundry in the drier, exhausting the
humidity outside, or to just hang them in the basement and let the
dehumidifier do the job, or is it the same? Assuming nice weather so
that you're not pumping out air you had to warm or cool, and that the
dehumidifier has enough excess capacity. I can't think of a basis to
differentiate.


Even better, someone patented your idea in 1977:

http://tinyurl.com/rlvjl

You'll need a way to view TIFF images if you want to see the drawings.

Looks like those who noted it'd cost more to produce than the energy
savings netted were probably on target.

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
"Rudeness is the weak man's imitation of strength."

dpb wrote:
The Reverend Natural Light wrote:
...
I wonder why we bother using heated air to dry clothes. Instead, seal
the dryer and evacuate all the air. ...

Because the cost of building/maintaing a high-volume vacuum pump would
exceed that of a conventional drier by far more than the energy
savings...

But what if you have like a whole house vacuum cleaner, with a big pump
already downstairs? It could even be beefed up for higher performance.
As somebody who's always stocked his house with stuff from Lab
Supplies, I've always thought lab-type things like vacuum and
compressed air taps would be almost as handy around the house as around
the lab. For us nerds, anyway.

You haven't lived until you've got a roll of real tin foil instead of
the aluminum crap.

The Reverend Natural Light wrote:
Well, it is a grand idea, but there are more challenging obstacles in
the way than simple economics.

The first time a woman put her laundry into the VacuDry(tm) heatless
clothes dryer and pulled out a crusty mess of wrinkled clothes, it'd be
back to the drawing board. We depend on the fluff of the hot air
dryer.

Keep the drier rotating to avoid wrinkles, maybe toss in one of those
spiky rubber balls for fluffiness.


But the concept would make for a very entertaining hair dryer.


-rev



wrote:
I find this area interesting and will run it by a buddy who is a
engineer tonight.

i have some vacuumn pumps sitting unused and may try it on a small
scale just out of curosity

Jeff Wisnia wrote:
z wrote:

Just wondering:
does it use more energy to dry my laundry in the drier, exhausting the
humidity outside, or to just hang them in the basement and let the
dehumidifier do the job, or is it the same? Assuming nice weather so
that you're not pumping out air you had to warm or cool, and that the
dehumidifier has enough excess capacity. I can't think of a basis to
differentiate.


Even better, someone patented your idea in 1977:

http://tinyurl.com/rlvjl

You'll need a way to view TIFF images if you want to see the drawings.

Looks like those who noted it'd cost more to produce than the energy
savings netted were probably on target.

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
"Rudeness is the weak man's imitation of strength."

Yeah, but look at all the folks who get a vacuum sealer for their
kitchen.

This is why we need to colonize space. Simple access to free vacuum.
"Mother's coming over and the house is pretty dusty. Honey, put the air
mask on the cat, I'm going to vacuum again." Sound of airlock
opening......

Frank wrote:
z wrote:
Just wondering:
does it use more energy to dry my laundry in the drier, exhausting the
humidity outside, or to just hang them in the basement and let the
dehumidifier do the job, or is it the same? Assuming nice weather so
that you're not pumping out air you had to warm or cool, and that the
dehumidifier has enough excess capacity. I can't think of a basis to
differentiate.

Thermodynamically they should be the same, but since drier also ejects
hot air, the extra energy to just heat the air would favor drying in
the basement. Best thing to do is dry outside
Frank

Well, I don't know, though. The one way, you expend energy to heat the
air to evaporate the water...
the other way, the water evaporates by sucking heat out of the ambient
air, which you are not heating at this season (given the parameters of
my posted question) but you have to expend energy to condense the water
out of the air.
I guess if that was all there was to it, the second way would have to
expend more energy to cover entropy etc., but there are efficiency
questions involved.....
Life was easier in school when everything was frictionless, 100%
efficient, and spherical.