For those who rarely fill their refrigerators.....
Shadowland
place containers of water into the empty areas.
Once that water cools, it acts like a cold sink. When you open the
refrig door, all the cool air gets out and the all the new air must be
cooled again.
With containers of water filling up empty space...that just means
there's less air that needs to be cooled.
That water keeps the coolness much better than the air.
With a filled refrig you'll find your frig saving energy.
Don K
news:1192307907.1...@i13g2000prf.googlegroups.com...
> If you find that your refrigerator is say usually only half full,
> place containers of water into the empty areas.
> Once that water cools, it acts like a cold sink. When you open the
> refrig door, all the cool air gets out and the all the new air must be
> cooled again.
> With containers of water filling up empty space...that just means
> there's less air that needs to be cooled.
> That water keeps the coolness much better than the air.
>
How about filling it with plastic peanuts instead?
Being an insulator, the peanuts will absorb heat from the outside
air slower than containers of water.
Or air-bag packing? Or thermos bottles? Or defunct vacuum tubes?
Don
Shadowland
> How about filling it with plastic peanuts instead?
> Being an insulator, the peanuts will absorb heat from the outside
> air slower than containers of water.
>
> Or air-bag packing? Or thermos bottles? Or defunct vacuum tubes?
Yes any of these will work.
However I'll add that should you have a power outage, containers of
cold water will keep your food cool longer than those others you
mention.
George
that water and I think it has a twenty year storage life.
Al Bundy
>
> news:1192307907.1...@i13g2000prf.googlegroups.com...
>
> > If you find that your refrigerator is say usually only half full,
> > place containers of water into the empty areas.
> > Once that water cools, it acts like a cold sink. When you open the
> > refrig door, all the cool air gets out and the all the new air must be
> > cooled again.
> > With containers of water filling up empty space...that just means
> > there's less air that needs to be cooled.
> > That water keeps the coolness much better than the air.
>
>
>
>
> Don
Right Don. Who doesn't have a stock of old 6CA7,EL34,6BQ5/
EL84,6L6,6K6,5881,6V6,and KT66 tubes around? The packages tend to get
real soggy though.
Rod Speed
You'll actually find that you save so little energy that it doesnt
even save as much as cooling that water down does.
Siskuwihane
> Don K wrote:
> > "Shadowland" <saints2...@yahoo.com> wrote in message
Why buckets? We just use Cool Whip by itself.
Bob F
"Abe" <no...@nowhere.com> wrote in message
news:5ni2h35ck0pcernue...@4ax.com...
Only if you want to spend energy cooling them down. And lose it when you take
them out. If you are just trying to cut door-opening losses, bags of foam
peanuts would help more.
Bob
AllEmailDeletedImmediately
"George" <geo...@nospam.invalid> wrote in message
news:IaCdnRaur-NkqYza...@comcast.com...
with the bonus of being edible ! NOT!!!!
>
AllEmailDeletedImmediately
why don't we just stack some slate in there. they absorb heat all day
and let it out at night. maybe they work in reverse.
>
timeOday
> I think you need something with mass.
Nah, air in airtight containers won't flow out of the fridge when you
open the door any more than water would.
Of course when you open the door the air bottles will absorb a little
heat from the ambient air, but so would water bottles.
Somebody mentioned keeping the fridge cold during a power outage, which
is a different matter...
nicks...@ece.villanova.edu
No.
Nick
E Z Peaces
It would take about 12 k joules to cool it from 70 to 40 F. With a
COP of 2, that would be about 0.00333 kWh of electricity. At 10 cents
per kWh, it would cost you 0.03 cents or 0.0003 dollars.
It appears that the major cost of opening the door is in the heating of
the solids and liquids inside by the flow of air and radiation from the
room. That would depend more on how long you kept the door open than on
how many times you opened it.
George
least 20 years. I guess one could also substitute it with Walmart
embalmed "fresh meat" for the same effect.
throwitout
> >"Shadowland" <saints2...@yahoo.com> wrote in message
I use lead. It's fairly dense but much cheaper than gold.
Jeff
I think this is an urban myth. Anyone ever do a actual research on this?
Water has a very high specific heat and it will take a lot of energy
to remove the BTUs of heat. If you never put in the water jugs you'd
never have to remove their heat. Air on the other hand has a really low
specific heat per cubic foot (and so would those plastic peanuts that
have been mentioned).
What the water does is store thermal energy and even out any
temperature swings. But it has to be cooled itself and that is power
that you never would have spent if you hadn't put it in! And that power
drain is not just initial, but continuous. I think a better question is
just how much less electricity will an empty fridge use than a full one.
Any one with a "kill a watt" want to give that a try? I think the
losses of door openings are more of length of time than number of
openings. Just like you shouldn't leave your front door open on a cold
day, you shouldn't leave your fridge door open while you are thinking.
Jeff
>
Jeff
That's a good question. And the oddball that is keeping their 6L6s
elsewhere I suppose will have to use their obsolete incandescent light
bulbs. Or maybe just keep that old CRT monitor in the fridge. You could
always hide the last beer behind it, who would look?
Jeff
nicks...@ece.villanova.edu
>What the water does is store thermal energy and even out any
>temperature swings...
... which don't affect the fridge power consumption.
>But it has to be cooled itself and that is power that you never would have
>spent if you hadn't put it in! And that power drain is not just initial,
>but continuous.
It's mostly initial, but adding mass surface inside the fridge increases
airflow and condensation when the door is open, so the fridge gains more
heat when the door is open and uses more energy over time, IMO.
Nick
Bob F
"Jeff" <dont_...@all.uk> wrote in message
news:13h6lqs...@corp.supernews.com...
If your fridge is empty, you will obviously save energy, as you will have no
reason to open the door.
I suppose that jugs of water could increase efficiency by lengthening the cycle
time. Has anyone ever done tests on this?
Bob
Logan Shaw
> What the water does is store thermal energy and even out any
> temperature swings. But it has to be cooled itself and that is power
> that you never would have spent if you hadn't put it in! And that power
> drain is not just initial, but continuous.
I think you're 100% correct up to the "not just initial, but continuous"
part. I don't think that part is true because if it were, the jugs of
water would be a magical source of heat. Heat enters through the walls
of the fridge at a fixed rate (given a certain temperature inside), and
what's inside the fridge doesn't affect how much heat enter.
However, a larger thermal mass will cause the temperature inside to shift
more slowly because more heat is required to raise the temperature a given
amount. And that is the reasoning for keeping a full fridge: the heat
gain from the exterior is the same, but if the thermal mass is higher,
the cycle time of the refrigeration system will be longer. To the extent
that there is overhead in starting up the refrigeration system, this could
increase the efficiency slightly.
> I think a better question is
> just how much less electricity will an empty fridge use than a full one.
Yes, that is the ultimate test. I suspect the thermal mass of the
inside and its effect on cycle time is pretty well overwhelmed by other
factors, like how much insulation there is in the walls of the fridge,
whether the door seals are sealing properly, and whether the coils have
been cleaned recently.
- Logan
Logan Shaw
> It's mostly initial, but adding mass surface inside the fridge increases
> airflow and condensation when the door is open, so the fridge gains more
> heat when the door is open and uses more energy over time, IMO.
That probably depends on how you arrange things physically within the
fridge. If you, say, never use the bottom shelf and you put a 5-gallon
jug of water down there, and orient it so that it blocks the air from
sinking out, it could reduce the airflow a lot and maybe only increase
the condensation a little. Also, if you fill the fridge *really* full,
you are reducing the total volume of air in the fridge, and thus reducing
the airflow (because it takes force to move air through narrow passages,
due to friction).
I guess the best plan is to get a fridge with an airlock instead of a
door. Or remodel your kitchen and make it much larger so that you can
fit in a chest fridge / freezer. Or maybe work on antigravity. Or
get some of those clear plastic strips they hang as a curtain in doors
to prevent excess airflow.
- Logan
Rod Speed
> Jeff wrote:
>> What the water does is store thermal energy and even out any
>> temperature swings. But it has to be cooled itself and that is power
>> that you never would have spent if you hadn't put it in! And that
>> power drain is not just initial, but continuous.
> I think you're 100% correct up to the "not just initial, but continuous" part.
I initially had the same reaction but decided its just clumsy wording
and he really means that there will be an ongoing effect on the
amount of heat they are involved in every time the door is opened,
in the sense that nick spelt that out more clearly, rather than
continuous in the sense of what happens when the door is kept closed.
> I don't think that part is true because if it were, the jugs of water would be a magical source of heat. Heat enters
> through the walls of the fridge at a fixed rate (given a certain temperature inside), and what's inside the fridge
> doesn't affect how much heat enter.
I doubt he doesnt realise that.
> However, a larger thermal mass will cause the temperature inside to shift more slowly because more heat is required to
> raise the
> temperature a given amount. And that is the reasoning for keeping a full fridge: the heat gain from the exterior is
> the same, but if the
> thermal mass is higher, the cycle time of the refrigeration system
> will be longer. To the extent that there is overhead in starting up
> the refrigeration system, this could increase the efficiency slightly.
And you may well get the effect nick proposed, the extra surfaces
of the containers of water may well provide a place for condensation
to occur every time the door is opened, and that condensation has
to be cooled as well.
>> I think a better question is just how much less electricity will an empty fridge use than a full one.
> Yes, that is the ultimate test.
I bet its actually surprisingly difficult to test, because the amount of
energy required to cool the air that replaces what falls out of the
fridge without the containers of water is so low, that it may well
be swamped by the variations in the different airflow with the
containers of water, and the effect of condensation in that situation etc.
> I suspect the thermal mass of the inside and its effect on cycle time is pretty well overwhelmed by other factors,
> like how much insulation there is in the walls of the fridge, whether the door seals are sealing properly, and whether
> the coils have been cleaned recently.
And how often the door is opened in spades, and the
state of the air outside the fridge, particularly humidity wise.
Jeff
> Jeff wrote:
>
>> What the water does is store thermal energy and even out any
>> temperature swings. But it has to be cooled itself and that is power
>> that you never would have spent if you hadn't put it in! And that
>> power drain is not just initial, but continuous.
>
>
> I think you're 100% correct up to the "not just initial, but continuous"
> part. I don't think that part is true because if it were, the jugs of
> water would be a magical source of heat. Heat enters through the walls
> of the fridge at a fixed rate (given a certain temperature inside), and
> what's inside the fridge doesn't affect how much heat enter.
I'm unsure of this myself. Most of the loss is initial, but there is
a cycle of slight cooling and slight warming (including the defrost
cycle) and more mass will take more power to drive that. Note also
Nicks post about another surface for moisture to condense on when the
door is open.
>
> However, a larger thermal mass will cause the temperature inside to shift
> more slowly because more heat is required to raise the temperature a given
> amount. And that is the reasoning for keeping a full fridge: the heat
> gain from the exterior is the same, but if the thermal mass is higher,
> the cycle time of the refrigeration system will be longer. To the extent
> that there is overhead in starting up the refrigeration system, this could
> increase the efficiency slightly.
Could be, but I think the start up surge is a small compared to the
run time. I remember when we discussed fluorescent starting surge that
another urban myth of leaving fluorescent lights on saved money was
debunked.
>
>> I think a better question is just how much less electricity will an
>> empty fridge use than a full one.
>
>
> Yes, that is the ultimate test. I suspect the thermal mass of the
> inside and its effect on cycle time is pretty well overwhelmed by other
> factors, like how much insulation there is in the walls of the fridge,
> whether the door seals are sealing properly, and whether the coils have
> been cleaned recently.
Refrigerator power useage has dropped dramatically. In the last decade
it plummeted and if you go back another decade or so you'll see a
another step in efficiency. How much of that is compressor technology
and how much is insulation or even poor maintenance I don't know.
Curiously while researching that I ran across this. "Ten tips to
reduce refrigerator power consumption":
<URL:
http://ezinearticles.com/?10-Tips-To-Reduce-The-Power-Consumption-Of-The-Refrigerator&id=526324
/>
And the urban myth of the jugs of water is nowhere to be found.
Wish I could find the power consumption stats, funny how I kept
running across those while I was looking for something completely different!
Jeff
>
> - Logan
8org...@gmail.com
long had a fairly distinct understanding, mostly I think from general
(mostly online) reading though also possibly from Consumer Reports
which I follow and have sometimes subscribed to, that:
For Refrigerators, the least power consumption is "apt" to be at about
only 1/3 full; nearly as good is about 1/2 full.
Of course, in practical terms, this is going to vary a great deal
depending upon many variables--even probably with the type of food
involved. Another possibly big factor, I think, might be humidity
level: I think there might be "little comparison" between how much
energy at least initially, it'd take to cool down very humid air,
compared to nonhumid. Think of travelling, say biking or walking,
down a country road on a cool night--near wetlands or swamps, the air
is suddenly vastly warmer!--because, the humid air there very much
holds the heat. Just which way this bounces as to net effect with
refrigerators, I don't know, except to think that with my refrigs
which I tend to keep quite full (small farmer here), I think the air
tends to be very humid, so probably I get an advantage since losing
cold humid air would clearer be a greater loss than the equivalent of
lowly humid air, and so fullness here would probably be helping me
quite a bit.
That said, I do agree I think that in general, losing reasonable
amounts of air from a frig, is probably not such a big deal, and the
air/air's coolness is easily restored--which, I guess probably means I
think in most refrigerators (unlike mine with lots of fruit, wet
freshly washed produce etc) the frig air is probably kept at low
humidity, by the frig by design (except crispers, which, if they kept
at high humidity to keep produce moist and unwilted, would seem to
demonstrate the basic low-humidity plan of the (rest of) the frig not
counting the crispers.
As for stuff/amount of stuff in the refrig and the effect of such
'ballast" in helping maintain coldness, what about the shelf systems
and such? Extensive shelving, especially glass, must be able to hold
onto a lot of coolness.
The thing I personally orry about (along with my biggest concern of
all: keeping the good contained preserved and intact) more, is airflow
in the frig compartment overall--especially possibly near wherever the
thermostat happens to be, which I think varies among different makes--
because after all, the basic governance of refrigerator chilling
efforts overall, other than use factors, settings chosen and possibly
things like the mentioned humidity factor--would seem very much
revolve upon what's sensed, as to temperature, by that thermostat.
Which, I suppose, is why the thermostats are I think, usually toward
the back wall, where they will be more shielded by food present and by
distance from the door.
..."my thoughts" on the topic, if little more than that,
anyway...while as a berry grower/small farmer, the topic "is" one I
have had to take seriously both for walk-in cooler and regular refrigs.
nicks...@ece.villanova.edu
>... If you, say, never use the bottom shelf and you put a 5-gallon jug of
>water down there, and orient it so that it blocks the air from sinking out,
>it could reduce the airflow a lot and maybe only increase the condensation
>a little.
Near the bottom seems better than near the top, since cool air falls.
And empty seems better than water-filled, for less condensation. And
thin vs thick walls with more thermal mass, eg balloons vs jugs.
>Also, if you fill the fridge *really* full, you are reducing the total
>volume of air in the fridge...
That's good, after the door closes. Cooling 1 ft^3 of 0.075 lb/ft^3 70 F air
with a 0.24 Btu/lb-F specific heat to 36 F takes 0.075x0.24(70-36) = 0.6 Btu,
ie 0.18 watt-hour of heat energy, vs 1 Btu (0.29 Wh of electrical energy)
for each compressor start, vs a frugal fridge consuming 1 kWh/day.
If we open a 14 ft^3 fridge door 12 times per day, how much electrical energy
can we save by reducing it to a 7 ft^3 fridge with tightly-packed balloons?
Recall that 1 kWh of electrical energy can supply 3 kWh of coolth for a fridge
with a COP of 3. How much can we save with a 4- vs 1-hour cycle time?
>and thus reducing the airflow (because it takes force to move air through
>narrow passages, due to friction).
With gaps larger than 1/8" or so, more cold surfaces not only increase
condensation when the door is open. They also increase the rate of room
airflow through the fridge when the door is open, since room air that enters
the fridge leaves colder, and the air density difference driving the flow
is larger... cfm = 16.6Asqrt(HdT). I'd guess more condensation and airflow
in a fridge packed with water jugs waste a lot more energy than smaller
air volume and longer cycle time save.
Nick
E Z Peaces
>
> Could be, but I think the start up surge is a small compared to the
> run time. I remember when we discussed fluorescent starting surge that
> another urban myth of leaving fluorescent lights on saved money was
> debunked.
Ann Landers once settled the controversy by ruling that it's more
economical to leave your lights on if you don't plan to be gone more
than four hours. She said that's the final word on the subject.
Don K
news:ff5m4t$j74$1...@registered.motzarella.org...
And thus the feud with Dear Abbey started.
Don
AllEmailDeletedImmediately
"E Z Peaces" <ca...@invalid.invalid> wrote in message
news:ff5m4t$j74$1...@registered.motzarella.org...
i don't know about ann, but i thought it was 30 mins.
Logan Shaw
I doubt it's that high. More like 30 seconds (or even 3 seconds) if you're
talking purely about the break-even point with energy usage.
Basically, imagine you have a 100W light bulb. If it draws extra power
for the first 1 second it's on, and if it draws so much extra power that
it would take 30 minutes of regular usage to equal that, then it would
have to be drawing 30 * 60 * 100W or 180000W during that first second.
And that amount of power would vaporize the wires.
You can take into account the cost of replacing a light bulb as well.
That's a little more, but since bulbs are something like 50 cents, and
can be switched off and on hundreds of times, that doesn't add up to
30 minutes either. Let's say the bulb can be switched off and on 500
times. Then it costs 0.1 cents to turn it off and on. If a kilowatt-hour
of electricity costs 10 cents, you only need to save 0.01 kilowatt-hours
to make up that 0.1 cents of wear and tear on the bulb. And a 100W bulb
will use that much power in 6 minutes. And you can probably switch a
bulb off and on more than 500 times.
The math might be a little different for fluorescent bulbs (both compact
fluorescent and traditional) since the bulbs cost more, use less energy,
and might not be able to stand as many off/on cycles. But I still would
be surprised if it's worth leaving them on for 30 minutes.
- Logan
Jeff
> AllEmailDeletedImmediately wrote:
>
>> "E Z Peaces" <ca...@invalid.invalid> wrote in message
>> news:ff5m4t$j74$1...@registered.motzarella.org...
>>
>>> Jeff wrote:
>>>
>>>> Could be, but I think the start up surge is a small compared to
>>>> the run time. I remember when we discussed fluorescent starting
>>>> surge that another urban myth of leaving fluorescent lights on saved
>>>> money was debunked.
>>>
>>> Ann Landers once settled the controversy by ruling that it's more
>>> economical to leave your lights on if you don't plan to be gone more
>>> than four hours. She said that's the final word on the subject.
>>
>>
>> i don't know about ann, but i thought it was 30 mins.
>
>
> I doubt it's that high. More like 30 seconds (or even 3 seconds) if you're
> talking purely about the break-even point with energy usage.
It's in the low to single seconds. Every flicker is an additional turn
on surge (if you have fluorescents that blink for a while), but you
don't want that. And every turn on wears the bulb a bit, I think it was
in the low minute range. Anyhow, Don K, covered this rather completely
some months back if you want to google it, or search Dons site.
In general, just turn it off.
>
> Basically, imagine you have a 100W light bulb. If it draws extra power
> for the first 1 second it's on, and if it draws so much extra power that
> it would take 30 minutes of regular usage to equal that, then it would
> have to be drawing 30 * 60 * 100W or 180000W during that first second.
> And that amount of power would vaporize the wires.
Nicely put.
Jeff
Jeff
I just came back from visiting the refrigerator section of my local
Home Despot. I looked in the biggest fridge they had and the Energy
Guide ratings listed it as $40/year (420 kWhr). Now that ain't much.
Cheaper but still large fridges were in the $50/year range. Smaller
refrigerators were under $30/year.
I'm thinking that at $4/month there are better targets for saving
money. That's if you have a relatively new fridge. I guess that as
expensive as they are you may have about a 20 year payback...
Jeff
nicks...@ece.villanova.edu
>The math might be a little different for fluorescent bulbs... since the bulbs
>cost more,
$2
>use less energy,
34W
>and might not be able to stand as many off/on cycles.
Each start uses up about 6 minutes of something like a 20K hour lifetime.
Nick
E Z Peaces
run them four hours at a time. If I'd seen data for shorter on-times, I
could have calculated the wear and tear of starting a tube.
I hate it when F40 tubes get blinky, for fewer stores carry them these
days. In the kitchen I switch my twin fixture off several times an hour
when I'm popping in and out. I've wondered about the break-even point.
Suppose a pair of tubes cost $6. Each cycle would depreciate them 0.003
cents. If the fixture uses 100 watts at 10 cents a kWh, that's .00028
cents a second. I imagine any starting surge is much less than .00028
cents.
So the break-even point is 11 seconds, excluding switch wear. (This
house has switches that have been in daily use since 1925.) If I won't
need the lights for six minutes, switching them off also means fewer
shopping trips to find tubes.
The big reason to switch off the lights every time I leave the kitchen
is not to get into the habit of leaving all lights on whenever I'm home,
as Ann Landers seemed to recommend.
Shaun Eli
cooling the water would exceed any future savings, wait until winter
and leave the water outside before you put it in the fridge.
Anyway, the water coming out of my tap is usually pretty cold in the
wintertime anyway.
Shaun Eli
www.BrainChampagne.com
Brain Champagne: Clever Comedy for Smart Minds (sm)
now with a nine minute comedy video available free on the website
Seerialmom
> Shadowland <saints2...@yahoo.com> wrote:
> > If you find that your refrigerator is say usually only half full,
> > place containers of water into the empty areas.
> > Once that water cools, it acts like a cold sink. When you open the
> > refrig door, all the cool air gets out and the all the new air must be
> > cooled again.
> > With containers of water filling up empty space...that just means
> > there's less air that needs to be cooled.
> > That water keeps the coolness much better than the air.
>
> > With a filled refrig you'll find your frig saving energy.
>
> even save as much as cooling that water down does.
That sure sounds like a challenge for the Mythbusters, doesn't it?
Rod Speed
Yeah, but its not that easy to measure and they made rather spectacular
fools of themselves with a much simpler problem, the question about
whether its better to drive with the windows up and the aircon on in
summer or to drive with the windows open fuel consumption wise.
Jeff
> If you find that your refrigerator is say usually only half full,
> place containers of water into the empty areas.
> Once that water cools, it acts like a cold sink. When you open the
> refrig door, all the cool air gets out and the all the new air must be
> cooled again.
> With containers of water filling up empty space...that just means
> there's less air that needs to be cooled.
> That water keeps the coolness much better than the air.
OK. I'm giving this a test run. I didn't have any jugs of water, so I
put in two cases of beer. Liquid is liquid.
The preliminary results so far have been satisfying.
Jeff