Can We Discuss Vintage Refrigerators For A Minute

[launderess]

Ok, whilst doing the housework this afternoon, had PBS on and a program came on about the history of "cold", which ended with how refrigeration and air condition were "discovered" and changed how we all live.

Seem to remember reading at one time there were several methods of home refrigerators, but now mainly one type dominates, how did that happen? Also recall reading an advert for vintage Frigidaire refrigerators/freezers that had a unique "frost free" system that used what they called dry cooling instead of relying on defrosting/heating units to keep the freezer frost free, what was that system and is it still used?

One can understand why auto-defrost models of freezers dominate, but they are not very energy efficient. Is there any benefit to "natural" refrigeration where the condenser allows cool air to follow a natural path (down), while hot air rises, or is having a motor push better?

Just asking.

L.

 

[sudsmaster]

Fan driven air flow became necessary when refrigerators moved the freezer unit into a separate compartment above (or below) the fresh food compartment. Older fridges had the freezer compartment and its coils in the same space as the fresh food compartment.

Obviously the lack of need for a fan to circulate cool air in the older designs was more energy efficient. However, modern fridges make up for the energy needed for such a fan by using more efficient compressors, better insulation, and more efficient defrost cycles, so that a modern frost free top freezer might not use any more energy than an old freezer-in-fridge unit of the same capacity.

As far as Frigidaire's "Dry cooling" slogan, all refrigerators with freezers will dehydrate as they chill. The moisture in the air condenses on the coils, where it is frozen. This results in dry air and so-called "freezer burn" for unprotected foods. Regardless of whether it's frost free or manual defrost. This is why virtually all fridges need to have crispers for vegetables that would otherwise dehydrate and wilt prematurely if not given a higher humidity chamber. I believe the "dry cooling" slogan is simply another way of selling an automatic defrost machine. Fridgidaire might have been one of the first to offer an automatic defrost and/or bottom freezer configuation. Someone else could probably comment on that part.

 

[sudsmaster]

By the way, for a time the ice industry tried to fight the encroachment of electric powered home refrigerators by touting the ability of a true ice box to keep vegetables fresh without the need for a crisper.

I guess Frigidaire would call that "wet cooling", lol.

 

[launderess]

Well according to the above mentioned program, the ice people were fighting a loosing battle. Power companies were happy to sell or at least support refrigerators in the home because they ran on electric power.

The ice people had a really good run thoug, one of the first millionare's in the United States (at a time when even one thousand dollars was rich), was the man who made a killing shipping ice from the northeast all over the country and world. Had always wondered why ice didn't melt as it travelled all over in ships or on trains, but the program explained. Something to do with physics and how much energy it takes to melt ice is equal to heat, or something.

L.

 

[travis]

Efficiency...

While modern refrigerators have better door gaskets and cabinet insulation, they cost more to run that an older manual defrost(yourself) model.

We hooked up a 1931 GE here and figured that it cost less than $2 a month to run. At that price, I am not that concerned about what insualtion may be in there.

Defrosting is easy. You move all the food from on fridge into another and unplug the one that you need to defrost. What! You only have on fridge.

 

[sudsmaster]

I tested a '47 GE manual defrost fridge, and figured it would use about 350 Kwh/yr. At 10cent/Kwh, which would work out to about $1.70/mo. And that is competitive with a modern Energy Star auto defrost fridge of the same volume - which is probably about 18 cu ft, if that.

Granted the '47 GE needs a new door gasket, but I think it wasn't all that much more efficient that a modern fridge of the same capacity could be.

 

[sudsmaster]

Correction: 350 kwh/yr would be about $3/mo for the old manual defrost fridge.

 

[sudsmaster]

I dimly recall from my chemistry years in college that there is something called the heat of crystallization. There is a certain amount of energy required to melt a crystal. I suppose this is because a crystal is more ordered and therefore is a more stable configuration than the liquid. More likely, however, is the fact that a large mass of ice in a ship's hold tends to reduce the surface area available for warming, and keep things frozen longer. As in a glacier in the sun. Or, the advice to keep a freezer filled with frozen food for lower energy consumption than an empty freezer (not taking into the account in turning cold food into frozen food).

I saw the same program, and am looking forward to the next episode. I found the explanation about how the King's magician made the great hall chilly in the middle of summer - using ice and salt - a bit unconvincing. After all, where did he get the ice in the middle of summer? Also, it skipped the fact that if you dissolve some salts, they consume heat and "produce cold" (as in cold packs). Don't know if the alchemists of those times knew about that, though. One such salt is ammonium nitrate, which when it dissolves in water it consumes heat from the water, making it colder. The driving force for it dissolving in water is the increase in entropy gained when it goes from solid crystal to dissolved hydrated ions, even in the face of requiring heat to do it. An alchemist who knows about explosive things (as many did) might know about ammonium nitrate's power to cool things as it hydrates. I'm a bit surprised the show didn't discuss this possibility.

In the case of ice boxes and manual defrost fridges, a fair amount of water is released as the ice melts, either in the normal operation of the ice box, or the manual defrosting of the fridge. Of course, jut as much water is released by an automatic defrost fridge as a manual defrost fridge, but the homekeeper usually doesn't see it, as it is shunted to a pan underneath the fridge where the air circulated by a fan evaporates it into the room.

Back when I was in college I used to be amused by the method some roommates would use to manually defrost a fridge. They'd attack the blocks of ice with an ice pick or screwdriver. Usually I would catch this in time, and show them how to do it with much less effort by placing pans of hot water in the freezer compartment, gently melting the ice blocks so that they would fall away from the coils, without the risk of puncturing a coil. But of course there would be inevitable moisture released and a thorough wipedown of the fridge interior was required to avoid having the released water from being redeposited on the freezer coils as soon as the door was closed and the fridge returned to operation.

 

[sudsmaster]

Anybody catch the second hour of the "Absolute Zero" program?

Fairly exotic physics... chilling and compressing gases down to near absolute zero... achieving a quantum state called a "Bose-Einstein condensate", where matter ceases to act like it's made of individual particles but instead as a single synchronized wave (oversimplified, of course). Also the usual superconductors and such. And I don't think anyone could be quite as nerdy as some of the physicists interviewed for the program.

Interesting sidelight... after a leading physicist named Dewar was beat to the liquification of Helium, he abandoned low temperature research and focused on the science of soap bubbles... wonder what his favorite laundry detergent was...?

 

[bajaespuma]

Yes, it was some of the most fascinating stuff I've seen in a long time on TV that didn't involve someone named "spears". I remember being fascinated by the concept of O degrees Kelvin in high-school chemistry class because, as we were taught, matter simply "collapsed" as in a black hole. Was Dewar related to the whiskey people?

 

[sudsmaster]

Dewar invented the vacuum flask, or thermos, but I don't think he had any connection to the whisky of the same name.

http://en.wikipedia.org/wiki/Sir_James_Dewar