Fast Company report - Whirlpool's new refrigerators will be colder and thinner
Whirlpool Refrigerator Technology
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Fast Company report - Whirlpool's new refrigerators will be colder and thinner
My bachelor's thesis I finished in October is quite literally in part about insulation in a refrigerator.
Vacuum insulation is nothing new and is indeed the future of the refrigerator sector.
Vacuum insulation panels - short VIPs - are usually made of some kind of low thermal conductivity material (a foamed polymer, not unlike polystyrene or such; alternatively glass fibre) and a getter that absorbs any gasses that could infiltrate over the decades these panels have to keep a high vacuum.
The inner hollow area is evacuated during production of the panels down to a pressure in 1/1000 range of atmospheric pressure, or lower. The inner walls of that panel are sometimes treated with a finish so radiant heat transfer between the walls is reduced.
The panels are arranged around the compartment during production and then foamed in to create a structurally sound appliance with no thermal bridges.
The thermal conductivity of a VIP compared to typical foam insulation is about 1/3 with equal thickness.
Now, there are 2 HUGE red flags in that article.
First is, that the material of the casing is metal.
Metal is SO MUCH more thermally conductive it's not even funny.
I did some calculations about heat transfer out of the heat exchanger in a typical fridge design here in the EU.
The heat exchanger is bonded onto a metal plate which in turn is bonded on the outside walls of the fridge compartment.
Calculating the temperature drop (or rise in that case) across that barrier resulted in basically all temperature drop was through the plastic fridge walls.
In numbers, aluminium has a heat transfer capability of 160W through 1 meter at 1°C of temperature difference across it.
Steel has 50.
Simple, typical polyurethane foam? 0.03 watts.
Or in short: ANY METAL in ANY thermal insulation system is just stupid. You don't use metal across thermal barriers, period.
Second is that they filled the void with something.
Polyurethane foams are pretty good insulators, aerogels are about 1/3 less thermally conductive.
But even then, a regular, "empty" VIP is about half as thermally conductive.
Simply because for the largest part, there is nothing in it that could conduct heat.
So, filling the void back up with any material reduces the advantages of VIPs further and further.
That's one of the reasons VIPs are "only" 50% better than aerogels - you need really strong side walls to carry the force of that whole hollow, evacuated space and resulting pressure differential.
So...
Yeah..
I don't see what or how that technology changes anything or makes anything really new.
I guess some of the description is "press speech" so people get impressed and don't ask questions.
But most it tells me that something there isn't quite adding up.
Vacuum insulation is nothing new and is indeed the future of the refrigerator sector.
Vacuum insulation panels - short VIPs - are usually made of some kind of low thermal conductivity material (a foamed polymer, not unlike polystyrene or such; alternatively glass fibre) and a getter that absorbs any gasses that could infiltrate over the decades these panels have to keep a high vacuum.
The inner hollow area is evacuated during production of the panels down to a pressure in 1/1000 range of atmospheric pressure, or lower. The inner walls of that panel are sometimes treated with a finish so radiant heat transfer between the walls is reduced.
The panels are arranged around the compartment during production and then foamed in to create a structurally sound appliance with no thermal bridges.
The thermal conductivity of a VIP compared to typical foam insulation is about 1/3 with equal thickness.
Now, there are 2 HUGE red flags in that article.
First is, that the material of the casing is metal.
Metal is SO MUCH more thermally conductive it's not even funny.
I did some calculations about heat transfer out of the heat exchanger in a typical fridge design here in the EU.
The heat exchanger is bonded onto a metal plate which in turn is bonded on the outside walls of the fridge compartment.
Calculating the temperature drop (or rise in that case) across that barrier resulted in basically all temperature drop was through the plastic fridge walls.
In numbers, aluminium has a heat transfer capability of 160W through 1 meter at 1°C of temperature difference across it.
Steel has 50.
Simple, typical polyurethane foam? 0.03 watts.
Or in short: ANY METAL in ANY thermal insulation system is just stupid. You don't use metal across thermal barriers, period.
Second is that they filled the void with something.
Polyurethane foams are pretty good insulators, aerogels are about 1/3 less thermally conductive.
But even then, a regular, "empty" VIP is about half as thermally conductive.
Simply because for the largest part, there is nothing in it that could conduct heat.
So, filling the void back up with any material reduces the advantages of VIPs further and further.
That's one of the reasons VIPs are "only" 50% better than aerogels - you need really strong side walls to carry the force of that whole hollow, evacuated space and resulting pressure differential.
So...
Yeah..
I don't see what or how that technology changes anything or makes anything really new.
I guess some of the description is "press speech" so people get impressed and don't ask questions.
But most it tells me that something there isn't quite adding up.
Whirlpool’s new refrigerator, insulation technology
Hi Glenn, thanks for posting, this has been coming for a while. I’m glad we’re full is going to be one of the leaders in this effort.
Using steel to form the structure for the panels is actually a good idea. The steel is too thin to affect the overall wall insulation and to affect the overall energy efficiency of the design.
I do doubt the comment that refrigerators are going to find themselves all over the house in furniture etc. I don’t see that happening very quickly or being all that useful, that’s a little fanciful idea.
John L
Hi Glenn, thanks for posting, this has been coming for a while. I’m glad we’re full is going to be one of the leaders in this effort.
Using steel to form the structure for the panels is actually a good idea. The steel is too thin to affect the overall wall insulation and to affect the overall energy efficiency of the design.
I do doubt the comment that refrigerators are going to find themselves all over the house in furniture etc. I don’t see that happening very quickly or being all that useful, that’s a little fanciful idea.
John L
Interesting
Very cool to see this in practice.
I had imagined a dishwasher design that used vacuum insulation to reduce running costs. Of course, that may be a potential design in the near future.
Very cool to see this in practice.
I had imagined a dishwasher design that used vacuum insulation to reduce running costs. Of course, that may be a potential design in the near future.
Insulating dishwashers for heat loss
Since the dishwasher is only running for an hour or two a day, the savings would not justify a big investment and insulation. Plus you want the dishwasher to lose heat in order for the condensation drying principle to work so if the dishwasher was highly insulated, you would have to use much more fan and heat energy to dry the dishes.
John
Since the dishwasher is only running for an hour or two a day, the savings would not justify a big investment and insulation. Plus you want the dishwasher to lose heat in order for the condensation drying principle to work so if the dishwasher was highly insulated, you would have to use much more fan and heat energy to dry the dishes.
John
How secure is the vacuum integrity of the liner? What's the fix if there's a breach in the integrity, vacuum lost?
Henrik, what do you think of Silica?
www.miele.de
Refrigeration from Miele: Top-class energy efficiency over many years
Miele presents new K 4000 free-standing generation at IFA trade show | High-quality insulation makes the difference
www.miele.de
Silica
Silica is the "getter" material from what I understand.
You can't really create 100% diffusion proof polymers - or more so insulation materials.
That means even if the panel isn't breached, over the years and decades a fridge exists, some gases get into that panel, no matter what.
And the insulation quality QUICKLY declines with even minimal gas intrusion.
A "getter" collects those molecules that do get in there by chemical means and/or physical means (adhesion).
It's in there, but the panel isn't "filled" with it.
As far as I know, basically, ALL VIPs contain such a getter, and usually, we're talking a few grams from what I've seen, not a full panel.
You certainly know the silica packets that come in shoes or such.
Same principle, similar material, just different application.
On the topic of integrity.
Once the VIP is breached, it's trash.
You can't cut it out and replace it, like you can't replace the foamed insulation on any fridge.
If it's the door, you can of course replace the entire door, but that's it.
However, once they are assembled, the likelihood of a breach is VERY small.
You have basically a sandwich of the metal cabinet, a bit of foamed insulation, the VIP, then some more foamed insulation and then the plastic liner.
There isn't much mechanical stress on that system.
To get the VIP damaged, you'd have to damage and/or breach either the inner or outer liner and the foam holding the panel in place.
Of course, if you transport the fridge and drop it from a significant height on a corner, sure, that certainly can happen.
But at that point, you would have the same issue either way: Broken in shipping, no longer sellable.
Silica is the "getter" material from what I understand.
You can't really create 100% diffusion proof polymers - or more so insulation materials.
That means even if the panel isn't breached, over the years and decades a fridge exists, some gases get into that panel, no matter what.
And the insulation quality QUICKLY declines with even minimal gas intrusion.
A "getter" collects those molecules that do get in there by chemical means and/or physical means (adhesion).
It's in there, but the panel isn't "filled" with it.
As far as I know, basically, ALL VIPs contain such a getter, and usually, we're talking a few grams from what I've seen, not a full panel.
You certainly know the silica packets that come in shoes or such.
Same principle, similar material, just different application.
On the topic of integrity.
Once the VIP is breached, it's trash.
You can't cut it out and replace it, like you can't replace the foamed insulation on any fridge.
If it's the door, you can of course replace the entire door, but that's it.
However, once they are assembled, the likelihood of a breach is VERY small.
You have basically a sandwich of the metal cabinet, a bit of foamed insulation, the VIP, then some more foamed insulation and then the plastic liner.
There isn't much mechanical stress on that system.
To get the VIP damaged, you'd have to damage and/or breach either the inner or outer liner and the foam holding the panel in place.
Of course, if you transport the fridge and drop it from a significant height on a corner, sure, that certainly can happen.
But at that point, you would have the same issue either way: Broken in shipping, no longer sellable.
There are panels designed with quasi solid cores.
It is possible those are being advertised here.
I however know these with similar design, but basically hollow cores which in turn reduces conduction.
Creating the "structure" inside from silica itself might be a way to cut cost.
Whirlpools claim of "encased in metal" might just be talking about the foil around them which is multi layered and can have metalised layers.
Those foils however are just microns thick.
It is possible those are being advertised here.
I however know these with similar design, but basically hollow cores which in turn reduces conduction.
Creating the "structure" inside from silica itself might be a way to cut cost.
Whirlpools claim of "encased in metal" might just be talking about the foil around them which is multi layered and can have metalised layers.
Those foils however are just microns thick.
Actually, correction on my self:
Silica is sometimes used as structural material, and the getter is applied to it.
Silica itself is NOT the getter.
Silica is sometimes used as structural material, and the getter is applied to it.
Silica itself is NOT the getter.
