In the smaller Tesco and Co-Op they have drinks and other stuff in big
open-fronted fridges, but the drinks are always really cold.

How do they work? Are they just more powerful than a home fridge (which
wouldn't do much if you left the door wide open) or is there some scientific
sorcery at work?

On 08/09/2013 15:01, Mentalguy2k8 wrote:
In the smaller Tesco and Co-Op they have drinks and other stuff in big
open-fronted fridges, but the drinks are always really cold.

How do they work? Are they just more powerful than a home fridge (which
wouldn't do much if you left the door wide open) or is there some
scientific sorcery at work?


No sorcery. They blow the cold air inwards, so that helps to keep the
cold in. There's bound to be some mixing of hot and cold air, but the
thermal capacity of air is quite low, and they just have powerful motors
to compensate.

In article ,
GB writes:
On 08/09/2013 15:01, Mentalguy2k8 wrote:
In the smaller Tesco and Co-Op they have drinks and other stuff in big
open-fronted fridges, but the drinks are always really cold.

How do they work? Are they just more powerful than a home fridge (which
wouldn't do much if you left the door wide open) or is there some
scientific sorcery at work?


No sorcery. They blow the cold air inwards, so that helps to keep the
cold in. There's bound to be some mixing of hot and cold air, but the
thermal capacity of air is quite low, and they just have powerful motors
to compensate.

They drop a curtain of cold air from the top, and try to capture as much
of it as possible at the bottom to be recycled, so it's not lost into the
supermarket isles, although when you have an isle with open refrigerated
units both sides, it normally needs warm air blown down from the ceiling
to keep the walk space comfortable. They are much more powerful than a
domestic fridge, but they are still built to be as efficient as possible
given the design contraints of an open front (which your fridge isn't).
Nowadays, they don't operate in isolation, and are part of the whole
design for the supermarket aircon system.

When the store is closed, an insulated roller blind will be pulled down
the front to make the units more efficient.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 08/09/2013 19:55, Andrew Gabriel wrote:
although when you have an isle with open refrigerated
units both sides, it normally needs warm air blown down from the ceiling
to keep the walk space comfortable.

We've had a good summer, so I have to make a special effort to remember
to take a jumper with me when visiting the supermarket.

On 08/09/2013 19:55, Andrew Gabriel wrote:
In article ,
GB writes:
On 08/09/2013 15:01, Mentalguy2k8 wrote:
In the smaller Tesco and Co-Op they have drinks and other stuff in big
open-fronted fridges, but the drinks are always really cold.

How do they work? Are they just more powerful than a home fridge (which
wouldn't do much if you left the door wide open) or is there some
scientific sorcery at work?


No sorcery. They blow the cold air inwards, so that helps to keep the
cold in. There's bound to be some mixing of hot and cold air, but the
thermal capacity of air is quite low, and they just have powerful motors
to compensate.

They drop a curtain of cold air from the top, and try to capture as much
of it as possible at the bottom to be recycled, so it's not lost into the
supermarket isles, although when you have an isle with open refrigerated
units both sides, it normally needs warm air blown down from the ceiling
to keep the walk space comfortable. They are much more powerful than a
domestic fridge, but they are still built to be as efficient as possible
given the design contraints of an open front (which your fridge isn't).
Nowadays, they don't operate in isolation, and are part of the whole
design for the supermarket aircon system.

When the store is closed, an insulated roller blind will be pulled down
the front to make the units more efficient.

The temperatures of the aisles in some shops are incredibly low. Indeed
in one local shop the floor in front of the units feels close to
freezing. Must take my IR thingy with me sometime soon.

I would really like to know what their electricity bills are like.

--
Rod

On 08/09/2013 19:55, Andrew Gabriel wrote:


When the store is closed, an insulated roller blind will be pulled down
the front to make the units more efficient.


In some supermarkets they appear to be experimenting with leaving the
slatted transparent curtains in place during opening hours.
--
mailto:news{at}admac(dot}myzen{dot}co{dot}uk

"alan" wrote in message
...
On 08/09/2013 19:55, Andrew Gabriel wrote:


When the store is closed, an insulated roller blind will be pulled down
the front to make the units more efficient.


In some supermarkets they appear to be experimenting with leaving the
slatted transparent curtains in place during opening hours.

The smaller Tescos have started putting sliding doors on their fridges, the
ones that don't give you enough time to reach in and grab a can of drink
before they shut & trap your arm.

In message , at 20:17:49 on
Sun, 8 Sep 2013, alan remarked:
When the store is closed, an insulated roller blind will be pulled down
the front to make the units more efficient.

In some supermarkets they appear to be experimenting with leaving the
slatted transparent curtains in place during opening hours.

I noticed this during the recent heatwave. Sainsbury's also put up signs
apologising.
--
Roland Perry

Roland Perry wrote:
I noticed this during the recent heatwave. Sainsbury's also put up signs
apologising.

I was in a tiny Co-op in a heatwave a few years ago (just down the road from
where Roland used to live). It's roughly the size of a one-car garage, with
3 aisles, and about half of it is open fridges. The fridges were working
hard, so they were pumping out lots of heat out the back.

But the shop is unventilated, so the heat was coming out the back of the
fridges, spilling into the room, and coming back into the front of the
fridges again. It was one big viscious circle of heat-pump positive
feedback, and the room got hotter and hotter.

Theo

In article ,
Roland Perry writes:
In message , at 20:17:49 on
Sun, 8 Sep 2013, alan remarked:
When the store is closed, an insulated roller blind will be pulled down
the front to make the units more efficient.

In some supermarkets they appear to be experimenting with leaving the
slatted transparent curtains in place during opening hours.

I noticed this during the recent heatwave. Sainsbury's also put up signs
apologising.

The open displays can only cool a certain amount below the room temp.
If the room temp is not controlled, or cannot be kept below the max
which still allows the refrigerated display to work, then they will need
to close the display front. It will make them more efficient, but it will
also significantly dent sales.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 08/09/2013 20:17, alan wrote:
On 08/09/2013 19:55, Andrew Gabriel wrote:


When the store is closed, an insulated roller blind will be pulled down
the front to make the units more efficient.


In some supermarkets they appear to be experimenting with leaving the
slatted transparent curtains in place during opening hours.

I suspect it reduces sales as, where I have seen it tried, the curtains
have since gone. Certainly I find they make it more difficult to see
what is on the shelves.

Colin Bignell

Andrew Gabriel wrote:
In article ,
GB writes:
On 08/09/2013 15:01, Mentalguy2k8 wrote:
In the smaller Tesco and Co-Op they have drinks and other stuff in big
open-fronted fridges, but the drinks are always really cold.

How do they work? Are they just more powerful than a home fridge (which
wouldn't do much if you left the door wide open) or is there some
scientific sorcery at work?

No sorcery. They blow the cold air inwards, so that helps to keep the
cold in. There's bound to be some mixing of hot and cold air, but the
thermal capacity of air is quite low, and they just have powerful motors
to compensate.

They drop a curtain of cold air from the top, and try to capture as much
of it as possible at the bottom to be recycled, so it's not lost into the
supermarket isles, although when you have an isle with open refrigerated
units both sides, it normally needs warm air blown down from the ceiling
to keep the walk space comfortable. They are much more powerful than a
domestic fridge, but they are still built to be as efficient as possible
given the design contraints of an open front (which your fridge isn't).
Nowadays, they don't operate in isolation, and are part of the whole
design for the supermarket aircon system.

When the store is closed, an insulated roller blind will be pulled down
the front to make the units more efficient.

And as they're due for replacement, most large supermarkets are
replacing them with glass fronted cabinets.

The first time I saw this was in Amsterdam, and there was a notice next
to the fridges telling all and sundry the impressive amount of reduction
in CO2 production they caused each year. It was possible from the
figures on the notice to work out the (quite short) payback period of
installing them.

--
Tciao for Now!

John.

On 08/09/2013 20:57, John Williamson wrote:

And as they're due for replacement, most large supermarkets are
replacing them with glass fronted cabinets.

They didn't at the very recently expanded and fully refitted Morrisons
here. Nor at the very recently opened Lidl (though their cool cabinets
seem to spill less than those in other shops - and their low-level
refrigerators and freezers both have effective lids). Nor, somewhat
longer ago, when they refitted parts of Asda (definitely including cool
cabinets) nor the ground-up new Sainsbury.

I am hoping that they do - as the coolth can be unpleasant. And at the
end of the line we are paying for their profligate waste.

--
Rod

polygonum wrote:
On 08/09/2013 20:57, John Williamson wrote:

And as they're due for replacement, most large supermarkets are
replacing them with glass fronted cabinets.

They didn't at the very recently expanded and fully refitted Morrisons
here. Nor at the very recently opened Lidl (though their cool cabinets
seem to spill less than those in other shops - and their low-level
refrigerators and freezers both have effective lids). Nor, somewhat
longer ago, when they refitted parts of Asda (definitely including cool
cabinets) nor the ground-up new Sainsbury.

I am hoping that they do - as the coolth can be unpleasant. And at the
end of the line we are paying for their profligate waste.

Maybe I'm going into the wrong supermarkets, then.

--
Tciao for Now!

John.

On 08/09/2013 20:57, John Williamson wrote:
....
And as they're due for replacement, most large supermarkets are
replacing them with glass fronted cabinets...

I've seen that for frozen foods, but not for chilled.

Colin Bignell