I've got some great feedback from this group before, let's what people
know about this one...
I'm curious about those refrigerators you see in businesses like take
out restaurants and cafeterias. They have things like bottled soda,
fruit, yogurt, and other things you can just grab and consume, without
opening any door. They are fully exposed to the elements. My curious
question is how they can be efficient and effective, while leaving the
refrigerator at home open for more than a minute is "so bad." I was
always told not to leave it open for more than a few seconds. Yet save
for some plastic perforated sheeting, these things never are fully
Is there some intricate fan device that keeps the cold air in? Or are
these just a conservationist's nightmare?
Obviously they're not as efficient as an enclosed refrigerator. It's a
convenience trade-off. The main difference in the open display case is
that it doesn't have the opening at the very bottom like an open
refrigerator door. There's usually a lip at the bottom that helps keep
the cold in so it can be collected. The refrigerated air is recycled,
pumped into the case at the top and sucked out at the bottom. With
that arrangement of air cycling there isn't as much mixing of air as
you might think.
Conservationist's nightmare? Have you noticed what these things are
Designer water, mostly.
The main purpose of the gizmo is to sell product - energy efficiency is way
down the list of desirable features.
Maybe I'm not thinking about the same display cases, but what about almost
every grocery store? The entire row where the milk, juice, eggs, cheese etc?
THOSE are open cases. What about the aisle that has the open FREEZER cases.
The kind that are about waiste high that have frozen orange juices and
stuff? or are we talking about something else?
#1 they aren't very efficient. You can feel the cold air around these
coolers as soon as you get near them. It's a trade-off to the owner.
The convenience of having the products easily accessible to the
customer means the customer is more likely to buy them, but having it
in the open will cost the owner more in electricity. Apparently, it
must pay off since these things are everywhere.
#2 they probably aren't as cold as a refrigerator. They're not meant
to keep food preserved for long periods of time. They exist only to
keep food cool (in the case of drinks); and fresh for a couple of hours
(fruit, etc.). It takes less energy to cool air from 70F down to 45F
than it does to cool it down to 35F.
#1 they are NOT efficient. You can feel the cold air around them when
you get near them. It's a trade-off for the owner, and having the
products in the open where people are more likely to buy them is the
winning strategy apparently, since many businesses are willing to pay
for the higher electrical cost of running these coolers
#2 they probably do not run as cold as a refrigerator. They only have
to keep drinks cool and food fresh for short periods of time. It takes
less energy to cool ambient air to 45F than it does to cool it to 35F.
I have worked with these for years. They are only good for drinks. Meats
dairy products will never keep until use by date. They are fine for
suoermarket that turns food over quickly, but nit good for
storing anything over
a period of time. Also you will need a good
refrigeration man and deep pockets
to keep it running well.
they have an "air curtain". problems occur when improper stocking of goods
blocks the curtain. look at the display cases when your shopping next time,
you'll find a stocking line which is not supposed to be crossed with
If you look overhead at the front of the cabinet you will see
what looks like a bundle of straws, just the ends... this
creates whats called in the business a high velocity laminar
flow air screen as the fans in the case blow air into a plenum
above these bundles creating the 'air screen' when cold air
tries to leave the case it is drawn into this air screen down
to the cold air return and recirculated.
"case parts' company in LA Calif will sell you the media used
to create such air screens.
when warm outside air tries to enter the case it hits the
outside of the air screen is and is drawn down and away.
cross flow ventilation, or even people walking by and disrupt
the air screen and it will mix warm outside air with the
refrigerated case air.
yes they are less efficient than a case with doors... but
products sell better with open cases. A closed case, thats
with glass doors, 10' long might have a 1/2 or 3/4 hp
refrigeration package on it... an open case that long might
have a 1 hp refrig package on it.
They are most viable for tightly packaged and sealed foods
that can stand the occasional excursion to 40F or a little
higher... they are not viable for say fresh meat, that idealls
should be kept as close to freezing as possible 32 or 33 def
So you see these on cheeze, and packaged process meats...a lot
in the vertical configuration (the worst but sells product the
You see horizontal open cases for package meats running close
to 34F....because cold air is denser than warmer air and will
lay low in a horizontal case. those do not have air
screens... but gentle low velocity air drifting across the top
from back to front.
Packages that sit into this flow will disrupt this air flow,
creating turbulence that involves the warmer ambient air and
its heavy moisture load...this warms the case, causes ice to
develop on the evaporator coil... generating more defrost
cycles... the case warms a bit during defrost... shelf life of
the product is reduced proportionally.
Refrigeration contractor since 1450
Phil, it's come to our attention that your resume states that you've
been a refrigeration contractor since before the industrial revolution.
Well, what with the CEO of RadioShack resigning due to his fabricated
qualifications, some board members reviewed your employment
application. Admittedly, it is a bit belated, but we have discovered
some discrepancies. To wit:
- you do not in fact hold the patent for ice
- Moses parted the Red Sea, not you
- if you stop dreaming, we don't all die, as you've threatened numerous
Although we have no proof on the last item, we're pretty confident
we're right...if not - we're only kidding!
The pharohs used ice from that mountain in africa at the
source of the nile river. floated it to the palaces on barges,
and stored it underground insulated with hay. Then used
bellows to blow air through it on hot days to keep the pharoh
I have my resume out these days... trial balloon mostly to
test the larger market and get over going ballistic when
recruiters call... I had to figure out what the hell is going
on with those people.
I tell some of the recruiters that if the company is as lame
as their position requirements and HR staff that they need to
locate a moron if they want a good fit... these are real
concerned with fit these days.
. That hasnt been working out real well... but its
I read where Manpower inc says there is a world wide shortage
of talent in the sales rep and the engineering and technical
areas..due to get worse fast.
Ive seen some of that lately but not much...if it gets to be a
disaster as many have predicted it will be a good chance for
some of us to become complete pains in the ass.
that will be good.
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