After only 30 years it looks like one of my apple cooler's compressor and
evaporator unit needs to be replaced. It uses 502 refrigerant. This was the
best choice for low temperature coolers with electric defrost when I got it
new.

Not many 502 systems are installed today because 502 is so hard to get. (Its
very similar to the now banned R12) But I own a 30 lb. jug plus about a 10
lb. charge in the old system.

A fella told me the 502 systems are inherently more efficient because they
run at lower operating pressure. Efficiency is important, the electric is
north of $1K per month when it runs.

I'm searching all the commercial cooler units catalogs and I'm finding
nothing on efficiency. Most compressor/evaporators can be set up for more
than one refrigerant.

So, what's best?

Karl

Karl Townsend wrote:
After only 30 years it looks like one of my apple cooler's compressor and
evaporator unit needs to be replaced. It uses 502 refrigerant. This was the
best choice for low temperature coolers with electric defrost when I got it
new.

Not many 502 systems are installed today because 502 is so hard to get. (Its
very similar to the now banned R12) But I own a 30 lb. jug plus about a 10
lb. charge in the old system.

A fella told me the 502 systems are inherently more efficient because they
run at lower operating pressure. Efficiency is important, the electric is
north of $1K per month when it runs.

It is a lot more complicated than that. Operating pressure has
nothing to do with efficiency. R502 is a mixture of two
different gases, see
http://www.free-ed.net/sweethaven/MechTech/Refrigeration/coursemain.asp?lesNum=4&modNum=1
for more info.

Efficiency has to do with how much work it takes to condense the
gas, compared to how much heat that vaporizing gas absorbs. The
numbers are different for every gas. Of course, you want the
condenser to operate at the lowest possible pressure and
temperature to make the load on the compressor lower. That's
why a lot of commercial refrigeration units use water-cooled
condensers and evaporative cooling towers.
I'm searching all the commercial cooler units catalogs and I'm finding
nothing on efficiency. Most compressor/evaporators can be set up for more
than one refrigerant.

So, what's best?
I have a Fortran program that evaluates performance given some
numbers on the compressor, evap and condenser temperatures, etc.
Unfortunately, I haven't converted this program to run on my
Linux system, but it might be able to be converted by f772c.
It has data for R502, as well as a number of other refrigerants
common many years ago. I did some simulation with the program
and found Propane was the best refrigerant for comfort cooling
(air conditioning). It produced the same cooling at something
like 20% less energy input to the compressor.

At 1 K $ /month, maybe you need to look at some alternative
energy schemes, like solar-powered cooling. You can heat a heat
transfer fluid with solar collectors and use that to run an
absorption chiller. That might only be the first stage of a
cascade chiller, but it would handle the majority of the work.
An absorption chiller can easily deliver 40 F water. If you
tweak the parameters, you can get Lithium Bromide to produce
much colder temperatures with lower heat load.

Jon

On Tue, 28 Aug 2007 19:29:28 -0500, "Karl Townsend"
wrote:

After only 30 years it looks like one of my apple cooler's compressor and
evaporator unit needs to be replaced. It uses 502 refrigerant. This was the
best choice for low temperature coolers with electric defrost when I got it
new.

Not many 502 systems are installed today because 502 is so hard to get. (Its
very similar to the now banned R12) But I own a 30 lb. jug plus about a 10
lb. charge in the old system.

A fella told me the 502 systems are inherently more efficient because they
run at lower operating pressure. Efficiency is important, the electric is
north of $1K per month when it runs.

I'm searching all the commercial cooler units catalogs and I'm finding
nothing on efficiency. Most compressor/evaporators can be set up for more
than one refrigerant.

So, what's best?

Karl

Before you start, did you call the local power co-op and work on
that problem of getting 3-phase out to the farm? This is another
motor that can be changed over, besides the water well. The added
efficiency means it costs less to run a compressor on 3-phase than
single-phase, and every little bit helps.

As to refrigerant selection, that's way above my pay grade (haven't
done it for money in a while). The chart says R-404a is the long term
choice to replace R-502 for low temp applications. But confirm this
with the equipment makers, they have it all figured out.

Unless you have a local service company that stocks all the esoteric
refrigerants needed to service walk-in refrigeration, you need to keep
a stock of refrigerant, a few spare filter-driers and other parts and
the right gauge manifold on site - especially handy if you call for
service and find out Fred's taking a week off to go fishing, and you
have to figure it out yourself...

-- Bruce --

On Tue, 28 Aug 2007 19:29:28 -0500, "Karl Townsend"
wrote:

After only 30 years it looks like one of my apple cooler's compressor and
evaporator unit needs to be replaced. It uses 502 refrigerant. This was the
best choice for low temperature coolers with electric defrost when I got it
new.

Not many 502 systems are installed today because 502 is so hard to get. (Its
very similar to the now banned R12) But I own a 30 lb. jug plus about a 10
lb. charge in the old system.

A fella told me the 502 systems are inherently more efficient because they
run at lower operating pressure. Efficiency is important, the electric is
north of $1K per month when it runs.

I'm searching all the commercial cooler units catalogs and I'm finding
nothing on efficiency. Most compressor/evaporators can be set up for more
than one refrigerant.

So, what's best?

Karl

This was ~25 years ago, but all the big storage's around
this area were using ammonia. I remember one of them had a
three phase 150hp motor driving the compressor. It wasn't
uncommon back then to find a four wheel trailer with an
ammonia tank on it wheeled right into the compressor area
and hooked on. At least until they figured out where the
leak was and didn't have to keep adding more to it

Only the small systems used freon back then and weren't very
common.

--
Leon Fisk
Grand Rapids MI/Zone 5b
Remove no.spam for email

According to Jon Elson :

[ ... ]

I have a Fortran program that evaluates performance given some
numbers on the compressor, evap and condenser temperatures, etc.
Unfortunately, I haven't converted this program to run on my
Linux system, but it might be able to be converted by f772c.

Is this a commercial Fortran program, or one of your own
programming?

Note that linux systems usually use gcc (Gnu C Compiler), and
the more recent versions can bet tweaked to also produce a Fortran 77
compiler (g77).

Also, the lastest "Studio11" and Studio12" compiler suites (now
free) from Sun include f77, f90, and f95, FWIW.

Is there somewhere where I can pick up this program? I would be
interested in playing with it. (Note -- you probably *can't* simply
e-mail me the source, because my system is set up to totally block *any*
e-mail larger than 30K total size -- before I ever get a chance to see
who it is from. This keeps all the virus e-mail out of my mailboxes and
mailing lists.

An anonymous FTP site -- or a web site would work, since that
could bypass the e-mail blocking.

Thanks,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On Aug 28, 6:29 pm, "Karl Townsend"
wrote:
After only 30 years it looks like one of my apple cooler's compressor and
evaporator unit needs to be replaced. It uses 502 refrigerant. This was the
best choice for low temperature coolers with electric defrost when I got it
new.

Not many 502 systems are installed today because 502 is so hard to get. (Its
very similar to the now banned R12) But I own a 30 lb. jug plus about a 10
lb. charge in the old system.

A fella told me the 502 systems are inherently more efficient because they
run at lower operating pressure. Efficiency is important, the electric is
north of $1K per month when it runs.

I'm searching all the commercial cooler units catalogs and I'm finding
nothing on efficiency. Most compressor/evaporators can be set up for more
than one refrigerant.

So, what's best?

Karl

I've several old engineering manuals that put ammonia gas as #1 for
overall efficiency. Nasty stuff, but still used for large warehouse
and ice-making operations. Also biodegradeable and ozone-friendly.
You probably won't find the information you need out of a catalog,
efficiency depends on a lot of things, one reason the books are so
thick...

Stan

On Thu, 30 Aug 2007 20:23:22 -0700, wrote:


I've several old engineering manuals that put ammonia gas as #1 for
overall efficiency. Nasty stuff, but still used for large warehouse
and ice-making operations. Also biodegradeable and ozone-friendly.
You probably won't find the information you need out of a catalog,
efficiency depends on a lot of things, one reason the books are so
thick...

Stan
But have you ever been near a leaking SO2 system?
Gerry :-)}
London, Canada

Gerald Miller fired this volley in
:
But have you ever been near a leaking SO2 system?

Ayupp! When I was 13, I made a "Globe Refrigerator" from copper, SO2,
and silica gel.

You heated the "condensor" (absorber) in a fire while cooling the
evaporator in a bucket of water.

Then you placed the evap in the ice chest/cooler/cabinet, and put the
absorber in a bucket of cool water, and let the SO2 slowly boil out of
the evap.

It would cool for five or six hours on a "charge".

SEVERAL leaks manifest themselves during the first cycle of assembly,
charging, uncharging, and leak-fixing. G

LLoyd

Gerald Miller wrote:
On Thu, 30 Aug 2007 20:23:22 -0700, wrote:



I've several old engineering manuals that put ammonia gas as #1 for
overall efficiency. Nasty stuff, but still used for large warehouse
and ice-making operations. Also biodegradeable and ozone-friendly.
You probably won't find the information you need out of a catalog,
efficiency depends on a lot of things, one reason the books are so
thick...

Stan

But have you ever been near a leaking SO2 system?
Gerry :-)}
London, Canada

Back when I was in grade school (1940s) a family had one (household
refrigerator using amonia) leak, fortunately only the pet (forget
what kind of pet) was home. Did it in. Nasty stuff to breathe.
...lew...

Lew Hartswick wrote:

Gerald Miller wrote:

On Thu, 30 Aug 2007 20:23:22 -0700, wrote:



I've several old engineering manuals that put ammonia gas as #1 for
overall efficiency. Nasty stuff, but still used for large warehouse
and ice-making operations. Also biodegradeable and ozone-friendly.
You probably won't find the information you need out of a catalog,
efficiency depends on a lot of things, one reason the books are so
thick...

Stan


But have you ever been near a leaking SO2 system?
Gerry :-)}
London, Canada


Back when I was in grade school (1940s) a family had one (household
refrigerator using amonia) leak, fortunately only the pet (forget
what kind of pet) was home. Did it in. Nasty stuff to breathe.
...lew...
Woops Maybe that was S O 2 Now that I think about it again.
...lew...

On Aug 29, 5:10 am, Jon Elson wrote:
Karl Townsend wrote:
After only 30 years it looks like one of my apple cooler's compressor and
evaporator unit needs to be replaced. It uses 502 refrigerant. This was the
best choice for low temperature coolers with electric defrost when I got it
new.

Not many 502 systems are installed today because 502 is so hard to get. (Its
very similar to the now banned R12) But I own a 30 lb. jug plus about a 10
lb. charge in the old system.

A fella told me the 502 systems are inherently more efficient because they
run at lower operating pressure. Efficiency is important, the electric is
north of $1K per month when it runs.

It is a lot more complicated than that. Operating pressure has
nothing to do with efficiency. R502 is a mixture of two
different gases, see
http://www.free-ed.net/sweethaven/MechTech/Refrigeration/coursemain.a...
for more info.

Efficiency has to do with how much work it takes to condense the
gas, compared to how much heat that vaporizing gas absorbs.


Doesn't a lower operating pressure imply that less work is done
to condense the gas?

It IS much more complicated than that, but operating pressure is
relevant.

--

FF

On Fri, 31 Aug 2007 08:32:35 -0600, Lew Hartswick
wrote:

Gerald Miller wrote:
On Thu, 30 Aug 2007 20:23:22 -0700, wrote:



I've several old engineering manuals that put ammonia gas as #1 for
overall efficiency. Nasty stuff, but still used for large warehouse
and ice-making operations. Also biodegradeable and ozone-friendly.
You probably won't find the information you need out of a catalog,
efficiency depends on a lot of things, one reason the books are so
thick...

Stan

But have you ever been near a leaking SO2 system?
Gerry :-)}
London, Canada

Back when I was in grade school (1940s) a family had one (household
refrigerator using amonia) leak, fortunately only the pet (forget
what kind of pet) was home. Did it in. Nasty stuff to breathe.
...lew...


The reefer here in my RV was ammonia charged. Blew a fitting about a
year ago (which is why its now my dry storage).

Prior to that..Id had an ant problem here in the RV park.

Havent seen an ant, spider, moth, roach or any other critter since
then inside the RV.

Nasty!

Gunner

On Aug 31, 10:57 am, Gunner wrote:
On Fri, 31 Aug 2007 08:32:35 -0600, Lew Hartswick





wrote:
Gerald Miller wrote:
On Thu, 30 Aug 2007 20:23:22 -0700, wrote:

I've several old engineering manuals that put ammonia gas as #1 for
overall efficiency. Nasty stuff, but still used for large warehouse
and ice-making operations. Also biodegradeable and ozone-friendly.
You probably won't find the information you need out of a catalog,
efficiency depends on a lot of things, one reason the books are so
thick...

Stan

But have you ever been near a leaking SO2 system?
Gerry :-)}
London, Canada

Back when I was in grade school (1940s) a family had one (household
refrigerator using amonia) leak, fortunately only the pet (forget
what kind of pet) was home. Did it in. Nasty stuff to breathe.
...lew...

The reefer here in my RV was ammonia charged. Blew a fitting about a
year ago (which is why its now my dry storage).

Prior to that..Id had an ant problem here in the RV park.

Havent seen an ant, spider, moth, roach or any other critter since
then inside the RV.

Nasty!

Gunner- Hide quoted text -

- Show quoted text -

Most of the RV fridges are absorption types, can use propane or
electric heaters to do the boiling. Active stuff is ammonia gas,
water and a little hydrogen. Uses heat of solution rather than heat
of vaporization. Not as efficient and doesn't work at as high a
pressure as compressor-type ammonia systems. Also needs to be held
level to work. But well-suited for the purpose, no electric current
needed and it's quiet.

Stan

I didn't get the original message but Karl, you can use R-408 as a drop in
replacment for R-502. The tech manuals will not agree but We have done it
many times, sometimes on a unit with a hermeticly sealed compressor where
there was not an easy way to change the oil. On an apple box I suspect you
have semi-hermetic compressors. The efficiency will be very close to
original with only slightly higher head pressures. Keep those condensers
clean! If you equipment is shot maybe it is time to upgrade. But if the
system has lost it's charge then use the R-408. I recommend if the system is
very short, remove the refrigerant change oil to alkybenzine (avoid poe if
possible it cleans the system and cloggs strainers) change filter, evacuate
and charge with R-408. If system is only slightly short of refrigerant top
it off . BTW R-502 is closer to the very popular R-404 today's choice than
R-12 in terms of pressures.
Good Luck Lyndell

wrote in message
ps.com...
On Aug 28, 6:29 pm, "Karl Townsend"
wrote:
After only 30 years it looks like one of my apple cooler's compressor and
evaporator unit needs to be replaced. It uses 502 refrigerant. This was
the
best choice for low temperature coolers with electric defrost when I got
it
new.

Not many 502 systems are installed today because 502 is so hard to get.
(Its
very similar to the now banned R12) But I own a 30 lb. jug plus about a
10
lb. charge in the old system.

A fella told me the 502 systems are inherently more efficient because
they
run at lower operating pressure. Efficiency is important, the electric is
north of $1K per month when it runs.

I'm searching all the commercial cooler units catalogs and I'm finding
nothing on efficiency. Most compressor/evaporators can be set up for more
than one refrigerant.

So, what's best?

Karl

I've several old engineering manuals that put ammonia gas as #1 for
overall efficiency. Nasty stuff, but still used for large warehouse
and ice-making operations. Also biodegradeable and ozone-friendly.
You probably won't find the information you need out of a catalog,
efficiency depends on a lot of things, one reason the books are so
thick...

Stan