do it yourself
Allan Adler
I have seen discussions on groups such as rec.metalworking about
building your own steam engines and making your own furnaces
and foundries. These things are all hot. I would like to think
about how to make things cold, specifically, how to design
and build special purpose refrigeration units. On rec.metalworking
I learned about Lindsay, which sells books on metalwork, including
some of the hot items mentioned above, but ntohing on refrigeration
as far as I can tell. If there is an analogous source of books for
do-it-yourself refrigeration, I would be interested in knowing
about it.
Allan Adler
a...@altdorf.ai.mit.edu
Disclaimer: I am a guest and *not* a member of the MIT Artificial Intelligence
Lab. My actions and comments do not reflect in any way on MIT.
Morever, I am nowhere near the Boston metropolitan area.
Allan Adler
Someone has kindly brought to my attention that my naive question
about do-it-yourself refrigeration is likely to be quite unpopular
on this newsgroup; he also explained some of the reasons why (licensing,
laws, and international treaties). So I would like to apologize
for any offense my posting might have caused and to let you know
that I am cancelling that posting.
Let me try to explain what I have in mind. Maybe this isn't the
newsgroup for it, in which case I'd appreciate being directed to
a more appropriate newsgroup.
I don't have immediate plans to build anything. It occurred to
me that there are some kinds of work that need to be done in
special cold environments. I didn't want to be specific because
I'm just starting to think about stuff like this and I'm sure that
my ideas for what to build will change very quickly. But let me
give you one concrete example.
Suppose that the interior of a glove box needs to be very cold but
you don't want the room that the glove box is in to be that cold.
How do you design such a glove box? (I realize this depends on the
temperature one wants).
I don't assume that there is a commercial solution to this problem,
although it wouldn't surprise me. It would surprise me if I could
afford one, though.
Also, I wasn't assuming that conventional refrigeration techniques
would be used. (By conventional, I mean what one finds in household
refrigerators.) I was allowing the possibility that some other
technique might be used. I don't know if there are techniques
that don't require an EPA license, but if the international
treaties are about chlorofluorocarbon control, then it seems
that solutions that don't use chlorofluorocarbons might be
exempt from such laws and treaties.
Anyway, I promise I will not try to build anything without knowing
to ten decimal places why it is legal and safe to do so, even for me.
But I do at least want to be able to think about it. When I ask
for books and stuff like that, it means I'm planning to read and learn
and think; it doesn't mean I'm planning to build anything. In the event
that my thinking gets to the point where I decide I really have to have
something built specially, I'll have it built by someone competent. But
at least I will have some idea how to talk to that person about technical
details.
Neon John
Allan Adler wrote:
>
> Someone has kindly brought to my attention that my naive question
> about do-it-yourself refrigeration is likely to be quite unpopular
> on this newsgroup; he also explained some of the reasons why (licensing,
> laws, and international treaties). So I would like to apologize
> for any offense my posting might have caused and to let you know
> that I am cancelling that posting.
No one ownes this group (though a few think they do). Go right
ahead and ask your questions. There are enough of us out there
willing to help you experiment that you'll get your answers. You'll
end up with a better undersstanding of refrigeration than the
majority of those who will criticize you for experimenting. I've
done everything from building a multi-zone central A/C system with
ice bank cold storage for my first house using junkyard car parts to
commissioning a 5 million pound ice condenser in a nuclear plant and
100% of my refrigeration training was self-taught.
The EPA "green card" thing is a sham. True, you have to have one to
buy refrigernat, do work for others and a few other things, but
getting it involves little more than paying a little bit of money.
I got mine from an outfit called IMACA. (online, I think). $20, 20
questions, with the questions on the right hand side of the page and
the answers on the left.
For experimentation, you don't even need a halogenated hydrocarbon
refrigerant. Propane is a good substitute for R-22. A mix of
propane and isobutane is a good substitute for R12. Suggest you go
to deja vu and search in the rec.autos.* for my name, George Goble,
j...@dixie.com and g...@ecn.purdue.edu. There you will find a vast
amount of information on using hydrocarbons as refrigerants. Most
of that predates this group and was during the early 90s when the
status of automotive air conditioning was in a state of flux from
the greenhouse thingie.
John
--
John De Armond
johngd...@bellsouth.net
Neon John's Custom Neon
Cleveland, TN
"Bendin' Glass 'n Passin' Gas"
Scott Lee
workpieces be lifted off the work surface? If not, a cold plate may suffice
instead of a cold atmosphere) then you might be able to use peltier devices (solid
state coolers) to cool the cold plate, dumping the waste heat to heat sinks on the
outside of the glove box. I have done similar type control systems using melcor
peltiers and a watlow controller. The cold plate would need to be finned on the
bottom, with possibly a blower to assist convection from the fins.
A dry nitrogen or argon environment inside the glove box might also help keep
things a bit more stable, especially if this is a semiconductor processing
environment.
If you are going to use a working fluid refrigeration loop, whats wrong with
ammonia? Is it verboten for some reason, or am I just old fasioned??
Scott Lee
Allan Adler wrote:
> Someone has kindly brought to my attention that my naive question
> about do-it-yourself refrigeration is likely to be quite unpopular
> on this newsgroup; he also explained some of the reasons why (licensing,
> laws, and international treaties). So I would like to apologize
> for any offense my posting might have caused and to let you know
> that I am cancelling that posting.
>
rto...@oanet.com
>>
>> Someone has kindly brought to my attention that my naive question
>> about do-it-yourself refrigeration is likely to be quite unpopular
>> on this newsgroup; he also explained some of the reasons why (licensing,
>> laws, and international treaties). So I would like to apologize
>> for any offense my posting might have caused and to let you know
>> that I am cancelling that posting.
>
>ahead and ask your questions. There are enough of us out there
>willing to help you experiment that you'll get your answers. You'll
>end up with a better undersstanding of refrigeration than the
>majority of those who will criticize you for experimenting. I've
>done everything from building a multi-zone central A/C system with
>ice bank cold storage for my first house using junkyard car parts to
>commissioning a 5 million pound ice condenser in a nuclear plant and
>100% of my refrigeration training was self-taught.
>
>The EPA "green card" thing is a sham. True, you have to have one to
>buy refrigernat, do work for others and a few other things, but
>getting it involves little more than paying a little bit of money.
>I got mine from an outfit called IMACA. (online, I think). $20, 20
>questions, with the questions on the right hand side of the page and
>the answers on the left.
>
>For experimentation, you don't even need a halogenated hydrocarbon
>refrigerant. Propane is a good substitute for R-22. A mix of
>propane and isobutane is a good substitute for R12. Suggest you go
>to deja vu and search in the rec.autos.* for my name, George Goble,
>j...@dixie.com and g...@ecn.purdue.edu. There you will find a vast
>amount of information on using hydrocarbons as refrigerants. Most
>of that predates this group and was during the early 90s when the
>status of automotive air conditioning was in a state of flux from
>the greenhouse thingie.
>
>
Hear! Hear!
We need experimenters, not critics. Go ahead and ask any question you
wish.
Allan Adler
Well, ok, my first question is this:
what is the simplest cool temperature-controlled unit I can set up
without previous experience and without breaking any laws or treaties?
My second question is: what book, aimed at beginners, would explain
how to do this and guide one through the construction?
Just to give an idea of the level I have in mind, there are
metal working books by David Gingery which tell you how to build your
own lathe from scrap aluminum and which guide you through the
construction, starting with building your own foundry.
I did my first melt of scrap aluminum in such a makeshift foundry
a few weeks ago and it was an important hurdle, the first of many
still left to go. I need to identify and pass the analogous first
hurdle for refrigeration.
p...@see_my_sig_for_address.com
and wrote:
>a...@altdorf.ai.mit.edu
>
>Disclaimer: I am a guest and *not* a member of the MIT Artificial Intelligence
> Lab.
Prove it. Say something really dumb, offer some non sequitors
that suggest you would fail Turing... anything.... :-)
Paul
>~~>~~>~~>~~>~~>~~>~~>~~>~~>~~>~~>~~>~~>~~>~~>~~>~~>~~>~~
pjm@(remove this part )pobox.com
My ( newly revised ) WWW site is at http://www.pobox.com/~pjm, featuring free HVAC software.
The Sci.Engr.Heat-Vent-AC and Alt.HVAC FAQ is at http://www.elitesoft.com/sci.hvac/
Allan Adler
In my last posting on this topic, I asked for the simplest cool
temperature- controlled container a beginner could make without
breaking any laws or violating any treaties.
On p.151 of UNESCO's "700 Science Experiments For Everyone", published
by Doubleday in 1962, I find Experiment XIII.D.7, entitled "The cooling
effect of a dry wind". To carry out this experiment, we are told to
obtain two similar thermometers, wrap the bulb of one in a wet cloth,
shield both from drafts and wait until they show the same temperature.
Then we are supposed to place them on a window sill in an air current.
The thermometer with the wet bulb will show the lower temperature.
I recall now that a low tech air conditioning system has long been
in use in India, where long grasses are suspended from the ceiling
and sprayed with water. I forget whether fans are waved at the grass.
The evaporation of the water from the grass cools the place.
This suggests that if I want to cool a cabinet, I can make the cabinet
watertight and simply set up a water fountain that showers the cabinet.
Done carefully, the front and doors of the cabinet don't need to get wet.
This sounds wasteful of water.
Recycling the water with a pump might generate heat from the pump, but
letting the water run constantly could be very wasteful of water.
What would be nice would be if there were some kind of intricate arrangement
of some material, such as cotton fibre or plastic, which could be sprayed
with water and the water allowed to evaporate. The intricate arrangement
would serve the purpose of containing a large surface area in a small
volume. One thing that occurs to me would be to stick a lot of velcro
on the outside of the cabinet but there must be better solutions. Can
someone suggest some?
When full of water, the fibres would weigh much more than when they are
dry, so if there were some device to monitor the weight, it could trigger
a valve which would let the water flow to spray the fibres when the
weight dropped. Alternatively, a device could monitor the temperature in the
cabinet and control the water valve.
If one aimed a fan at the fibres, it would facilitate evaporation, so that
can be part of the design. I removed a fan from a refrigerator a couple of
weeks ago, so maybe I can use that fan.
If this really won't work or if I've overlooked important design
considerations, I'll be glad to have it pointed out. One point that
is not clear to me is what temperatures I can hope to achieve this
way if the room it is being done in is not itself poorly ventilated
poorly thermally insulated and at temperatures around 100 degrees
Fahrenheit.
Allan Adler
a...@altdorf.ai.mit.edu
Disclaimer: I am a guest and *not* a member of the MIT Artificial Intelligence
Neon John
Allan Adler wrote:
>
> Well, ok, my first question is this:
>
> what is the simplest cool temperature-controlled unit I can set up
> without previous experience and without breaking any laws or treaties?
>
> My second question is: what book, aimed at beginners, would explain
> how to do this and guide one through the construction?
>
> Just to give an idea of the level I have in mind, there are
> metal working books by David Gingery which tell you how to build your
> own lathe from scrap aluminum and which guide you through the
> construction, starting with building your own foundry.
I'm kinda of a Gingery fan too. Started casting aluminum before I
got his books but I've learned a BUNCH from them. Unfortunately I
don't know of anything printed like that for refrigeration. If you
go back and do the dejavue search I mentioned earlier, you'll find a
lot of experimental stuff written up as Usenet postings. George and
I met because we were both refrigeration hackers and were both
working in parallel (unbeknownst to each other) on a grassroots
solution to the freon ban. George went on to make a commercial
product and I went off to do some things that didn't make much money
:-(
Anyway, the first thing you need to do is to get yourself a
refrigeration handbook. There are several titles out there. One I
like is "Modern Refrigeration & Air Conditioning". All the
different titles I've seen have a lot in common, they're large,
they're heavy, they're comprehensive and they're moderately
expensive. Most refrigeration wholesalers carry one of the titles.
I recently saw one in the Science department of Barns & Nobles
(store, not the web). These books are aimed at the service
technician. Some people might recommend the ASHRAE handbooks but
IMHO, they are too advanced for a beginner.
You should also look for old books. I collect old refrigeration
books. 50+ years ago, a refrigeration operator or service man was
expected to know everything about the systems he was responsible for
and was expected to repair compressors and other components and not
just change out parts. Many plants were still manually operated.
That is, an operator started and stopped and/or loaded the
compressor by hand and the expansion device was an ordinary
refrigeration globe valve that had to be set by hand. I have one
old book that covers nothing but the operation of a manual ammonia
plant! Audel used to publish a series of books on refrigeration,
electricity, carpentry, etc. I have an old set of Audel
refrigeration books and like them. One nice thing about old
refrigeration books is you usually pay, oh, 50 cents or so for 'em.
Not exactly collector's items.
One of the first things I did when I was starting out many years ago
was to set up a fully manual refrigeration system. Found an old
chest freezer that still used a condensing package with service
valves. Stripped the condensing unit out and set it up to freeze
homemade ice cream, as it turns out. Nothing like the anticipation
of homemade ice cream as one sits there carefully watching the
suction pressure and temperature while tightening down on the
expansion device/needle valve! I've even made glass evaporators and
condensers so I could see what was going on inside. Of course, back
then R-12 was 20 cents a pound and available at K-mart and you
didn't really care if you popped a load after some screwup.
R-22 is probably the easiest refrigerant to work with today. Still
pretty cheap, low ODP (if you believe that matters), minimally
controlled by the EPA and can be replaced with propane if you don't
want to get a green card. An old window air conditioner is a good
place to start. Runs on 120 volts, rugged compressor and
self-contained. You can recover the R-22 using a salt-ice bath and
a suitable container and then reuse it to play. Though they won't
last forever when run this way, you can get away with running a
window AC compressor at pretty low temperatures and pressures long
enough to experiment with it. If you decide to use propane, use the
propane torch cylinder gas. Gas grill gas (or other bulk-sold gas)
is too wet for refrigeraton use.
One of the neat things George did back when they were first starting
out on the trade show circuit was to use copper tubing to bend up
the letters of his product name - kind of like neon - then connect
it to a condensing unit and put the letters over his booth. With
the condenser unit running, the tubing would frost up and look like
white neon!
The handbook will show you what kind of tools you'll need. You
don't need them all at once, of course. In terms of test equipment,
a set of gauges, a good digital thermometer, a DVM and a good
amp-clamp will get you going.
get your handbook, read up and then ask more questions.
roger perkins
applications. Swamp coolers only work in dry climates. They cool the air by
humidifying it.
The thermometer with the sock over it is called Wet bulb temperature. The
dry bulb temperature and wet bulb temperature is a reflection of the
relative humidity of the air.
Allan Adler <a...@zohar.ai.mit.edu> wrote in message
news:y93oggy...@zohar.ai.mit.edu...
Charles Wood
My two cents --
Unfortunely to my knowledge there is not one source of information
that will allow you build your own refrigeration system.
Before 'package systems' (and this is the short answer) we had to
match components, that is, a design temp. and load was specified and
than the design process of component selection and match-up started.
Today that time consuming method of design has already been done by
the manufacturer except for some special applications as I assume that
you are pursuing. You can start with the ASHRAE (American Society of
Heating, Refrigerating and Air Conditioning Engineers) series as a
starting point. If you are at MIT I am sure you will have no trouble
finding this series and any other supplemental theory that you will
need. As far as implementation as a first approxiamation do a web
search starting with the Copeland site. All the major HVAC
manufacturers (Carrier, Trane, York, Rheem, American Coil, etc, etc,)
have links to other sites and most of them have specs for there
product at their web site. This is where you will find the real-world
information that you will need after you have done your homework.
Hope this gives you a starting point.
Best Regards,
Charles Wood C.P.E.
KTLA AIR MAN
On 19 Jul 1999 16:21:32 -0400, Allan Adler <a...@zohar.ai.mit.edu>
wrote:
>
>I have seen discussions on groups such as rec.metalworking about
>building your own steam engines and making your own furnaces
>and foundries. These things are all hot. I would like to think
>about how to make things cold, specifically, how to design
>and build special purpose refrigeration units. On rec.metalworking
>I learned about Lindsay, which sells books on metalwork, including
>some of the hot items mentioned above, but ntohing on refrigeration
>as far as I can tell. If there is an analogous source of books for
>do-it-yourself refrigeration, I would be interested in knowing
>about it.
>
>
David Threlkeld
wrote:
>Suppose that the interior of a glove box needs to be very cold but
>you don't want the room that the glove box is in to be that cold.
>How do you design such a glove box? (I realize this depends on the
>temperature one wants).
>
>I don't assume that there is a commercial solution to this problem,
>although it wouldn't surprise me. It would surprise me if I could
>afford one, though.
There is a very simple but expensive solution to this one.... wait for
BMW to mass produce thier latest proto type car. It has and air
conditioned glove box that stays at either 34 or 43 deg F I dont
remember which one it was.
Now for the big question... WHY? hehe my maps dont care if its hot or
cold lol.
Regards,
Dave
rto...@oanet.com
I'm afraid someone here doesn't know what a glove box is. The writer
didn't say glove compartment, he said glove box. A glove box is a
device for handling components in a controlled atmosphere using glove
sleeves as a way of isolating the hands from the work area inside the
box.
Neon John
David Threlkeld wrote:
>
> On 20 Jul 1999 01:13:34 -0400, Allan Adler <a...@zohar.ai.mit.edu>
> wrote:
>
> >Suppose that the interior of a glove box needs to be very cold but
> >you don't want the room that the glove box is in to be that cold.
> >How do you design such a glove box? (I realize this depends on the
> >temperature one wants).
> >
> >I don't assume that there is a commercial solution to this problem,
> >although it wouldn't surprise me. It would surprise me if I could
> >afford one, though.
>
> There is a very simple but expensive solution to this one.... wait for
> BMW to mass produce thier latest proto type car. It has and air
> conditioned glove box that stays at either 34 or 43 deg F I dont
> remember which one it was.
Damn, another missed opportunity. I knew I should have patented the
idea when I built a refrigerated glove box into my then-new '75
280Z.
>
> Now for the big question... WHY? hehe my maps dont care if its hot or
> cold lol.
Yeah, but your beer does. :-) Er, in these PC days, I meant "soda".
How to do it is easy. Most modern AC systems run the AC part to
achieve a set evaporator temperature, usually near freezing, and
then set the cockpit temperature by tempering the air with either
heat or outside air or both. Evaporator temperature control is
pressure control either by POA valve, etc or compressor clutch
cycling. In either system, the compressor operation follows heat
load.
Knowing this, the solution easily follows. Simply set up another
expansion loop in the glove box. When I did my Z-car box, I coated
the outside of the box with aerosol insulating foam (good stuff or
equiv) and formed 1/4" copper tubing to conform to the inside of the
box, arranging a couple of paths. Tapped off the liquid line to a
new expansion valve and brought the evap exhaust back to a tee in
the compression suction line. If your system has a POA valve (GM's
name - goes by many other names), even better. If you tap your
suction downstream of the POA, you can achieve a much lower
temperature in the glove box than possible when running at the AC
evap pressure. If you need the box not to freeze, use a POA valve
(also known as a backpressure regulator) on the glove box to control
the minimum pressure and thus the lowest possible temperature. This
is much simpler and much more responsive than trying to do it with a
thermostat.
This is REALLY handy. In addition to beverage storage, other
opportunities arise. I used to do a lot of pro photography. Pro
film needs to be refrigerated. instead of having to lug around an
ice box like most photogs, I simply plopped the film in the glove
box. Would leave the engine running on location so the goodies
would stay cool. This is one of those things that you never
realized you needed until you had it and then you can't live without
it.
David Threlkeld
>I'm afraid someone here doesn't know what a glove box is. The writer
>didn't say glove compartment, he said glove box. A glove box is a
>device for handling components in a controlled atmosphere using glove
>sleeves as a way of isolating the hands from the work area inside the
>box.
>
I've always known those as a clean box or iso (isolation) box.
Dave
Tony Matthews
Allan Adler wrote:
> Someone has kindly brought to my attention that my naive question
> about do-it-yourself refrigeration is likely to be quite unpopular
> on this newsgroup; he also explained some of the reasons why (licensing,
> laws, and international treaties). So I would like to apologize
> for any offense my posting might have caused and to let you know
> that I am cancelling that posting.
>
> Let me try to explain what I have in mind. Maybe this isn't the
> newsgroup for it, in which case I'd appreciate being directed to
> a more appropriate newsgroup.
>
> I don't have immediate plans to build anything. It occurred to
> me that there are some kinds of work that need to be done in
> special cold environments. I didn't want to be specific because
> I'm just starting to think about stuff like this and I'm sure that
> my ideas for what to build will change very quickly. But let me
> give you one concrete example.
>
> Suppose that the interior of a glove box needs to be very cold but
> you don't want the room that the glove box is in to be that cold.
> How do you design such a glove box? (I realize this depends on the
> temperature one wants).
>
> I don't assume that there is a commercial solution to this problem,
> although it wouldn't surprise me. It would surprise me if I could
> afford one, though.
>
> Also, I wasn't assuming that conventional refrigeration techniques
> would be used. (By conventional, I mean what one finds in household
> refrigerators.) I was allowing the possibility that some other
> technique might be used. I don't know if there are techniques
> that don't require an EPA license, but if the international
> treaties are about chlorofluorocarbon control, then it seems
> that solutions that don't use chlorofluorocarbons might be
> exempt from such laws and treaties.
>
> Anyway, I promise I will not try to build anything without knowing
> to ten decimal places why it is legal and safe to do so, even for me.
> But I do at least want to be able to think about it. When I ask
> for books and stuff like that, it means I'm planning to read and learn
> and think; it doesn't mean I'm planning to build anything. In the event
> that my thinking gets to the point where I decide I really have to have
> something built specially, I'll have it built by someone competent. But
> at least I will have some idea how to talk to that person about technical
> details.
>