Propane Refrigerator Conversion

It seems I can't find suitable information nor parts suppliers regarding the conversion of a normal domestic refrigerator to one that uses Propane.

I have a customer who wants me to convert any given refrigerator (specifically an 18-22 cubic refrigerator) to Propane for campsite use.

I need information on how to do the conversion please.

What cap tube size, suggestions on safety valves, where to get fittings to adapt from the standard propane tank (US-20pound) for use on the refrigerator, etc., and estimated fuel usage per day/week/month.

I don't want to convert the refrigerator to R717 (ammonia) or use any kind of funky adsorbtion system.

How to get the cold control to operate a valve, the fan to work, etc without using anything more than a small square 6 volt battery or two like the kind you use in large flashlights?

The customer can manually defrost the refrigerator.

I supose a small static invertor could be used to drive the lightbulb and fan. But the electrically operated valve for the propane is the question........

Why do you, or rather your customer, want to change the refrigerant in these fridges ?

Is there a lack of electricity to run them ? If that is the case then why not run a generator on the propane to run the fridges ?

Or is he hoping to just blow propane through the fridge components in a total loss system ?

I am confused...

The customer doesn't want to run a generator.
A total loss system would suit his needs as long as the loss is low.

He and a few of his friends run a campsite out in the boonies where there are no utilities, except the propane they bring with them.

He already has propane lighting and heating, but doesn't want to spend $2200 to $3500 for an 18 cubic foot frig (ammonia type, propane heated).

If I can design a system to convert existing used refrigerators to one's he can use, I would satisfy his needs and make a little money for myself.

I could sell them for $500-$1000 (US).

I already have in mind how to take care of spent propane and have a good idea on safety valves to be used.

Is this the type of thing you are looking for?
http://www.rangercamping.com.au/Rang...s/Chescold.htm

:confused:

Frank

absorption is the best bet zolar, and you can use propane, lit dung manure or whatever you fancy to get the ammonia going round the system.

as for designing a system using only propane, because the guy has tonnes of it........i dont know, it has me beat

but then who knows, youre the brains zolar, you might come up with something and change the world

so my advise to your mate is, go buy an absorption fridge and get over and done with it

Hi, Zolar:)
just to diverge what about those 12v compressors you can get, you could fit one of those to a ordinary fridge, even if it was a bit small you would still get enough refrig to keep the essentials from going off for afew days.
Have fun. Regards. Andy.:D

My customer wanted to convert a regular frig to use propane only.

I am unable to convert a regular newer frig to absorbtion type.

So, basically you want to modify a fridge with an electromotor-driven compressor in it to use propane instead of electricity to drive it.

This is not exactly a trivial task. You could switch to absorption cooling (the intermittent cycle using NH3 is easy), or use an automotive compressor coupled to a small 4-stroke fuel engine running on propane.

Another option is to inject liquid propane into the evaporator and dump the evaporated propane either in the atmosphere or route the evaporated propane to other propane equipment. However, this causes a serious consumption of propane since you are only using the latent heat of vaporisation instead of the chemical energy.

I would go either for the fuel engine (small lawnmower?) with external compressor, or the intermittent NH3 cycle

Thank you.

Regarding NH3, the only thing I know about it is how to clean floors with the stuff.

My instructor skimmed over that part about ammonia, just enough to tell me that 1) it is hazardous, and 2) it does work well.

So, unless I can find FREE information regarding how to design and use ammonia systems, I have to resort to the practical method - trial and error........sigh

hmmm....maybe pigs on a conveyor belt would drive the generator? LOL

...tell him, okay...... I'll convert it, and it might cost you $2,200 to $3,500 for the conversion.:p

Haul the old fridge off to the shop to perform the conversion.

:rolleyes:

Show up with a new propane fridge (absorption unit). Place the new "converted unit", hook up the propane and light the pilot light.

There..... it's converted!:D

............. I'm serious ................

If you anticipate him fussin' over, "Well that's not the same machine.....", be sure to remove the door handle from the old fridge, and fit it onto the new (performed at the shop, of course, i.e, "the conversion"). Then you would reply, "well sure it is, the handle was what did NOT require refitting!"

:)

So we come back to the same thing...........an absorption unit run on propane !

Zolar..........you do come up with some weird concepts!
Me, I like to keep things simple
and enviromentally freindly
and I like to sleep contentedly at night

But I guess we need an enquiring mind like yours for the sake of progress

I hope you crack it

Good luck I say.......despairingly

well,

you could "gut" the box, cut a hole in it, and apply one of these ice ball things.....


http://www.ggw.org/~cac/IcyBall/crosley_icyball.html


:D

That's hilarious!

Zolar...

There are actually directions for building that device.....

...... I wasn't joking........

:D

I've seen a Crosley Icey Ball in a refrigeration museum. A neat gadget in its time. :)

A neat gadget indeed, but it is quite heavy and wouldn't get cold enough to support a standard 18-20 cubit foot refrigerator for any length of time, especially when kids open & close the frig door umpteen zillion times a day.

I have an idea though....no ammonia or electricity needed, no heat either.............

Now if I can find the time to design and build the thing........

Zolar,

The minimum temperature obtained by the described device that I have recommended is -7degF to -18degF. I beleive that this would be adequate for the application. put fins on the "cold" ball to improve heat transfer!!!!!

You are concerned about the weight (we're not packing this thing on a 50-mile hike are we?), however, my observations regarding the home built units that I have observed are construction of real novices, using steel pipe fittings. I think a couple of disposable refrigerant canisters would suffice (though don't tell anyone that I recommended it if one blew up in your face!!!).

c'mon, man.. build it, and they will come......

as for the kid's opening and closing the doors, well you'll have to re-charge the ball more often, or I'm sure that Marc can figure out what volume of ammonia to apply, and the required volume of the high and low side balls. Apply solar-powered fan motors to 'blow" over the cold-ball fins, and you've got good recovery for the uncontrolled kids who are in charge of their parents !!!!! LOL!!

We're really getting a good design going, here.

:)

But Zolar, I'm beginning to think that you are going to propose your invention of the wheel........ in order to transport the ice to the deer camp ice chest......... LOLOLOLOLOLOLOL!!!!!

The design was a horse & buggy. Then drive to Mc Donald's.

Ok...just talked to an expert. She said 'NO WAY! I'd rather be having fun camping than to mess with fire and icy balls"

Of course, the expert is my wife...LOL

Perhaps a survey would be in order? Everyone ask their significant other if they want to build a fire, charge up an icy ball, let it cool, tote it to a frig, install it, and repeat the process at least daily, all the while the guys are sitting around drinking warm beer and complaining. Of course the process would probably take an hour or two from start to finish.

The idea would be more practical if used by us guys on a month long "roughing it" excursion.

Now, the design of the 'balls' and fins would be interesting..........

I do not have a welder, or access to welding equipment. Best I could do would either pray to win the lotto and buy the needed equipment or maybe draw it on paper.

It's been so slow that I still have a few pounds of R414b left after 3 months of using it before I could have ONE of the 2 containers. BTW, that was the SAME hotshot I had when I ordered George's R406a 6 months ago.

It would take till June of next year (at my current rate) to use another bottle up.

Now, about my design mentioned before. How about a gravity refrigeration system with no moving parts, no electricity needed, and no additional heat input?

Zolar

Hi, Zolar:)
that would be thermosyphon would it? Where you boil off refrigerant in the evap then the vapour rises into the condenser where it is condensed as normal and returns as liquid by gravity to the flooded evap.
You could use air to cool the evap, but the fridge would be warmer than ambient inside or water from a lake/river, but that might require a pump.
Better just drop those beers in a keep net in the river.:D
Regards. Andy.

Thermosyphon seems to be the term I'm looking for, but....

What if you used water in a wide tub for the condensing coils? Evaporation of the water could cool refrigerant vapor to liquid form a little faster.

Suppose you used the Bernoulli effect inside the discharge line from the evap to the condensor inlet?

I was thinking...maybe get the kids to run on a ramp to drive a compressor? lol

Sometimes weird ideas can inspire ingenius designs from the experts...........

Another thought here.

Suppose you placed the 20 pound propane bottle IN the water. As you used propane, the bottle would absorb heat and enhance the process.

They would only have to keep a few lights on depending on the insulating values of the refrigerator walls.

Hi,Zolar1:)
I am not sure what you mean by putting the bottle in the water is it to boost the pressure in the bottle to feed lights ect?
The idea of using water to recondense the refrigerant is sound, if you had some way of spraying on the water to aid the evaporative effect (any water falls near you camp?) or you could have a fridge that works well in the rain:D
What about a small water wheel to power say a 12v alternator and fit a 12v compressor to your fridge?
Regards. Andy.

Place the propane bottle in a large pan of water with the tubing shaped into a coil, submerged into the water. Use humidifier pads to aid in evaporation.

Just a thought?

http://www.laganga.com/gas_ford.htm
try this; you are making life more difficult than it is I think.

That he is, I grew up for a good part in a logging camp and we'd have died laughing if some one suggested wasting such a valuable resource such as propane!

Now you said you have kids? I'm guessing they have bikes? and a car A/C compressor is rather easy to acquire!

lol no, but on a serious note that is what I will suggest, wind or water to spin it, that or do as they have suggested and get a 12volt compressor, a solar cell (They are dirt cheap now days) and over size the condenser and there you go, and teach the kids to use their brains and not open the door all the time and be quick when hey do need to open it. Oh and a deep cycle, that system put togeather well will last many many many years (The one the guy made at camp with a home made inverter and a standerd compressore has lasted till now and from what I hear going, so thats the real viable option you have, that or pelts but that will consume way more then needed)

So basicly you are saying your customer wants to burndown or blowup his cabin? since Propane is very flamable & lays in invisible pools when released to atmusphere.

Expensive but possible: Two sets of Peltier heat modules:
You heat one side of set A by burning Propane or a by-product of oven/stove they produce electricity to run the B set to cool the fridge. Watch temperature limits!
Have seen big boys toys (wine coolers etc) and camping gear using these, in some case they are attached to a refrigerant spider to improve heat transfer. Though the cost to power ratio is high: and they are usually run at 12-15ºC - above safe food storage temperatures.
Also battery, solar, and water wheel compatible, very good for current CO2 global warning concerns;).