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Old 26-05-2016, 18:33   #46
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Re: Propane Refrigeration

There is no correlation of the fiery pictures and propane in that search. It is a false "illustration".

I don't think the cost of the whole system (panels, wire, fridge, controller etc.) could possibly be less than a current Dometic.
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Old 26-05-2016, 19:05   #47
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Re: Propane Refrigeration

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Originally Posted by Therapy View Post
There is no correlation of the fiery pictures and propane in that search. It is a false "illustration".

I don't think the cost of the whole system (panels, wire, fridge, controller etc.) could possibly be less than a current Dometic.

10 amp MPPT controller, $100
140 watt panel $275
cables $25
Danfoss DB-35 compressor driven fridge $1000
or decent invertor $350 and WallyWorld 120V 10cu ft fridge $250

Zero propane costs for 10+ years.....
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Old 26-05-2016, 19:12   #48
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Re: Propane Refrigeration

Do not be confused between Propane used as a refrigerant gas inside a compressor system, and an absorbtion refrigerator (Electrolux patent)

In any case why would you select a fuel that cannot be renewed every morning when the sun comes up? I suggest that a Danfoss type 12/24v system is more reliable, and much more efficient, and, it runs on solar and wind power, so no need to carry such a large amount of compressed gas bombs on your boat.

We had them in our mess on frigates, a right PITA....
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Old 26-05-2016, 20:12   #49
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Re: Propane Refrigeration

Surprised that no one has brought up the issue of surveys and insurance. Many marine insurers will not insure boats with propane refrigerators because they do not meet ABYC standards. Any SAMS or NAMS surveyor is going to flag that issue in a survey which will bring it to the attention of the underwriters.
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Old 26-05-2016, 23:24   #50
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Re: Propane Refrigeration

My understanding of absorption refrigerators is that they exploit the extremely high solubility of ammonia in water to generate their refrigeration cycle. The heat source raises the temperature of the water/ammonium mixture which drives off ammonia vapour which is cooled to a liquid in a condenser, the liquid ammonia then evaporates in the evaporator the change of state requiring heat of evaporation pulls down the temperature in the ice box, simultaneously the lean water/ammonia mix is cooled in a second heat exchanger after which it is bought into contact with the ammonia vapour coming from the evaporator and the ammonia is absorbed by the water starting the entire cycle again.


It appears that this cycle would be amenable to direct heating by sunlight making it a candidate for solar powered refrigeration without the batteries, panels, regulators wiring etc.


I think the absorption fridges also have hydrogen in them and run at about 400psi internal pressure but I would not swear to this.
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Old 26-05-2016, 23:37   #51
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Re: Propane Refrigeration

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Originally Posted by Dymaxion View Post
10 amp MPPT controller, $100
140 watt panel $275
cables $25
Danfoss DB-35 compressor driven fridge $1000
or decent invertor $350 and WallyWorld 120V 10cu ft fridge $250

Zero propane costs for 10+ years.....
The replacement propane unit runs about $750.

Your total system runs $1400 + installation costs for the solar system of maybe an extra $500 (assuming installing the actual fridge is a wash)

We go thru maybe 4 20lb tanks per year at around $20/tank.

So after 10yrs, if neither system requires any maintenance or repair:
- Electric system: $1900
- Propane system: $1650

This is probably understating the savings as I have dealt with 3 propane fridges with zero repairs. The youngest is 20yrs old. The oldest is pushing 40yrs old.
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Old 26-05-2016, 23:51   #52
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Re: Propane Refrigeration

My full size RV propane only fridge burned about 1.5 lbs of propane per day in the Bahamas, a number confirmed by Dometic tech support. I would think 4/tanks/yr must spend a lot of time at the dock. I carried (4) 20# tanks stuck under the flybridge of my previous trawler. No comments from the surveyors when I bought or sold.
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Old 27-05-2016, 10:15   #53
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Re: Propane Refrigeration

OK. Here is my main point.
Propane stuff is not a bomb waiting to go off. If it does catch fire it does not explode. It just doesn't. - as in, find me three documents, Every propane tank that you have ever heard about ( I know you haven't seen one explode) or seen on film is from Hollywood. And what you see is not propane either. Notice the red flames with black edges? You know they make lead bullets spark on plastic and steel cars too right? You have been lied to and believe it.

I know if I was sailing again I would prefer a solar/electric if possible but I had a boat with a fine propane fridge and was not going to throw it away to spend even more boat bucks. It was fine for the purposes.

So argue cost and efficiency if you want but this fear of Bombs and explosions is ridiculous to the point that some think that boat "regulations" ban it.

Wanna move on to GASOLINE! It almost NEVER explodes unless inside an engine where it actually doesn't. it just burns fast. Try to make your dingy gas can explode. I dare you. You can't do it. It might catch fire but your Hollywood will not happen.

How about a good anchor thread.....
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Old 27-05-2016, 10:46   #54
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Re: Propane Refrigeration

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Originally Posted by Therapy View Post
OK. Here is my main point.
Propane stuff is not a bomb waiting to go off. If it does catch fire it does not explode. It just doesn't. - as in, find me three documents,

Wanna move on to GASOLINE! It almost NEVER explodes unless inside an engine where it actually doesn't. it just burns fast. Try to make your dingy gas can explode. I dare you. You can't do it. It might catch fire but your Hollywood will not happen.

How about a good anchor thread.....

I can't believe these comments, pure ignorance. Had a natural gas explosion in a house near me, incredible explosion, it rained fibreglass insulation and strips of siding for half the block, house was flattened. It's the vapours that blow up nicely, just needs the correct air-fuel ratio. Want research, scan for BLEVE, boiling liquid expanding vapour explosions. This is what happens to propane tanks too close to a fire. Let me save you the effort. https://en.wikipedia.org/wiki/Boilin...apor_explosion. The military use aerosol based explosives to clear caves.....
So, put your money where your mouth is. Go sit on a near empty gas can and just keep flicking your lighter near the spout. Perfectly safe, go ahead, knock yourself out.
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Old 27-05-2016, 11:42   #55
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Re: Propane Refrigeration

Quote:
Originally Posted by Therapy View Post
OK. Here is my main point.
Propane stuff is not a bomb waiting to go off. If it does catch fire it does not explode. It just doesn't. - as in, find me three documents, Every propane tank that you have ever heard about ( I know you haven't seen one explode) or seen on film is from Hollywood. And what you see is not propane either. Notice the red flames with black edges? You know they make lead bullets spark on plastic and steel cars too right? You have been lied to and believe it.

I know if I was sailing again I would prefer a solar/electric if possible but I had a boat with a fine propane fridge and was not going to throw it away to spend even more boat bucks. It was fine for the purposes.

So argue cost and efficiency if you want but this fear of Bombs and explosions is ridiculous to the point that some think that boat "regulations" ban it.

Wanna move on to GASOLINE! It almost NEVER explodes unless inside an engine where it actually doesn't. it just burns fast. Try to make your dingy gas can explode. I dare you. You can't do it. It might catch fire but your Hollywood will not happen.

How about a good anchor thread.....
I guess you never light a brush fire with gas! I do regularly. a couple cups of gas spread throughout limbs and brush will ignite very much like an explosion, loud and strong enough to rattle the windows in the house 200 feet away. (my wife hates it!) BOOM!
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Old 27-05-2016, 12:40   #56
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Re: Propane Refrigeration

Apologies for the thread drift, but to "throw some fuel" to the gasoline debate...

Gasoline in a liquid state does not burn. It's the vapors that burn. A car engine needs to first vaporize the gas then add air to burn.
One of the most powerful non-nuclear bombs created is the gas-air bomb. It operates by first "exploding" the fuel container, vaporizing the gas and then a second explosion detonates the hugh gas "cloud" formed by the first explosion.
Gas tank leaks are often welded by first filling the tank completly first. (With gasoline)
Sounds crazy and takes a leap of faith to do this, but it's done.

A citation. http://www.esfd.org/index.php/facts-and-safety-tips/fire-safety/

As to the reefer, hard to beat solar.
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Old 27-05-2016, 14:16   #57
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Re: Propane Refrigeration

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Originally Posted by RaymondR View Post
My understanding of absorption refrigerators is that they exploit the extremely high solubility of ammonia in water to generate their refrigeration cycle. The heat source raises the temperature of the water/ammonium mixture which drives off ammonia vapour which is cooled to a liquid in a condenser, the liquid ammonia then evaporates in the evaporator the change of state requiring heat of evaporation pulls down the temperature in the ice box, simultaneously the lean water/ammonia mix is cooled in a second heat exchanger after which it is bought into contact with the ammonia vapour coming from the evaporator and the ammonia is absorbed by the water starting the entire cycle again.


It appears that this cycle would be amenable to direct heating by sunlight making it a candidate for solar powered refrigeration without the batteries, panels, regulators wiring etc.


I think the absorption fridges also have hydrogen in them and run at about 400psi internal pressure but I would not swear to this.
Yes, but your milk goes off overnight
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Old 27-05-2016, 19:49   #58
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Re: Propane Refrigeration

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Yes, but your milk goes off overnight
Eutectic and I only use powdered milk anyway.
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Old 28-05-2016, 05:48   #59
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Re: Propane Refrigeration

Greetings and welcome aboard the CF, Jruesr.
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Old 28-05-2016, 17:00   #60
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Re: Propane Refrigeration

OH great. One natural gas leak catching and the whole marine industry can't use propane safely. Uhhuh.
My money and my mouth say it works fine, and it does.
Propane tanks too close to a fire? You put propane near a fire? Wait, I thought the fire was the propane. Huh?

Military "gas bombs" are a bit different no? Yes. They are set up precisely. Like a car. Pouring gas on the ground to start a fire any monkey can do. Sure it will light (with an open flame) if the concentration is right.
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