A/C ideal

[GeorgeTelford]

Hi arti

The original Question was using an RV fridge

Some of your suggestion's are of course do-able, but would you really want to?

[Artificer]

Hi arti

The original Question was using an RV fridge

Some of your suggestion's are of course do-able, but would you really want to?

What I posted as a freezer, is actuall a refrigerator/freezer. I've seen similar sized units in RV's. Granted, they'er monstous in size, but they'er still RVs.

... but would you really want to? Uhm... YES. 450-1000 watts of electrical power, 2000BTU's of AC, small refrigerator with freezer, hot water, all propane powered? If I can pull this off, it'll be great for the way we typically travel. Back roads, no campsites. Doing digital photography without haveing to have a loud generator going. Besides which... it has a high "coolness factor", at least for me.

[GeorgeTelford]

Hi Arti

I see your error now, you have assumed 1700 Btu's of energy consumption is 1700Btu's of cooling, sorry but its not the same thing at all

Think Microwave they say 800 W but thats the cooking output, the electrical input is say 1200w

The other problem is completely exhausting all the heat created.

[Guy]

Dear Art,

Here is a site, RParts, with a forum for both technical advice and DIY. The company has a very nice tech who answers all questions as do the users.

http://www.rparts.com

[Artificer]

Hi Arti

I see your error now, you have assumed 1700 Btu's of energy consumption is 1700Btu's of cooling, sorry but its not the same thing at all

Think Microwave they say 800 W but thats the cooking output, the electrical input is say 1200w

The other problem is completely exhausting all the heat created.

Nope, I know what I'm talking about. COP of ammonia absorption systems is arount .2 Stirling cooling can be around .4 Vapor compression systems are around 3 (more or less depending on the system).

Using a conservative COP of .15, and 20,000BTU/lb of propane, you would get about 1.5hr of cooling from 1 lb of propane. (2000btu/hr) So a 20lb tank would last for 30 hours. Its a gas hog, but I'm willing to pay the $5-$6 for a good nights sleep even if there isn't any shore power.

Exhausting the heat is the simple part. Everything is external to the trailer, and uses hydronic heat exchange for cooling/heating. The coils may be large, but I'm envisioning a folding system.

I admit this is a very personal choice, and most people would think it nuts. I'm working on it more as a "can I do it" rather than its the best possible solution. If I get it working, it will be a posssible alternative for those who do dry/offroad/backwoods camping.

The most practical solution would probably to try a true sine wave inverter with the petcool. Sonetpro tried it with a regular inverter, and only had a 50%-60% electrical conversion rate. Ends up being too high a draw on the batteries. As I said before, this is a project after the trailer project is done. Some people build second (third, fourth) trailers, this is what I intend to do.

Guy: I've been to the rparts.com before. They don't stock it, but I've been drooling over the Danfoss BD100CN compressor. 12-24V DC, R290 refrigerant (propane-no license needed). Combine that with the other items from rparts, and you might have an A/C system, or at least an extreame refrigerator/freezer.

[Sonetpro]

Artificer,
Here's a update on the petcool. It is working out sweet. In the pic's you can see how I mounted it in the galley. Holes drilled through the cabin wall. I then got a 3" PVC and made a plenum and then 2 2" pool hoses going up to 2 Porshe vents I got off ebay above the cabinet. I have tested it with just tarps over the doors and it is going to work great. It'll run 7 hours on a tank off the generator. So a good nights sleep for about 3 bucks in fuel.

[GeorgeTelford]

Hi Arti

You said and I quote

The little LP powered fridges you see only put out around 250btu/hr. Thats why they take so long to cool down. You can find a propane unit that has the capacity, such as this freezer. 1700BTU

But if you check the link that you gave it clearly says that that is the input or gas consumtion BTU's, not the cooling BTU's and thats a world of difference

Quote from your link "Energy Consumption:* 1700 BTU/hr "

[Artificer]

Hi Arti

You said and I quote

The little LP powered fridges you see only put out around 250btu/hr. Thats why they take so long to cool down. You can find a propane unit that has the capacity, such as this freezer. 1700BTU

But if you check the link that you gave it clearly says that that is the input or gas consumtion BTU's, not the cooling BTU's and thats a world of difference

Quote from your link "Energy Consumption:* 1700 BTU/hr "

My mistake. I was too quick looking at the specs of the larger unit. I thought the 1700BTU was the heat transfer, not the energy input. Sorry about that.

The absorption system is still a damn cool idea. The reason you'll never see them on semi's, is that they are less efficient than engine driven compressor systems. (as well as more expensive) In industry, however, if you have waste heat, you can use it to get free refrigeration. A typical example is a company with drying ovens/kilns. Use some of that heat to power the abosorption A/C. Also works great for co-gen.

Sonetpro: good news on the pet-cool. Nice install, btw. Since you're reading this thread... are your inverters modified sine wave, or true/pure sine wave units? I'm trying to figure out why you were getting such a bad conversion efficiency.

[Sonetpro]

Sonetpro: good news on the pet-cool. Nice install, btw. Since you're reading this thread... are your inverters modified sine wave, or true/pure sine wave units? I'm trying to figure out why you were getting such a bad conversion efficiency.

Modified sine wave. True sine wave are
I think I'm going to stick with the Genset.