Using the sun to power air conditioning -- just like the TM fridge

**ShrimpBurrito** · 08-27-2009, 07:12 PM

I found this to be a fascinating, yet a simple and proven concept. Using the sun to power an air conditioning system -- and I'm not talking about using a solar panel to generate electricity to power an air conditioner.

Just as the TM fridge uses propane or electricity to power a heater that in turn chills your food, they use the sun to heat water which is pumped to an absorption cooler, which in turn pumps cold water throughout the building to distribute cool air.

http://www.latimes.com/business/la-f...0,996681.story

Dave

08-27-2009, 08:25 PM

That is very interesting, but to stay within the GCWR rating, you would have to leave the TM home and just tow the solar power system.

**Bill** · 08-28-2009, 07:34 AM

It is fun to think about, but don't misinterpret it.

As you said, the concept of using heat to produce cold has been well known and well-used for decades. Absorption refrigerators (the kind in our TMs, and the kind described in the linked article) were invented in 1922, and household propane refrigerators were common in the 1930's wherever there was no electricity. Any source of heat will do, whether it is a propane flame, an alcohol burner, an electric heater, sunlight, or any other. Concentrated (very hot) heat is better, explaining the big mirrors in the article.

Unfortunately, a heat-driven chiller takes a lot of heat to make a small amount of cold. Consider that the refrig in the TM is a well-insulated box, and it takes about 150 watts to cool the small space inside the box. By contrast, the inside of a TM has about 500 times as much space, and is poorly insulated by comparison. It would take more than 15KW to chill it using a heat-driven chiller, compared to the 2 KW using the conventional air conditioner in the TM.

The main point of the article is not a new way to make cold. It is the use of sunlight as a source of heat. And for a utility, it is a great thing. Again, it is fun to think about, but don't plan on replacing the TM air conditioner.

Bill

**ShrimpBurrito** · 08-28-2009, 10:11 AM

Quote:

Originally Posted by Bill

The main point of the article is not a new way to make cold. It is the use of sunlight as a source of heat. And for a utility, it is a great thing. Again, it is fun to think about, but don't plan on replacing the TM air conditioner.

I'm definitely not thinking it is going to replace the TM air conditioner. I just think it's neat that someone has harnessed the sun to cool a building without using power.

One of the main disadvantages of solar energy is that you can't harness it when it's dark. There is a pilot generation plant that was built a few years ago in the California desert that directed thousands of mirrors to a solar collector sitting atop a tower in the center of the panels. That collected heat would melt a tank of salt. The heat from the molten salt would then boil water to generate steam to turn turbines to generate power. The neat thing about the plant was that, apparently, since molten salt has a very high heat capacity, the plant could continue generate power throughout the night until the sun came up the next day.

I think there are plans to expand upon the concept.

Dave

08-28-2009, 01:46 PM

Another limitation of solar is you have to have sun.

I nearly always either camp in a valley in a dense forest or camp in the winter on the coast in a dense redwood forest in the fog.

Solar is very close to worthless for me.

Alaska becomes interesting. During the camping season, as long as you are not in a forest or a deep valley, there should be plenty of sun, but perhaps not high enough.