Ausra Co-Founder Returns With Solar Air Conditioner—"75% efficient!?"

[OKIsItJustMe]

http://www.greentechmedia.com/articles/ausra-co-founder-returns-with-solar-air-conditioner-5893.html

Ausra Co-Founder Returns With Solar Air Conditioner

Using the sun's heat to cool a room isn't as much of a contradiction as it sounds. Chromasun, from Ausra's former CEO, says it can run air conditioners on solar power.

by: Michael Kanellos
Bullet Arrow March 16, 2009

Use the sun's heat to cool a room. It sounds like a contradiction, but Peter Le Lievre says solar air conditioners could become a key element for relieving stress on the grid during peak periods.

…

Le Lievre, a co-founder and former CEO of solar thermal specialist http://www.ausra.com/">Ausra, has formed a new company – Chromasun – that hopes to capitalize on the small, but growing market for multifunctional solar systems (see http://www.greentechmedia.com/articles/solar-panels-and-solar-thermal-all-in-one-5484.html">All-in-One Solar Panels and Solar Thermal). The company has erected a working prototype in San Jose, Calif. and is currently raising money to build larger prototypes that will be installed in the U.S. and overseas. By the first quarter of next year, he wants to be in mass production.

Multifunctional solar devices harvest both light and heat from the sun. Traditional PV cells only harvest light and are only around 23 percent efficient in converting photos to electric power. Solar thermal systems collect heat, and are about 48 percent efficient at best. Utility-scale solar thermal systems are closer to 20 percent efficient because the captured heat gets converted to electricity.

Chromasun's device is 75 percent efficient. The device – at 10 foot by 4 foot sealed box – is essentially a utility scale solar thermal plant and a utility-scale concentrating solar PV plant in miniature. It contains mirrors, receivers and a concentrator for generating solar thermal energy as well as silicon solar cells.

…

[tangent90]

1. 75 percent efficient is still less than 150 watts per square meter.

That 10 x 4 foot box might generate enough electricity to run a small TV set.

[OKIsItJustMe]

2. It's not running a typical air conditioner

…

Chromasun's system works the same was as natural gas double-effect chillers. Water or an oil in a sealed tube gets heated to 220 degrees Celsius. The heat is then used to warm a solution that contains a refrigerant. The refrigerant boils away. The solution and refrigerant are later reunited, exploited to cool and room, and pumped through another heating and cooling cycle.

…

[AlecBGreen]

3. heating water to 220C?

Is it under extraordinary pressure? I always thought that 212 was a hot as water could get under normal conditions, right? Even steam & water vapor cant be raised above 212. Or so I thought. What am I missing?

[Massacure]

4. Water boils at 212 degrees Fahrenheit which is 100 degrees Celsius

Of course the 212 degrees figure assumes normal atmospheric pressure at sea level. Increase the pressure and the boiling point rises. Decrease the pressure and the boiling point falls.

[AlecBGreen]

5. oh

so this is why people in Denver have a hard time boiling pasta?

[AZCat]

7. Yes.

The water isn't boiling at the same temperature. That's why you have to cook the pasta longer.

[OKIsItJustMe]

8. Or, you could use a pressure cooker

A pressure cooker allows the water to get hotter than its (normal) boiling point.

[AZCat]

9. Can you cook pasta in a pressure cooker?

I'm ignorant of most things related to cooking. Do people use pressure cookers with pasta?

[OKIsItJustMe]

10. Absolutely!

http://www.missvickie.com/howto/pastas/pastatiming.htm

[OKIsItJustMe]

6. It's in a "sealed tube."

A typical car's cooling system is often heated above the boiling point of the coolant. If you remove the radiator cap from a hot engine, you'll relieve the pressure, and the coolant may quickly boil (spraying scalding hot fluid.)

If you develop a leak in a cooling system, it will blow steam, as the fluid instantly boils.