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MarkG

I doubt this system could have flown past the Open Source radar, but I'm noting it here just in case. I'm interested in steam power on the micro scale with emphasis on cogeneration. Open Source seems to have interest in somewhat larger systems. Well, it seems this particular configuration is perfect for the Open Source project. The company uses Skinner compounded unaflow piston steam engines that were manufactured as late as the 1940's. Solar concentrators generate high pressure steam that is provided to the high pressure cylinder. The engine can be operated in high power mode by providing full expansion through the engine, or the steam can be exhausted from the high pressure cylinder to condense at high temperature in a large insulated pressure vessel (standard steel propane storage tanks). When fully charged to their rated pressure of 18 bar, any high pressure steam generated will be fully expanded through the engine for high power. At night, the system permits operation by flashing the pressurized saturated water to steam for use in the low pressure cylinder of the engine. In this manner the system achieved 24 hour operation on solar energy. No batteries. No electronics. http://www.terrajoulecorp.com/unexpected-technology/how-it-works/

roleic

Are the cheapeer propane tanks also rated for the higher temperatures of
a steam accumulator? I guess that propane is not supposed to heat up to
such high temperatures.

roleic

MarkG

I'm only sharing the info - I suggest you contact Terrajoule with questions. In any case, a somewhat lower pressure and temp could be used in the storage vessel. More important is that overall cycle efficiency is not adversely affected by this configuration as the energy that would otherwise be used to support full expansion in the engine when high pressure steam is available during the day is stored for later use at night or during inclement weather.

NOTE: I believe the storage vessel pressure is lower than I suggested before. One reference I saw suggested on the order of 100 psig saturated water. This actually makes a lot more sense as the pressure on expanding through the first stage of the engine would be a lot lower than 250 psig. However, again, I recommend contacting Terrajoule for specifics.

Coloredcoat

So is the big draw to this super heated water energy storage system that it contains no electronics and is simply mechanical?

Even if you heat water stored in a propane tank system to a generous 410 psi and 446 degrees F, there's only enough energy stored in the hot water to flash approximately 24% of the water to steam at 212 degrees F. Hardly an ideal storage system, especially since the thermal transfer losses will be far in excess of any other energy storage and conversion system using PVC and batteries. That's not even counting the extremely high cost of this equipment needed for this design for the heat collectors, piping, tanks, steam engine, generator, etc.

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