[Stoves] Green Steam Engine

[Kevin]

Dear Bryce

Thanks for the feedback.

"Condensing" is simple in concept. Simply pass the steam exhausted from the engine through a "condenser." :-) A "Condenser" is a heat exchanger that is cooled with air or water, and it creates a vacuum, enabling the piston to extract more work from the steam.

For example, if the temperature of the water leaving the condenser was about 140 F, the vacuum in the condenser would be about -12  psig, and effectively, 50 psig steam would be as 'powerful" as 62.3 psig steam.  A problem with the Green steam engine could be that when the steam was expanded enough to get the vacuum, there could be leakage of air in past the O-rings, and a de-aerator would then be required to remove the air. Additionally, you also need a boiler water feed pump, operating under vacuum, to recover the water from vacuum of the condenser, and lift it up to boiler pressure of 50 psig.

They say, as you quote below: 
" There are numerous reasons that this design is considerably more efficient than standard historical steam engines."
There are also numerous reasons why condensing systems are not used on small systems, two reasons of which are cost and complexity.

Best wishes,

Kevin
  ----- Original Message ----- 
  From: Bryce L Nordgren 
  To: Discussion of biomass cooking stoves 
  Sent: Wednesday, May 15, 2013 12:48 PM
  Subject: Re: [Stoves] Green Steam Engine





  On Wed, May 15, 2013 at 9:25 AM, Kevin <kchisholm at ca.inter.net> wrote:

    Dear Bryce

    I couldn't find his claim for 24% efficiency, but it seems to be very high. I calculate that the useable energy in the steam is less than 3%. 

  Yeah, for a website with only three pages, it sure needs work. The claim is on the "Licensing" page. I wasn't trying to review his claims, because that's a bit out of my niche. I just wanted to see where the provided numbers took us. 

  The 24% figure was for recondensing the steam around the boiler. I can't fathom how that works since the exhaust steam is at 1 atm. How would the boiler be cold enough to recondense 1 atm steam to liquid if it has to be hot enough to make steam at 4-9 atm?

  Here's the snippet: 


      When the steam is simply exhausted to atmosphere while running a generator, for example, efficiency is relatively low; in the area of 15%. When the exhaust is condensed and recycled back to the boiler, the efficiency is around 24% to 30%. When the exhaust is condensed through a heat exchanger whereby the condensation process is used fully by heating water, space and distilling water, for example, the efficiency can be in the 70% range.
      In addition to the potential for efficient energy use and production, the designs' simplicity, economy and weight more than justifies its utilization. It is important to note that utilizing free or cheap fuel makes efficiency less important. There are numerous reasons that this design is considerably more efficient than standard historical steam engines.


   


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