[Gasification] Homemade gas turbines

[Kevin Chisholm]

Dear Harmon

I think the mistake they are making is to confuse Turbine Efficiency 
with Overall Efficiency.

A very well designed turbine can indeed have a Turbine Efficiency in the 
range of 85%. This has to do with only Isentropic Expansion efficiency, 
friction, windage losses, etc, and it has nothiong to do with overall 
system efficiency. The exhaust gas turbine on an engine turbocharger may 
have a 60% efficiency, perhaps less, because efficiency is not all that 
important.

The most common "gas turbine cycle" is the Brayton Cycle. Under good 
conditions, the Braton Cycle may have an efficiency of about 25%, about 
the same as the Otto Cycle.

Under conditions attainable  by an enthusiastic and resourceful amateur, 
perhaps the cycle efficiencies would be in the range of 15% to 20%

The Backyard person could perhaps expect Overall Efficiencies in the 
range of 60%x15% = 9%, to 60%x20% = 12%

Best wishes,

Kevin

Harmon Seaver wrote:
> Michael Redler wrote:
>> Harmon wrote: "Tubines suck for efficiency"
>>
>> Internal combustion engines and gas turbines are typically comparable to each other and some statistics even state that turbine efficiencies are better than ICE engines.
>>
> 
>    If turbines are as efficient as IC engines, it's funny they've never
> caught on in cars and trucks. And one place where they were more
> recently tried, the US military tanks, they have been replaced at great
> expense with diesels to get more range.
> 
>