[Gasification] tesla turbine

[Ken Boak]

Gents,

I started reading Schmidt's paper and got to the bottom of page 2.

I think I need an explanation of the term Isoentropic efficiency.  Page 15 
states

Isoentropic turbine efficiency = shaft power / energy in the heated 
compressed gas  entering the turbine relative to ambient conditions.

Further to the report on page 7, it states that compressed air was available 
at up to 290 psig at 500cfm, and a head of 80psi was maintained so as to run 
the combustor at 40 psig. Running a compressor to meet these requirements 
consumes considerable energy in its own right.   During test runs, between 
9600 and 15,000 standard cu ft /hr of air was consumed at above 40psig - all 
this has to be deducted from the efficiency figures.  A rough estimate 
suggests that a 16kW compressor would be needed to supply the lower of these 
two figures at only 40psig!   The tesla turbine would probably spin on the 
airflow alone without introducing gaseous fuel !


Two cases stated:

(1) Running on natural gas with a firing rate of 173,000 BTU/hr   Power = 
4.6hp

(2) Running on biomas at 192,600 BTU/hr Power = 4.3 hp

1 hp/ hr  = 2544.43 BTU

So efficiency (1)  = (4.6 x 2544.43)/ 173000   = 6.765%    ( Isoentropic 
eff. 12.25% quoted)

So efficiency (2)  = (4.3 x 2544.43)/ 192600   = 5.68%      ( Isoentropic 
11% quoted)

Whilst Schmidt concludes that the isoentropic efficiency needs to rise,  I 
cannot see any startling results with the thermo-mechanical efficiency that 
would get me excited over this device in its current state.

However to its merit is its simplicity and the reduced requirement for gas 
treatment following a gasifier.



Ken