[Gasification] Fw: Underwater gasification?

[Henri Naths]

ps 
 I think the beauty of the a Humphrey-inspired water jet is that it would have relatively no moving parts so it's weight to  power ratio of efficiency is better than that of other engines overcoming the friction losses of a conventional water jet engine (as per water ski)
H.
----- Original Message ----- 
From: Henri Naths 
To: Discussion of biomass pyrolysis and gasification 
Sent: Thursday, May 26, 2011 8:57 AM
Subject: Re: [Gasification] Underwater gasification?


Hi Daniel,and list
<  I don't think it would be an efficient means of low speed marine propulsion though; it would suffer from low propulsive efficiency because the jet velocity would be too high.>
Have you considered the propulsion end of a jet ski or a Jet Boat in your analysis . True the efficiency is slightly lower than a straight prop boat but it is expelling a relatively small stream of water at a high velocity. I hear what you are saying about the jet engines  but as I previously pointed out in a post , water has 700 times the density than that of  air so you have to factor that in the formula.
Thanks 
Henri  
  ----- Original Message ----- 
  From: Daniel Chisholm 
  To: Discussion of biomass pyrolysis and gasification 
  Sent: Sunday, May 22, 2011 5:51 PM
  Subject: Re: [Gasification] Underwater gasification?


  A Humphrey-inspired water jet is an interesting idea. 


  FWIW I don't think it would be an efficient means of low speed marine propulsion though; it would suffer from low propulsive efficiency because the jet velocity would be too high.  The efficiency of a reaction engine (which is something that generates thrust by accelerating and expelling mass - a very broad category that includes not just jet and rocket engines but also propellers on aircraft and ships) depends on the speed at which the mass is expelled.  Accelerating a small mass to a large speed, is not as efficient as accelerating a larger mass to a lesser speed.  If you look at aircraft jet engines today (high bypass ratio turbofans) you will notice that they are much larger in diameter than the jet engines of the 1950s (turbojets) - this is why.




  -- 
  - Daniel
  Fredericton, NB  Canada



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