definitely needs work...
H.
----- Original Message ----- From: "Rolf Uhle" <[email protected]> To: "Discussion of biomass pyrolysis and gasification" <[email protected]>
Sent: Thursday, May 26, 2011 10:40 AM
Subject: Re: [Gasification] Fw: Underwater gasification?




But it must have a big volume of pressureproof vessel inside the hull.
And if I calculate it right, the Humphrey pump delivers some 260
net kW. No idea how high it's efficiency is, shure not 100 %!
Neither how efficient a jet propulsion like this could be.
But even 260 kW are not much for a big ship with a huge vessel inside.
ICE's compress the air much more and have a higher energy density.
Sometimes beauty and virtue don't go the same way !

Rolf

Am Donnerstag, 26. Mai 2011 17:13:30 schrieb 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.







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