| Re: OK off Topic but this is useful to us all and i will share [message #322090 is a reply to message #322088 ] |
Mon, 12 May 2008 17:26   |
 Charlie Zureki
Messages: 1366
Registered: April 2008
Location: Detroit Area |
Has No Life |
|
|
Me Too!
Hammer
Be prepared, you'll need it!
|
|
|
|
| Re: OK off Topic but this is useful to us all and i will share [message #322113 is a reply to message #321870 ] |
Mon, 12 May 2008 18:28 |
 Kristian Johnsen
Messages: 525
Registered: August 2007
Location: Norway |
Has No Life |
|
|
| Quote: |
Zepplins get a bad rap, just like nuclear power. I would differentiate petroleum for making plastics from airplane fuel. I believe they have already successfully liquefied coal for use in airborne turbines, and Virgin did a test flight with bio-fuel. So again, we'll survive with minor economic adjustments.
JR
|
Last year I went on a minicruise and on "captain's night" I watched with great interest as he held a session informing the listeners on all kinds of technical aspects of the vessel. One very interesting fact is that the entire ship runs on a standard commercial jet engine (used to boil water to run a generator that runs the electric motors moving the ship as well as every other mechanical thing on board). They do have two engines, mainly for redundancy, but will sometimes use both simultaneously when moving at full speed in very warm climates.
My point, anyway, is that the jet engines on board run on bio diesel, so this seems to be technology already in use 
[Updated on: Mon, 12 May 2008 18:29]
|
|
|
|
| Re: OK off Topic but this is useful to us all and i will share [message #322138 is a reply to message #322129 ] |
Mon, 12 May 2008 19:50 |
Andy Zimmerman
Messages: 235
Registered: April 2004
Location: Illinois |
Has No Life |
|
|
| SteveKirby wrote on Mon, 12 May 2008 19:01 |
Somehow this seems like an extra conversion loss. The jet engine produces rotational energy and reactive energy (the propulsive thrust). The heat of the output is simply an inefficiency of burning the fuel. I would imagine that there are more efficient ways of using biofuel to boil water. Now if they were using the jet engines to turn generators, and then capturing the heat to boil water for additional conversion efficiency, maybe.
|
My only experience with gas turbine naval propulsion was with a coworker that served aboard a destroyer or cruiser with a gas turbine. He remarked about how quickly they could get underway, which seems to indicate a direct mechanical drive rather than going through a steam system. However, I found this article which may explain the cruise ship's propulsion method:
http://en.wikipedia.org/wiki/COGAS
Interesting concept, I would have never thought about sticking a boiler on the end of a jet engine, but it makes sense now...
[Updated on: Mon, 12 May 2008 19:52]
|
|
|
|
| Re: OK off Topic but this is useful to us all and i will share [message #322204 is a reply to message #322172 ] |
Mon, 12 May 2008 22:38 |
 |
Mike Butler (media)
Messages: 2735
Registered: October 2005
Location: southern connecticut |
Has No Life |
|
|
Not to worry, the gas turbine is used for much more than boiling water. The above-mentioned rotational energy output of this engine is applied to the props through reduction gear, much the same way as with any other engine, with variable pitch props helping to make the power more controllable (which might account for the impressive takeoffs). It is the waste heat from the exhaust which is used for steam generation, and this represents energy which would otherwise be lost.
http://www.mikebutlermedia.com
Mike Butler Media * AV/video production * corporate event production * presentation services * marketing support * creative research * graphic design * photography
|
|
|
| Re: OK off Topic but this is useful to us all and i will share [message #322214 is a reply to message #322204 ] |
Mon, 12 May 2008 23:06 |
|
Most modern cruise ships al use electric motors to drive the props, usually mounted on Azipods: (http://en.wikipedia.org/wiki/Azipod). The gas turbine is used to turn a generator, which powers the electric propulsion systems of the ship. Using exhaust heat to generate steam is just a way to increase efficiency. None of these ships use gas turbines to mechanically drive a prop.
-JB
[Updated on: Mon, 12 May 2008 23:07]
|
|
|
|
|
| Re: OK off Topic but this is useful to us all and i will share [message #322317 is a reply to message #322214 ] |
Tue, 13 May 2008 09:51 |
|
Mike Butler (media)
Messages: 2735
Registered: October 2005
Location: southern connecticut |
Has No Life |
|
|
| Jim Bowersox wrote on Tue, 13 May 2008 00:06 |
Most modern cruise ships al use electric motors to drive the props, usually mounted on Azipods: (http://en.wikipedia.org/wiki/Azipod). The gas turbine is used to turn a generator, which powers the electric propulsion systems of the ship. Using exhaust heat to generate steam is just a way to increase efficiency. None of these ships use gas turbines to mechanically drive a prop.
-JB
|
Sure, that's a technique similar to that of railroad locomotives, where a diesel engine turns a generator which powers electric motors (traction motors) at the wheels.
Azipods are not commonly used on naval vessels due to the vulnerability of all that vital equipment outside the hull (propulsion and steering would be easy for enemy ships to destroy), but there are quite a few cruise ships and commercial vessels using them.
Either way, the turbine is being used for its rotational power, not just to boil water (that would be what a nuclear reactor does). The use of waste heat to generate steam and additional electrical power is just a means of increasing the energy efficiency of such a powerplant (and we all want that, right?).
http://www.mikebutlermedia.com
Mike Butler Media * AV/video production * corporate event production * presentation services * marketing support * creative research * graphic design * photography
|
|
|
|
|
|
|
|
Forum Home
Login
Forum Search
Register
FAQ
