Go Back   Motorcycle Forum > Other > Motorcycle.Com Lounge

Reply
 
Thread Tools
Old 07-09-2009, 08:55 AM   #11
pushrod
Founding Member
 
pushrod's Avatar
 
Join Date: Nov 2001
Location: Baja 'Bama
Posts: 3,642
Default

At their designed power output, GTs are more efficient than IC engines.

However, if they are operated anywhere below their design rate, they 'waste' fuel, for lack of a term. For instance, when you are sitting still, they are burning a bunch of fuel and sending it out the exhaust. IC engines likewise waste fuel at idle, but nothing like a GT.

Mind, you don't use a GT engine like a jet does. The 'generator' end of the engine (which is the part that would hang on a plane wing) provides the hot gas to drive a 'power turbine'. That, through a series of reductions, turns whatever you want to, be it an electrical generator, a helicopter rotor, or a propeller shaft. So, you lose quite a bit of 'efficiency' through the transmission of the power.

You'll notice the specs on the big Wartsila show that its most economical fuel rate is damn near its max power rate. The operators will wait as long as possible to fire that big sum***** up, and want to get in the seaway ASAP, so they can spin it up to where it likes to run.

I'm sure Sarnali will chime in and give us some more detail.

Cuddy, as an Engineeing Officer of the Watch, the worst sound in the world was when we'd drop the electrical load, and you'd hear the air starting system on the Emergency Diesel (#2, right over our heads), but the damn thing wouldn't start.

We would then enjoy an extended period of "Hot, Dark and Quiet". Well, 'quiet' except for the bridge and the CHENG screaming at us on the SP phones.
__________________
You would not understand,
this is not how I am...

I have become -
Comfortably Numb.
pushrod is offline   Reply With Quote

Sponsored Links Remove Advertisements
Motorcycle Forum
Advertisement
Old 07-09-2009, 10:17 AM   #12
mscuddy
MODERATOR X

 
mscuddy's Avatar
 
Join Date: Jun 2007
Location: Next to my still checkin the temp.
Posts: 5,448
Default

Yeah, the Indy. Was watching the Military channel last night, they had Desert Storm on, and quite a few shots of CV62. I missed the IO cuise by a few months, since my EOS was November 1980. A few numbnuts went UA when they hit the P.I. and missed ships movement. Did you make that cruise? I would have killed to do a Westpac....instead of Naples, Naples, and more Naples....
__________________
A gun is a tool, Marian; no better or no worse than any other tool: an axe, a shovel or anything. A gun is as good or as bad as the man using it. Remember that.
mscuddy is offline   Reply With Quote
Old 07-09-2009, 10:46 AM   #13
Kenneth_Moore
Registered Member
 
Kenneth_Moore's Avatar
 
Join Date: Jun 2007
Location: VIsiting the GIft Shop in the Pit of DIspair
Posts: 7,118
Default

Quote:
Originally Posted by pushrod View Post
At their designed power output, GTs are more efficient than IC engines.

However, if they are operated anywhere below their design rate, they 'waste' fuel, for lack of a term. For instance, when you are sitting still, they are burning a bunch of fuel and sending it out the exhaust. IC engines likewise waste fuel at idle, but nothing like a GT.

Mind, you don't use a GT engine like a jet does. The 'generator' end of the engine (which is the part that would hang on a plane wing) provides the hot gas to drive a 'power turbine'. That, through a series of reductions, turns whatever you want to, be it an electrical generator, a helicopter rotor, or a propeller shaft. So, you lose quite a bit of 'efficiency' through the transmission of the power.

Hmm, so maybe the Klazy Ken Yacht Propulsion system I dreamed up a few years ago wasn't so Klazy after all. I took some time off from my real job and did deliveries and sea-trials on yachts for a couple of years. I was thinking that a gas turbine, powering a generator/battery/induction motor system would make a dandy yacht drivetrain. The GT could run at it's happy speed constantly, driving a generator which drives the electric motors, and your batteries could absorb the excess power. But maybe diesel ICs are better for that too; that's pretty much the drive train for locomotives minus the batteries.

One company was building a 150' yacht that had 4 MTU diesels for day to day power, and a direct-drive turbine for those days when the owner was in a hurry. Hmm, let me see if I can dig up a link on that...
__________________
www.kennethmoore.org
Kenneth_Moore is offline   Reply With Quote
Old 07-09-2009, 11:16 AM   #14
pushrod
Founding Member
 
pushrod's Avatar
 
Join Date: Nov 2001
Location: Baja 'Bama
Posts: 3,642
Default

[IMG]file:///C:/DOCUME%7E1/smcclain/LOCALS%7E1/Temp/moz-screenshot.png[/IMG]



It wasn't one of these, was it?




The powerplants that use both Diesel engines and GTs are called CODAG, for COmbined Diesel and Gas turbine.
__________________
You would not understand,
this is not how I am...

I have become -
Comfortably Numb.
pushrod is offline   Reply With Quote
Old 07-09-2009, 11:19 AM   #15
SmokeU
Registered Member
 
SmokeU's Avatar
 
Join Date: Jun 2007
Location: pet****...pet****...pet****
Posts: 1,864
Default

Quote:
Originally Posted by pushrod View Post
[IMG]file:///C:/DOCUME%7E1/smcclain/LOCALS%7E1/Temp/moz-screenshot.png[/IMG]



It wasn't one of these, was it?




The powerplants that use both Diesel engines and GTs are called CODAG, for COmbined Diesel and Gas turbine.

How'd you get that picture of my ship?!?!
SmokeU is offline   Reply With Quote
Old 07-09-2009, 12:40 PM   #16
Kenneth_Moore
Registered Member
 
Kenneth_Moore's Avatar
 
Join Date: Jun 2007
Location: VIsiting the GIft Shop in the Pit of DIspair
Posts: 7,118
Default

Quote:
Originally Posted by pushrod View Post
[IMG]file:///C:/DOCUME%7E1/smcclain/LOCALS%7E1/Temp/moz-screenshot.png[/IMG]



It wasn't one of these, was it?




The powerplants that use both Diesel engines and GTs are called CODAG, for COmbined Diesel and Gas turbine.
"Fire up the turbine, the Captain wants to slalom again..."
__________________
www.kennethmoore.org
Kenneth_Moore is offline   Reply With Quote
Old 07-12-2009, 05:52 PM   #17
seruzawa
The Toad

 
seruzawa's Avatar
 
Join Date: Nov 2001
Location: 8501 ft.
Posts: 17,461
Default

Quote:
Originally Posted by pushrod View Post
At their designed power output, GTs are more efficient than IC engines.

However, if they are operated anywhere below their design rate, they 'waste' fuel, for lack of a term. For instance, when you are sitting still, they are burning a bunch of fuel and sending it out the exhaust. IC engines likewise waste fuel at idle, but nothing like a GT.

Mind, you don't use a GT engine like a jet does. The 'generator' end of the engine (which is the part that would hang on a plane wing) provides the hot gas to drive a 'power turbine'. That, through a series of reductions, turns whatever you want to, be it an electrical generator, a helicopter rotor, or a propeller shaft. So, you lose quite a bit of 'efficiency' through the transmission of the power.

You'll notice the specs on the big Wartsila show that its most economical fuel rate is damn near its max power rate. The operators will wait as long as possible to fire that big sum***** up, and want to get in the seaway ASAP, so they can spin it up to where it likes to run.

I'm sure Sarnali will chime in and give us some more detail.

Cuddy, as an Engineeing Officer of the Watch, the worst sound in the world was when we'd drop the electrical load, and you'd hear the air starting system on the Emergency Diesel (#2, right over our heads), but the damn thing wouldn't start.

We would then enjoy an extended period of "Hot, Dark and Quiet". Well, 'quiet' except for the bridge and the CHENG screaming at us on the SP phones.
Short answer: After years of argument the latest variants of the M1 tank are slated to be diesel powered. That two fuel trucks per tank thingie is just too hard to support.
__________________
"Make no mistake, Communism lost a big argument - one we know today as the 20th century."
seruzawa is offline   Reply With Quote
Old 07-13-2009, 07:28 AM   #18
sarnali2
Aging Cafe` Racer

 
sarnali2's Avatar
 
Join Date: Jun 2007
Location: Sittin' down by my window, lookin' at the rain.
Posts: 8,719
Default

Quote:
Originally Posted by seruzawa View Post
Short answer: After years of argument the latest variants of the M1 tank are slated to be diesel powered. That two fuel trucks per tank thingie is just too hard to support.
That really is a blindingly stupid error, Maybe you can't stop an Abrams with an RPG but you can sure as hell stop a fuel truck.......



Regarding gas Turbines Pushrod, I know steam turbines inside out literally but gas turbines propulsion systems are after my time I'm afraid. Still I would assume they had a sweet spot just like a steam turbine does. Boiler run most efficiently at around 80% of rated capacity, everything is nice and heat saturated and expanded, no cool spots, good flow everywhere.....

Commercial steam turbines will typically run on the governer at around 5000 RPM for a steady load like a generator, then the deciding factor is the amount of extraction and exhaust you can stuff down the pipe. The more steam you can pull out at the extraction stage the more electrical load you can impose on the generator the more steam is req'd to maintain 5k rpm and the more steam you're dumping out the exhaust so the deciding factor is the exhaust capacity. If you dump exhaust into the Hot Well it's usually not a problem, you're just preheating your feedwater. However if you dump it into the DA tank and/or Absorbtion chiller it becomes a limiting factor as they can only absorb so much heat before they start to overpressure..

Small turbines like fans and pumps usually swing around on the throttle valve depending on load if they have a straight reduction gear set up. I would assume a ship board gas turbine would be operating at a fixed RPM and driving a variable speed transmission instead of a reduction gear but like I said I really don't know...
__________________
"Carpe` Throttelum -Loud Suits Save Lives"

"He said he's farting because of his medication"...

Last edited by sarnali2 : 07-13-2009 at 07:30 AM.
sarnali2 is offline   Reply With Quote
Old 07-13-2009, 08:35 AM   #19
pushrod
Founding Member
 
pushrod's Avatar
 
Join Date: Nov 2001
Location: Baja 'Bama
Posts: 3,642
Default

Most GT plants I've seen are running Controllable Pitch propellers. Heck, I think the big (not HUGE) marine diesel plants are, too.

Thus the shaft spins at a constant rate, but speed (and direction) is controlled by the prop.
__________________
You would not understand,
this is not how I am...

I have become -
Comfortably Numb.
pushrod is offline   Reply With Quote
Old 07-13-2009, 09:09 AM   #20
schizuki
Founding Member
 
schizuki's Avatar
 
Join Date: Nov 2001
Posts: 5,030
Default

Now I know how chicks feel when dudes talk about cars.
__________________
Reverēre meam auctōritātem

Bill Clinton and Chuck Schumer are praising the Supreme Court for overturning an anti-gay-marriage law that they both signed.
schizuki is offline   Reply With Quote
Reply


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off