Posted: Thu Jul 23, 2009 12:37 pm
I still don't understand how they could get away with actually closing down weather stations. You would have thought honest climate scientists would have picked up on it and kicked up a fuss.
a discussion forum for Polywell fusion
https://talk-polywell.org/bb/
I think you have answered your own question.jmc wrote:I still don't understand how they could get away with actually closing down weather stations. You would have thought honest climate scientists would have picked up on it and kicked up a fuss.
jmc wrote:1) It depends on three things, the price of petrol, the price of electricity and the capital cost of the vehicle. With the way the capital costs of vehicles are going with the tata ($1000) and the like, it may not be long before a vehicle will have a similar cost to 1 or 2 year's worth of fuel consumption. If that happens then you may well prefer to have two vehicles, one for short range commutes that runs on cheap electricity and one for the occassional long range commute which runs on more expensive oil. In terms of efficiency this makes more sense that a plug-in hybrid since the electric vehicle isn't lugging around the unecessary load of a petrol engine and the petrol vehicle doesn't lug around the unnecessary load of the battery.TallDave wrote: 1) But you don't want to buy another car for the other 10%. Example: shortly after graduating I had to drive most of the way across IL (about 700 miles in all, I think) to take the CPA exam. I could not have done that in an electric car.
2)Of course, many people who live in the city don't own cars at all. Electrics have to fit into a fairly specialized niche where you don't need power or distance, but it's too far to bike or walk.
2) Not just distances that are too far to bike or walk but also loads. I'm prepared to bike 10 miles, but not while carrying my weekly shopping!
Already been done. One application I've seen uses a sub 2 litre 90hp diesel motor to run a full-sized bus. It runs steady while the bus stops and starts, with energy recovery as well. The question of this setup was how to analyse the maximum 'duty cycle' [acel-decel-stop-repeat] that the bus could go through that the 90hp motor could do the job and how to maximise efficiency whilst minimising engine load and wear-out issues that you get with running smaller motors flat out.ravingdave wrote: The idea is simple. You put a small, (5 hp @ 3700 watts ) motor generator optimized for one speed efficiency. (no pumping loses. H@ll, make it a diesel!) and a large enough battery to get you 10-20 miles.
I never thought the idea was original to me. I just wondered why something so obvious wasn't more commonly tried. As for the motor wearing out, if it's a small motor, the rebuild costs are much cheaper than a full sized engine. Especially if it is simplified to just drive a generator.chrismb wrote:Already been done. One application I've seen uses a sub 2 litre 90hp diesel motor to run a full-sized bus. It runs steady while the bus stops and starts, with energy recovery as well. The question of this setup was how to analyse the maximum 'duty cycle' [acel-decel-stop-repeat] that the bus could go through that the 90hp motor could do the job and how to maximise efficiency whilst minimising engine load and wear-out issues that you get with running smaller motors flat out.ravingdave wrote: The idea is simple. You put a small, (5 hp @ 3700 watts ) motor generator optimized for one speed efficiency. (no pumping loses. H@ll, make it a diesel!) and a large enough battery to get you 10-20 miles.
I love the Atkinson cycle,(or the easier to implement Miller cycle) and I have long wondered why other car companies haven't pursued it. It is another of those "no brainer" ideas that ought to be obvious, but for some reason isn't. So you lose a little power. Big deal ! Increase engine size to accommodate the power discrepancy and continue on. Heat engine design is one of my hobbies, and I've got one idea that I think will beat the Atkinson cycle, but for the quickest improvement in current engine design, the Miller cycle is the fastest and easiest modification to any engine to improve efficiency. (just change the cam shaft.)chrismb wrote: You can also run non-otto cycles in the setup you're describing. The Atkinson cycle runs an over-stroked power phase. This is good for efficiency but bad for engine flexibility. But you don't need that flexibility if you're using it to generate power rather than pull away. The Prius uses an Atkinson cycle rather than Otto, I'm lead to believe, for much the same reason.
chrismb wrote: There does seem to be less-and-less that is new under the Sun. So long as we don't fall into the same trap as the Victorians (might as well close the patent office, all is now known) and keep fiddling with the ever diminuishing details then maybe there are a few doors still to discover.
While I hope not to be pointlessly snarky, there's this thing, it's called a turbocharger.when the exhaust valve opens on an engine, the pressure in the chamber is a substantial amount of pressure, and every exhaust from the cylinder throws away this unutilized energy!
The issue with Atkinson is that if you try and drive it, it bogs down as the engine speed tries to pick up, as that extra energy being sucked out of the stroke can no longer go into driving the transient increase in BMEP in the induction stroke. It becomes somewhat "undriveable" - like trying to drive an engine that's running too rich/lean, you have to ease in the throttle real careful.ravingdave wrote: A diesel version would be better still, though i've never heard of anyone doing this.
MSimon wrote:
And greenies are not allowing new refineries to be built.
Well yes. As long as WTI and similar light crude is available in abundance we are fine.Roger wrote:Thats a Green Herring, :-), refinery capacity has kept pace just fine. Seriously, thats NIMBY.MSimon wrote:
And greenies are not allowing new refineries to be built.
TDPerk wrote:While I hope not to be pointlessly snarky, there's this thing, it's called a turbocharger.when the exhaust valve opens on an engine, the pressure in the chamber is a substantial amount of pressure, and every exhaust from the cylinder throws away this unutilized energy!
To take that to an unworkable/uneconomic extreme, regard the Napier Nomad.
Yours, TDP, ml, msl, & pfpp
chrismb wrote:The issue with Atkinson is that if you try and drive it, it bogs down as the engine speed tries to pick up, as that extra energy being sucked out of the stroke can no longer go into driving the transient increase in BMEP in the induction stroke. It becomes somewhat "undriveable" - like trying to drive an engine that's running too rich/lean, you have to ease in the throttle real careful.ravingdave wrote: A diesel version would be better still, though i've never heard of anyone doing this.
An otto diesel can already be built to do much the same as the Atkinson, because it already has such a high expansion ratio there's little left to be sucked out. As mentioned, using a variable geometry turocharger also sucks out the last few joules, to the benefit of improved volumetric efficiency at induction. There's no big benefit, given the driveability disadvantages.
My VAG 1896cc variable turbo was so efficient that you could drive it at 55mph, about 1750rpm, right on the BMEP max, and after driving for however-long, the rear exhaust pipe was still cool to the touch, virtually ambient. Carnot tells you that there's not much more to be got out of the process with that level of efficiency.
Current european diesels are up against the last few opportunities for efficiency saving in internal metal friction and oil viscosity. They're right up at close to 60% thermal efficiency these days. VAG had some difficulty pushing into the 150bhp range for these engines as the combustion temperatures were getting so hot that they were melting the piston crowns, this is how maxed-out the technology has got over here. the only practical ways to do this are to make smaller engines with fewer cylinders, and so some form of pull-off augmentation is going to be required - 'mild'-hybrid diesels with miniscule 3 cylinder engines will be able to drive full sized cars to 100mpg.
You're in for a fuel-economy shock over in the US once Federal standards give the right consumer environment for these things to become possible/more popular purchases, and as DPF kit gets perfected to satisfy the EPA. Even the latest big jaguar diesels can do over 55mpg.