Obelix Posted August 6, 2013 Share Posted August 6, 2013 This is a world of difference from a Hydrogen powered vehicle. Mainly because it's complete cobblers and doesnt work. ---------- Post added 06-08-2013 at 10:45 ---------- Couldn't agree more, there's no where near enough hydro production going on - or money being pumped in for research. The government seems hell-bent on sticking up those god awful wind-turbines, which never ever produce the amount of energy they claim. I think the only reason they do it is because it's such a massive striking object it make it look like something good is being done. Like most places, all the good hydro sites in Britain were taken decades ago. I'd much prefer they dumped the coal stations when they close and stick up nuclear in their place. Link to comment Share on other sites More sharing options...
Alcoblog Posted August 6, 2013 Share Posted August 6, 2013 I read an article recently that stated that out of a tank of fuel, 33% of energy is used for engine cooling, 36% is wasted in exhaust heat and 4% to friction to the road. Only 27% of the fuel is used to produce propulsion. That's only just a little over a quarter of the fuel is used to move the vehicle ... virtually all the rest is turned into heat. I'm pretty sure that if this is the case, many people will be working to improve these percentages in favour of forward motion. A thought occurs to me though ... would it be more efficient to use the petrol engine to produce steam which then can be used for forward propulsion? (I'm pretty sure I'll get pulled to pieces for being stupid enough to suggest this) Link to comment Share on other sites More sharing options...
geared Posted August 6, 2013 Share Posted August 6, 2013 I think it's far more than 4% lost to road/wind friction. Link to comment Share on other sites More sharing options...
Obelix Posted August 6, 2013 Share Posted August 6, 2013 I read an article recently that stated that out of a tank of fuel, 33% of energy is used for engine cooling, 36% is wasted in exhaust heat and 4% to friction to the road. Only 27% of the fuel is used to produce propulsion. That's only just a little over a quarter of the fuel is used to move the vehicle ... virtually all the rest is turned into heat. I'm pretty sure that if this is the case, many people will be working to improve these percentages in favour of forward motion. A thought occurs to me though ... would it be more efficient to use the petrol engine to produce steam which then can be used for forward propulsion? (I'm pretty sure I'll get pulled to pieces for being stupid enough to suggest this) It depends on the fuel and the engine type, as well as if you have a turbocharger fitted. Very roughly, about 3/8th of the energy goes out the exhaust as heat, another 3/8 is lost to engine friction, pumping losses and heat from the radiator, and a quarter is left to move the vehicle for a petrol engine. A decent diesel engine is more efficient, so that 3/8th lost out the exhaust is reduced considerably due to better extraction in the piston and recovery from the turbocharger, a decent road going "fast" diesel is about 40% efficient. A slow diesel like on a container ship (100rpm as opposed to 2000rpm) is up to 55% efficient. Diesels used on trains like the HST are somewhere in the middle. The theoretical efficiency of any reciprocating heat engine is controlled by the Carnot cycle, which states that you want the hottest possible temperature at combustion (without melting the engine) and the coldest possible exhaust - if you extract more energy by cooling the working fluid as much as possible you increase efficiency. Steam locomotive engines are very bad in this regard, as you can have a start flame that is exceedingly hot, say 2000K, but if your working fluid, ie the steam is only raised at 550K and then worked to say 400K you dont have a large working range. The old coal powered steam locos were as bad as 6-8% efficient overall! Power stations use superheat, condense to vacuum etc, to boost the efficiency up high but the gear needed is impractiably huge and cannot fit on a car. Link to comment Share on other sites More sharing options...
davyboy Posted August 7, 2013 Share Posted August 7, 2013 What's even worse is a one or two ton vehicle is used to transport a ten to fifteen stone person. Link to comment Share on other sites More sharing options...
RootsBooster Posted August 7, 2013 Share Posted August 7, 2013 What's even worse is a one or two ton vehicle is used to transport a ten to fifteen stone person. Good point, think of how much fuel would be saved and how many fatal accidents would be reduced if cars were lighter Link to comment Share on other sites More sharing options...
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