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Yobi
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Sorry when I said : "I am wondering about NOx emissions too" I was talking about the Tsci concept, not your project. I know that with no N2, there is no way to create NOx ! About yours now : have you run an adiabatic flame temperature calculation (chimical thermodynamic), I am pretty sure that with pure oxygen and poor inert gas, it could go goes pretty high, more than 2500 K, and then cooling of engines parts will be a big issue. That's also one reason why you'll still need a radiator to take care of your heat rejection through combustion process (even with cooled exhaust gases). Also, methanol stochiometric combustion is 6.5:1 I think, why are talking about 1:1? Do you mean, equivalent ratio of 1, as in most gasoline engine ?
I looks like a pretty good concept. I am wondering about NOx emissions too, are they expected to be lowered too that way ? As there is no premixed phase anymore... Azmi : I would be interested to read your paper. Using Oxygen instead of air would lead to a very high combustion temperaure, so I think that s why you use water cooling. But I would you feed the engine with pure oxygen for a non steady application ? With high pressure bottles of O2 ? In that case, what would be the expected range of such a car ? For instance, a truck engine of 150 kW can use around 1200 m3/h of air, so around 240 m3/h of 02... May be the answer is in the paper.
I am dreaming of the 1.4 T + dry DCT + 15 kW electric motor in between. That would make a great parralel hybrid !
Ten years ago, Honda made for the S2000 a 240 HP normally aspirated 2.0 liter, 4 cylinders: 120 HP / l. This is impressive. Speaking of fuel enrichment: Theoretically maximum power is obtained at stoichiometric ratio : equivalence ratio 1. However due to dissociation phenomena you can still increase the power by injecting more fuel. Then a big part of HC does not burn completely and cannot turn fully into CO2 due to the lack of O2 available (rich mixture). CO is thus created (exponentially) and combustion efficiency gets lower. The optimum for maximum power is around equivalence ratio 1.1. Now it happens sometimes, that you need to really cool the exhaust gases as you are working at high load and that you are getting too close to you limited exhaust manifold temperature (around 930°C for gasoline, 830°C for diesel). So you inject even more gasoline and goes up to equivalence ratio 1.15, 1.2, even 1.25 just to use the latent heat of the fuel. The fuel does not burn in the cylinder, and do not increase the power anymore (it actually slightly decreases it). Another example of this is used for cold start, when also you ll inject up to E.R 1.2 to improve combustion stability (like the choke button on carburetors). Diesel engine is far more stable in cold condition once started. Some people are also looking at using other ways (like EGR) on gasoline to reduce exhaust gases temperature instead of using this strategy, which is a wonderful waste.
I do not share the desire that everybody should ride a bicycle, but I would like to fight for a more efficient way of transportation. Non convention sources as bitumen petroleum has to be avoided. It is a consequence of high prices and shows us how desperate we are to produce oil and how far can we go for it. 1 barrel is consumed to produce 2 of them that way. Consuming less petrol will prevent that, and will slow down the speculation. Diesel engines are not anymore dirty, we can now get more than 100HP/L and still meet Euro 6 regulation even before gasoline engines. Yes, to do that we need DPF, SCR or Denox, we it is clean then and much more efficient than any Gasoline even downsized engine. By the way, particulate matter will also be a problem for direct injection gasoline engine, and DPF could also be needed to meet regulations. Also, more and more petroleum will come from heavy oil in the future, how the huge gasoline market will cope with that ? Refiners are thinking hard to solve that. Gasoline engines are not so clean as it looks, fuel enrichment at high load is used (fuel is so abundant that we use it to cool exhaust gases) and it creates a lot of HC and CO. HCCI a solution? it does work at partial load (and creates a lot of HC by the way, I also did smell it). But it becomes harder at high load, and very difficult to control. I you ready to have the same engine with half of the power that you had before running HCCI ? About the use of double VVT on this engine : you can use a late intake valve closing of course to partially throttle the engine, but since years we know the importance of a good tuning on a normally aspirated engine. To get the maximum power you need to get the maximum of fresh air in the cylinder. So you try to increase the volumetric efficiency by using propagation waves at the intake and exhaust. As your pipes are fixed in length (except for some old cases in formula one), you will adapt your cam timing to always get the maximal amount of air inside at different engine speed. On the exhaust side, you ll try to also get the best compromise between volumetric efficiency and pumping losses. So having a double VVT is also a way to increase the specific power of the engine and improve his efficiency. I am just very unhappy that they just started to do that in 2010, just because a dollar spent on that wasn’t a dollar earned. It s now a small step to a more efficient engine, but too small to me.
What a wonderful but such non efficient engine. Double VVT is really the only technology which is supposed to impove the engine and save fuel ? It will still be throttling most of the time ! When will they understand that this cheap way of making engines is not viable anymore. We need downsizing, turbocharged/supercharged + direct injection -> clean scavenging possibilities...fully variable camshaft. For instance a VW 1.4 tsi 180 HP is 128.5 HP/l, and has a amasing torque curve. This is a bunch of technologies that I would pay for.
I agree that the grid is still the best solution, especially in a city. Let's keep this solution for desert highways such as in Australia. I would love to experiment a trip from Port Augusta to Darwin with those kind of renewable energy station on my way every 150km. No need anymore to carry petrol on road trains (and pay it 1.8 dollar/liter), take the energy from where you are. It could actually be a sustainable station in that case according to the poor number of people on those roads and the massive quantity of sun !
Yobi is now following TypePad France
Dec 26, 2009