Efficiency Improvements for Internal Combustion Engines

[autoteach]

well, that design is a turbine, void of pistons, con rods, and reciprocation. It also using a pressure wave design that is pretty neat, but I wonder how the length of the intake tract effects the effective output and different speeds.

[NeilBlanchard]

Those bits on the sides sure look like cylinders; complete with cooling fins.

Again, how do we improve the efficiency of internal combustion engines?

[autoteach]

Well, I wont argue that they are cylinders, by the definition of shape. The difference is that I actually took some time to look at their website and to review the technology. the placement of the "cylinders" is necessary for the operation of the turbine wheel.

As for your question, I feel like we have put some ideas out there. I also feel as though you ignore those ideas or proof of designs that go against your thoughts. You dislike the poppet valves, but the idea that you have is not ideal. There is an alternative to a rotating disc, and I posted that pages back. The coates valve train has been proven to function, but it doesnt seem to have made it anywhere? Why is that?

[dcb]

Originally Posted by NeilBlanchard

how do we get a much more efficient ICE design?

What's wrong with multiple engines? a smallish 2 cylinder and one twice as large? Make them both atkinson style, or diesel (I don't think sterling is on the table here), and each can be de-clutched from the transmission individually or run together. I'll skip further delving into the driveline details there, excepting that lets assume it can all be conveniently button operated and not aggrivate any existing conditions (and not cause serious losses).

If you have, i.e. a 500cc and a 1000cc engine, you can choose between 500cc, 1000cc or 1500cc, whichever is most efficient for conditions. If you can tie 3 small engines together, i.e. a 250, a 500 and a 1000, then you have 7 displacements to choose from. 250,500,750,1000,1250,1500,1750

[roflwaffle]

Originally Posted by dcb

I don't know about that whole tap dance there, glad I could clear up how bsfc charts are used for you.

But weight is a much more consistent unit of measure when dispensing energy, as you can see from that scatter plot, hydrogen at various pressure (or temperature) levels contains the same energy content for a given amount of weight. Hopefully that is intuitive.

And it is also interesting to note that your 200-250 bsfc numbers (which was NOT power/gallons, in case there is still confusion there no thanks to mech) clearly put the improved efficiency of diesels in a new light. Despite gasoline having slightly more energy by weight, gas engines are frequently found with %25 worse fuel consumption at peak bsfc, per unit of power output.

Brake Specific Fuel Consumption (BSFC) Maps - EcoModder

What the bsfc charts are telling you is that, for essentially the same ENERGY input, diesels are still more efficient. You need to rethink your diesel assertions.

I think that's an artifact of comparing older powertrains because the diesels tended to have more lenient NOx emissions requirements (if a certain group of engines can run leaner they'll probably exhibit lower fuel consumption). Now that all engines have to comply with the same standards they're pretty much equivalent in terms of efficiency, at least AFAIK.

Edit-I think taller gearing/displacement on demand is easier than running multiple small engines and firing them up as more power is needed.

[NeilBlanchard]

From a blog post I wrote a while back in 2008:

For new 4-cylinder internal combustion engine designs, the crankshaft could be split with a hydraulic coupling that can automatically disengage two cylinders completely; saving all the pumping and friction losses, for situations when 2 cylinders are enough to provide the required torque to move the vehicle.

This may make the engine a little more efficient, but at the thermal efficiency level -- why isn't an internal combustion engine as efficient (or even close to the same efficiency) of an electric motor? I'm talking quantum leaps here. Streamlining cranks ain't going to be enough.

It has to be the connecting rod / crankshaft that are causing the greatest loss within the engine, or the long 3 strokes of coasting, or something basic, that is keeping ICE's from being 50-60-70-80-90% efficient, right? Why aren't they that efficient? Gasoline / diesel is a wonderfully compact fuel, right? Why can't we get a lot more work out of burning it?

[NeilBlanchard]

Hi,

Originally Posted by autoteach

Well, I wont argue that they are cylinders, by the definition of shape. The difference is that I actually took some time to look at their website and to review the technology. the placement of the "cylinders" is necessary for the operation of the turbine wheel.

So, the vectors of this engine are good at transferring explosive burning of fuel into rotary motion, right? Is that why they didn't put those cylinders centered on the main shaft? Hmmm.

I think we all want the same thing -- to figure out how to make engines much more efficient.

Any more comments on the Garric engine? If the valves could be made to seal well enough, it certainly has the mechanical torque issue solved. Could some sort of a corkscrew / helix / Archimedes type devece be made to function as a valve in the Garric setup?

[autoteach]

Well, I think if you were to consider the physics of the turbine that they are spinning, there is no other way to do it except to align with the tangent of the turbine to direct the force of the blast. HMMMMMMMMM As far as efficiency, mechanical will be high with an engine like this, but it may not be chemically as efficient with larger carbon chain fuels. Hydrogen is so reactive that this is not an issue.

as for the garric, I wonder if they are making progress. 2009 was a long time ago, and they havent updated. I am sure that there are some significant design challenges, and there doesnt seem to be enough information for me to make a significant judgement on the design. Interesting, but I do wonder if it will fall prey to similar problems found in the wankel.

[UFO]

Originally Posted by NeilBlanchard

This may make the engine a little more efficient, but at the thermal efficiency level -- why isn't an internal combustion engine as efficient (or even close to the same efficiency) of an electric motor? I'm talking quantum leaps here. Streamlining cranks ain't going to be enough.

It has to be the connecting rod / crankshaft that are causing the greatest loss within the engine, or the long 3 strokes of coasting, or something basic, that is keeping ICE's from being 50-60-70-80-90% efficient, right? Why aren't they that efficient? Gasoline / diesel is a wonderfully compact fuel, right? Why can't we get a lot more work out of burning it?

No, the greatest loss is the chemical conversion of energy to mechanical energy at the shaft. Electric motors have a fundamentally different energy conversion physics.

If you want to know the hard and fast limits on chemical engines, look no further than thermodynamics and the Stirling engine if you intend to do a chemical to mechanical energy conversion.

You can potentially improve energy conversion of a fuel by using a fuel cell, but then you will be directly competing with electric batteries for energy delivery and density.

I think we will be improving on current designs only marginally until electrics overtake the market. Materials with higher temperature tolerance offer higher thermal efficiency potential -- ceramics have yet to make much impact though. All of these radical engine designs offer only small improvements in frictional or pumping losses, while having serious flaws in longevity or manufacturability. Call me a nay-sayer, but I think the future is bright for renewable fuels for the short term and electric for the long term.

[roflwaffle]

Originally Posted by NeilBlanchard

This may make the engine a little more efficient, but at the thermal efficiency level -- why isn't an internal combustion engine as efficient (or even close to the same efficiency) of an electric motor? I'm talking quantum leaps here. Streamlining cranks ain't going to be enough.

Engine efficiency is limited by the combustion temperature (hot source) and the local (cold sink) temperature. We can't do a whole lot to lower the temperature of the cold sink, so the best we can do is design materials that can take higher combustion temps and/or use fuels with high combustion temps. Heavy duty diesels tend to be more efficient than heavy duty gasoline engines because diesel has a higher temperature of combustion (This gets tossed out the window due to EGR if the engines have to meat the same emissions regs), so those tend to be the best at ~54% for large low speed diesels that don't need to accommodate emissions regulations and are run at maximal efficiency. To get beyond that we would probably need another hotter fuel source and better materials. Electric motors aren't bound by the same efficiency constraints, and as such their efficiency is much much higher.