This is Ingenious

Comparison of various cycles


SPCCI Cycle


Pressure Profiles

Diesel engines have been getting a lot of bad news recently, but there is a another form of compression ignition that has been lurking in the laboratory for years.

A diesel compresses the air, and then squirts in fuel, which ignites in the hot air.

The other form of compression ignition compresses a fuel air mixture until it all ignites simultaneously.

Theoretically, this could result in superior fuel economy and low levels of pollution.

This is a tremendously difficult thing to do since things like this, since the line between ignition and nothing is a very fine line, and things like ambient temperature, barometric pressure, etc. can cause premature ignition, i.e. pinging, which hits the inside of an engine like a hammer.

Nissan has come up with an innovative way to fix the timing, they have added a spark assist so that they can control the timing.

As opposed to a conventional spark ignited engine, where the flame front progresses from the spark, in their "Skyactive X®" technology, and the initial local ignition kicks up the pressure and temperature enough for the compression ignition to kick in.

Mazda is now has a car with this technology on the road:

Despite rumors to the contrary, the internal combustion engine is far from dead. Recently we've seen several technological advances that will significantly boost the efficiency of gasoline-powered engines. One of these, first reported back in August 2017, is Mazda's breakthrough with compression ignition. On Tuesday, Mazda invited us to its R&D facility in California to learn more about this clever new Skyactiv-X engine, but more importantly we actually got to drive it on the road.

The idea behind Skyactiv-X is to be able to run the engine with as lean a fuel-air mixture (known as λ) as possible. Because very lean combustion is cooler than a stoichiometric reaction (where λ=1 and there is exactly enough air to completely burn each molecule of fuel but no more), less energy is wasted as heat. What's more, the exhaust gases contain fewer nasty nitrogen oxides, and the unused air gets put to work. It absorbs the combustion heat and then expands and pushes down on the piston. The result is a cleaner, more efficient, and more powerful engine. And Skyactiv-X uses a very lean mix: a λ up to 2.5.

………

This is known as homogeneous charge compression ignition, or HCCI, an idea that Kyle Niemeyer covered in depth for us back in 2012. HCCI has some other advantages, too. On top of burning cooler and with fewer pollutants, the combustion event happens faster, with a higher pressure peak, so you get more work out of the same energy. All of that sounds pretty wonderful, so you're probably asking yourself why every gasoline engine on the road doesn't just use HCCI.

Unfortunately, it has been one of those ideas that worked in the lab but couldn't ever quite be translated into a production engine. The biggest problem has always been controlling exactly when during the engine cycle compression ignition occurred, something that you want as close to top-dead center as possible.

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Obviously, this wasn't without challenges. The fuel:air mix needs to be a little richer near the spark for it to ignite than you want it to be throughout the rest of the cylinder. These need to be distinct regions to avoid λ dropping to 2 or below (which won't undergo compression ignition). That's achieved by swirling the air inside the cylinder and generating a vortex effect, where the calm center has a low enough λ to ignite by spark, surrounded by a high λ region that then undergoes compression ignition.

Mazda's next challenge was to prevent pre-ignition, or knock. Higher compression ratios increase the potential for knock, which is why higher compression ratio engines usually also require more expensive, higher octane fuel that is knock-resistant. Now, technically, compression ignition is knock, but if it occurs before you want it to—at top dead center—bad things can happen, because a combustion event will exert downward pressure on the piston as it's moving up on a compression stroke.

The solution here was to use less time to heat the fuel:air mix. There's a small initial injection of fuel at first, then the bulk of the fuel is introduced into the cylinder as late as possible during the compression stroke. This is done using multiple orifice injectors to increase atomization and mixing of fuel and air.

If all that wasn't enough, there's the added problem of keeping track of compression ignition. In the past, this has been one of the hardest problems for HCCI engines to solve. Ideally you want combustion to happen at the same point in the engine cycle each time—about four degrees after top dead center. But as ambient conditions change—a cold day in Denver versus a hot one in Houston—the time needed for the fireball to reach sufficient pressure also changes. So the engine ought to be able to change spark timing to keep the peak pressure at the right spot.

It's basically an ingenious use of the stratified charge engine to create an HCCI engine.

Neat.

How Not to Design Reasonably

One of the fails going around the internet is Juicero, which is selling a press to squeeze raw juices from its pouches into a cup.

This press recently had its price reduced to "only" $400, for a juicer.

What's more reporters at Bloomberg discovered that you could get about the same amount of juice from the pouches using the Mark 1 human hand.

Not bad for a company that has raised $120 million in VC funding  ……… For a juice squeezer.

After all of this product designer Ben Einstein did a a disassembly and a deep dive, and  he found a ridiculously over-designed mess.

The short version is that there is a press using a custom motor and custom gear train, a half dozen machined aluminum parts which drives an aluminum plate against the pouch to uniformly apply pressure.

Einstein inventoried the following:

• An extremely complex plastic molding, including co-molded parts.
• A heavy custom machined aluminum frame.
• A custom power supply.
• Massive custom hinges on the door.
• Custom sliders.
• A very robust custom gearbox.  
• Etc.

Looking at this problem, I immediately have a better way of doing things.

I could make a prototype using an off the shelf aquarium pump for less than $100 in in parts.  (It would work like the so called "Neat Squeeze" toothpaste tube), or do something similar with a store bought pasta maker retailing for $29.99.

That took me all of 15 minutes to think about it.

This is all of Silicon Valley dysfunction in a squeezable pouch.

If I am Sounding a Bit Incoherent, It's Because I am a Bit Incoherent

Major deadline at work, and I put in 14 hours today.

I got everything done that I needed to do today, but I am completely knackered.

Tomorrow should be fascinating. (Not snarking here)

More on That Zeppo Thing

Basically, I was trying to come up with a way of holding two things together that would allow for simple installation and removal of a payload on top of a mast.

After coming up with a number of rather ugly potential solutions, I remembered that Zeppo (Herbert) Marx had developed a clamp in his post showbiz career as an Engineer and manufacturer, developing the Marman Clamp^* (pictured), which found extensive use as a stage separation mechanism in space craft in addition to securing the "Fat Man" inside the B-29 "Bock's Car" when it dropped the atomic bomb on Nagasaki.

The clamp, plus a couple of pins for alignment, and I had a solution that was clean, dirt cheap, robust, and nearly soldier proof.^†

Needless to say, I am feeling rather smug about this.

^*It appears that Zeppo did not invent the clamp, but rather he was the one to bring it to mass production.

^†Nothing can be made soldier proof. It simply can be made somewhat soldier resistant.

Could My Relatives Please Confirm Who Sent Which T-Shirt?

OK, I know that Dad sent me this, because it came with gummy worms:


But who sent me this one?


Sometimes, Chanukah is confusing.

Huh, Neat Tech

It appears that machining titanium at cryogenic temperatures extends tool life:

Cryogenic titanium machining improves cutting-tool life by a factor of 10 with appropriate material removal processing speed. The Joint Program Office in coordination with the F-35 Fracture Control Board (FCB) approved the new process for standard roughing operations, impacting the most time-consuming and cost-intensive machining processes associated with manufacturing titanium parts. Broadly applied, this new technology could improve affordability and efficiency in the production of the F-35, which is approximately 25 percent titanium by weight.

My guess would that this generates smaller chips, that it might prevent material from adhering (galling, welding, etc.) to the tools, and it might slow the formation of an oxide coating, but I'd love to hear the theory behind it.

I would make an observation here:  If you have an aircraft that is 25% by weight titanium, you have a very expensive aircraft.

It's Been a Weird Year for the Auto Industry

Play them off, Jon Stewart

With the recall of more than 6½ million to repair a sticky accelerator pedal, Toyota's sales fell by 47% from December, and 16% year over year, which was enough for both Ford and GM outsell to outsell the Japanese car firm.

Of course, we now know that it's not just accelerator pedals, but also the brakes on its Prius hybrid, where it appears to be a software issue that creates unsteady breaking in the interplay between regenerative and mechanical braking.

It may not be any consolation to the Toyoda family, but Ford just rolled out a software update for its hybrid vehicles:

Ford Motor Co. announced Thursday that it will ask owners of its Ford Fusion Hybrid and Mercury Milan Hybrids sedan to bring their car into their Ford dealer to replace software that operates the car's braking system.

While the cars maintain full braking ability, Ford said, drivers may occasionally experience a strange feeling in the brakes under certain circumstances.

So the latest problems may be an artifact of the move to "drive by wire" technologies for hybrid vehicles, you pretty much have to, because managing the battery/engine balance cannot be done manually by the driver.

In any case, the juxtaposxition of glitches in software and automotive hardware, it seems appropriate to invoke the proven to be false by Snopes joke:

At a computer expo (COMDEX), Bill Gates reportedly compared the computer industry with the auto industry and stated: "If GM had kept up with the technology like the computer industry has, we would all be driving $25.00 cars that got 1,000 miles to the gallon."

In response to Bill's comments, General Motors issued a press release (by Mr. Welch himself) stating:

---

If GM had developed technology like Microsoft, we would all be driving cars with the following characteristics:

1. For no reason at all, your car would crash twice a day.
2. Every time they repainted the lines on the road, you would have to buy a new car.
3. Occasionally, executing a manoeuver such as a left-turn would cause your car to shut down and refuse to restart, and you would have to reinstall the engine.
4. When your car died on the freeway for no reason, you would just accept this, restart and drive on.
5. Only one person at a time could use the car, unless you bought 'Car95' or 'CarNT', and then added more seats.
6. Apple would make a car powered by the sun, reliable, five times as fast, and twice as easy to drive, but would run on only five per cent of the roads.
7. Oil, water temperature and alternator warning lights would be replaced by a single 'general car default' warning light.
8. New seats would force every-one to have the same size butt.
9. The airbag would say 'Are you sure?' before going off.
10. Occasionally, for no reason, your car would lock you out and refuse to let you in until you simultaneously lifted the door handle, turned the key, and grabbed the radio antenna.
11. GM would require all car buyers to also purchase a deluxe set of road maps from Rand-McNally (a subsidiary of GM), even though they neither need them nor want them. Trying to delete this option would immediately cause the car's performance to diminish by 50 per cent or more. Moreover, GM would become a target for investigation by the Justice Department.
12. Every time GM introduced a new model, car buyers would have to learn how to drive all over again because none of the controls would operate in the same manner as the old car.
13. You would press the 'start' button to shut off the engine.

Everything old is weird again.

Bad Ideas: Combining Nuclear Power With Explosive Metals

I understand that there advantages to Sodium cooled reactors, particularly the fact that, because of the small cross section of the nucleus of Sodium, you can get a much more complete burn with fewer waste products, but that the Sodium-Cooled Fast Reactor Prototype Development, memorandum of understanding (MOU) will lead nowhere.

The U.S Department of Energy (DOE), the French Atomic Energy Commission (CEA) and Japan Atomic Energy Agency (JAEA) have expanded cooperation to coordinate Sodium-Cooled Fast Reactor Prototype development through a Memorandum of Understanding (MOU). The MOU establishes a collaborative framework with the ultimate goal of deploying sodium-cooled fast reactor prototypes. A sodium-cooled fast reactor uses liquid sodium to transfer heat, burning the plutonium and other transuranic elements in the process producing clean, safe nuclear power, less waste and increasing non-proliferation goals.

This makes the Hindenberg look like a cap gun.

Liquid Sodium explodes on contact with air.

NTSB: Design Flaw Caused Minnesota Bridge Collapse

The NTSB has determined that the gusset plate were under-size for the structure.

The interesting thing is that this is below spec for the 1960s, when the bridge was constructed. Since then, with more sophisticated analysis tools, the safety factors on designs have gotten smaller.

Yes, It's a Cheap Pun, but that's a Weakeness of Mine

Well, it appears that the corrosive properties of pigeon excrement may have contributed to the Minneapolis bridge collapse.

To quote noted Internet wit Bladesmith, "Like I said elsewhere, it's all fun and games till the shit hits the span".

Sigh, someone else who writes better than I do.