Comment by jeffwass | Hacker News Reader

Comment by jeffwass | Hacker News Reader

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Please cut this diesel apologist Bullshit! Your defense of diesel entirely ignores exhaust and emissions.

Sorry to be rude but this is a very personal and emotional topic to me and you’ve really pissed me off by saying “They are superior to gasoline engines in every way.” You apparently aren’t living in a city where the poor-sighted decision was made to promote Diesel engines over gasoline for marginally better CO2 metrics, and now get to breathe air that exceeds annual EU pollution limits in mere days.

Diesel is terrible in urban settings. It’s dirty as hell. I have no idea where you live but Diesel engines are entirely on their own choking the streets of London with their particulates and NoX exhaust. Gasoline engines are much cleaner by comparison.

I’ve gotten bronchitis several times in the past few years. I’ve finally tracked it down to the nox fumes, primarily from buses and heavy trucks where it’s a very noticeable sharp smell. I’ve gotten a bit better by avoiding high streets whenever possible, and I’m also proactively going up to drivers in idling diesel cars and asking them to cut the engine. It’s been estimated that 10k people are dying a year in London alone from effects of the exhaust!!

> I’ve gotten bronchitis several times in the past few years. I’ve finally tracked it down to the nox fumes

Oh, I'd really love to hear how you did that.

Correlation of coughing fits with noticing an earlier exposure to walking through a NOx cloud. The NOx smell is unmistakable once you identify it.

The tricky part is that there’s usually a delay of a few hours between exposure and cough attack. Intentionally avoiding high streets has helped for me. I still get coughing fits but not as many full on cases.

Diesel particulates (aka: soot) comes from unburned fuel during the combustion process due to insufficient heat in the combustion chamber. This can be reduced with software that eases into the throttle instead of literally translating the input from the gas pedal into throttle input. Applying the throttle slower results in more complete fuel burn. Here in the USA when you crank up your injectors to create the black cloud of smoke it's called "rolling coal." It's how you get more power out of a diesel engine without changing anything else. Just pour in more fuel. Because they don't have butterfly valves in the intake or throttle plates, diesel engines usually operate at or in excess of 100% volumetric efficiency. So while a 2.0L gas engine will consume 900cc of air at partial throttle, a diesel engine WILL ALMOST ALWAYS consume approximately it's displacement worth of air on an intake stroke. So a 2.0L diesel, even at part throttle, is consuming around 2.0L (or more) of air per intake stroke.

So to limit particulates, add a throttle limiter that limits throttle changes to a certain speed where the temperature of combustion increases proportionate to the fuel being injected.

You can also reduce soot output by filtering the fuel. You can refine diesel until you're blue in the face, but the fact of the matter is you get to a point where the cost of refining it isn't worth the benefit coming out of the tail pipe.

Not to mention the soot falls back to Earth and doesn't stay in the atmosphere as long as you think it does. So much of that black cloud is getting washed into your sewers when it rains.

You've found a bug in your code and you want to throw it all out and start over?

This doesn’t even touch on NOx emissions, which are way worse (at least for me).

Though you appear to have some vested interest in the proliferation of Diesel engines.

My vested interest comes as a result of enjoying vehicles. I am as much a gearhead as I am a hacker, and seeing something so efficient, so powerful, and so useful that LITERALLY built the industrialized world by powering 18 wheeled trucks and trains and container ships get crapped on by people who don't even know what the difference between their Corolla and a diesel engine actually are.

I owned a 1990 CTD Dodge W350 truck and that thing would do a brakestand from a 3rd gear clutch drop AT IDLE... with 300k miles on the clock. Find me a V8 gasser that can do that and pull a trailer through the Kangamangus at 20+mpg.

1) if it’s so simple, why isn’t it done yet? And no trade-offs?

2) references please (for you arguments)

The trade off is drive-ability and throttle feel. The vehicle will feel sluggish, but it won't "roll coal" if you ease into the throttle. This can be proven by gasp actually driving a diesel powered vehicle and a) stomping on the gas pedal and b) easing into the gas pedal.

The more common solution it diesel particulate filters in-line of the exhaust pipe that cause the soot to completely burn off. This is a trade-off because the DPF requires maintenance. Some systems even go so far as to implement aggressive exhaust gas recycling, pumping already burned exhaust back into the intake to be burned again.

And for references... 1. Why do diesels produce black smoke..... https://commercial.lubrizoladditives360.com/black-smoke-caus...

2. What is diesel exhaust..... https://en.wikipedia.org/wiki/Diesel_exhaust

3. Diesel misconceptions..... https://phys.org/news/2011-06-myths-diesel.html

These are carefully cherry picked. Your diesel misconceptions link only addresses soot particulates but not NOX or other toxins.

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