From: B.Hamilton@irl.cri.nz (Bruce Hamilton)
Subject: Re: Are new Cars ONLY 95% cleaner than 30 years ago?
Date: Tue, 27 May 1997 09:14:59 +12
In article <email@example.com>
firstname.lastname@example.org (Hugh Lippincott) writes:
>|> Although comparing apples and oranges, here's some of the
>|> regulations ( it needs updating though )
>|> Year Federal California
>|> HCs CO NOx Evap HCs CO NOx Evap
>|> g/mi g/mi g/mi g/test g/mi g/mi g/mi g/test
>|> Before regs 10.6 84.0 4.1 47 10.6 84.0 4.1 47
>|> add crankcase +4.1 +4.1
>|> 1966 6.3 51.0 6.0
>|> 1968 6.3 51.0 6.0
>|> 1970 4.1 34.0 4.1 34.0 6
>|> 1997 ULEV 0.04 1.7 0.2
>|> 2004 0.125 1.8 0.16 2
>|> Bruce Hamilton
>Very interesting numbers Bruce, even for legal limits.
>I notice that there is this Evap grams/test allowance.
>Gan you explain it. It appears to dominate the later numbers.
I'm away from my references, but basically it measures the
total evaporative emissions from a vehicle during a test
cycle in which the vehicle is placed in a sealed chamber and
all hydrocarbons measured. Basically it will be the front
end, highly volatile fraction, and that is one reason why the
new reformulated gasoline has a lower vapour pressure than
older gasolines in the same season and location. Evaporative
emission are being increadsingly targetted as the tailpipe
emissions are imporoved, as are refuelling emissions.
I can post more detail later if you wish.
>Are there any regulations on the emissions at startup or are they all
>for a warmed up, operating car?
The actual emission are for a driving cycle, and most driving
cycles do have a cold start, and in fact one of the major
problems for the automakers has been to reduce the cold
start emissions, hence the development of fast-light-up catalysts,
electrically-heated catalysts, and now smaller, thermally-durable
catalysts that can be placed right near the exhaust port to
reduce cold start emissions. Cold-start emmisions can represent
a significant % of the emissions in Urban driving cycles.
>Are there any other loop holes in the regs, other than accidents
>that break open the system, and self-refueling spills?
>Please don't take "loop holes" the wrong way, the system we're now
>running serves us very well.
Operation at WOT ( Wide Open Throttle ). All of the driving cycles
have been fairly mild, based on studies of driving styles performed
years ago. Recent studies have shown that drivers are far more
aggressive, and actually do go WOT. Until very recently, no driving
cycles had a WOT stage, and thus automakers would allow the
management system to go open loop and move slightly to the
rich side which was helpful for knock-free power.
For the last few years there have been intensive discussions about
a more realistic driving cycle, and it's fairly likely ( if it's not already )
thata new cycle will include WOT. Automakers have probably already
moved to make WOT closed loop ( like the rest of the engine map ),
as the improved design of engines has meant that there is little
need to move to rich, as maximum power is now very much closer
to the stoichiometric ratio.
There will be more changes, probably mainly looking at the
toxins and particulates, and also moving to bring trucks into line
with the stricter automobile limits. There will be changes to the
fuel, but I suspect that will depend a bit on whether the problem
of oxygenates and groundwater contamination is as serious as
it is appearing to become, and what the results of research into
global carbonyl pollution tell us about the consequences of
extensive use of oxygenates and alcohol fuel . We may move
away from oxygenates and focus on remote sensing of gross
polluters combined with a more refined ( more expensive )
hydrocarbon fuel. Ultimately, I hope, the drive will be to choose
more appropriately-sized transportation. It's silly having a
1000 kg vehicle carting around an 80kg person most of the time.
Damn, the crystal ball power supply just failed...