Emissions Analysis With Hydrogen Boost
hooked up our 5 gas emissions analyzer and computer to an inverter
plugged into the cigarette lighter of my Saturn SL1. With the Hydrogen Boost system shut
off I had my wife drive around town as I recorded the readings on the
readout of the analyzer, which was on the computer. The following is what I found:
At idle for extended
periods of time the ECU of the vehicle was quite good at optimizing the
fuel ratio to take advantage of the catalytic converter, bringing the
emissions down to fairly low levels.
times could actually get down close to zero.
times could get down fairly low.
NOx took a while but eventually got down below 50.
acceleration the emissions would climb considerably and during deceleration
they would climb even more. Then
once again if the throttle was set steady the ECU would work out an
optimum fuel ratio to minimize the emission once again. The problem is that any change in
throttle setting would send the emissions readings into a
gyration. For a steady cruise on
a flat road this would work fairly well in keeping emissions down. But changing throttle settings are a
reality of vehicle operation and most throttles are not steady for more
than a few seconds, even while using cruise control.
With the stock vehicle operating
normally I noticed that the emissions readings on the readout were as
times would climb to 7.82%
times would climb to 400 PPM
NOx at times would climb to 800 PPM
reason for these bad readings is that whenever the throttle setting is
changed there is an immediate change in fuel ratio which does not meet
the criteria of the perfect burn that the emissions control system is
designed to handle. Whenever the
fuel ratio is too rich the CO and HC are elevated, and when the fuel
ratio is too lean the NOx is elevated. And since the throttle setting is
almost always changing, the fuel ratio is always wrong for the design
and the emissions are higher than they could be.
are a couple things that can be done to improve this situation. One is to increase the speed at which
the ECU changes the amount of fuel being injected, and the other we
will discuss later. Enhancing
the adjustment speed of the ECU will not completely take care of the
gyrations because they are caused by fuel already injected and sitting
in the intake manifold during deceleration.
day electronic fuel injection systems are a vast improvement over
carburetor and early fuel injection systems. But much could still be done to make
the combustion more efficient and reduce the emissions further.
Let us address the
efficiency issue first. Liquid
fuel doesn’t burn until it is first vaporized. Heating of the fuel can vastly
improve the rate at which the fuel will vaporize and thus hasten when
it will combust. This is why the
Hydrogen Boost system has a fuel heater.
Another thing that could be
done to improve efficiency is to ignite the air/fuel mix quicker so the
advanced timing can be reduced to a minimum so the combustion and
compression are not fighting against each other during the initial part
of the combustion, which is actually done during the later part of the
compression stroke. This is one
purpose of the added hydrogen (Brown’s gas) to the combustion chamber
with the Hydrogen Boost system.
The third thing that can be
done is to lean the target air/fuel mixture to the mixture that gives
us the greatest power per stroke (greatest torque). This is the purpose of the Hydrogen
Boost system’s electronic control circuit. At the moment the circuit is
relatively crude and in need of more sophistication in optimizing the
fuel ratio. We would certainly
like to accomplish that goal in the future.
Of course a couple things
could be done to improve the efficiency of the vehicle that have
nothing to do with combustion but are indeed incorporated into the
Hydrogen Boost system. One is to
make the inside of the engine more slippery so there is less friction
and drag. We have done this with
the addition of the XCEL PLUS permanent engine treatment and XCEL PLUS
upper cylinder lubrication treatment.
And the last thing we could do is to get the vehicle to roll
down the highway with less drag.
We have done this by increasing the tire pressure beyond the vehicle
manufacturer’s recommended pressure but within the tire manufacturer’s
safety limits. We have addressed
this in our February 2002 newsletter.
each of these affect the emissions of the vehicle? Let me address that question. First heating the fuel, this could
increase evaporative emissions if you had a leaky fuel system, but that
would only be for defective vehicles.
Certainly combustion of vaporized fuel can only cause less CO
and HC emissions because the fuel can burn more completely while it is
still in the combustion chamber.
The addition of hydrogen in
the combustion mix also gets more of the fuel to combust while it is
still in the combustion chamber so that is also good.
Leaning the fuel ratio slightly
will decrease CO and HC emissions because it insures enough oxygen to
combust all the fuel to completion but it can increase NOx production because the presence of excess
oxygen in the combustion chamber during hot combustion allows the
nitrogen in the air to combine with the excess oxygen and form NO2 and
NO3. This is not a good thing
but it can be minimized in two ways.
Firstly, most engines have a system to do this called the EGR,
or exhaust gas recycling system.
The other way is to decrease the temperature of the combustion
so the needed energy to combine the nitrogen and the oxygen is not
present. This may be a task that
might actually reduce our engine’s efficiency because we really would
like to operate at the highest exhaust gas temperature to get the
highest torque. The methods we
could use to reduce the exhaust temperature is to further lean the
air/fuel mixture or to trade some of that excess heat for increased
pressure by adding some water mist into our air/fuel mix. This would capture the energy of the
excess heat and turn it into torque.
I have not tested this option at this writing because the idea
just came to me as I was writing this report. I have tested the addition of water
mist in relation to fuel economy with the Hydrogen Boost system and
found no benefit, but I haven’t tested the possible benefits of
reduction in NOx emissions by adding water
mist because at the time of testing I didn’t own an emissions gas
tester. I have tested further
leaning the mixture and am reporting on that here.
When testing the emissions
with the Hydrogen Boost system turned on and operating I recorded the
CO emissions were always as
low as the scale would go, basically zero.
HC emissions were always as
low as the scale would go, basically zero.
emissions would depend on power output and our electronic control
circuit adjustment setting.
The first two above make
perfect sense because with excess oxygen there is plenty of oxygen to
combine with the CO and HC to make CO2 and H2O. NOx emission
would be elevated with any air/fuel ratio between stock
and 20:1. At around 20:1 fuel
ratio the combustion temperature is low enough to keep the NOx emissions to a minimum but the available
torque/power of the engine is less than what I like. I prefer to run with a fuel ratio
between 16:1 and 18:1 but at these settings the NOx
emission are not so good.
Following are the readings
of NOx I recorded versus air/fuel ratio
A/F 15:1 NOx
A/F 16:1 NOx
A/F 17:1 NOx
A/F 18:1 NOx
A/F 19:1 NOx
A/F 20:1 NOx
Remember we are comparing
with stock vehicle NOx emissions of 50-800
Below is a rough sketch of
a graph of estimated emissions versus air/fuel ratio for the typical
engine, based on the tests that we have run with the Saturn SL1. Note that the normal ECU operation
emission is likely to have a combination of emissions with higher total
emissions than the lean burn operation of Hydrogen Boost. The only exhaust emission that is
likely to be higher with Hydrogen Boost is NOx
emissions during heavy throttle operation. Since Hydrogen Boost drivers are more
likely to be interested in better mileage they are not likely to be
using heavy throttle setting very often.
Conclusion: Compared to stock vehicle operation
the hydrogen Boost system can virtually eliminate all CO and HC
emissions while possibly elevating NOx
emissions, except at an air/fuel ratio that borders on loosing
available power/torque. But,
since the optimum air/fuel ratio that gives comparable NOx emissions as a stock vehicle is coincidentally
the best fuel ratio for best indicated mileage (A/F 18:1), the present
Hydrogen Boost system can drastically reduce total emissions when
adjusted for best mileage.
Further testing will be done with more water mist or vapor
injection in an attempt to further reduce the NOx
emissions. A slight modification
to the present design of our hydrogen generator may be all that is
required. This would likely not
increase the cost of the Complete Hydrogen Boost system.
week later, after discovering an easy modification to the hydrogen
generator that increased the gas production by about 30%, I took the
Hydrogen Boost Emissions Challenge.
The challenge was intended to be an offer to a technician that
owned a five gas analyzer and wanted a Hydrogen boost system. The challenge was for us to install a
Hydrogen Boost system on a technician’s vehicle and achieve better
emissions without a catalytic converter than the stock vehicle
emissions with a catalytic converter.
I had no takers on the challenge and now have my own five gas
analyzer so I decided to take the challenge myself.
I drilled a hole in the exhaust
pipe in a convenient place in front of the catalytic converter and
inserted the emissions tester probe and secured it to the bottom of the
vehicle. Then with the Hydrogen
Boost system turned on I took an extended drive, testing all driving
conditions and throttle settings.
The result was no surprise to anyone who knows about a catalytic
converter and has read the above article.
me explain the workings of the catalytic converter. The purpose of the converter is to
insure that all CO and HC emissions in the exhaust pipe are encouraged
to react with oxygen in the exhaust, and at the same time rob any
oxygen from any NOx in the exhaust to supply
it to the CO and HC. At the
perfect stoichiometric fuel ratio the converter does the job quite
well, but as we have seen above, the stock vehicle never has the
perfect ratio because it is always changing.
let’s get back to the emissions in the Hydrogen Boost equipped
vehicle. If there are no CO and
HC emissions in the exhaust pipe there is no place to force the oxygen
in the NOx to go, so reducing NOx is not done by the catalytic converter. If there is no CO and HC in the
exhaust and the converter can’t reduce the NOx
without them, there is no need for the catalytic converter, and the
emissions would basically be the same in front of the converter as they
would be at the tail pipe. I
knew this before I did the test but I had to follow through to prove
it. Plus I couldn’t win the
challenge and give myself the tester without following the challenge
can say that the emissions were not always perfect in front of the
catalytic converter, because there was the rare occasion that excess
fuel vapors from the tank would increase the fuel ratio from our ultra
lean setting. You might think
that this should show increased CO or HC in the exhaust pipe in front
of the catalytic converter, but that is not the case. Actually there was increased NOx at these times, which proves to me that the
hydrogen generator and ignition system were doing a proper job of
igniting the air/fuel mixture and there was still plenty of oxygen to
burn the fuel. The increased NOx was very short lived and on very rare occasion,
like when accelerating after sitting at a traffic light for long
periods at idle, which no self-respecting good mileage driver would do.
rare occasion of increased emissions is when the engine would skip or
buck, because of poor ignition.
This could be caused by a too lean mixture that the system is
barely igniting and occasionally not igniting. This show me
that it would be nice to have some more hydrogen in the mix. This has spurred me to investigate
ways to increase our hydrogen production and I have already found one
easy modification to increase the gas production of our latest
production model generators by about 30%. If you have purchased our system
between January 2006 and July 2006 you can email me at email@example.com for
the modification instructions.
The modification takes about 5 minutes if you have the hydrogen
generator in your hand or have easy access to the top of it.
Related information: The reduced emissions are closely
related to the increased mileage benefits of the lean-burn ability of
the Hydrogen Boost system. See www.hydrogen-boost.com/complete.html
for more details.
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