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Old 07-13-2008, 01:39 AM   #130 (permalink)
john_bud
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Quote:
Originally Posted by oldschool View Post
I wonder what that guy was messin with , 100 amps is way out ot the park for most cells.The smack boosterusually runs about 20 amps max, and your car radio takes 10amps. I see a lot of people splicing into the hot wire on their windshield wiper motor for power so the draw can't be that much.

No this isn't perpetual motion, thats crazy, and maybe it takes more energy to make the gas then it gives back to burn it , I don't know , but the alternator is spinnin and the power in many cases is doin nuthin, which is more wastefull in my eyes.

a 20 amp draw on an efficient cell will make 1.7 liters of gas a minute which equates to on average 20% bettermpg on large vehicles and 30% on small ones
There are some slight technical weaknesses in your point of view wrt alternators. They don't generate any "extra" power, nor do they produce a very great drag when not needed. You may not be conversant with the normal operations of one. As an electrical load is applied to the system (turn on lights, radio, washers, heated seat, etc), the system voltage sags or drops. The voltage regulator energizes the field in the alternator when the voltage potential drops below a preset threshold. When that happens, it takes power to turn the alternator. 2-8 hp is the usual figure depending on the size of the alternator, the rpm and the current load it is supplying. When the system voltage reaches the high set point, the voltage regulator then no longer energizes the field in the alternator and the power requirements to turn it drop to just frictional losses. So, there is very very very little wasted energy from the alternator that you can tap into for "free".

The scientific papers I have read indicate t a fumigation rate of at least 10% (that's total air volume to hydrogen volume in ratio of 10 air to 1 hydrogen or 10:1) is needed to make meaningful improvements in extremely lean conditions. Extremely lean is where the air to fuel ratio (on a mass basis) is over 20:1, preferably 25:1. In fact, you can increase the hydrogen slightly and lean out the fuel to the point where it is not spark combustible and the hydrogen will provide the combustion initiation. That's where you get the fuel economy gains. The down side is dramatically higher combustion temperatures and dramatically higher formation of NOx's. Oxides of nitrogen are the principle component in smog, brown haze, 1970 vintage LA air.

You can make your engine operate in those conditions, but you will need to get a different ECM map, spark timing, different O2 sensor, and a few other things too. And you will certainly not pass any smog sniff test, as you will be spewing more gunk out your tail pipe than '55 Buick running on 5 of 8 cylinders.

You can do the math on the amount of hydrogen you need to evolve by knowing the displacement of the engine, the operational RPM's and the manifold vacuum. You need to also understand that a 4 cycle engine consumes 1/2 it's displacement every 360 degrees of rotation.

For a 1000 cc (1 liter) engine operating at 2000 rpm with a manifold vacuum of 20 in hg it will consume the following volume of air. (ambient air pressure is about 30 in hg)

1 liter * 1/2 * 2000 rpm * (1-20/30) = 166 liter of air per minute. (I used a 1 liter engine so you can multiply by the actual size of you engine to get your requirements.)

Note that I'm neglecting the thermal effects of expansion as the hydrogen / oxygen gas is evolved at approximately the same temperature as the air being consumed due to the heating from the electrolysis process and the thermal environment of the engine compartment.

So, to get to a 10% level, you would need to evolve 16 liters of hydrogen per minute. Using your number of 20 amps = 1.7 liter per minute of TOTAL gas, that's just over 1 liter of hydrogen as the gas mix is 2/3 H2 and 1/3 O2. So to make a meaningful impact, you should generate 15 times that amount of gas and would need 300 amps of current. That's a pretty tall order. Remember to multiply the gas and current requirement by the actual engine size too. So a 3 liter engine would need 900 amps of current and 45 liters of hydrogen or 60 liters of total gas evolution. That's a bunch! Now imagine what it would be at 5000 rpm's at at full throttle (zero manifold vacuum).

3 liter*1/2*5000* (1-0/30)=7500 liters per minute air consumption and you would need 750 liters of hydrogen (1250 liters total gas). It would take 14,700 amps of current using your 20 amps = 1.7 total gas figure. Hope you have a LARGE alternator!

The other area to address would be the variability in air consumption. At idle with closed throttle compared to 5000 rpm with wide open throttle, there is a dramatic difference in air requirements. I have yet to see where the electrolysis cells are modulated to produce 20:1 variable volumes of gas to maintain a constant 10% hydrogen in the combustion chamber. Also, the time lag between pressing the throttle and the generation of the gas would be annoying. It takes several seconds for the gas evolution to pick up and until it does (in an extremely lean engine) the combustion process would fail as the air/fuel is not in a spark ignitable ratio. I certainly wouldn't enjoy flooring it and having the engine die! I suppose transient enrichment could be programmed in to the ECM, but that adds a further layer of parameters to account. But what happens when you merge into traffic on the freeway at wide open throttle, start to generate the 1250 liters per minute of gas, then you close the throttle? Does the engine continue to rev up as you are still feeding it that gas rate for several seconds as the dissolved gas in the water forms bubbles and those bubbles pop? It would also be troublesome to have the engine over rev when you want to stop. I suppose you could vent the hydrogen, but spewing out a highly flamable gas does not sound smart.

The actual combustion of fuel into heat, water and CO2 is about 98% to 99.8% efficient. Meaning there is very little unburnt hydrocarbons exiting the combustion chamber of a modern engine in working order. Cold start there is a lot and that's why you have a cat converter. But once warmed up, you could cut if off and wouldn't materially effect pollution. The often quoted 25-30% efficiency is in converting the chemical energy into work. The Otto cycle gasoline engine is not very good at that and it has tremendous amounts of waste heat. That heat goes out the exhaust as hot gasses and is transfered out the radiator and engine compartment as hot air.

Hope that helps,
jb
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