Burning Hydrogen Question


by jackmccarron
Tags: burning, hydrogen
jackmccarron
jackmccarron is offline
#1
Dec7-09, 12:39 PM
P: 4
I'm interested in hydrogen injection for my 1 ton Dodge diesel truck to improve fuel mileage and power as well as lower pollutants. Electrolysing water to produce a stoichiometric mixture of hydrogen and oxygen (called HHO or hydroxy or "Brown's gas") and then injecting it into the turbo intake is supposed to significantly improve the burning efficiency of the diesel fuel (like from the normal 75% to 90%)

I want to ask a question about burning the gas mixture of hydrogen and oxygen (2H+O). Namely, what happens to the volume of the mixture during and after the explosion. Does the volume increase (due to heat) or decrease (if the gas "collapses" to water)? Since the initial result is probably steam, does the resulting steam occupy more or less volume than the original gas? (I assume more since the number of moles of gas hasn't changed, and it's now hotter.) If the original gas were a rising bubble in water when detonated, I assume the bubble would at first get larger and then vanish as the steam condenses to liquid water. Is this correct?

If my assumption is correct, if you have a certain volume of the gas is at room temp and sea level pressure, approximately at what temperature and what volume would the steam occupy at the instant the combustion is complete?

For more info on hydroxy injection, see

http://burnhydrox.com/customers.html

Thanks,
Jack
Phys.Org News Partner Chemistry news on Phys.org
Repeated self-healing now possible in composite materials
Potent, puzzling and (now less) toxic: Team discovers how antifungal drug works
Research offers 'promise' of improved food safety
mgb_phys
mgb_phys is offline
#2
Dec7-09, 01:24 PM
Sci Advisor
HW Helper
P: 8,961
Quote Quote by jackmccarron View Post
I'm interested in hydrogen injection for my 1 ton Dodge diesel truck to improve fuel mileage and power as well as lower pollutants
It won't.

Electrolysing water to produce a stoichiometric mixture of hydrogen and oxygen (called HHO or hydroxy or "Brown's gas") and then injecting it into the turbo intake is supposed to significantly improve the burning efficiency of the diesel fuel (like from the normal 75% to 90%)
i would be surprised if your current dodge engine is 75% efficient, that's about 10% more than the theoretical efficiency of a diesel ICE.
How exactly were you planning on electrolysing the water? Where does the energy to do that come from?
Do you think you are likely to get more power out than you put in?

Namely, what happens to the volume of the mixture during and after the explosion. Does the volume increase (due to heat) or decrease (if the gas "collapses" to water)?
2 moles of H2 and 1 mol of O2 will form 2 moles of H2O, so the volume will halve.
Except the temperature will go up, so you need to know what the initial and final temperatures will be,

(I assume more since the number of moles of gas hasn't changed, and it's now hotter.)
The number of moles of gas has changed.

If the original gas were a rising bubble in water when detonated, I assume the bubble would at first get larger and then vanish as the steam condenses to liquid water. Is this correct?
No idea what you mean here

ps You might want to consider what doing this will do to the engine of your truck.
i assume you know more about the thermodynamics, metallurgy, hydrogen embrittling and oxygen compatibility of the materials than the makers.
mgb_phys
mgb_phys is offline
#3
Dec7-09, 01:35 PM
Sci Advisor
HW Helper
P: 8,961
pps. Sorry if you aren't a crank!!!
The water-gas car injection thing comes up regularly here.

It's normally followed by the sort of logic that goes -
I use the output of the alternator to make H2/O2 that makes more power - which means I can make more H2O2. And pretty soon they are planning to use their Chevy to power Chicago.

Then it's followed by a belief that everyone could do this if the car companies weren't in the pay of the oil companies.

Then when somebody here questions the wisdom somebody without high school chemistry trying to inject oxygen at 1000bar into an aluminium engine full of various flammable fuels - it's because we are part of the conspiracy.

jackmccarron
jackmccarron is offline
#4
Dec7-09, 06:11 PM
P: 4

Burning Hydrogen Question


to mgb_phys: "i would be surprised if your current dodge engine is 75% efficient, that's about 10% more than the theoretical efficiency of a diesel ICE.
How exactly were you planning on electrolysing the water? Where does the energy to do that come from? Do you think you are likely to get more power out than you put in?"

Sorry, I read somewhere in the web that the usual efficiency of a diesel is 75% burned fuel. Not knowing any better I quoted that number.

I Would plan to get hydroxy (HHO, or OxyHydrogen) from electrolysis of water (with KOH catalyst ) using 12volt power from anternator/battery. Of course I don't expect more power out from just burning the HHO. I understand the 2nd law of thermodynamics. The gain in overall power comes from more efficiently burning the diesel fuel itself. My understanding is that the injection of gaseous hydrogen (or propane or methane) into the diesel fuel causes it to burn much faster and more completely. Normally (without hydrogen injection), I'm told, the diesel fuel continues to burn for the entire downward travel of the piston during the power stroke - and even somewhat into the exhaust stroke, wasting energy. Faster burning of the diesel allows the capture of significantly more of the chemical energy of the diesel fuel. This would imply higher initial pressures within the cylinder, but I've heard no "stories" about blown head gaskets, etc.


"2 moles of H2 and 1 mol of O2 will form 2 moles of H2O, so the volume will halve.
Except the temperature will go up, so you need to know what the initial and final temperatures will be,"

So why wouldn't the volume be 2/3 not 1/2? (disregarding effects of temperature change.)



"If the original gas were a rising bubble in water when detonated, I assume the bubble would at first get larger and then vanish as the steam condenses to liquid water. Is this correct?

No idea what you mean here"

This was just a thought experiment to visualize the volume change when burning HHO. Picture a large bubble of HHO rising in a column of water. If the bubble could somehow be ignited while it traveled upward (like passing over a spark plug), how would the bubble behave as the HHO burns? As the hydrogen/oxygen mixture burns, I would assume it "instantly" converts to hot steam at some (probably larger?) volume. Then as the steam condenses (being surrounded by cool water) it enters the liquid water phase, joins the surrounding water and the bubble "vanishes". Does this seem correct???


"ps You might want to consider what doing this will do to the engine of your truck.
i assume you know more about the thermodynamics, metallurgy, hydrogen embrittling and oxygen compatibility of the materials than the makers."


I have wondered about hydrogen embrittlement, and have checked the internet on this. Nobody I found has any definite info on this, but most seem to think it would take years to cause any problem. May or may not be true. Actually, I'm more likely to go with a propane injection system, although this obviously requires buying propane and storing it onboard the truck (danger!).

Propane injection into diesel engines has be used since the early 1900s in farm tractors. It is being used by many power enhanced diesel trucks today with apparently little affect on the engine. Instead, I've heard from several truck mechanics, that the most common problem is failed transmissions - as the heavy footed boys show off their trucks. I'm an old fart (full-time RVer and retired EE) who's interested in fuel economy, not how fast I can leave the stoplight. According to most of the internet info I've found, propane, hydrogen, HHO, and methane can all be used to get the diesel fuel burning acceleration effect. This also reportedly works with gasoline engines. However, some adjustment to the car's oxygen sensor feedback to the ECU is necessary. See http://www.hho2u.com/OXYGEN_SENSORs.html if you're interested.


Register to reply

Related Discussions
Hydrogen Burning and the Suns Nuclear Fusion Introductory Physics Homework 8
BTU Q's about burning water vs. burning gassoline... Chemistry 2
Burning Calories, Burning Wood, Grams to Cals?! General Physics 21
Can burning trees replace burning coal? General Discussion 9
BTU Q's about burning water vs. burning gassoline... Chemistry 3