HHO according to Wikipedia

Oxyhydrogen
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"Knallgas" redirects here. For bacteria which oxidize hydrogen, see Knallgas-bacteria.

Oxyhydrogen is a mixture of hydrogen and oxygen gases, typically in a 2:1 atomic ratio, the same proportion as water.[1] This gaseous mixture is widely used for torches for the processing of refractory materials.

Properties

Oxyhydrogen will combust when brought to its autoignition temperature. For a stoichiometric mixture at normal atmospheric pressure, autoignition occurs at about 570 °C (1065 °F).[2] The minimum energy required to ignite such a mixture with a spark is about 0.02 millijoules.[2] At normal temperature and pressure, oxyhydrogen can burn when it is between about 4% and 94% hydrogen by volume.[2]

When ignited, the gas mixture converts to water vapor and releases energy, which sustains the reaction: 241.8 kJ of energy (LHV) for every mole of H2 burned. The amount of heat energy evolved is independent of the mode of combustion, but the temperature of the flame varies.[1] The maximum temperature of about 2800 °C is achieved with a pure stoichiometric mixture, about 700 degrees hotter than a hydrogen flame in air.[3][4][5] When either of the gases is mixed in excess of this ratio, or when mixed with an inert gas like nitrogen, the heat must spread throughout a greater quantity of matter and the temperature will be lower.[1]

Production

A pure stoichiometric mixture is most easily obtained by water electrolysis, which uses an electric current to dissociate the water molecules:

electrolysis: 2 H2O → 2 H2 + O2
combustion: 2 H2 + O2 → 2 H2O

The energy required to generate the oxyhydrogen always exceeds the energy released by combusting it; see Electrolysis of water:Efficiency.

Applications

Limelights used an oxyhydrogen flame as a high-temperature heat source


Historic uses

Many forms of oxyhydrogen lamps have been described, such as the limelight, which used an oxyhydrogen flame to heat a piece of lime to white hot incandescence.[6] Because of the explosiveness of the oxyhydrogen, limelights have been replaced by electric lighting.

It was much used in platinum works, as platinum could be melted (at a temperature of 1768.3 °C) only in an oxyhydrogen flame, or an electric furnace (which is now used instead).

Oxyhydrogen torch

An oxyhydrogen flame

An oxyhydrogen torch is an oxy-gas torch, which burns hydrogen (the fuel) with oxygen (the oxidiser). It is used for cutting and welding metals, glass, and thermoplastics.[6] An oxyhydrogen torch is used in the glass industry for "fire polishing"; slightly melting the surface of glass to remove scratches and dullness.

The oxyhydrogen flame begins a short distance from the torch tip; if the distance is great enough the torch tip can remain relatively cool.[7]

Water torch

A bubbler apparatus used to mitigate potential flashback.[8]

A water torch is a kind of oxyhydrogen torch that is fed by oxygen and hydrogen generated on demand by water electrolysis. The device avoids the need for bottled oxygen and hydrogen, but requires electricity. Water torches must be designed to mitigate flashback by strengthening the electrolytic chamber. Use of an intermediary water bubbler eliminates potential electrolyzer damage from flashback, with a dry flashback arrestor being ineffective due to flame velocity. The bubbler is connected directly in series with the output gas. A water bubbler is sometimes referred to as a wet flashback arrestor, and effectively captures any remaining electrolyte in the output gas. Suitable electrolytes include sodium or potassium hydroxide, and other salts that ionize well.[7] Also "the electrolyzer system must be of high enough pressure to keep the gas velocity at the nozzle above the combustion velocity of the flame, or the system will backfire".[7] For images of water torch equipment see these links: [1] [2] [3][4][5][6][7][8].


The series cell design by Yull Brown.[8]

Brown's design

Some models of water torches mix the two gases immediately after production (vs. the torch tip) making the gas mixture more accurate.[8] This electrolyzer design is referred to as "common-ducted",[7] and the first was invented by William A. Rhodes in 1966.[9] Oxyhydrogen gas produced in a common-ducted electrolyzer is commonly referred to as "Brown's gas", after Yull Brown who received a utility patent for a series cell common-ducted electrolyzer in 1977 and 1978 (the term "Brown's gas" is not used in his patents, but "a mixture of oxygen and hydrogen" is referenced).[8][10] Brown's torches also used an electric arc to increase the temperature of the flame (called atomic welding):[8]

The claimed varying flame temperature can be explained by inaccurate infrared thermometry,[11] and measurement of the target material rather than the flame itself.

As a fuel supplement

* Oxyhydrogen gas is effective at improving emissions and efficiency in internal combustion engines when used as a fuel supplement. See Hydrogen fuel enhancement; hydrogen affects the burn rate of fuels and lean combustion capabilities of internal combustion engines.[12][13][14] Fuel Enhancement systems are designed "to feed the hydrogen and oxygen gases directly to an internal combustion engine without intermediate storage".[15]

* For diesel applications, it is claimed that "When the hydrogen enriched air is compressed, the diesel fuel is introduced with a resulting improvement in fuel efficiency and maximized combustion of the fuel".[16] Fuel enhancement has the potential to substantially reduce pollution emissions of internal combustion engines; research in 2004 concluded that "HC-emissions as well as NOx-emissions could be reduced to near zero".[17] A 50% reduction in gasoline consumption, at idle, was reported by numerically analyzing "the effect of hydrogen enriched gasoline on the performance, emissions and fuel consumption of a small spark-ignition engine".[18] Hydrogen "addition can guarantee a regular running", of the engine "with many advantages in terms of emissions levels and fuel consumption reduction".[17] Hydrogen fuel enhancement can be optimized by implementing established lean burn concepts, and at minimum to achieve an actual increase in gas mileage the air/fuel ratio needs appropriate modification.[13][12][17][19] Although such claims do not consider the emissions formed in generating the oxyhydrogen. "Overall, increases in engine efficiency are more dominant than the energy loss incurred in generating hydrogen, resulting in improved fuel economy for the system as a whole".[13] This is supported by computational analysis that "has marked the possibility of operating with high air overabundance (lean or ultra-lean mixtures) without a performance decrease, but with great advantages on pollution emissions and fuel consumption".[18]

Heating

* Sang Nam Kim claims "an energy generating apparatus using the cyclic combustion of Brown gas wherein a heat generating unit is heated to a temperature of 1,000°C".[20]

Klein's design

HHO gas or Klein gas is an oxyhydrogen mixture made by water electrolysis, which has been trademarked Aquygen by the firm Hydrogen Technology Applications.

Claims

Dennis Klein's patent states that his electrolyzer differs from Yull Brown's in that it lacks the electric arc feature.[21]

The HHO trademark is associated with an unproven state of matter called magnegases, and a discredited theory about magnecules,[22] [23] which is the basis for a number of fraudulent claims, and water-fuelled car scam attempts similar to the water fuel cell hoax.

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I hope this will help enlighten you about HHO... :-)