Wikipedista:Rainbof/oxyhydrogen

Na tuto kapitolu jsou přesměrována hesla Knallgas, bacteria which oxidize hydrogen a Knallgas-bacteria.

[2] Tato směs může být také označováno jako knallgas (německy, "Bang-plyn"), i když někteří autoři definují knallgas být generický termín pro směs paliva se přesné množství kyslíku potřebného pro dokonalé spalování, tak 02:01 třaskavého by být nazýván "vodíkové-knallgas". [3] Brownův plyn [4] a HHO jsou okrajové vědy podmínky pro směsi 2:1 oxyhydrogen; její zastánci tvrdí, že má zvláštní vlastnosti.

Elektrolyzér pro produkci oxyhydrogenu z devatenáctého století.

Oxyhydrogen je směs dvou plynů vodík (H₂) a kyslík (O₂) gases. Tato plynná směs se používá jako palivo hořáků při zpracování žáruvzdorných materiálů, zároveň je to první plynná směs použitá pro svařování. Teoretický poměr 2:1 vodík:kyslík je dostačující pro to aby bylo dosažebi maximální účinnosti; V praxi je však zapotřebí poměru 4:1 nebo 5:01, aby se zabránilo vzniku oxidačního plamene.

Tato směs je také označována jako knallgas (z Němčiny, "Výbušný plyn"), někteří autoři slovo knallgas za generický termín používanou pro ideální směs paliva o přesném množství kyslíku potřebného pro dokonalé spalování. Oxyhydrogen v poměru 2:1 (tedy v ideálním poměru) se tak často označuje "hydrogen-knallgas".

Brown's gas and HHO are fringe science terms for a 2:1 mixture of oxyhydrogen; its proponents claim that it has special properties.

Properties

Oxyhydrogen will combust when brought to its autoignition temperature. For the stoichiometric mixture, 2:1 hydrogen:oxygen, at normal atmospheric pressure, autoignition occurs at about 570 °C (1065 °F). The minimum energy required to ignite such a mixture with a spark is about 20 microjoules. At standard temperature and pressure, oxyhydrogen can burn when it is between about 4% and 95% hydrogen by volume.

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 Šablona:Hydrogen burned. The amount of heat energy released is independent of the mode of combustion, but the temperature of the flame varies. The maximum temperature of about 2 800 °C (5 070 °F) is achieved with an exact stoichiometric mixture, about 700 °C (1 292 °F) hotter than a hydrogen flame in air. When either of the gases are 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.

Production

A pure stoichiometric mixture may be 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

William Nicholson was the first to decompose water in this manner in 1800. The energy required to generate the oxyhydrogen always exceeds the energy released by combusting it, even at maximum efficiency, the input energy of a closed system will always equal the output energy, as the first law of thermodynamics states. (See Electrolysis of water#Efficiency).

Applications

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

Lighting

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. Because of the explosiveness of the oxyhydrogen, limelights have been replaced by electric lighting.

Oxyhydrogen blowpipe

Nineteenth century bellows-operated oxy-hydrogen blowpipe, including two different types of flashback arrestor

The oxy-hydrogen blowpipe was developed by English mineralogist Edward Daniel Clarke and American chemist Robert Hare in the early nineteenth century. It produced a flame hot enough to melt such refractory materials as platinum, porcelain, fire brick, and corundum, and was a valuable tool in several fields of science. It is used in the Verneuil process to produce synthetic corundum.Šablona:Citation needed

Oxyhydrogen torch

An oxyhydrogen torch is an oxy-gas torch, which burns hydrogen (the fuel) with oxygen (the oxidizer). It is used for cutting and welding, metals, glass, and thermoplastics.

Due to competition from the acetylene-fueled cutting torch and from arc welding, the oxyhydrogen torch is seldom used today, but it remains the preferred cutting tool in some niche applications—see oxy-fuel welding and cutting.

Oxyhydrogen was once used in working platinum because at the time such a torch was the only device that could attain the temperature required to melt the metal 1 768,3 °C (3 214,9 °F). These techniques have been superseded by the electric arc furnace.

Fringe science and fraud

"Brown's Gas" is oxyhydrogen with a 2:1 molar ratio of H₂ and O₂ gases, the same proportion as in water. It is named after Yull Brown, who claimed that it could be used as a fuel for the internal combustion engine. It's also called "HHO gas" after the claims of fringe physicist Ruggero Santilli, who claims that his HHO gas, produced by a special apparatus, is "a new form of water", with new properties, based on his fringe theory of "magnecules".

Many other pseudoscientific claims have been made about Brown's Gas's pretended ability to neutralize radioactive waste, help plants to germinate, etc.

Oxyhydrogen is also often mentioned in conjunction with vehicles that claim to use water as a fuel. The most common and decisive counter-argument against producing this gas on board to use as a fuel or fuel additive is that more energy is needed to split water molecules than is recouped by burning the resulting gas. Additionally, the number of liters per minute of gas that can be produced for on-demand consumption through electrolysis is very small in comparison to the liters per minute consumed by an internal combustion engine.

An article in Popular Mechanics reports that Brown's Gas cannot even increase the miles per gallon (MPG) of your vehicle, and that the only real savings come from tampering with your engine, which may confuse the anti-smog controls.

"Water-fueled" cars should not be confused with hydrogen-fueled cars where the hydrogen is produced elsewhere and used as fuel or where it is used as fuel enhancement.