CHAPTER I

INTRODUCTION

1.1 INTRODUCTIONThermal cutting, i.e. gas cutting, is a wide-spread technology. In practical applications, gases such as propane-bu- tane and acetylene prevail. Hydrogen is practically not used due to its high production cost and its explosiveness. Oxy hydrogen welding is a gas welding process using a combustion mixture of hydrogen and oxygen for producing a gas welding flame. Oxy hydrogen welding is used for joining metals with low melting points like aluminum, magnesium, etc.

Fig 1.1: Simple gas welding

Oxy-hydrogenis a mixture ofhydrogen(H2) andoxygen(O2) gases. This gaseous mixture is used for torches to processrefractorymaterials and was the first gaseous mixture used forwelding. Theoretically, a ratio of 2:1 hydrogen: oxygen is enough to achieve maximum efficiency; in practice a ratio 4:1 or 5:1 is needed to avoid anoxidizing flame. Oxy-hydrogen willcombustwhen brought to itsauto ignition temperature. For thestoichiometricmixture, 2:1 hydrogen: oxygen, at normalatmospheric pressure, auto ignition occurs at about 570C (1065F).[5]The minimum energy required to ignite such a mixture with a spark is about 20micro joules.Atstandard temperature and pressure, oxy-hydrogen can burn when it is between about 4% and 95% hydrogen by volume.

When ignited, the gas mixture converts towater vaporandreleases energy, which sustains the reaction: 241.8kJof energy (LHV) for everymoleofH2burned. The amount of heat energy released is independent of the mode of combustion, but thetemperature of the flamevaries.[6]The maximum temperature of about 2,800C (5,070F) is achieved with an exact stoichiometric mixture, about 700C (1,292F) hotter than a hydrogen flame in air.When either of the gases are mixed in excess of this ratio, or when mixed with aninert gaslike nitrogen, the heat must spread throughout a greater quantity of matter and the temperature will be lower.

1.2 BASIC CHARACTERISTICS OF COMBUSTION OF HYDROGEN AND OXYGENHydrogen is a colourless, odourless, and tasteless elementary gas. It is not poisonous. In nature it is rarely found in its atomic form. With an atomic weight of 1,008, temperature in hydrogen combustion in air attains 1700 C, and in oxygen 2400 C. When mixed with air, hydrogen forms an explosive mixture (an explosive gas). Its ignition temperature is 560 C whereas its explosion range is from 4 to 75 vol. % at atmospheric pressure.

1.3 PRODUCTION A pure stoichiometric mixture may be obtained bywater electrolysis, which uses anelectric currentto dissociate the water molecules:Electrolysis: 2 H2O 2 H2+ O2Combustion: 2 H2+ O2 2 H2O

1.4 OXY-HYDROGEN WELDING TORCHAnoxy-hydrogen torchis anoxy-gas torch, which burns hydrogen (thefuel) with oxygen (theoxidizer). It is used for cutting andwelding, metals, glass, andthermoplastics. Due to competition from the acetylene-fueled cutting torch and from arc welding, the oxy-hydrogen torch is seldom used today, but it remains the preferred cutting tool in some niche applications. Oxy-hydrogen was once used in workingplatinumbecause at the time such a torch was the only device that could attain the temperature required to melt the metal 1,768.3C (3,214.9F).

Fig 1.2: Oxy hydrogen welding torch

CHAPTER II

ELECTROLYSIS OF WATER

2.1 INTRODUCTIONElectrolysis of wateris thedecomposition of water into oxygen andhydrogengas due to anelectric currentbeing passed through the water. An electrical power source is connected to twoelectrodes, or two plates (typically made from some inert metal such asplatinum,stainless steeloriridium) which are placed in the water. Hydrogen will appear at thecathode(the negatively charged electrode, whereelectronsenter the water), and oxygen will appear at the anode(the positively charged electrode). Assuming idealfaradaic efficiency, the amount of hydrogen generated is twice the number ofmolesof oxygen, and both are proportionalto the totalelectrical chargeconducted by the solution.However, in many cellscompeting side reactionsdominate, resulting in different products and less than ideal faradaic efficiency.

Electrolysisofpurewater requires excess energy in the form ofover potentialto overcome various activation barriers. Without the excess energy the electrolysis of purewater occurs very slowly or not at all. This is in part due to the limitedself-ionization of water. Pure water has anelectrical conductivityabout one millionth that of seawater. Manyelectrolytic cellsmay also lack the requisiteelectro catalysts. The efficiency of electrolysis is increased through the addition of anelectrolyte(such as asalt, anacidor abase) and the use ofelectro catalysts.

2.2 EQUATIONSIn pure water at the negatively charged cathode, areductionreaction takes place, with electrons (e) from the cathode being given to hydrogen cations to form hydrogen gas (the half reaction balanced with acid):Reduction at cathode: 2 H+(aq) + 2e H2(g)At the positively charged anode, anoxidationreaction occurs, generating oxygen gas and giving electrons to the anode to complete the circuit:Oxidation at anode: 2 H2O(l) O2(g) + 4 H+(aq) + 4eThe same half reactions can also be balanced with base as listed below. Not all half reactions must be balanced with acid or base:Cathode (reduction): 2 H2O(l) + 2e H2(g) + 2 OH-(aq)Anode (oxidation): 4 OH-(aq) O2(g) + 2 H2O(l) + 4 eCombining either half reaction pair yields the same overall decomposition of water into oxygen and hydrogen:Overall reaction: 2 H2O(l) 2 H2(g) + O2(g)The number of hydrogen molecules produced is thus twice the number of oxygen molecules. The number of electrons pushed through the water is twice the number of generated hydrogen molecules and four times the number of generated oxygen molecules.

Fig 2.1 Simple setup for electrolysis of water

CHAPTER III

HHO DRY CELL

3.1 INTRODUCTIONIn electrolysis, people have tried different ways to increase the output of gas while decreasing the input of current. Some designs are more effective than others. Some people have tried to improve the conventional way, called wet system, consisting on plates or tubes submerged in water, while others have tried a design called dry cell where the water run through the plate.

Fig 3.1 HHO dry cell

Dry cell designs are cheaper. This design can vary in shape or size, making in it very easy to install anywhere. The material used for the plates is stainless steel 316, and uses regular rubber O-rings to separate them. At the same time the amount of current input required to produce hydrogen is small. The wet system design consists in a more complicated manufactured process. This design is more expensive since the parts and the arrangement are more likely hard to produce. This system uses two different diameters of tubes in order to accommodate one inside the other one with different polarities, positive the inner and negative the outer. As a container, this kit uses a material capable to satisfy some important parameters. Resist higher temperatures, since the electrolysis process generates a significant amount of heat. The pressure built inside, sometimes up to 60 psi. And very important, it has to be a dielectric material in order to avoid electrolysis between the tubes and the inner wall of the container.

3.2 THEORITICAL CALCULATIONSIn order to quantitate the process of electrolysis, we have found some equations that relate the current needed to obtain a certain volume for a gas. The process for this calculation at room temperature and at 1 atm is: Cathode (reduction): 2 H2O(l) + 2e H2(g) + 2 OH-(aq)Anode (oxidation): 4 OH-(aq) O2(g) + 2 H2O(l) + 4 e

Calculation of the number of moles of electrons that were transferred: Amperes X time = Coulombs 96,485 coulombs = 1 Faraday (F) 1 Faraday = 1 mole of electrons Example: 60(amps) * 3600(sec) = 216000(coulombs)216000C * () = 2.239 F2.239 F * () = 2.239 mole Calculation of the moles of hydrogen and oxygen produced using the number of moles of electrons calculated and the stoichiometries from the balanced half-reactions. According to the equations, 2 moles of electrons produce 2 mole of and 4 moles of electrons produce 1 mole of gas:2.239 mole * = 2.239 mole 2.239 mole * = 0.560 mole

Calculation of the volume of each gas using ideal gas law (V=nRT/P). Where, n: number of moles. R: Boltzmann constant = 0.08206 (L atm/mol K) T: temperature in kelvin. Volume of Hydrogen and oxygen gas:

These calculations have shown that for a current of 60 amps during a period of 1 hour, the electrolysis of water yields 54.75 liters of hydrogen gas and 13.69 liters of oxygen gas.

3.3 MAJOR COMPONENETS The main component in a Hydrogen-on-Demand system is the HHO or Hydroxy gas generator. This device can be a simple one cell unit or have as many cells as needed to produce the quantity of HHO gas desired. Electrolysis is the driving force for such generator. it separates chemically bonded compounds by passing an electric current through them. Another component used to produce HHO is an Electrolyte. Any substance containing free ions that behaves as an electrically conductive medium. Catalyst is the correct term because of the function it performs to speed up the production of HHO gas. Another important component for regulation is the Amp Meter, this is a tool used to measure the amperage flowing through a wire or other conductive material. It is a very important tool when adjusting your HHO generator or Hydrogen on demand system for maximum output.

Fig 3.2: HHO dry cell generator3.4 STRUCTURAL DESIGN AND SPACING Pure water is an insulator. It will not conduct electricity; but pure water is rare. River water, stream water, well water, and city water all contain minerals that conduct electricity. The higher the mineral content the better the water will conduct (pass an electric current).So what does this have to do with cell spacing? Well consider the distance between your plates. If water is an insulator, then the more water you have between two plates, the higher the resistance will be between the plates. If you know anything about Ohms Law, an increase in Resistance causes electron flow to be reduced. Electron flow is the amperage your cell is drawing. The farther apart your plates are, the less amps your cell will draw through the water. The closer the plates are, the more amperage your cell will draw. Amperage plays a big part in HHO production. Without it, your cell will produce nothing.

If we add Electrolytes to the water, we will make the water conduct better by decreasing the Resistance between the plates. A decrease in resistance allows more current to flow; thus increasing the possibility of producing more HHO. A cell that has wide spacing can be made to produce just as much HHO as a cell with close spacing. The difference is going to be the amount of electrolytes added to the water. The cell with wide spacing will need larger amounts of electrolytes.

As for plate spacing, I use 1mm. That is about as close as possible and still get good bubble flow. Closer spacing needs fewer electrolytes. It does not produce more gas or less gas; per say. Gas production is caused by amperage. Since water does not conduct electricity without adding electrolytes or minerals, we will have to add electrolyte or minerals no matter what the spacing is. Close spacing makes our cells more compact. Sometimes spacing comes about by what we have to use as an insulator to separate the plates. Ours is gaskets for instance. Gaskets need to be strong andpliable enough to endure the process of taking the cell apart and putting it back together.

Fig 3.3: HHO dry cell spacing

3.5 DRY CELL DIGITAL PROTOTYPING The dry cell design and animation was done in 3D Modeling software - Autodesk Inventor. The digital prototype made our job easier to plan our sequence of operations to be carried out to reach our goal. Though this prototype we were able to identify the materials to be procured for the construction of the dry cell clearly. The animation video helped us to place the power plates and neutral plates at proper position with the required spacing.

Fig 3.4: Isometric view of digital prototype of HHO dry cell

Fig 3.5: front view of digital prototype of HHO dry cell

CHAPTER IV

CONSTRUCTION OF HHO DRY CELL

4.1 MATERIAL REMOVAL OPERATIONS

4.1.1 Drilling We have drilled 8 holes of 12 mm diameter on the corners and 16 mm diameter holes in the upper and lower middle areas for each metal plate and Teflon sheet.

Fig 4.1: Drilling of metal sheets on radial drilling machine

4.1.2 Grinding To remove the burrs after the drilling of metal plates for the provision of compact sealing of dry cell, we did the grinding of metal plates.

Fig 4.2: Grinding of drilled metal sheets

4.1.3 Cutting of steel studs Since the bolts of long lengths are not available so we took long mild steel studs of 10 mm diameter and we have cut them into required pieces using hack saw.

Fig 4.3: Cutting of mild steel studs for tightening of cell

4.2 FLASH BACK ARRESTORS We have made this flashback arrestor using a copper rod of 12 mm internal diameter and stainless steel wool, air mesh, 2 bronze nuts of 12 mm diameter. Firstly we inserted the stainless steel wool into the copper rod. Then we did counter boring on the bronze nuts and inserted the air mesh into it perfectly. Then with the help of brazing we joined the copper rod and bronze nuts on its both sides and made the flash back arrestor.

Fig 4.4: Construction of flash back arrestor using copper rod

Fig 4.5: Construction of flash back arrestor using air stone with our project guide

4.3 WATER TANK AND BUBBLER

Fig 4.6: water tank and bubbler4.4 HHO DRY CELL GENERATORThis is the HHO dry cell generator after construction. The water tank is placed above the dry cell for the easy flow of water into the cell from tank. The water is mixed with the KOH pallet and is sent into the dry cell from water tank through pipeline. The plates of the cell are given the positive and the negative polarities and connected to a battery source of 24 volts via a pulse width modulator. The hydrogen and oxygen gases are evolved and enter into the bubbler. From there the HHO gas enters into the welding torch after getting passed through two flashback arrestors. The gas coming out fron the nozzle is fired using a lighter and welding of plates is done using that flame.

Fig 4.7: Finished HHO dry cell generator setup17