Chemical Transducer

8/2/2019 Chemical Transducer

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Chemical TransducerFuel Cells


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Submitted By:

Dador, Judy Anne D.S.

ECE109 / A12

Submitted To:

Engr. Joseph Bryan G. Ibarra


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What is a Transducer?

A transducer is an electronic device thatconverts energy from one form to another.

Transducers can be used to sense a wide rangeof different energy forms such as movement,

electrical signals, radiant energy, thermal ormagnetic energy etc, and there are manydifferent types of both analogue and digitalinput and output devices available to choosefrom.

Common examples of transducers includemicrophones, loudspeakers, thermometers,position and pressure sensors, and antenna.


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Types of Transducers

There are two types of Transducers: InputTransducers and Output Transducers.

Input type transducers, commonly known assensors, produce a proportional output voltageor signal in response to changes in the quantity

that they are measuring (the stimulus) and thetype or amount of the output signal dependsupon the type of sensor being used.

Output transducers or actuators are designedto achieve some end effect, for example,opening of a valve or deflection of a controlsurface on an aircraft. Actuators, therefore,normally operate at high power levels.


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Chemical Transducers

A chemical transducer is an electronic devicethat converts chemical energy into anotherform of energy (ex. electricity) by means of achemical process.


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Fuel Cells

A fuel cell is a device that converts the chemicalenergy from a fuel into electricity through achemical reaction with oxygen or anotheroxidizing agent.

Hydrogen is the most common fuel, buthydrocarbons such as natural gas and alcoholslike methanol are sometimes used.

Fuel cells are different from batteries in thatthey require a constant source of fuel andoxygen to run, but they can produce electricitycontinually for as long as these inputs aresupplied.


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Characteristics

Fuel Cells are made up of three segments whichare sandwiched together: the anode,the electrolyte, and the cathode. Two chemicalreactions occur at the interfaces of the threedifferent segments. The net result of the tworeactions is that fuel is consumed, water orcarbon dioxide is created, and an electriccurrent is created, which can be used to powerelectrical devices, normally referred to as the

load. The energy efficiency of a fuel cell is generally

between 40-60%, or up to 85% efficient if wasteheat is captured for use.


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How it Works

At the anode a catalyst oxidizes the fuel, usuallyhydrogen, turning the fuel into a positively chargedion and a negatively charged electron. Theelectrolyte is a substance specifically designed soions can pass through it, but the electrons cannot.The freed electrons travel through a wire creating

the electric current. The ions travel through theelectrolyte to the cathode. Once reaching thecathode, the ions are reunited with the electronsand the two react with a third chemical, usuallyoxygen, to create water or carbon dioxide.

A fuel cell system which includes a "fuel reformer"

can utilize the hydrogen from any hydrocarbon fuel -from natural gas to methanol, and even gasoline.Since the fuel cell relies on chemistry and notcombustion, emissions from this type of a systemwould still be much smaller than emissions from thecleanest fuel combustion processes.


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Fuel Cell Process


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Design Features

The most important design features in a fuelcell are:

The electrolyte substance. The electrolyte substanceusually defines the type of fuel cell.

The fuel that is used. The most common fuel is

hydrogen. The anode catalyst, which breaks down the fuel into

electrons and ions. The anode catalyst is usually madeup of very fine platinum powder.

The cathode catalyst, which turns the ions into the

waste chemicals like water or carbon dioxide. Thecathode catalyst is often made up of nickel.


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Factors affecting its Output

A typical fuel cell produces a voltage from 0.6 Vto 0.7 V at full rated load. Voltage decreases ascurrent increases, due to several factors: Activation loss

Ohmic loss (voltage drop due to resistance of the cell

components and interconnects) Mass transport loss (depletion of reactants at catalyst

sites under high loads, causing rapid loss of voltage).

To deliver the desired amount of energy, the fuelcells can be combined in series and parallel

circuits, where series yields higher voltage, andparallel allows a higher current to be supplied.Such a design is called a fuel cell stack. The cellsurface area can be increased, to allow strongercurrent from each cell.


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Applications

Power - Stationary fuel cells are used forcommercial, industrial and residential primaryand backup power generation. Fuel cells arevery useful as power sources in remotelocations, such as spacecraft, remote weather

stations, large parks, communications centers,rural locations including research stations, andin certain military applications. A fuel cellsystem running on hydrogen can be compactand lightweight, and have no major moving

parts. Because fuel cells have no moving partsand do not involve combustion, in idealconditions they can achieve up to 99.9999%reliability.This equates to less than one minuteof downtime in a six year period.


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Applications

Transportation - In terms of transportation,there are over 100 fuel cell buses deployedaround the world today. Most buses areproduced by UTC Power, Toyota, Ballard,Hydrogenics, and Proton Motor. UTC Buseshave already accumulated over 970,000 km(600,000 mi) of driving. Fuel cell buses have a30-141% higher fuel economy than diesel busesand natural gas buses. Other vehicles that use

fuel cell nowadays are Forklifts, Motorcycles,Airplanes, Boats, Heavy-duty Trucks, etc.


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Applications

Consumer Electronics - Fuel cells will changethe telecommuting world, powering cellularphones, laptops and palm pilots hours longerthan batteries. Companies have alreadydemonstrated fuel cells that can power cell

phones for 30 days with out recharging andlaptops for 20 hours. Other applications formicro fuel cells include pagers, video recorders,portable power tools, and low power remotedevices such as hearing aids, smoke detectors,

burglar alarms, hotel locks and meter readers.These miniature fuel cells generally run onmethanol, an inexpensive wood alcohol alsoused in windshield wiper fluid.


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References

http://en.wikipedia.org/wiki/Fuel_cell http://www.fuelcells.org/

http://www.electronics-tutorials.ws/io/io_1.html

http://stereos.about.com/od/glossaryoftermst/g

/transducer.htm

Documents

Chemical Transducer