chap66 pps Automotive technology at University of Cambridge

start Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 OBJECTIVES: After studying Chapter 66, the reader should be able to: • • • • • Explain how a fuel cell generates electricity Discuss the advantages and disadvantages of fuel cells List the types of fuel cells Explain how ultracapacitors work Discuss alternative energy sources Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 KEY TERMS: double-layer technology • electrolysis • electrolyte • energy carrier • energy density farads • fuel cell • fuel cell hybrid vehicle (FCHV) • fuelcell stack • fuel cell vehicle (FCV) homogeneous charge compression ignition (HCCI) • hydraulic power assist (HPA) • inverter low-grade heat Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 KEY TERMS: membrane electrode assembly (MEA) • NEDRA plug-in hybrid electric vehicle (PHEV) • polymer electrolyte fuel cell (PEFC) • proton exchange membrane (PEM) • range • specific energy ultracapacitor • wheel motors • wind farms Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 FUEL CELL TECHNOLOGY What Is a Fuel Cell?  A fuel cell is an electrochemical device in which the  chemical energy of hydrogen and oxygen is converted into electrical energy,  discovered in 1839 by Sir William Grove, a Welsh physician In the 1950s, NASA put this principle to work in building devices for powering  space exploration vehicles. In the present day, fuel cells are being developed to  power homes and vehicles while producing low or zero emissions Figure 66–1 Ford Motor Company has produced a number of demonstration fuel-cell vehicles based on the Ford Focus Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 The chemical reaction in a fuel cell is the opposite of electrolysis,  in which electrical current is passed through water in order to  break it into its components, hydrogen and oxygen Energy can be retrieved by allowing hydrogen and oxygen to  reunite in a fuel cell. It is important to note that while hydrogen  can be used as a fuel, it is not an energy source. Instead, hydrogen  is only an energy carrier, as energy must be expended to  generate the hydrogen and store it so it can be used as a fuel Hydrogen is an excellent fuel because it has a very high specific  energy when compared to an equivalent amount of fossil fuel.  One kilogram (kg) of hydrogen has three times the energy content  as one kilogram of gasoline. Hydrogen is the most abundant  element on earth, but it does not exist by itself in nature.  Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Hydrogen is also found in many other compounds, most notably  hydrocarbons, such as natural gas or crude oil. In order to store  hydrogen for use as a fuel, processes must be undertaken to  separate it from these materials.  Figure 66–2 Hydrogen does not exist by itself in nature Energy must be expended to separate it from other, more complex materials Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Benefits of a Fuel Cell  A fuel cell can be used to move a vehicle by generating  electricity to power electric drive motors. Fuel cells by themselves do not  generate carbon emissions such as CO 2. The only emissions are water vapor and  heat, and this makes the fuel cell an ideal candidate for a ZEV (zero­emission  vehicle) Another benefit of fuel cells is they have very few moving parts and potential to  be very reliable. A number of OEMs have spent many years and millions of  dollars in order to develop a low­cost, durable, and compact fuel cell that will  operate satisfactorily under all driving conditions.  Figure 66–3 The Mercedes-Benz B-Class fuel-cell car was introduced in 2005 Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 A fuel­cell vehicle (FCV) uses the fuel cell as its only source of  power, where a fuel­cell hybrid vehicle (FCHV) would also have  an electrical storage device that can be used to power the vehicle Most new designs of fuel­cell vehicles are now based on a hybrid  configuration due to the significant increase in efficiency and  driveability that can be achieved with this approach.  Figure 66–4 The Toyota FCHV is based on the Highlander platform and uses much of Toyota’s Hybrid Synergy Drive (HSD) technology in its design Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Fuel­Cell Challenges While major automobile manufacturers  continue to build demonstration vehicles and work on improving  fuel­cell system design, no vehicle powered by a fuel cell has been  placed into mass production. There are a number of reasons: High cost Insufficient power density Insufficient vehicle range; lack of refueling infrastructure Safety perception; lack of durability Freeze starting problem All of these problems are being actively addressed by researchers,  and significant improvements are being made. Once cost and  performance levels meet that of current vehicles, fuel cells will be adopted as a mainstream technology Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Because electric vehicles have a relatively short range, charging  stations must be available in areas where these vehicles are driven.  For example, when the state of California mandated the sale of zero­ emission vehicles (ZEV), charging stations were set up in many  areas, usually in parking lots of businesses and schools.  Figure 66–28 A typical electric vehicle charging station on the campus of a college in Southern California The parking spaces near the  charging stations were  designated for electric vehicles  only and could be used for free  to recharge electric vehicles.  Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Charging Methods  When the state of California set up electric  vehicle charging stations, both a conductive­ and inductive­type  charger was made available at each station Conductive Charging  Uses an plug that makes physical contact  with terminals in the vehicle. The charger can be powered by 110­ V AC, or most commonly 220­V AC.  This type of charger  connection is used on some Ford and Honda electric vehicles Inductive Charging  Achieved by inserting a paddlelike probe  into a charging receptacle (opening) in the vehicle. The charger is  powered by 220­volt AC and does not make physical contact with  the vehicle See Figure 66–29 and 66­30 Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 66–29 A conductive-type charging connector This type of battery charging connector is sometimes called a AVCON connector, named for the manufacturer Figure 66–30 An inductive type electric vehicle battery charger connector This type of connector fits into a charging slot in the vehicle, but does not make electrical contact Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 An inductive charger paddle contains a coil of wire and the AC  current from the charger flows through the winding, which creates  a moving magnetic field around the paddle Inside the charging receptacle of the vehicle is another coil of  wire. The alternating magnetic field induces an AC voltage in the coil winding The electronics in the vehicle then changes the induced AC  current into DC current to charge the batteries. Inductive­type  chargers are used with the General Motors EV­1, as well as  Nissan and Toyota electric vehicles Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 What is NEDRA? NEDRA is the National Electric Drag Racing Association that holds drag races for electric-powered vehicles throughout the United States The association does the following: Coordinates a standard rule set for electric vehicle drag racing, to balance the needs and interests of all those involved in the sport Sanctions electric vehicle drag racing events, to: • Make the events as safe as possible • Record and maintain official records • Maintain consistency on a national scale • Coordinate and schedule electric vehicle drag racing events Promotes electric vehicle drag racing to: • Educate the public and increase people’s awareness of electric vehicles while eliminating any misconceptions • Encourage participation in electric vehicle drag racing • Have fun in a safe and silent drag racing environment Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 66–3 (a) The motor in a compact electric drag car This 8-inch-diameter motor is controlled by an electronic controller that limits the voltage to 170 volts to prevent commutator flash-over yet provides up to 2,000 amperes This results in an amazing 340,000 watts or 455 Hp (b) The batteries used for the compact drag car include twenty 12-volt absorbed glass mat (AGM) batteries connected in series to provide 240 volts Visit the National Electric Drag Racing Association on the  Internet at www.nedra.com  Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 WIND POWER Wind power is used to help supplement electric power generation  in many parts of the country. Because AC electricity cannot be  stored, this energy source is best used to reduce the use of natural  gas and coal to help reduce CO2 emissions.  Often, windmills are supplemental power in the evenings when it is most needed, and allowed to stop rotating in daylight hours  when the power is not needed. Windmills are usually grouped to  form wind farms, where the product is electrical energy Energy from wind farms can be used to charge plug­in hybrid  vehicles, as well as for domestic lighting and power needs See Figures 66–32 and 66–33.  Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 66–32 Wind power capacity by area (Courtesy of U.S Department of Energy) Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 66–33 A typical wind generator that is used to generate electricity Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 HYDROELECTRIC POWER Hydroelectric power is limited to locations where there are  dammed rivers and hydroelectric plants. however, electricity can  and is transmitted long distances—so electricity generated at the  Hoover Dam can be used in California and other remote locations Electrical power from hydroelectric sources can be used to charge  plug­in hybrid electric vehicles, thereby reducing emissions that  would normally be created by burning coal or natural gas to create  electricity Hydro electric plants are limited as to the amount of power they  can produce, and constructing new plants is extremely expensive.  See Figure 66–34 Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 66–34 The Hoover Dam in Nevada/Arizona is used to create electricity for use in the southwest United States Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 SUMMARY The chemical reaction inside a fuel cell is the opposite of  electrolysis in that electricity is created when hydrogen and  oxygen are allowed to combine in the fuel cell A fuel cell produces electricity and releases heat and water as  the only by­products The major disadvantages of fuel cells include: • High cost • Lack of hydrogen refueling stations • Short range • Freezing­temperature starting problems Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 SUMMARY (cont.) Types of fuel cells include PEM (the most commonly used), PAFC,  MCFC, and SOFC Ultracapacitors are an alternative to batteries for the storage of electrical  energy A gasoline­powered engine can be more efficient if it uses a  homogeneous charge compression ignition (HCCI) combustion process Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 SUMMARY (cont.) Plug­in hybrid electric vehicles could expand the range of  hybrid vehicles by operating on battery power alone Wind power and hydroelectric power are being used to recharge plug­in hybrids and provide electrical power for all uses, without harmful emissions Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 end Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458