Chapter 66

[object Object],[object Object],[object Object],[object Object],[object Object],OBJECTIVES: After studying Chapter 66, the reader should be able to:

[object Object],[object Object],[object Object],[object Object],KEY TERMS: Continued

[object Object],[object Object],[object Object],KEY TERMS:

FUEL CELL TECHNOLOGY ,[object Object],Continued Figure 66–1 Ford Motor Company has produced a number of demonstration fuel-cell vehicles based on the Ford Focus.

[object Object],Figure 66–2 Hydrogen does not exist by itself in nature. Energy must be expended to separate it from other, more complex materials. Continued

Figure 66–3 The Mercedes-Benz B-Class fuel-cell car was introduced in 2005. ,[object Object],Continued

[object Object],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

[object Object],Continued ,[object Object],[object Object],[object Object],[object Object],[object Object],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.

[object Object],See the chart on Page 798 of your textbook. The design best suited for automotive applications is the Proton Exchange Membrane ( PEM ). It must have hydrogen to operate, and this may be stored on the vehicle or generated as needed.

PEM FUEL CELLS ,[object Object],Continued

[object Object],Continued NOTE: Remember a fuel cell generates direct current (DC) electricity as electrons only flow in one direction (from the anode to the cathode).

Figure 66–5 The polymer electrolyte membrane only allows H ions (protons) to pass through it. This means electrons follow the external circuit and pass through the load to perform work. Continued

[object Object],Figure 66–6 A fuel-cell stack is made of hundreds of individual cells connected in series. Continued The fuel cells are connected in series so total voltage of the stack is the sum of the individual cell voltages. The fuel cells are placed end-to-end in the stack, much like slices in a loaf of bread. Automotive fuel-cell stacks contain upwards of 400 cells in their construction.

[object Object],CO Poisons the PEM Fuel Cell Catalyst Continued

[object Object],Figure 66–7 A direct methanol fuel cell uses a methanol/water solution for fuel instead of hydrogen gas. Continued Another approach has been to fuel a modified PEM fuel cell with liquid methanol instead of hydrogen gas.

[object Object],Figure 66–8 A direct methanol fuel cell can be refueled similar to a gasoline-powered vehicle. Continued This means a fuel-cell vehicle can be refueled with a liquid instead of high-pressure gas. This makes refueling simpler and produces greater vehicle driving range.

[object Object],When is Methanol Considered to be a “Carbon-Neutral” Fuel?

FUEL CELL VEHICLE SYSTEMS ,[object Object],Continued

Figure 66–9 Power train layout in a Honda FCX fuel-cell vehicle. Note the use of a humidifier behind the fuel-cell stack to maintain moisture levels in the membrane electrode assemblies. Continued

[object Object],What is the Role of the Humidifier in a PEM Fuel Cell?

[object Object],Figure 66–10 The Honda FCX uses one large radiator for cooling the fuel cell, and two smaller ones on either side for cooling drive train components. Continued The heat generated by a fuel cell is classified as low - grade heat . This means that there is only a small difference between the temperature of the coolant and that of the ambient air. Heat exchangers with a larger surface area must be utilized.

[object Object],Figure 66–11 Space is limited at the front of the Toyota FCHV engine compartment, so an auxiliary heat exchanger is located under the vehicle to help cool the fuel-cell stack. Continued An electric water pump and a fan drive motor are used to enable operation of the fuel cell’s cooling system. In the Toyota FCHV, an auxiliary heat exchanger is underneath the vehicle to increase the cooling system heat-rejection capacity. These and other support devices use electrical power generated by the fuel cell, and decrease overall efficiency of the vehicle.

[object Object],Figure 66–12 The secondary battery in a fuel-cell hybrid vehicle is made up of many individual cells connected in series, much like a fuel-cell stack. Continued The secondary battery is built similar to a fuel-cell stack. It is many low-voltage cells connected in series to build a high-voltage battery. In most FCHV designs, a high-voltage nickel-metal hydride (NiMH) battery pack is used as a secondary battery. This is most often located near the back of the vehicle, either under or behind the rear passenger seat.

[object Object],Figure 66–13 The Honda ultracapacitor module and construction of the individual cells. Ultracapacitor cells are based on double - layer technology , in which two activated-carbon electrodes are immersed in an organic electrolyte. The electrodes have a very large surface area and are separated by a membrane that allows ions to migrate but prevents the electrodes from touching. Continued

[object Object],Figure 66–14 An ultracapacitor can be used in place of a high-voltage battery in a hybrid electric vehicle. This example is from the Honda FCX fuel-cell hybrid. Total capacitance = sum of individual cells Ultracapacitors that are used in fuel-cell hybrid vehicles are made up of multiple cylindrical cells connected in parallel. Greater capacitance means greater storage ability, and contributes to greater assist for the electric motors in a fuel-cell hybrid vehicle. Continued

[object Object],Figure 66–15 Drive motors in fuel-cell hybrid vehicles often use stator assemblies similar to ones found in Toyota hybrid electric vehicles. The rotor turns inside the stator and has permanent magnets on its outer circumference. Continued This design is very reliable as it does not use a commutator or brushes, but has a three-phase stator and permanent magnet rotor. An electronic controller (inverter) is used to generate the three-phase high-voltage AC current required by the motor.

[object Object],Figure 66–16 The General Motors “Skateboard” concept uses a fuel-cell propulsion system with wheel motors at all four corners. It is also possible to use wheel motors to drive individual wheels, which allows greater control of the torque being applied to each individual wheel. Continued

Figure 66–17 The electric drive motor and transaxle assembly from a Toyota FCHV. Note the three orange cables, indicating that this motor is powered by high-voltage three-phase alternating current. ,[object Object],Transaxles used in fuel-cell hybrid vehicles are extremely simple with few moving parts. They are extremely durable, quiet, and reliable. Continued

[object Object],Figure 66–18 The power control unit (PCU) on a Honda FCX fuel-cell hybrid vehicle is located under the hood. Continued

Figure 66–19 Toyota’s FCHV uses a power control unit that directs electrical energy flow between the fuel cell, battery, and drive motor. ,[object Object],It is also responsible for maintaining the state of charge of the battery pack. Also for controlling and directing the output of the fuel-cell stack. Continued

[object Object],Figure 66–20 This GM fuel-cell vehicle uses compressed hydrogen in three high-pressure storage tanks. Continued

[object Object],Continued High-Pressure Compressed Gas Most current fuel-cell hybrid vehicles use compressed hydrogen that is stored in tanks as a high-pressure gas. This approach is the least complex of all the storage possibilities, but also has the least energy density. Multiple small storage tanks are often used rather than one large one in order to fit them into unused areas of the vehicle.

[object Object],Figure 66–21 The Toyota FCHV uses high-pressure storage tanks that are rated at 350 bar. This is the equivalent of 5,000 pounds per square inch. The tanks used for compressed hydrogen storage are typically made with an aluminum liner wrapped in several layers of carbon fiber and an external coating of fiberglass. There is also a special electrical connector that is used to enable communication between the vehicle and the filling station during the refueling process. Continued

Figure 66–22 The high-pressure fitting used to refuel a fuel-cell hybrid vehicle. ,[object Object],Figure 66–23 Note that high-pressure hydrogen storage tanks must be replaced in 2020. Continued

Figure 66–24 GM’s Hydrogen3 has a range of 249 miles when using liquid hydrogen. ,[object Object],This increases vehicle range, but impacts overall efficiency, as a great deal of energy is required to liquefy hydrogen and a certain amount of the liquid hydrogen will “boil off” while in storage. Continued

Figure 66–25 Refueling a vehicle with liquid hydrogen. Continued

[object Object],[object Object],Continued

[object Object],Hydrogen Fuel = No Carbon Figure 66–26 Carbon deposits, such as these, are created by incomplete combustion of a hydrocarbon fuel. If combustion is complete, then all the carbon is converted to carbon dioxide gas and exits the engine in the exhaust. However, if combustion is not complete, carbon monoxide is formed, plus leaving some unburned carbon to accumulate in the combustion chamber.

HYDRAULIC HYBRID STORAGE SYSTEM ,[object Object],Continued

[object Object],[object Object],[object Object],[object Object],Potential problems with this system include leakage problems with seals and valves, getting air out of the system, and noise. A 23% improvement in fuel economy and improvements in emissions reduction were achieved using a dynamometer. The HPA system could be developed for any type of vehicle with any type of drive train, it does add weight and complexity, which would add to the cost.

[object Object],HCCI Continued

Figure 66–27 Both diesel and conventional gasoline engines create exhaust emissions due to high peak temperatures created in the combustion chamber. The lower combustion temperatures during HCCI operation result in high efficiency with reduced emissions. ,[object Object],Continued

PLUG-IN HYBRID ELECTRIC VEHICLES ,[object Object],[object Object],[object Object],Continued

THE FUTURE FOR ELECTRIC VEHICLES ,[object Object],Continued ,[object Object],[object Object],[object Object]

[object Object],Continued ,[object Object],[object Object],[object Object]

[object Object],Continued ,[object Object],[object Object],[object Object],[object Object],[object Object],If electric vehicles are going to become widely used, charging stations will have to be established to allow necessary recharging for trips to work and back home.

[object Object],Figure 66–28 A typical electric vehicle charging station on the campus of a college in Southern California. Continued The parking spaces near the charging stations were designated for electric vehicles only and could be used for free to recharge electric vehicles.

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

[object Object],What is NEDRA? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

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

WIND POWER ,[object Object],Continued

Figure 66–32 Wind power capacity by area. (Courtesy of U.S. Department of Energy) Continued

Figure 66–33 A typical wind generator that is used to generate electricity. Continued

HYDROELECTRIC POWER ,[object Object],Continued

Figure 66–34 The Hoover Dam in Nevada/Arizona is used to create electricity for use in the southwest United States.

SUMMARY ,[object Object],[object Object],[object Object],Continued ,[object Object],[object Object],[object Object],[object Object]

SUMMARY ,[object Object],[object Object],[object Object],Continued ( cont. )

SUMMARY ,[object Object],[object Object],( cont. )

Chapter 66

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Chapter 66