Energy Exam 2 Transportation

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Force to overcome ground frictional forces

(resistance from the ground): Depends on the mass, the velocity, and the quality of tires and bearings (related to tire in contact with the road) Fr = Crmv (Cr is .01 for miles/sec) Cr reflects the quality of tires and bearings. **increase the quality of the tire so find the material with the lowest coefficient of friction and keep them properly inflated, also should drive SLOW for efficiency purposes-->this will reduce force

Drag Coefficients

-1928 Model T Cd= .8 -1930 Chrysler Airflow CD= 0.5 -Geff Gordon's Chevy CD= .2 -2004 Jaguar XJ-Series XJ8 4dr Sedan CD= .4

Hybrid Cars

-A combination of gasoline and batteries, or gasoline and flywheel. -The gasoline and batteries are available right now. These automobiles can go up to 70 mpg. -Reclaiming energy from the brakes to charge the battery -Using the battery to assist the gas engine when the power is needed -Running completely on the battery when you come to a stop Examples: -Honda Civic Hybrid $22,800 The Civic Hybrid rides, handles, and looks just like the conventional Civic—and delivers fuel economy comparable with the best hybrids. -Toyota Prius $20,000, 50 MPGThe Toyota Prius has become nearly synonymous with "hybrid car," and epitomizes the best that hybrid technology has to offer. Expect you have to wait at least 6 - 8 months to buy the car, if you can get it at all. -Ford Escape Hybrid $27,000 The first SUV hybrid and the first American hybrid. -Honda Insight $19,000 This two-seater hatchback, released in 1999 as the first hybrid in the U.S., is the leader of the pack in terms of gas mileage.

Hydrogen Fuel Cells

-Hydrogen is extremely abundant in nature but not as free gas. -In combination with other elements, it is present as methane (CH4), water (H2O), etc. -However, free hydrogen is rare. It is so light that it escapes the earth's gravitational field into the universe. -Hydrogen can be used as a fuel: H2 + O2 --> H2O + Energy

Power Losses in Automobiles

-Power in fuel combustion 100% losses: water heating 36% exhaust heat 38% motor friction 6% -effective power of motor 20% drive train 2% rear tires 2% front tires 1% -effective power of car 15% -air resistance 8% -reserve for hill-climbing, acceleration, and accessories 7%

Sources of Hydrogen

-Steam on heated carbon C + H2O --> 2H +CO -decomposition of certain hydrocarbons with heat, CH4 --> C +2H2 -reaction of sodium or potassium hydroxide on aluminum Al + NaOH -->Na-Al-O + H -electrolysis of water, 2 H2O --> 2H2 + O2 -displacement from acids by certain metals. Issues: -Catalyst: Mostly platinum based -Hydrogen storage -Fuel economy

Vehicle Design and Fuel Efficiency

-The fuel efficiency is directly related to the factors discussed in last slide. -There is not much you can do about the heat loss due to engine efficiency: Remember efficiency = (1- Tcold/Thot)x 100 -But something can be done about other design factors: -First 3 factors (Fa, Fh, Fr) are proportional to the mass of the vehicle. This is difficult to reduce due to safety considerations. -Fourth, Fad, is related to the vehicle frontal area which can be modified. -The third and the fourth terms (Fr, Fad) increases as the velocity increases. Therefore, slower speed reduces fuel consumption.

Force needed to overcome Aerodynamic Drag

-This force is small at low speeds but grows very rapidly. -Above 40 MPH this is the dominating force and have the highest effect on the fuel economy. Fad = CDAfv2/370 Af=front area -CD is the Aerodynamic Drag Coefficient Ft = Fa + Fh + Fr + Fad *to reduce power and therefore reduce force which reduces consumption make it more streamlined which would effect the drag coefficient. also could minimize the frontal area, lower velocity

Fly Wheel Car

-What happens to all the energy that is lost when we put the breaks on? -This energy can be harnessed to turn a fly wheel. -Fly wheels (also known as "electromechanical batteries") are nothing more than perfectly balanced and rapidly turning discs (100,000 rpm), which store energy. -When harnessed to a generator, flywheels provide steady and reliable power, along with delivering big surges for quick acceleration. -Unlike electric car batteries, flywheels contain no corrosive or toxic materials. -Problems: Safety issue: Because they turn so fast, a flywheel freed from its housing is a dangerous projectile.

Fiberglass

-a way to reduce the mass -you don't lose the mechanical integrity yet it is very light

Improving Efficiency by engine design

-automobile engine and gear train design improvements to increase fuel efficiency -switch from carburetors to fuel injection -switch from breaker point ignition to electric ignition -sensors for autocorrecting gas mixture

Fuel Efficiency

-better lubrication and bearings -all these actions have improved the fuel efficiency, as shown in the figure

How will hydrogen be obtained?

-by a process call electrolysis in which electric power is used to break hydrogen into H2 and O2. -H2O + Electric Energy --> H2 + O2 -It takes more energy to get hydrogen then the energy generated by burning hydrogen. -There is another way Hydrogen gas can be used to power automobiles in an environmentally friendly way.

Design Elements to reduce drag

-drag reduction device

Hybrid Cars- Driving Solutions

-hybrids use advanced technology and smart design to go farther on a gallon of gas- cutting pollution, saving oil, and slashing costs at the gas pump -regenerative braking: captures energy normally lost during braking to charge the electric motor -high strength, lightweight materials: using materials like aluminum reduces weight without compromising safety -continuously variable transmission: boosts fuel economy through better "gear ratios" -Aerodynamic Design- improves fuel economy by reducing drag and wind resistance -Integrated starter-generator: saves fuel by shutting down gas engine when idling in traffic -Hybrid Engine- combines small internal combustion engine with electric motor -Variable Valve Control Engine- improves engine performance by controlling the mix of air and fuel more precisely

Power needed to move a vehicle

-knowing total force required, the power needed to move the vehicle can be determined -power is force times the velocity with which the vehicle is moving: power(ft.lb/sec) = force(lb) x velocity (ft/sec) ^you can get to this by starting with f=ma, w=fd, p=w/t *how do we reduce the power so that we are more efficient? we reduce the mass. f=ma. changing certain times of metals in the car will reduce the weight. ----example: changing from an iron block to an aluminum block-->aluminum has a melting point of 740 degrees C, iron has a melting point of 1020 degrees C. we would rather work with iron because we can heat it to a much higher temperature without melting. for aluminum, you have to use special fuel or in horsepower: power(hp)= force(lb) x velocity (ft/sec) x (1hp/550 ft.lb/sec)

The H2's "off-road shipping crate"

-shape is an aerodynamic brick, with a drag coefficient exceeding 0.57 and nearly flat glass all around, windshield included

An electric car

-under the hood, there are a lot of differences between gasoline and electric cars: -the gasoline engine is replaced by an electric motor -the electric motor gets its power from a controller -the controller gets its power from an array of rechargeable batteries -a gasoline engine, with its fuel lines, exhaust pipes, coolant hoses and intake manifold, tends to look like a plumbing project. an electric car is definitely a wiring project the 50 kw controller, the vacuum pump is left of center, the water heater, the 120/240 volt charging system

Latest and the Greatest VW XL

0.189

WHAT IS THE EFFICIENCY OF AN AUTOMOBILE

15%

How many cars in the US?

250 million cars in the US, we own 1/3 of world's cars

We consume ______ of the gasoline we have of our own

70%

Alternate Energy Sources for Automobiles 1) Electric Cars: Zero Emission Vehicles (ZEV)

Advantage: Electric cars are more efficient (40%) as opposed to gasoline cars (15%) Disadvantage: However, energy stored in batteries is only 1% of the same weight of gasoline. 13,0000 Wh/kg to 25 Wh/kg Disadvantage: Therefore, the range of electric vehicles is very short. Advantages: Quiet operation Lower maintenance Regenerative breaking Reduction of emissions Energy can be derived from a variety of sources

Carburetors Repair Advice: Why did the car makers change from carburetors to fuel injection?

Answer:The standard reply to this question is because fuel injection provided a better way to meet government fuel economy and emission standards, which is true. But equally important is the fact that fuel injection is an all-round better fuel delivery system. Fuel injection has no choke, but sprays atomized fuel directly into the engine. This eliminates most of the cold start problems associated with carburetors. Electronic fuel injection also integrates more easily with computerized engine control systems because the injectors are more easily controlled than a mechanical carburetor with electronic add-ons. Multiport fuel injection (where each cylinder has its own injector) delivers a more evenly distributed mixture of air and fuel to each of the engine's cylinders, which improves power and performance. Sequential fuel injection (where the firing of each individual injector is controlled separately by the computer and timed to the engine's firing sequence) improves power and reduces emissions. So there are some valid engineering reasons as well for using fuel injection. TYPES OF FUEL INJECTION The earliest fuel injection systems were mechanical and were more complex than carburetors. Consequently, they were expensive and their use was limited. Chevrolet introduced a Rochester mechanical fuel injection system back in 1957, and it became the "hot" setup on Corvettes up through 1967. The Europeans, however, were the real leaders in fuel injection technology. Bosch offered an early electronic system on Volkswagen Squarebacks in the late 1960s and early 1970s. By the early 1980s, almost all of the European auto makers were using some type of Bosch multiport fuel injection system. In the mid-1980s, the domestic auto makers first turned to "throttle body" injection as a stop-gap system as they made the transition from electromechanical carburetors to fuel injection. THROTTLE BODY INJECTION (TBI) Throttle body injection is much like a carburetor except that there's no fuel bowl, float, needle valve, venturi, fuel jets, accelerator pump or choke. That's because throttle body injection does not depend on engine vacuum or venturi vacuum for fuel metering. Fuel is sprayed directly into the intake manifold instead of being siphoned in by intake vacuum. A TBI fuel delivery system consists of a throttle body with one or two injectors and a pressure regulator. Fuel pressure is provided by an electric pump. It's a relatively simple setup and causes few problems -- but doesn't provide all of the advantages of a multiport or sequential fuel injection system. MULTIPORT INJECTION The next step up from TBI was multiport injection. Engines with multiport injection have a separate fuel injector for each cylinder, mounted in the intake manifold or head just above the intake port. Thus, a four cylinder engine would have four injectors, a V6 would have six injectors and a V8 would have eight injectors. Multiport injection systems are more expensive because of the added number of injectors. But having a separate injector for each cylinder makes a big difference in performance. The same engine with multiport injection will typically produce 10 to 40 more horsepower than one with TBI because of better cylinder-to-cylinder fuel distribution. Injecting fuel directly into the intake ports also eliminates the need to preheat the intake manifold since only air flows through the manifold. This, in turn, provides more freedom for tuning the intake plumbing to produce maximum torque. It also eliminates the need to preheat the incoming air by forcing it to pass through a stove around the exhaust manifold. There are other differences between multiport injection systems. One is the way in which the injectors are pulsed. On some systems, all the injectors are wired together and pulse simultaneously (once every revolution of the crankshaft). On others, the injectors are wired separately and are pulsed sequentially (one after the other in their respective firing order). The latter approach is more complicated and requires more expensive electronic controls, but provides better performance and throttle response by allowing more rapid changes in the fuel mixture.

Energy Eater

At an average speed of 48 mph, 45% of the energy required to move a car goes into aerodynamic drag. Since drag increases with the square of speed, more than twice as much energy would be required to overcome drag at 70 mph

The winner is....

CD= .3 or less Porsche= 924 1988 Infiniti G35= 2002 Chevy Corvette= 2004

Drag Reduction

Concept vehicles being developed by government/industry partnerships have 40% less aerodynamic drag than conventional vehicles.

Battery Operated Cars

Disadvantage: How is the electricity for recharging is being produced in the first place? Advantage: Power plants generate electricity at 38% efficiency and automobiles use gasoline at only 15% efficiency, so it might be better to let the power plants generate electricity and cars recharge the batteries. Disadvantage: It takes a longer time for the batteries to charge. Possible solution: Completely change the batteries instead of charging. Disadvantage: Life of the battery is short (2 - 3 years). This is a 100 year old acid-lead technology. For now, best Solution is a Hybrid car running on both gas and batteries.

Alternative Fuels for Transportation: Ethanol/Methanol

Ethanol: Simple alcohol from Plant material Methanol: Natural gas or coal -Positive: Renewable resource (Ethanol), emissions are reabsorbed by plants, used be existing engines, Methanol used in fuel cells. for ethanol you are just recycling the carbon dioxide not adding anything -Negative: Low fuel efficiency so it is only used as blend (10 -25% in gasoline), more expensive, hard to ignite in cold weather

Force required for acceleration

Fa=ma *reduce force by reducing mass which therefore reduces power

Alternative Fuels for Transportation: Hydrogen

Hydrogen: Derived from water or Methane -Positive: No CO2 or other emissions, can be carried on board so not limited like batteries, used in fuel cells. -Negative: No free H is available so it has to be generated from other gases with "high energy cost", cost, storage, transportation, safety.

Truck Drag

It's estimated that 65% of a truck's engine output goes into overcoming drag when traveling at high speeds.

Alternative Fuels for Transportation: LPG, LNG, CNG

LPG, LNG, CNG: -Advantage- Lower emission, almost same cost as gasoline, local resources, delivery infrastructure already present. -Issues - Still emits CO2, Natural gas also used for electricity generation so there is a competition, Engine modification is required

Hydrogen Fuel Cells

Polymer Membrane Fuel Cell (PMFC) -Hydrogen from a source is split into Electron and proton via a CATALYST. H2 2H+ + 2 electrons -Only protons are allowed to pass through the membrane. -The electrons constitute the current that can be used to power the automobile. -On the other side of the membrane, the proton combines with oxygen to form water 2H + 2e + O H2O -The byproduct is H2O which does not harm the environment.

Honda Insight

Price (base MSRP): $19,800 Fuel Economy: 40/43 MPG Estimated Annual Fuel Cost: $731.71 Estimated annual fuel use: 293 gallons a year Estimated annual greenhouse gas emissions: 5,561 pounds a year

Toyota Prius

Price (base MSRP): $22,800 Fuel Economy: 51/48 MPG Estimated annual fuel cost: $600.00 Estimated annual fuel use: $240 gallons a year Estimated annual greenhouse gas emissions: 4,560 pounds a year

Honda Civic Hybrid

Price (base MSRP): $23,800 Fuel Economy: 40/45 MPG Estimated annual fuel cost: $714.29 Estimated Annual fuel use: 286 gallons a year Estimated annual greenhouse gas emissions: 5,429 pounds a year

In the news.....

Records: BMW Sets Speed Records for H2 IC Cars; HYSUN Does Berlin-Barcelona on 3 kg H2 -MIRAMAS, FRANCE - Going for a Sunday Drive took on a whole new meaning last month for what are now unarguably the world's fastest terrestrial hydrogenauts: -Fuel cell submarine "U 33" launched at HDWBy the name of "U 33", today Jutta Doenitz christened one of the most modern non-nuclear submarines in the world from Howaldtswerke-Deutsche Werft AG (HDW) in Kiel. The Class 212 A submarine is intended for service in the German Navy, and is the third of four submarines which are currently being built at HDW and at the Nordseewerke in Emden. After an extensive period of sea trials, it is expected that "U 33" will enter service on 31 January 2006.

Drag Coefficients

Sphere--> .47 Half-sphere--> .42 Cone--> .50 Cube--> 1.05 Angled Cube--> .80 Long Cylinder--> .82 Short Cylinder--> 1.15 Streamlined Body--> .04 Streamlined Half-body--> .09

Alternative Fuels for Transportation: Electricity

Tesla ($109,000) Nissan Leaf Chevy Volt E2 Cars ($7000 - 10,000) *they just have a motor, don't need hydrogen or anything

Force needed to move a vehicle

There are four types of forces that are needed to move a vehicle: -force required for acceleration -force to climb hill -force to overcome ground frictional forces -force needed to overcome aerodynamic drag

Force to climb hill

This force depends on the mass, the slope of the hill "s", and the acceleration due to gravity "g=32 ft/sec2 Fh=msg (s=slope or grade) **reduce the mass in order to reduce power because you can't reduce the slope or gravity If a car is moving at a constant velocity on a level road, both Fa and Fh are zero.

H fuel cells

available in the market, hydrogen fuel cell buses!

units

force: newton work or energy: joule power: joules/sec=watt acceleration: m/s^2 **make sure you know these

Alternative Fuels for Transportation: Bio Diesels

from cooking oil and soybean oil -Advantages: Similar to diesel, can be used directly without any engine modification, lower emissions that gasoline. less carbon so less emission. -Issues: more expensive (20 -30%), harsh on polymers so some delivery problems, still emits CO2, Higher NOx emission.

Norway

highest GP per capita, 200 million people

What is emitted from fuel cells?

nothing but water vapor