Posted tagged ‘heat’

DISI ENGINE

August 23, 2011

02-direct-injection-engine-disi engine-gasoline engine

In developing the DISI engine, we aimed to cool the interior of the cylinder as much as possible by promoting fuel vaporization and uniform mixing of atomized fuel and air. This produces a high charging efficiency of the air-fuel mixture and a high compression ratio, which results in significant improvements in both torque and fuel efficiency.


Characteristics of the direct injection engine:

  • Fuel is injected from a tiny nozzle into a relatively large cylinder, so it has a high latent heat of vaporization, which efficiently cools the air within (in-cylinder cooling effect).

  • The air temperature in the cylinder decreases, which means:

  • (1) more air may be charged into the combustion chamber, which produces increased torque.

  • (2) the engine is less prone to knocking. This contributes to increased torque, and enables a higher compression ratio that also contributes to good fuel efficiency.


In a direct injection engine, however, the fuel skips the waiting period it would have to endure inside a standard engine and instead proceeds straight to the combustion chamber. This allows the fuel to burn more evenly and thoroughly. For the driver, that can translate to better mileage and greater power to the wheels.

In the past, direct injection posed too many technical hurdles to make it worthwhile for mass market gasoline automobiles. But with advances in technology and greater pressure to make cars run more cleanly and efficiently, it looks as if gasoline direct injection — or GDI as it’s referred to in industry lingo — is here to stay. In fact, most of the major car manufacturers make or plan to soon introduce gasoline cars that take advantage of this fuel saving and performance enhancing system.

ULTIMATE ECO CAR

August 23, 2011

01-ultimate_eco_car-developments of hybrid technology-development of hydrogen fuel-fuel cell-hybrid technology

Continuous improvement in conventional engines, including lean-burn gasoline engines, direct injection gasoline engines and common rail direct-injection diesel engines, as well as engines modified to use alternative fuels, such as compressed natural gas (CNG) or electricity (for Electric Vehicle).

Engineers may disagree about which fuel or car propulsion system is best, but they do agree that hybrid technology is the core for eco-car development.


01-ultimate_eco_car-diesel hybrid-fuel cell vehicle-alternate fuel hybrid vehicles


“Plug-in hybrid” technology brings further potential for substantial CO2 emissions reductions from vehicles. It has a higher battery capacity and is thus more fuel-efficient than the current hybrid, assisted by the power of engine. For a short-distance drive, it could be run with electricity charged during the night. Depending on how electricity is generated, the vehicle could run with much lower CO2 emissions. In order to commercialize the plug-in hybrid, there is again a need for a breakthrough in battery technology. It is necessary to develop a smaller-sized battery with higher capacity. Plug-in hybrids could contribute to reducing substantial amounts of CO2 emissions from vehicles, as well as fossil fuel use, by charging from cleaner electricity sources in the future.

Challenges of increasing power performance

In order to improve the driving performance, its power train was completely redesigned. To increase motor output, a high-voltage power-control was adopted. Although this technology was used in industrial machines and trains, the idea of incorporating it into an automobile did not easily occur at first. First of all, the system itself would take up a substantial amount of space and secondly, there was no prior example of applying this method to a motor that switches between output and power generation at such a dizzy pace.

Once the development of the high-voltage power circuit began, there was a mountain of problems, such as what to do about the heat generated by increasing voltage and the noise generated. To reevaluate the power train, the project team had to produce prototypes and repeat numerous tests. The prototyping stage went to seven prototypes instead of the usual three, and the total distance driven by these prototypes during testing exceeded one million kilometers.

ULTIMATE ECO CAR

August 23, 2011

01-ultimate_eco_car-developments of hybrid technology-development of hydrogen fuel-fuel cell-hybrid technology

Continuous improvement in conventional engines, including lean-burn gasoline engines, direct injection gasoline engines and common rail direct-injection diesel engines, as well as engines modified to use alternative fuels, such as compressed natural gas (CNG) or electricity (for Electric Vehicle).

Engineers may disagree about which fuel or car propulsion system is best, but they do agree that hybrid technology is the core for eco-car development.


01-ultimate_eco_car-diesel hybrid-fuel cell vehicle-alternate fuel hybrid vehicles


“Plug-in hybrid” technology brings further potential for substantial CO2 emissions reductions from vehicles. It has a higher battery capacity and is thus more fuel-efficient than the current hybrid, assisted by the power of engine. For a short-distance drive, it could be run with electricity charged during the night. Depending on how electricity is generated, the vehicle could run with much lower CO2 emissions. In order to commercialize the plug-in hybrid, there is again a need for a breakthrough in battery technology. It is necessary to develop a smaller-sized battery with higher capacity. Plug-in hybrids could contribute to reducing substantial amounts of CO2 emissions from vehicles, as well as fossil fuel use, by charging from cleaner electricity sources in the future.

Challenges of increasing power performance

In order to improve the driving performance, its power train was completely redesigned. To increase motor output, a high-voltage power-control was adopted. Although this technology was used in industrial machines and trains, the idea of incorporating it into an automobile did not easily occur at first. First of all, the system itself would take up a substantial amount of space and secondly, there was no prior example of applying this method to a motor that switches between output and power generation at such a dizzy pace.

Once the development of the high-voltage power circuit began, there was a mountain of problems, such as what to do about the heat generated by increasing voltage and the noise generated. To reevaluate the power train, the project team had to produce prototypes and repeat numerous tests. The prototyping stage went to seven prototypes instead of the usual three, and the total distance driven by these prototypes during testing exceeded one million kilometers.

HOW FUEL CELL WORK?

August 23, 2011

An electrochemical reaction occurs between hydrogen and oxygen that converts chemical energy into electrical energy.

01-how fuel cell works-proton exchange membrane-hydrogen fuel cell

Think of them as big batteries, but ones that only operate when fuel—in this case, pure hydrogen—is supplied to them. When it is, an electrochemical reaction takes place between the hydrogen and oxygen that directly converts chemical energy into electrical energy. Various types of fuel cells exist, but the one automakers are primarily focusing on for fuel cell cars is one that relies on a proton-exchange membrane, or PEM. In the generic PEM fuel cell pictured here, the membrane lies sandwiched between a positively charged electrode (the cathode) and a negatively charged electrode (the anode). In the simple reaction that occurs here rests the hope of engineers, policymakers, and ordinary citizens that someday we’ll drive entirely pollution-free cars.

Here’s what happens in the fuel cell: When hydrogen gas pumped from the fuel tanks arrives at the anode, which is made of platinum, the platinum catalyzes a reaction that ionizes the gas. Ionization breaks the hydrogen atom down into its positive ions (hydrogen protons) and negative ions (electrons). Both types of ions are naturally drawn to the cathode situated on the other side of the membrane, but only the protons can pass through the membrane (hence the name “proton-exchange”). The electrons are forced to go around the PEM, and along the way they are shunted through a circuit, generating the electricity that runs the car’s systems.

Using the two different routes, the hydrogen protons and the electrons quickly reach the cathode. While hydrogen is fed to the anode, oxygen is fed to the cathode, where a catalyst creates oxygen ions. The arriving hydrogen protons and electrons bond with these oxygen ions, creating the two “waste products” of the reaction—water vapor and heat. Some of the water vapor gets recycled for use in humidification, and the rest drips out of the tailpipe as “exhaust.” This cycle proceeds continuously as long as the car is powered up and in motion; when it’s idling, output from the fuel cell is shut off to conserve fuel, and the ultra capacitor takes over to power air conditioning and other components.

A single hydrogen fuel cell delivers a low voltage, so manufacturers “stack” fuel cells together in a series, as in a dry-cell battery. The more layers, the higher the voltage. Electrical current, meanwhile, has to do with surface area. The greater the surface area of the electrodes, the greater the current. One of the great challenges automakers face is how to increase electrical output (voltage times current) to the point where consumers get the power and distance they’re accustomed to while also economizing space in the tight confines of an automobile.