November 18, 2008

The Internal Combustion Engine

Internal Combustion Engine

The engines in vehicles is a rather broad but interesting subject. People may be amazed to know that the ones currently in use today were drawn on several hundreds of blueprints before they were distributed to the market. The present models are the result of over a century worth of brainstorming and experience and will further influence the models of the future.

What is the ICE (Internal Combustion Engine)?

ICE stands for internal combustion engine wherein the combustion of fuel and an oxidizer occurs. The combustion chamber is the space where everything happens causing an exothermic reaction that produces gas at a high pressure and temperature. The expanding hot gases will directly put pressure on solid engine parts causing them to move. Pistons, rotors or the engine itself then begins movement which propels the entire vehicle.

The very first models of the ICE ran on an air/fuel mixture rather than compression. The initial part of the intake stroke sucks or blows in the mixture. Modern ICEs already incorporates in-cylinder compression. The engines were used in a variety of methods and industries like generators, boats, aircrafts and most particularly, automobiles.

The Operation

The internal combustion engine operates using a four-stroke cycle or the Otto cycle. The cycle involves four phases namely: induction, compression, power and exhaust. All of these aim to create an exothermic chemical process to start vehicle propulsion. During induction, oxygen or other oxidizers are introduced into the cylinder to act with the fuel. Compression then begins as the gases start a reaction that continuously increase temperature and pressure within the cylinder.

When enough pressure is applied on the corresponding engine parts, the engine begins to gain power through movement coming from direct force application. The aftermath of the entire compression process will lead to exhaustion of byproducts like carbon monoxide, carbon dioxide and nitrogen wastes. These gases are freely emitted into the atmosphere. The combustion process is started through engine ignition using the spark ignition method or the compression ignition system.

Where Does Gasoline Come In?

There are electric/gasoline-type systems that use a combination of lead-acid battery plus an induction coil to create a high-voltage electrical spark. The spark will then ignite the mix of air and fuel within the cylinder. The battery is rechargeable even during operation through an alternator or generator driven by the engine itself. Gasoline engines get an air and gasoline mixture to be compressed to less than 185 psi. The spark plug ignites the mixture during compression within the cylinder.

As for diesel engines, these require only heat and pressure produced by the engine during the compression process for ignition. Diesel compression is approximately three times higher compared to a gasoline engine. Diesel engines use air only. Some diesel fuel is sprayed into the cylinder with the use of a fuel injector just before peak compression to start ignition immediately. HCCI engines also require only heat and pressure but take in air and fuel. This process makes diesel and HCCI engines more prone to cold starts.

The Polluting Effects

Combustion products or the hot gases ignited and burnt inside the engine will have higher amounts of energy compared to the compressed fuel and air mixture. After available energy are used up to drive the engine pistons, remaining combustion products will be vented or exhausted through a valve or the exhaust outlet to bring back the piston in its original state also called TDC. Any heat which is not used up will become a waste product due to be removed from the engine via a liquid or air cooling system.

Air pollution emissions then result from incomplete combustion of carbonaceous fuel. Examples of engine byproducts are carbon monoxide, soot, nitrogen wastes, sulfur and uncombusted hydrocarbons. These also result if the products did not operate near the stoichiometric ratio required for effective combustion. The fuel would not have burnt very well due to factors like cool cylinder walls or lack of air. This is also known as quenching of the flame.

Both gasoline and diesel engines emit harmful gases that can be dangerous to humans as well as the environment. The greenhouse gases start trapping hot air within the atmosphere instead of allowing them to exit to space leading to global warming. The rise of the ICE or internal combustion engine finally showed its major flaw which is pollution.

November 15, 2008

Different Types of Vehicles

Do you know how many types of vehicles there are in all? Since the creation of the first crude automobile, several models and types have been created to suit the needs of people. These were developed in order to provide a safe, efficient and economical means of transportation. Some are built for luxury, others for practicality and some for environmental purposes.

Cruder Forms

Vehicles were first made thousands of years ago. The earliest forms of vehicles were actually living things like horses, elephants and camels. With the invention of the wheel around 3000 B.C., chariots, carts and horse-drawn carriages came into existence. The wheel has certainly paved the way for modern transportation as it is still very much present today.

Cycles were created around the 19th century which comes in many forms. Bicycles are one of the most common types of vehicles available today. There are also tricycles, quadricycles and unicycles. These vehicles mainly use a chain that goes around the wheels for propulsion. Cycling is a very important action in order to keep the transportation balanced. Later on, motorcycles were invented which incorporated a motor engine instead of manual pedals.

Origin of Alternate Fuel Sources

Electric vehicles or EVs were invented in the 1830's which uses one or more electric motors. The rotary or linear motors propel the vehicle through the wheels. Linear motors are used by tracked vehicles such as trains and MRTs. There are several sources of energy used to move the vehicle like an on-board RESS or rechargeable energy storage system, batteries, on-board super capacitors and direct connection to energy-generating plants. Fuel cells and nuclear energy have also shown to be very viable in propelling vehicles.

Steam engines are another alternate fuel source which uses an external combustion engine or ECE. ECEs are less efficient compared to ICEs but proper configurations can be made for the fuel burner in order to emit very low amounts of carbon monoxide, nitrogen oxide and other harmful gases making it environmentally friendly in the process. Steam cars do have a problem when starting from cold leading to the development of flash boilers.

The Automobile

Automobiles are the most common type of vehicle. The majority of automobiles today are powered by gasoline or diesel engines. Automobiles use an internal combustion engine or ICE which can be highly polluting due to the constant burning of harmful gases. This type of vehicle has shown to be very powerful, convenient and aesthetic as well making it the most popular of all time.

Gasoline engine vehicles are lighter and able to work at optimum rotational speeds. The invention of the electric starter has boosted its popularity beating steam and electric cars in the process. Carburetor and fuel injection are some of the most useful discoveries in enhancing automobile performance.

There are various innovations in the engine allowing exhaust gases to be less harmful. Others combine efforts to minimize the greenhouse effect by reducing emissions to zero. Gasoline engines are capable of running with different ethanol concentrations. Some may run on 15%, 85% or even 100% ethanol. Fuel burn efficiency of gasoline engine vehicles are around 27%.

Diesel engine vehicles are more cost-effective compared to gasoline engine ones because of their 50% fuel burn efficiency. However, power and performance is also compromised due to less concentration of fuel. Diesel also releases exhaust gases into the atmosphere from soot particles. 100% biodiesel has been developed to improve the downside of these vehicles.

Other Transports

A train is a series of vehicles moving along a guided track or rail. A separate locomotive provides power to propel the entire train. Diesel or electricity is the usual energy source of trains while older versions were dominantly powered by steam engines. There are special kinds of trains with special tracks like rubber-tired underground, high-speed and monorails. Some trains can have more than one locomotive or coach.

A road train has a prime mover pulling one or more trailers. Trucks are the simpler version of this. Since the weight and maneuverability are a challenge, these vehicles often require several wheels for more control. Speed should also be watched meticulously to make travel as safe as possible. Diesel engines usually power big heavy trucks and road trains for fuel efficiency and power.

Other unique types of vehicles are amphibious vehicles and snowmobiles. Amphibians can run on both land and water making them very versatile. There are amphibious bicycles, cars, trucks and ATVs developed for passenger and official use.

The advantages provided by amphibians made them very useful for military operations. Snowmobiles are propelled by a built-in track made of Kevlar composite or rubber in order to effectively move through snow. These are also powered by a motor engine that consumes gas for fuel. Tanks use the same mechanism as snowmobiles by running on steel tracks.

November 04, 2008

Parts of the Gasoline-Electric Hybrid Vehicles

Parts of the Gasoline-Electric Hybrid Vehicles

The typical gasoline powered car contains a combustion engine, fuel tank, and transmission, whereas with the gasoline-electric hybrid vehicle, it contains the following parts:

Gasoline Engine. The engine of a hybrid car is relatively smaller than its gasoline-only counterpart. This is because of two reasons: (1) the car doesn't require a big engine since there it uses another source of power, (2) a bigger engine means larger displacement, heavier weight, and poor fuel economy; since most hybrid cars are designed for maximum fuel efficiency, the engine has to be small. (Diesel engines for diesel-electric hybrid vehicles.)

Fuel Tank. The fuel tank is the energy storage device of the gasoline engine. The size of the fuel tank on a hybrid car may be reduced since the car has to accommodate the size of the batteries.

Transmission. Most hybrid cars use the same transmission as a conventional car.

Batteries. The batteries of a hybrid car are the energy storage device for the electric motor. The batteries perform 2 functions: they send energy to the electric motor and store energy that is being captured by the generator.

Electric motor. A hybrid electric motor is very sophisticated. It can perform as a motor as well as a generator. This means, the electric motor can draw the energy from the battery to accelerate the car or to assist the gasoline engine during acceleration. The electric motor can also act as a generator by slowing the car down and store the energy back to the battery.

Generator. The generator of a hybrid car is much the same as the electric motor but it only acts to produce electric power. Generators are mostly used on series hybrids.

Hybrid electric cars can be parallel or series. Parallel hybrid cars can use the electric motor or gasoline engine to drive the transmission which turns the wheels. Or, it can use both the electric motor and the gasoline engine to drive the transmission and turn the wheels.

Series hybrids, as opposed to parallel hybrids never directly use the gasoline engine to power the vehicle. Instead, the engine turns the generator which either powers the electric motor that drives the transmission or changes the batteries.

Be it a parallel or series structure, the hybrid vehicle uses two sources of energy to provide the same performance we expect from a passenger car and increasing fuel economy at the same time.