MAFUTA YA DIZELI YALIVYO NA MAENDELEO YA UBOLESHWAJI WAKE.(DIESEL FUEL & DIESEL IMPROVEMENTS AND BIODIESEL)

Diesel Fuel

Petroleum fuel starts off as crude oil that's naturally found in the Earth. When crude oil is processed at refineries, it can be separated into several different kinds of fuels, including gasoline, jet fuel, kerosene and, of course, diesel.

If you have ever compared diesel fuel and gasoline, you know that they are different. They certainly smell different. Diesel fuel is heavier and oilier. It evaporates much more slowly than gasoline -- its boiling point is actually higher than the boiling point of water. You will often hear diesel fuel referred to as "diesel oil" because it's so oily.

Diesel fuel evaporates more slowly because it is heavier. It contains more carbon atoms in longer chains than gasoline does (gasoline is typically C9H20, while diesel fuel is typically C14H30). It takes less refining to create diesel fuel, which is why it used to be cheaper than gasoline. Since 2004, however, demand for diesel has risen for several reasons, including increased industrialization and construction in China and the U.S.

Diesel fuel has a higher energy density than gasoline. On average, 1 gallon (3.8 L) of diesel fuel contains approximately 155x10⁶ joules (147,000 BTU), while 1 gallon of gasoline contains 132x10⁶ joules (125,000 BTU). This, combined with the improved efficiency of diesel engines, explains why diesel engines get better mileage than equivalent gasoline engines.

Diesel fuel is used to power a wide variety of vehicles and operations. It of course fuels the diesel trucks you see lumbering down the highway, but it also helps move boats, school buses, city buses, trains, cranes, farming equipment and various emergency response vehicles and power generators. Think about how important diesel is to the economy -- without its high efficiency, both the construction industry and farming businesses would suffer immensely from investments in fuels with low power and efficiency. About 94 percent of freight -- whether it's shipped in trucks, trains or boats -- relies on diesel.

                                                       A sample of diesel fuel

HEBU TUANGALIE KATI YA INJINI ZA DIZELI NA PETROL ( DIESEL ENGINES VS GASOLINE ENGINES)

Diesel Engines vs. Gasoline Engines

In theory, diesel engines and gasoline engines are quite similar. They are both internal combus­tion engines designed to convert the chemical energy available in fuel into mechanical energy. This mechanical energy moves pistons up and down inside cylinders. The pistons are connected to a crankshaft, and the up-and-down motion of the pistons, known as linear motion, creates the rotary motion needed to turn the wheels of a car forward.

Both diesel engines and gasoline engines covert fuel into energy through a series of small explosions or combustions. The major difference between diesel and gasoline is the way these explosions happen. In a gasoline engine, fuel is mixed with air, compressed by pistons and ignited by sparks from spark plugs. In a diesel engine, however, the air is compressed first, and then the fuel is injected. Because air heats up when it's compressed, the fuel ignites.

The diesel engine uses a four-stroke combustion cycle just like a gasoline engine. The four strokes are:

·         Intake stroke -- The intake valve opens up, letting in air and moving the piston down. ­

·         Compression stroke -- The piston moves back up and compresses the air.

·         Combustion stroke -- As the piston reaches the top, fuel is injected at just the right moment and ignited, forcing the piston back down.

·         Exhaust stroke -- The piston moves back to the top, pushing out the exhaust created from the combustion out of the exhaust valve.

Remember that the diesel engine has no spark plug, that it intakes air and compresses it, and that it then injects the fuel directly into the combustion chamber (direct injection). It is the heat of the compressed air that lights the fuel in a diesel engine. In the next section, we'll examine the diesel injection process.

COMPRESSION

When working on his calculations, Rudolf Diesel theorized that higher compression leads to higher efficiency and more power. This happens because when the piston squeezes air with the cylinder, the air becomes concentrated. Diesel fuel has a high energy content, so the likelihood of diesel reacting with the concentrated air is greater. Another way to think of it is when air molecules are packed so close together, fuel has a better chance of reacting with as many oxygen molecules as possible. Rudolf turned out to be right -- a gasoline engine compresses at a ratio of 8:1 to 12:1, while a diesel engine compresses at a ratio of 14:1 to as high as 25:1.

HEBU TUANGALIE NAMNA INJINI YA DIZELI INAVYOFANYA KAZI ( HOW DIESEL ENGINE WORK )

How Diesel Engines Work

One of the most popular  articles is How car work, which explains the basic principles behind internal combustion, discusses the four-stroke cycle and talks about all of the subsystems that help your car's engine to do its job. For a long time after we published that article, one of the most common questions asked (and one of the most frequent suggestions made in the suggestion box) was, "What is the difference between a gasoline and a diesel engine?"

Diesel's story actually begins with the invention of the gasoline engine. Nikolaus August Otto had invented and patented the gasoline engine by 1876. This invention used the four-stroke combustion principle, also known as the "Otto Cycle," and it's the basic premise for most car engines today. In its early stage, the gasoline engine wasn't very efficient, and other major methods of transportation such as the steam engine fared poorly as well. Only about 10 percent of the fuel used in these types of engines actually moved a vehicle. The rest of the fuel simply produced useless heat.

The 4.5-liter V-8 Duramax improves efficiency by 25 percent when compared with gasoline engines, while reducing pollutants and emissions. 

                                                 Rudolf Diesel, inventor of the diesel engine.

I­n 1878, Rudolf Diesel was attending the Polytechnic High School of Germany (the equivalent of an engineering college) when he learned about the low efficiency of gasoline and steam engines. This disturbing information inspired him to create an engine with a higher efficiency, and he devoted much of his time to developing a "Combustion Power Engine." By 1892 Diesel had obtained a patent for what we now call the diesel engine.

If diesel engines are so efficient, why don't we use them more often? You might see the words "diesel engine" and think of big, hefty cargo trucks spewing out black, sooty smoke and creating a loud clattering noise. This negative image of diesel trucks and engines has made diesel less attractive to casual drivers in the United States -- although diesel is great for hauling large shipments over long distances, it hasn't been the best choice for everyday commuters. This is starting to change, however, as people are improving the diesel engine to make it cleaner and less noisy.

If you haven't already done so, you'll probably want to read How Car Engine Work first, to get a feel for the basics of internal combustion. But hurry back -- in this article, we unlock the secrets of the diesel engine and learn about some new advancements.

MFUMO WA VALVE ZA INJINI (ENGINE) UNAVYOTUMIKA (ENGINE VALVE TRAIN )

Engine Valve Train

Most engine subsystems can be implemented using different technologies, and better technologies can improve the performance of the engine. Let's look at all of the different subsystems used in modern engines, beginning with the valve train.

 The camshaft

The valve train consists of the valves and a mechanism that opens and closes them. The opening and closing system is called a camshaft. The camshaft has lobes on it that move the valves up and down

Most modern engines have what are called overhead cams. This means that the camshaft is located above the valves, as you see in Figure 5. The cams on the shaft activate the valves directly or through a very short linkage. Older engines used a camshaft located in the sump near the crankshaft. Rods linked the cam below to valve lifters above the valves. This approach has more moving parts and also causes more lag between the cam's activation of the valve and the valve's subsequent motion. A timing belt or timing chain links the crankshaft to the camshaft so that the valves are in sync with the pistons. The camshaft is geared to turn at one-half the rate of the crankshaft. Many high-performance engines have four valves per cylinder (two for intake, two for exhaust), and this arrangement requires two camshafts per bank of cylinders, hence the phrase "dual overhead cams."

TUANGALIE BAADHI YA MATATIZO YA INJINI ( ENGINE PROBLEMS )

Engine Problems

So you go out one morning and your engine will turn over but it won't start... What could be wrong? Now that you know how an engine works, you can understand the basic things that can keep an engine from running. Three fundamental things can happen: a bad fuel mix, lack of compression or lack of spark Beyond that, thousands of minor things can create problems, but these are the "big three." Based on the simple engine we have been discussing, here is a quick rundown on how these problems affect your engine:

LEO NITAONGELEA MISINGI YA SEHEMU ZA INJINI ( BASIC ENGINE PARTS )

Basic Engine Parts

The core of the engine is the cylinder, with the piston moving up and down inside the cylinder. The engine described above has one cylinder. That is typical of most lawn mowers, but most cars have more than one cylinder (four, six and eight cylinders are common). In a multi-cylinder engine, the cylinders usually are arranged in one of three ways: inline, V or flat (also known as horizontally opposed or boxer), as shown in the following figures.

Different configurations have different advantages and disadvantages in terms of smoothness, manufacturing cost and shape characteristics. 

These advantages and disadvantages make them more suitable for certain vehicles.

Let's look at some key engine parts in more detail.

LEO TUANGALIE INJINI ( ENGINE ) ZA MAGARI NA JINSI ZINAVYOFANYA KAZI (HOW CAR ENGINES WORK )

KIMSINGI KUNA AINA MBILI KUU ZA INJINI ( ENGINE )

1. INJINI YA MAPIGO MANNE ( FOUR STROKE ENGINE )
2. INJINI YA MAPIGO MAWILI ( TWO STROKE ENGINE )

LEO TUANGALIE INJINI YA MAPIGO MANNE ( FOUR STROKE ENGINE )

INTRODUCTION TO HOW CAR ENGINE WORKS.

Have you ever opened the hood of your car and wondered what was going on in there? A car engine can look like a big confusing jumble of metal, tubes and wires to the uninitiated.

You might want to know what's going on simply out of curiosity. Or perhaps you are buying a new car, and you hear things like "3.0 liter V-6" and "dual overhead cam" and "tuned port fuel injection" What does all ­of that mean?

In this article, we'll discuss the basic idea behind an engine and then go into detail about how all the pieces fit together, what can go wrong and how to increase performance.

The purpose of a gasoline car engine is to convert gasoline into motion so that your car can move. Currently the easiest way to create motion from gasoline is to burn the gasoline inside an engine. Therefore, a car engine is an internal combustion engine -- combustion takes place internally.

Two things to note:

·         There are different kinds of internal combustion engines. Diesel engine are one form and gas turbine engines are another. See also the articles on HEMI engine, rotary engine and two stroke engine Each has its own advantages and disadvantages.

·         There is such a thing as an external combustion engine. A steam engine in old-fashioned trains and steam boats is the best example of an external combustion engine. The fuel (coal, wood, oil, whatever) in a steam engine burns outside the engine to create steam, and the steam creates motion inside the engine. Internal combustion is a lot more efficient (takes less fuel per mile) than external combustion, plus an internal combustion engine is a lot smaller than an equivalent external combustion engine. This explains why we don't see any cars from Ford and GM using steam engines.

Let's look at the internal combustion process in more detail in the next section

The Corvette ZR1's supercharged 6.2-liter V8 engine produces 620 horsepower standard.