Fuel-efficient and energetic. Where are all the diesel cars?

When it comes to diesel vehicles, what kind of pictures will emerge in our minds?

It must be those big trucks, engineering vehicles and long-distance buses driving on the road with black smoke and roar, doing heavy work and dirty work.

Like this:

In short, the inherent impression left by diesel vehicles is that they are stupid and black.

In the domestic automobile market, although some passenger cars will use diesel power, it is limited to some hard-core SUV models. For example, the ordinary family car we drive every day rarely uses diesel power. Why?

Where is the diesel oil?

Since all the cars around us use gasoline as fuel, some friends want to ask questions. Does this mean that there is more gasoline than diesel? Having said that, let me give you a general idea of the output of diesel and gasoline.

First, taking the crude oil processing data released by China Petrochemical Company 20 18 as an example, the gasoline output was 61160,000 tons, up by 7.24% year-on-year; Diesel oil output reached 64.72 million tons, down 3.06% year-on-year.

According to the published data, the processing amount of diesel oil is more than 3 million tons than that of gasoline, which is somewhat different from our inherent cognition. China's diesel production is not good at all, so what has diesel done?

First of all, transportation, warehousing and postal services account for the largest proportion in the diesel consumption structure, such as "three links and one arrival" running on the road every day, and SF Express trucks in JD.COM are all major consumers of diesel.

Secondly, industry, agriculture, forestry, animal husbandry, fisheries, construction and daily consumption are also inseparable from diesel. Because it is more suitable for heavy machinery, there is a great demand, and there will be no extra diesel for passenger cars to continue to use.

They are added to the fuel tank of heavy trucks to pull coal and deliver it to express delivery;

They are added to the fuel tank of construction machinery, and the "infrastructure madman" has a reputation;

They are added to the fuel tank of agricultural machinery, so that you can eat and eat corn;

……

Moreover, at some special time nodes, when the diesel supply is tight, there will be oil panic. At this point, I am quite touched. My uncle has a diesel version of H3. Every time I go to the gas station during the Chinese New Year, there is not only a long queue on the side where I add diesel, but sometimes it is limited.

What's the difference between a diesel engine and a gasoline engine?

Speaking of which, I have to mention the difference between diesel and gasoline. First of all, diesel oil and gasoline are processed from crude oil that looks "very black".

In the process of processing, the hydrocarbon chain of crude oil is decomposed and classified. The difference between diesel oil and gasoline lies in the length of this "chain".

The short chain will supply gasoline, and the long chain will supply diesel. The shorter the molecular chain, the easier it is to burn, so diesel is less likely to be ignited quickly than gasoline.

Different ignition methods

In addition, the ignition methods of diesel engines and gasoline engines are also very different. We all know that traditional cars have four strokes-intake, compression, combustion and exhaust.

The working process of gasoline engine is to mix and compress air with gasoline, then ignite it by ignition piston, and then burn it, while the working process of diesel engine is to mix and burn pure air with diesel oil directly injected into the cylinder to do work.

Because diesel engine relies on compression ignition, there is no ignition system, there are few auxiliary appliances and low speed, and the aging wear rate of parts is smaller than that of gasoline engine. It has more obvious innate advantages in failure rate and service life.

Interspersed with a short historical story, the diesel engine was invented by German inventor Rudolf Dissel in 1892. In memory of this inventor, the diesel engine is represented by his surname diesel, which is also called diesel engine.

Different compression ratios

In the compression process of gasoline engine, the mixing ratio of air and gasoline is 7: 1, the in-cylinder pressure is 8- 18bar, and the temperature is 400-600 degrees Celsius. The ratio of air to diesel mixture in diesel engine is 18: 1, the in-cylinder pressure can reach 30-50bar, and the temperature can reach 700-900 degrees Celsius.

Different engine compression ratios lead to different thermal efficiencies. We all studied physics in junior high school. The higher the compression ratio, the higher the thermal efficiency. Therefore, compared with gasoline engines, diesel engines have higher thermal efficiency, which means they are more fuel efficient.

In addition, the characteristics of low rotation and high torsion of diesel engine will be more excellent in dealing with some complex road conditions, climbing and high load. High torque is like saying that a person has energy, and then look back at these diesel-powered construction machinery, which one does not rely on strength to eat.

Higher security

Compared with gasoline engine, diesel engine has higher safety, and the danger of liquid can be judged according to its flash point. What is the flash point? It is the lowest temperature that can cause liquid to vaporize and catch fire.

The higher the flash point, the higher the safety. Generally, the flash point of gasoline is -50 ~-20℃, while the flash point of diesel is above 55℃, so the safety of diesel is higher than that of gasoline, and compared with gasoline, diesel is less volatile and easier to store and transport.

Disadvantages of diesel engine

Having said so much has advantages and disadvantages. Compared with gasoline engine, diesel engine is inferior to gasoline vehicle in speed increase and high-speed driving. For example, supercars such as Ferrari and Lamborghini use gasoline engines.

Moreover, diesel engines will produce more carbon dioxide emissions, and the amount of carbon dioxide produced by 7 liters of diesel is equivalent to that produced by 10 liter of gasoline.

As we said above, the compression of diesel engine is relatively high, which is subject to the factors of in-cylinder pressure. Compared with gasoline engines, diesel engines have greater mass and higher cost.

In addition to environmental pollution, high manufacturing cost and loud noise, it is easy to catch fire in the environment with low temperature in winter. Buying a diesel car to send a quilt may be a good marketing method.

Why not mainly promote diesel vehicles in China?

Since diesel engines have more outstanding advantages than gasoline engines, why not mainly promote diesel vehicles in China? Actually, there are many factors behind this. One by one, listen to me.

Early oil problems limited the introduction and development of diesel engines.

One of the main reasons is that the sulfur content of domestic diesel oil was particularly high in the past. As long as it is divided into two aspects, one is because imported crude oil itself belongs to high sulfur and high acid value crude oil; Second, China's refining technology is relatively backward and immature in the early stage.

In the process of refining, due to the serious corrosion of sulfur to refining equipment, in order to improve the quality of refined oil and reduce the sulfur content, it is necessary to increase the technical difficulty, the refining cost will also rise, and finally the price of diesel oil will also rise. Want quality and save money? It doesn't exist.

As early as 2005, the sulfur content of European standard diesel oil was below 0.005%, while the sulfur content of diesel oil in China was 0.035% at that time, a difference of 7 times. It can be seen that the oil quality at that time was not suitable for the large-scale introduction and promotion of diesel vehicles.

Diesel oil is mostly used in industrial production, and civil use is not the first.

This has been explained in the above diesel consumption structure. Although the output of diesel oil is more than that of gasoline, it cannot bear its huge demand, and even there will be oil shortage in the peak season.

The use of diesel oil can be said to involve all aspects of our lives. In addition, as a world-famous "infrastructure madman", construction machinery and heavy trucks run around the construction site day after day, consuming real diesel.

At the same time, industry, agriculture and construction are also inseparable from diesel. In other words, if our passenger cars use diesel as the main fuel, then the remaining diesel reserves are not enough to meet the huge demand of our people.

Our government tends to develop new energy vehicles.

With the increasingly strict environmental protection law, the automobile exhaust emission standards formulated by the government are getting higher and higher. Although diesel is economical and powerful, new energy vehicles such as hybrid and pure electric are the future development trends.

Thanks to China's leading position in new energy core technologies such as batteries and motors, it can make up for the unfavorable situation that China's passenger car engines lag behind foreign companies. In addition, the government has issued many policies to support new energy sources, such as unlimited purchase, subsidies and exemption from purchase tax, which further promoted the development of the domestic new energy vehicle market.

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