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What is the cleanest way to transport decarbonization?

In recent years, with the intensification of global warming and the vulnerability of traditional fossil energy to turbulence, the development and utilization of clean energy has been greatly accelerated, especially the emerging hydrogen energy. Electric vehicles and hydrogen fuel cells are one of the most prominent technologies that help us achieve this cause. But due to cost and slow adoption these technologies have not significantly reduced our overall emissions.

Fortunately, researchers at the University of New South Wales may have just created a near-perfect bridging technology that can easily convert diesel engines to use hydrogen as fuel to reduce carbon emissions, but how do they do it? Will this lead to a carbon-neutral revolution?

Researchers at the University of New South Wales in Sydney have modified a diesel engine that achieves up to 90 per cent of hydrogen energy in a hydrogen-diesel dual-fuel direct injection (H2DDI) lightweight single-cylinder compression ignition engine, reduces emissions by 85 per cent to 90 grams per kilowatt-hour, and increases engine efficiency by 26 per cent!

The oil-derived part of the fuel can be easily converted to biofuel, and with a little modification, the engine can be fully carbon-neutral. In addition, the engine does not have to use high-purity hydrogen, but can also use lower-purity hydrogen, which is cheaper and easier to produce.

But how does this engine work? Why is it better than pure biodiesel engines or pure hydrogen internal combustion engines? There are three reasons: nitrogen oxide emissions, efficiency and supply chain reliability.

Why choose hydrogen dual fuel engine?

First, nitrogen oxides. The operation mode of diesel engine is completely different from that of gasoline engine. Instead of spark triggering combustion, they use compression. When the piston is pulled down, it sucks in air and vaporized diesel, which is then mixed in the cylinder. When the piston rises, it compresses the gas and heats it. The pressure that the piston compresses can heat it enough to burn, pushing the piston back into position.

Hydrogen can be used in the same compression ignition engine, but it has two obvious disadvantages. First of all, it is not very efficient, which means that it produces much less power. This is because hydrogen burns much faster than diesel fuel, so it burns out before the piston reaches the bottom of the cylinder. This reduces the force exerted on the cylinder, thereby reducing the power of the engine.

Second, a uniform mixture of air and hydrogen produces more nitrogen oxides than diesel. The high pressure and high temperature environment inside the diesel engine causes nitrogen to react with oxygen to produce nitrogen oxides (also known as NOx). These emissions are then absorbed by the clouds and produce acid rain, causing great environmental damage. But because hydrogen burns faster, it eventually burns at a higher pressure than regular diesel (so the temperature is much higher). This leads to higher levels of nitrogen oxides in hydrogen-powered diesel engines.

So why not pure biodiesel? There is a big problem with biofuels. They take away our food supply and lead to the loss of habitat. To make a long story short, if we are to use biofuels, we need to use them very carefully to avoid ecological and humanitarian crises.

The working principle of the hydrogen dual-fuel engine, and what is commendable about the dual-fuel engine is that the research team retained the diesel injection device in the original engine and added hydrogen fuel injection directly to the cylinder. enables the engine to run at a constant speed of 2000 revolutions per minute.

More importantly, the team's efforts also found a way to get rid of the high nitrogen oxide (NO x) emissions associated with hydrogen engines. Instead of putting all the hydrogen into the engine and mixing it fully, as many expected, the researchers added it layer by layer, which could significantly reduce NO x emissions.

In this way, the flame speed of hydrogen can be slowed down, which also means that hydrogen can generate more force on the piston and burn at much lower pressure. In addition, hydrogen can be injected regularly at an ideal time (that is, later in the cylinder cycle), which means that hydrogen is present in some parts of the engine and less in others.

Overall, dual-fuel engines reduce nitrogen oxide emissions that lead to acid rain and air pollution.

In theory, it is possible to build an engine that uses hydrogen as the only fuel in this way. But researchers want to revamp diesel engines to achieve faster widespread use, so these engines are made differently. As a result, they still need to use 10% diesel to keep the cylinders ignited correctly. But the overall results are very good, the engine can be carbon-neutral without catastrophic ecological impact, and cleaner than standard diesel engines.

That's how this incredible engine works.

Advantages of hydrogen dual fuel engine

This system can be easily modified to any diesel engine. As a result, everything from tractors to mining rigs, trucks and even trains can be quickly switched to the system at a very low cost. This technology may be the quickest way to make these critical vehicles carbon neutral.

In addition, the hydrogen infrastructure should be easy to build and produce large amounts of low-purity hydrogen at little cost. But this hydrogen infrastructure can also be surprisingly efficient. One of the important problems with hydrogen fuel cell technology (which uses hydrogen to generate electricity and the only by-product is water) is its overall efficiency.

It is very energy-consuming and inefficient to power the electrolysis machine and then refine the hydrogen to a high enough purity. But these problems can be solved by using a hydrogen dual-fuel engine, because it can do more with less energy. Hydrogen dual-fuel engines only need to use low-purity hydrogen to operate normally, and can use less energy to generate the same power. Coupled with the energy efficiency improvement brought about by this dual-fuel engine, it should have a fairly good overall efficiency.

With all this in mind, it's no wonder that the researchers hope to commercialize the engine within the next 12-24 months. In a year or so, people around the world may convert their commercial and agricultural diesel machinery into carbon-neutral, ultra-efficient and clean-burning dual-fuel hydrogen diesel engines.

Conclusion the actual logistics of these transformations will be very difficult. After all, not all diesel engines are made the same way, so they may have to focus on one model at a time.

But at least in theory, it's a great way to quickly convert diesel-powered cars into carbon-neutral cars. This kind of bridging technology may be exactly what we need to combat climate change while gradually adopting electric vehicle technology.

This article comes from the official account of Wechat: new Research (ID:chuxinyanjiu), author: Tang Poems, compiled: Tang Poems

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