lets talk about the dual fuel engines [diesel + petrol in your vehicle]

As a Nigerian I believe you will find this interesting as a car owner, I can bet with whatever amount I have in my account that you have experienced fuel or gasoline scarcity at one point or the other and your next thought would have been why can’t I just use diesel?

Let me tell you a short story,

Many years ago, there was a time when we were traveling by road to my hometown and there was fuel scarcity everywhere we got to a filling station where we had to queue as we were uncertain the next filling station was going to have fuel or sell gasoline even if they have. (we are used to the gas station hoarding gas, Nigerians understand better)

One thing that got my attention after waiting for several hours was this cab which drove in only to fill in diesel in his car and off he went, I looked up and showed my dad and he said yes, there are cars like that that use diesel but ours doesn’t. it only works using petrol. I was dying for him to explain then but he is only a junior school teacher who teaches the English language.

Due to my interest in mechanical engineering, I found out later to the layman there are just two different types of an engine which are;

the spark ignition (petrol engine) and the compression ignition engine (diesel engine).

But there is a type of engine that uses both the petrol and diesel engine some even use gas alongside. That makes a mixture of three different types of fuel. How do these engines work and what really happens in the cylinder? Well, you are about to find out today.

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Diesel + Petrol = Bi-fuel engine

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Sometime last year (November to be precise) we were lucky in school to visit a power generating plant which worked using three different fuels which were the HFO (heavy fuel oil), LFO (light fuel oil), and gas. It was quite interesting and educative. That was the first time I heard about the possibility and reality of different kinds of fuel to power a single engine. With several regulations and control system, it is very possible to have two kinds of fuel running at the same time in that car engine of yours. So, I am advising you to get one of these types of engines in your car or just replace your car just in case Buhari decides to throw panic amidst us.

Well, enough of the mumble and jumble the dual fuel engine runs on both the gasoline and diesel at the same time and could be quite tricky when both are working together but as a quote says, “nothing is impossible because the word itself says I’m possible”.

As we all know or have learnt from one post or the other that the spark ignition engine or petrol engine as it is popularly called makes use of the spark plug in its compression stroke to cause ignition in the engine chamber while the compression ignition engine or diesel engines make use of compression at a very high temperature to ignite the air fuel mixture, but the dual fuel engine is a combination of both the diesel and petrol engine cycle which means it has a spark plug and it uses it during its compression stroke while working with petrol whereas while using diesel, it ignites by compression or something similar to when both fuels are used. This way it is called the pilot fuel the pilot fuel is like the trigger for combustion during the compression.

The dual fuel engine is like one of the recent engine developments with very low emissions and high efficiency than the usual gasoline and diesel engine. It makes use of the injector rather than the carburetor and with the spark plug playing an important role.

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How such engine works

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The main problem one could ever think of with these engines is the combination of both kinds of fuel. We all know that compared to diesel, petrol is flammable and even with the tiniest spark you could have an explosion whereas, you could be sitting on diesel while smoking *(I am not asking you to try that, Lol).*

What I am driving at is the difference in volatility between both and its control when both fuels are being used together in a single cylinder block and in such a way that one would not pre-ignite before its scheduled stroke. What I mean by pre-ignite, in this case, is when the combustion happens before its stipulated time.

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What happens when it functions with both fuel?

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As stated earlier you can read what happens in the engine block of the petrol and diesel engine by clicking on the links. I would try as much as I can to break this down to my readers.

The process by which the engine completes it cycle is the same with the spark and compression ignition engines what only differentiates them is the intake and the compression stroke.

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The intake stroke

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During this stroke, the intake valve opens and the piston travels down to the bottom of the cylinder and in the process drawing in a percentage mixture of both petrol and air as compared to the typical petrol or diesel engine which takes in only air.

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Compression stroke

After a certain mixture or amount of fuel and air has been drawn in, the fuel and air have to be balanced in such a way that it would not combust before the piston reaches the top of the cylinder.

Eventually, when it reaches the top of the cylinder, a small amount of diesel called the pilot fuel is injected into the fuel mixture and boom! The fire spreads out till all the fuel is burnt forcing the piston to travel down to the bottom of the cylinder. the movement or traveling of the piston back to the top of the cylinder leads to the products of combustion escaping out of the exhaust manifold.

This completes everything that happens in the mixed fuel operation, but it is surprising the kind of flexibility this kind of engine this is. The spark plug is present but would not at any point function during the mixed fuel operation.

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Single fuel operation

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During the single fuel mode of the engine meaning when you are using a single fuel in this engine the engine operates as either the petrol or diesel engine depending on the fuel that is being used. Since there is spark plug present in the engine the petrol engine combustion is made possible, same as the diesel engine which has enough to make the compression possible for the fuel(diesel) to combust at the appropriate time.

This means that the operation of this type of engine depends on the kind of fuel present in the fuel tank at that moment. The ability of this engine to switch instantaneously is one major advantage and therefore, it has great usage in power plants and uninterruptible power.

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What does this mean?

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This new generation of engines makes them versatile and flexible in the type of fuel they use not forgetting the amount of power these engines deliver. These engines have great efficiency and they are known for their flexibility in terms of fuel used. There is a new Mazda which uses this engine already and it is set to be released in 2019.

Did I forget to mention emissions? The emissions from these vehicles are minimal compared to any traditional petrol or diesel engine you see around. The next time there is petrol scarcity, just wave your hands at petrol and say bye and get diesel into that pretty engine you just bought.

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Conclusion

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What if I told you no engine has been discovered to be 75% efficient in getting the maximum power from your fuels?

Well, this may not be close to that but it is well above 50% by some research carried out in the University of Wisconsin. Which means the engine is better than the traditional petrol or diesel engine you can find all around and it may be very costly right now due to its recent developments and considering that it only came to be a few years ago. The bi-fuel engines are going to be one hell of a great engine especially to Nigerians who have at one point or the other gone through the stress of petrol purchase during fuel scarcity.

One can easily fill up one tank with diesel and the other with petrol or just fill either one and you are back on the road with a better emission and efficiency from your engine.
Thank you for reading please share your thoughts on this engine type.

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Reference

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knowledge is not just gotten by sleeping it is gotten from books or by listening. Here are some of the books and links I read:

• what-happens-deep-down-inside-the-engine-cylinder-the-compression-ignition-cycle
• the-spark-ignition-engine-the-otto-cycle-and-how-it-operates
• Diesel-Engine-vs-Petrol-Engine
• explainthatstuff diesel-engines
• dual-fuel-engine-working
• dual-fuel-engine-working wiki
• dual--fuel-engines
• dual-fuel