Exploring the combustion, emission and performance of n-Butanol with Deccan hemp oil methyl ester on dual fuel diesel engine

Diesel fuel is the primary energy source for many things, like cars, farm equipment, and ships1,2. When fossil fuels are burned, more greenhouse gases are released into the air. This makes the earth’s normal temperature rise2. Petrol prices are going up, and people are worried about the environment. Because of this, there is a greater need for fuel alternatives that are better for the environment and can be used in internal combustion (IC) engines. Diesel engines work well with plant oil, animal fats, and algae oil. Despite this, it has some problems, like being thicker than diesel and having less energy than diesel. Due to their high viscosity, these oils don’t break up into small enough particles, which means that too much air and fuel mix ends in incomplete burning.

On top of that, it causes the fuel injector to get clogged and carbon layers to form inside the cylinder3. To make the straight vegetable oil more straightforward, the transesterification method is used to make it less thick. You can call the oil made during the process “biodiesel.� Since it’s not made from pure vegetables, it has more calories, less stiffness, and lasts longer. This fuel is better than diesel because it has a higher cetane number, is lubricious, is non-toxic, and has less sulphur and aromatics. Still, bio-diesel isn’t as good as diesel in some ways. The main ones are that it has a lower or similar calorific content, a higher or similar density, and a shorter shelf life. Biodiesel is often mixed with gasoline in a number of different amounts so that it can be used in internal combustion engines. This method allows biodiesel to be made and used in many different engine types. It has been proven that making biodiesel from non-edible oils is the best way to avoid the problems that would come up if food oils were used in large amounts. It has been decided that this is the best way to get around the issues. Most of the fuel for non-edible oils comes from plants that do well in places that aren’t good for farming and only need a little water4. You can get these plants from a number of places. We will discuss a few studies that used biodiesel that can’t be eaten because of the fuel source.

In their study5, Patel et al. looked at the uncontrolled emissions produced by a car using a fuel mix of diesel, methyl ester of used cooking oil, and jatropha oil. A table was used to show the results of their study. With tables, they showed what their study had found once it was done. There was more uncontrolled emission when there were fewer loads but less uncontrolled emission when there were more loads. We learned that biofuel was the cause of the ethylene emissions. According to studies, adding up to 20% biodiesel has also been linked to more formic acid and formaldehyde emissions. Researchers from a different study discovered that adding biodiesel increased the amount of 1,3-butadiene, acetaldehyde, and formaldehyde released into the air. It also greatly affected how much the engine had to work6. This was found even though adding biofuel made the load on the engine lighter. It was also discovered that biodiesel had less polycyclic aromatic hydrocarbons and more oxygen. This meant that less particle emissions were released. Zhang et al7. and Nabi et al8. found that using biodiesel in an engine decreased the amount of particulate matter and the number of particles released. Tests were done on different mixes of gasoline and biodiesel, and it was found that soot precursors like acetylene, ethylene, and polycyclic aromatic hydrocarbon were lowered9. However, when biodiesel was added to the mixture, the levels of acetaldehyde and formaldehyde went up, even though they were still less than 45 parts per million. As a result, we can say that oxygenated fuels generally produce higher levels of uncontrolled emissions, which are bad for people and the environment, even though they are only small amounts10.

Deccan hemp oil (DHO) is another chemical that has been studied. It is not meant to be eaten by people, but it has been looked into. Hebbal et al11. tested running a diesel engine by adding different amounts of Deccan hemp oil and diesel fuel. The authors concluded that an engine running on a 25% blend of DHO had about the same performance as an engine running on diesel. They had to pre-heat the mix, though, to keep the same level of performance, even though they increased the amount of blend they used. Balasubramaninan et al12. used a chemical engineering process called transesterification to turn Deccan hemp oil into biodiesel. When the engine was running on 100% biodiesel, the CO2, CO, HC, and NOx emissions went down, but the emissions of smoke went up. In a different study, the Deccan hemp oil methyl ester was mixed with gasoline to see how it affected the engine’s performance and the amount of pollution it made13. Fourteen. Jayaraman et al. This helped reduce the total amount of fossil fuel used and carbon dioxide released into the air. While some emissions went down, others went up, including NOx emissions, which were higher than before. The authors found that both engine speed and emissions went up. Besides that, they found that pollution went down.

An important fact that everyone knows is that alcohols, like biodiesel, significantly impact how well engines work. Using this material, which has a relatively low number of carbon atoms, could reduce the production of greenhouse gases by a significant amount15,16. The lack of energy, low cetane number, and the fact that it damages engine parts mean that it can’t be used in a compression ignition in its pure form17. This is because it makes engine parts rust. Diesel and alcohol can be mixed to get around this problem. This mixture is more widely known as jenehol18,19. One other way to get fuel is to use these mixtures. Adding methanol and ethanol to diesel fuel makes the engine run much better and releases fewer air pollutants than direct diesel. These are not added to diesel in any way. 18 and 19: When these three fuels are mixed, they have the benefits listed here. If you want to run diesel engines, Jamrozik20 used binary blends of ethanol methanol and diesel. Diesel was used to power these blends.

The quantity of alcoholic drinks in the mixture ranged from 0 to 40% on a scale that measured alcohol by volume. The authors’ study shows that 40% ethanol to 30% methanol is the best balance between the two chemicals. Pollutants like carbon monoxide (CO), hydrocarbons (HC), and smoke were found to be much lower than with diesel. Oxides of nitrogen, however, were released into the air in much more significant amounts. People have tried long-chain alcohols like butanol and pentanol as possible fuel blends with diesel in an internal combustion engine that uses compression ignition. Yao et al21. looked into what would happen to the performance of a compression ignition engine if the amount of butanol to diesel in the fuel blend was changed. It was found that the mixes would increase the specific fuel used but decrease the amount of carbon monoxide and soot released into the air.

Additionally, it was found that butanol mixed better with gasoline than ethanol and methanol. That’s because butanol doesn’t boil as high as other alcohols do. Siwale et al22. researched and came to very similar conclusions. Researchers Yilmaz and Atmanli23 used a diesel engine to examine how diesel-1-pentanol blends affected the engine’s performance and the pollution it would cause. The amount of NOx that was released went down because pentanol can cool. This is because pentanol has a higher latent heat of vaporisation than other alcohols. The burning process became more efficient, which led to less carbon monoxide and hydrocarbons being released into the air.

Besides that, research was done using binary and ternary mixes of diesel, biodiesel, and alcohols. The results were pretty much the same. According to the study by Yasin et al24., adding a very small amount of methanol to biofuel made the engine need less power and give off less CO. It was a little faster for the heat to escape and for the pressure to reach its highest point inside the cylinder. There were also a few more NOx emissions. The experts who worked on the study by Huang et al25. mixed up 20% methanol with soybean biodiesel. They discovered that adding methanol increased benzene and acetaldehyde emissions, but the emissions of 1,3 buta-di-ene went down. It was found that adding methanol decreased the amount of CO pollution. Using a four-cylinder normally aspirated diesel engine and one mixed with ethanol-biodiesel, Tse et al26. looked at how well the two engines worked. They found the diesel engine with fuel mixed with something else was much better.

The speed of the test stayed the same the whole time. The ternary blend had a much higher in-cylinder pressure than diesel or biodiesel. The other two tried fuels. Making sure that both factors were kept was how this was done. Another line of study changed the load and speed of the engine while diesel-ethanol and diesel-biodiesel-ethanol mixtures were run through it27. Scientists discovered that ethanol mixtures made much less carbon monoxide, hydrocarbons, and smoke than combinations without ethanol. A smaller NOx emissions were also made possible using gasoline, biodiesel, and ethanol mixtures. Karin and her friends28 looked into the physical and chemical properties of the soot from a diesel engine that ran on a mix of biodiesel and ethanol. According to the experts, a single particle in the soot made by ethanol-biodiesel, biodiesel-diesel, and biodiesel mixed fuels is 29, 30, and 27 nm in size. However, scientists have found that using a mix of ethanol and biodiesel greatly reduces the amount of smoke that the car releases.

To find out what happens to the body when stronger alcohols like butanol and pentanol are mixed, researchers have also failed. Their ternary blend comprised butanol, microalgae biodiesel, and diesel. They used this blend to power the variable-speed diesel engine they were trying29. These numbers show that stopping power and torque decreased while the total emissions increased slightly. To make a diesel engine work, Yilmaz et al30. mixed butanol and biodiesel in different amounts in the same mixture. Researchers found that the amount of CO and HC emissions went up even more than the amount of NOx emissions. But the temperature of the exhaust gas went down. A few more jatropha methyl ester and n-butanol mixes were tried31. The scientists found that the device created less NOx, CO, and smoke opacity and was more thermally efficient. Even so, more fuels that hadn’t been burned were released into the air. In their study32, Zhang and Balasubramanian looked into the physical and chemical features of particles made by an engine that used a mix of biodiesel, butanol, and gasoline. In particular, they were interested in what kinds of particles the engine made and how they would behave. Scientists discovered that the butanol blend was less likely to cause cancer, had lower polycyclic aromatic hydrocarbons, and was less harmful to cells than the biodiesel mix. Also, the biodiesel mix had more polycyclic aromatic hydrocarbons than the other one. N-butanol was added to safflower biodiesel to make a binary mix. Biodiesel was added to diesel to make a ternary blend. Celebi and Aydin33 came up with this idea. This was a mix of these two different mixes that drove a CI engine. It generally uses about the same fuel as diesel but a little more of one fuel type.

Researchers Campos-Fernandes et al34. mixed different amounts of 1-pentanol with diesel and found that a 25% blend of 1-pentanol and diesel made the engine work as well as diesel without any changes needing to be made to the engine. The same thing was shown to be confirmed whether gasoline was used in the experiment or not. If Yoshimoto et al35. wanted to make an engine that ran on rapeseed oil work better, they used 1-pentanol as an oxidizer. The chemical was added, which made it possible to finish the job. The researchers found that 1-pentanol dissolves easily in rapeseed oil and didn’t change how much energy was needed to run the engine under stress. These two points of view came from the same group of people.

In contrast to using pure neem, Sivalakshmi et al36. found that adding 1-pentanol to neem oil improved engine performance while lowering emissions. In addition, Li et al37. looked into what they found about the emissions of a diesel engine. They gave this motor fuel a mix of pentanol, biodiesel, and diesel, as well as pentanol and diesel on their own. The experts found that the total amount of soot emissions had gone down.

New studies have shown that diesel or biodiesel can be used as the starter fuel in compression ignition engines along with a fumigant or various alcohols. According to the results of the study, this is what would happen. One study used diesel and oil from jatropha plants as test fuel, and methanol was added to the intake manifold38. Adding methanol almost completely cut down on the smoke made during the burning process, making it slightly more efficient at using heat. Another thing is that the addition of methanol is what caused more chemicals and carbon monoxide to be made. A different study tested a heavy-duty six-cylinder engine with diesel fuel and methanol injected into the intake port39. This was done so that both types of fuel could be used at the same time. It was found that increasing the pressure at which diesel was pumped and adding methanol decreased the amount of fuel used per mile, in particular. Also, the mean effective pressure’s coefficient of variation went up when methanol was injected, but it went down when high injection pressures were used. It was seen that way even though the injection pressure stayed the same. They improved a diesel engine by adding ethanol to its intake pipe40. This helped the engine burn diesel fuel more efficiently. The pilot fuel for this project was made by mixing diesel and safflower methyl ester in different amounts. The researchers found that adding ethanol made the pressure inside the cylinder drop, which was linked to a diffusion phase burning. One thing they learned from their research was this. The rhythmic fluctuation got bigger when ethanol was added to the system. It was found that when ethanol was added, the emissions of HC and NOx were higher than when diesel was used alone. However, the NOx emissions were lower. But it was found that more NOx was being released.

The researchers Gowtham et al41. put N-butanol and air into the entry manifold at volume percentages of 10, 20, and 30. It was found that when 20% n-butanol was injected instead of diesel, the engine’s thermal efficiency went up significantly compared to diesel running in single-fuel mode. Since n-butanol was added, the amount of acetaldehyde, acrolein, and NOx released into the air decreased. Still, the amount of acetone, formaldehyde, carbon monoxide, and hydrocarbons increases. Altun et al42. also put n-butanol into the intake manifold of a diesel engine running on a mix of gasoline and biodiesel in different amounts. While the engine was running at different temperatures, this was done. When butanol was added to a mixture of gasoline and 20% biodiesel, the specific fuel used went up. CO, HC, and smoke emissions decreased, but NOx emissions stayed the same at low loads and returned to normal at high loads. They43 compared the performance of an engine that ran on safflower oil biodiesel to one that ran on methanol and n-pentanol. They did this by injecting methanol and n-pentanol into the engine’s intake port. The fuel was put into the intake pipe to make this happen. The writers discovered that the engine worked better when 10% n-pentanol was used instead of methanol. However, the engine worked even better when 30% methanol was used instead of 10% n-pentanol. Because of the alcohol input, the CO, HC, and NOx emissions all went up, while the smoke emissions went down. The CO, HC, and NOx emissions increased while the smoke emissions decreased.

There are different ways to burn fuel, but the dual fuel mode is the only one that makes the engine more thermally efficient without making NOx pollution go up at the same rate. Many people think that NOx emissions from diesel engines are one of the most dangerous and important toxins they make. Several tests have shown that n-butanol is a better fuel than ethanol and methanol for use in a compression ignition engine. It has a higher enthalpy of burning, is less affected by water, and has a lower specific heat of vaporization than other compounds. Even though Deccan hemp oil is an alternative fuel, experts haven’t looked into how it works in dual fuel mode very much. Because of this, the methyl ester of Deccan hemp oil and diesel fuel were mixed in a 60:40 volume ratio (called B60) for this experiment. This combination was then used to power the directly injected engine. This study is very special: the mixture and n-butanol injection in the intake pipe has not been looked into in any other research. We used the engine tests to record how well the blends worked in single-fuel and dual-fuel modes. We looked at things like carbon monoxide (CO) emissions, specific energy consumption (BSEC), unburned hydrocarbon (HC) emissions, oxides of nitrogen (NOx) emissions, and smoke emissions. Then, these results were put next to those of diesel. One example is that the mixes had a better brake thermal efficiency (BTE) than gasoline. Different weights were used in a number of tests while the engine was running at its full speed.

Table 1 concisely overviews key studies on using Hibiscus Cannabinus seed as biomass feedstock and the impact of n-butanol injection on dual-fuel diesel engine performance. Each study contributes valuable insights, from combustion characteristics to economic viability and environmental impact assessment.

Fuel preparation

After the hemp plant seeds are picked, they must be left to dry out completely before the oil inside can be extracted. In the scientific world, it is usually called Hibiscus Cannabinus (Fig. 1). Herbaceous plants like this can grow up to five feet tall, and their height can change anytime. This plant can grow in any situation, even in dirt that isn’t good for growing plants. China, Bangladesh, India, Indonesia, Sri Lanka, and Thailand are just a few places that grow it. China is one of those places. Oil that isn’t processed can be made from the seed. The oil can be any colour from light yellow to dark green. Its colours are spread out all over the place. Researchers have found that this oil can help with a number of skin problems44,45. Deccan hemp seed is expected to be made around the world every year in amounts of 1,300,000 MT. Deccan hemp seeds are mainly grown in India because of good growth conditions. About 13.4 metric tonnes of them are grown every year46.

This is Deccan hemp oil, which is also known as DHO. Table 2 shows that it has a high viscosity. Because of this, it is possible to transesterify it with catalysts. This will lower its viscosity and make it better for CI engines. Transesterification can change the heavy molecules of vegetable oil into lighter molecules. In this method, the triglyceride reacts with methanol while KOH is present and acts as a catalyst. Melethyl ester, fatty acids, and glycerol are all mixed to make the end product. You can get glycerol and fatty acids from table oils through esterification. This process is also called “esterification.� The methyl ester that was finally made has qualities similar to diesel fuel. One of the many great things about it is that it is safe, biodegradable, and good for the earth. Besides that, it is good for the earth. When esterification happens, fuel has a low density, low viscosity, high cetane number, and high burning value. These properties make the fuel atomize and evaporate quickly.

Another thing is that this fuel atomizes and evaporates more quickly. A flow chart called Fig. 2 shows how Deccan hemp oil methyl ester is made. There is this picture on page 2.

Experimental apparatus and procedure

Kirloskar 4-stroke, single-cylinder, direct-injection, compression ignition engine tests were done in this study. This engine could make up to 5.2 kW of power at a steady speed of 1500 rpm. The engine always ran at 1500 rpm. Figure 3 is a sketch of the trial setup, and Table 3 lists details about the engine. An eddy-current dynamometer cooled by water was joined to the engine and tested so that it could be put under load. A hall-effect gauge that watched the crankshaft turn was used to determine how fast the engine was going. With this, the engine could be controlled with great accuracy. An AVL piezoelectric pressure gauge was put in place on the engine’s cylinder head. This sensor’s job was to determine the pressure inside the cylinder. The engine’s crankshaft had a crank angle tracker attached to it so that data could be gathered about how pressure and crank angle are related. Sending a signal at the right time for each degree of crankshaft spin is what this encoder does. The cylinder pressure, crank angle, engine load, and exhaust gas temperature readings were recorded and saved on a PC with the “Engine soft� program. This machine was also used to gather information. The average was over one hundred rounds done one after the other. A stopwatch and a burette were used to measure the exact amount of fuel used. To measure different types of exhaust pollution, such as carbon monoxide, carbon dioxide, oxides of nitrogen, and unburned hydrocarbon, an AVL 444 DI GAS exhaust gas analyzer was used. An AVL 437c smoke metre was utilised to measure the amount of smoke being made. Based on the measured variables and then put into a spreadsheet, calculations were made to find performance metrics like brake-specific fuel consumption and brake thermal efficiency.

The tests were broken up into two different stages. In the first part, the engine ran on diesel, pure Deccan hemp oil (also called DHO), Deccan hemp oil methyl ester (also called DHOME), and B60, a mix of diesel and Deccan hemp oil methyl ester. Everything the engine did was recorded and written down, such as its performance, combustion, and emissions. In the second step of the process, the engine was switched to dual fuel mode and ran with n-butanol going into the intake port and B60 being used for direct injection. It was possible to control and handle the injection of n-butanol well by using an open electronic control unit (ECU). The Electronic Control Unit (ECU) controls how much fuel is pumped into the engine by controlling how long the fuel injector stays open. The amount of mass made up of n-butanol injection stayed the same at 10%, 20%, and 30% in this study. It was written as B60Bu10, B60Bu20, and B60Bu30 in that order. It was also kept at 10%, 20%, and 30% for the amount of mass made up of n-butanol injection. These mass shares were considered because it was hard to keep the engine running smoothly when injecting bigger amounts of n-butanol. It was compared to tests that only used one fuel mode, and the efficiency, combustion and emission characteristics were studied. Each experiment underwent full and partial loading for each of its three runs. This was done so that a mistake in the experiment would have less of an effect on the results. Next, the maths was done by taking the average of these numbers. Table 4 shows an overview of the level of uncertainty that came with using different instruments during this experimental study.

Error analysis

The experiments give a number representing the uncertainty, the range of errors that could be present in the noticed numbers. Many things can cause uncertainty, such as the type of device used, how it was calibrated, and any mistakes that might have happened while the measurements were being taken. The uncertainty in the estimated results is found by looking at the error based on the unknowns present in the first experiments. You can figure out this amount of uncertainty by figuring things out. The equation for R is written as (Y_1, Y_2, Y_3,…., Y_n) because the result “R� is a Y1, Y2, Y3,……, Y functionn. The numbers W1, W2, W3,……, Wn show how unpredictable the independent variable is, and the letter WR shows how unclear the result is. Equation 1 can be used to do the math needed to figure out how uncertain the answer is.

The uncertainty of the experiment is

The total uncertainty of the experiment was found to be ± 2.6%.

(1) Engine block, (2) dynamometer setup, (3) pressure sensor device, (4) charge amplifier setup, (5) data acquisition system with computer (6) exhaust gas analyzer setup, (7) smoke meter analysis setup, (8) diesel/DHOME injector, (9) diesel tank with stand, (10) DHOME tank, (11) surge tank, (12) U-tube manometer device, (13) Butanol injector, (14) pressure gauge device, (15) pressure regulator device, (16) n-butanol tank, (17) pump setup, (18) battery setup, (19) ECU system, (20) switch control, (21) inlet manifold, (22) exhaust manifold.

A number of tests were done with different loads, like part-load and full-load, to get a full picture of the engine’s performance. The tests were meant to see how well the engine worked in terms of burning fuel and putting out pollution. The study looked at what happened when the engine was run in single fuel mode with different fuel types, like gasoline, unprocessed Deccan hemp oil, and its methyl ester. The results that were seen when the B60Bu10, B60Bu20, and B60Bu30 were used in the dual fuel mode were also examined. Diesel, raw Deccan hemp oil, and its methyl ester were the only fuels that could be used.

Brake thermal efficiency

To get this number, divide the amount of helpful work made by the amount of energy from the fuel. Some people call this ratio the “work-to-energy ratio.� Fig. 4 illustrates how the brakes’ thermal efficiency changed for diesel, DHO, DHOME, B60, and B60 with n-butanol at three different rates that were already mixed. The letters DHO and DHOME are dihydroxyacetone and dihydroxyacetone methyl ester, respectively. We did not do well because of this. Because of this, the fuel and air don’t mix well, worsening the combustion process and lowering the heat efficiency. The general level of thermal efficiency goes down because of this. Deccan hemp oil methyl ester can have much less volatility through transesterification. Because of this, combustion improves, and the heat efficiency increases everywhere and with all loads.

On the other hand, the engine that ran on methyl ester wasn’t as efficient as the one that ran on diesel. This is because methyl ester is less dense than diesel and has a smaller calorific value. Adding biodiesel, which is gasoline mixed with vegetable oil, to the fuel made it even more efficient.

The system’s thermal efficiency that uses Deccan hemp oil and its methyl ester and the 60% blend of methyl ester and diesel is higher when running with two fuel sources instead of one. This is true for both low-fuel load and high-fuel-load scenarios. On the other hand, its efficiency is about the same as diesel when 10% of the mass is made up of n-butanol. Running the engine with more n-butanol led to even higher thermal efficiency. Diesel is more efficient than the engine that has 10% n-butanol in it. It is very easy for n-butanol to evaporate once it is put into the intake pipe because it is very volatile. It also lowers the air’s temperature, making it denser because it has a high latent heat of vaporisation. Some people think this causes the spark delay to lengthen, which lets more fuel burn in the premixed phase and, in the end, makes the heat transfer more efficient. You could say that this is a good result of the situation.

Furthermore, when alcohol and air are mixed, they form a uniform mixture that burns more quickly, and the extra oxygen helps even more47,48,70,72. Diesel in the normal combustion mode had a 0.1%, a 4.71%, and an 8.1% increase in BTE for B60Bu10, B60Bu20, and B60Bu30, respectively. This was recorded when the engines were working with the most power.

Brake-specific energy consumption

Figure 5illustrates that BSEC changes for diesel, DHO, DHOME, B60, and B60 mixed with n-butanol at different already mixed input rates when the engine is part-loaded or fully loaded. All of these fuels show this difference. In single-fuel mode, when the machinery is fully loaded, the amount of energy used by the B60, DHOME, DHO, and diesel is 10.48, 12.25, and 10.94 MJ/kWh. The most energy was needed when the best vegetable oil was used. This is because the fuel had a lower calorific value and didn’t release as much heat when it burned. This means that more energy is needed to make the same amount of power, which means more energy is used. Biodiesel has a higher viscosity than regular diesel, so it uses more energy when you use it in your engine. The amount of extra energy used is directly related to the fuel’s viscosity. It is still better for the earth, even though the blend uses less energy than diesel. When diesel was added, the mix became less thick, had more oxygen, and had a higher calorific value. Not only that, but the blend had more oxygen in total. This made the burning better, meaning less energy was needed, and less energy was used overall. It was found that the BSEC went down when more n-butanol was added to the system. The BSEC for B60Bu10, B60Bu20, and B60Bu30 decreased by 9.5%, 18.6%, and 27.4% when put under full load conditions. Geo et al49. saw a similar drop in the car’s energy consumption while injecting alcohol into the intake manifold. While the car was being driven, this was written down. The delay in starting the combustion improved premixed combustion, which released more heat. This meant less fuel was burned to do more valuable work, reducing the energy needed to reach the goal. The burning took longer to start, which caused more heat to be released.

Exhaust gas temperature

Figure 6 illustrates that EGT changes when diesel, DHO, DHOME, B60, and B60 mixed with n-butanol are injected at different rates and when the engine runs at full or part load. These changes happen with all types of fuel. When the engine was running on a single fuel, DHO had the highest temperature in the exhaust gas at full load. Diesel, DHOME, and B60 were next. It was DHO fuel that made the temperature drop the most. The fuel for the DHO was the coolest of all of them. The spread combustion part of the process made a lot of heat, most of which was released when neat Deccan hemp oil was used as fuel. This meant less heat was used for work, and more heat was lost to the waste gas.

As a result, the exhaust gas got hotter, and the system’s thermal performance decreased. When the engine was run with diesel, Deccan hemp oil methyl ester, or a mix of the two, more heat was released during the premixed combustion phase. However, when the engine was run with diesel alone, the heat released did not change significantly. Because of this, the waste gas gave off less heat. When the engine was fully loaded, the exhaust gas temperatures were 380 degrees Celsius for fuel fractions B60Bu10, 372 degrees Celsius for B60Bu20, and 364 degrees Celsius for B60Bu30. The heat is then used to do useful work, which lowers the temperature of the waste gas and raises the engine’s thermal efficiency41,50,71,73.

Carbon monoxide emission

While an engine runs, carbon monoxide emissions show that the combustion process is not being carried out fully. In the combustion chamber, areas with many different fuel types make it hard for oxygen to reach the hydrocarbons reacting. This creates intermediate carbon monoxide fumes47. This is because oxygen is less available in areas with many rich blends. Because of this, carbon monoxide emissions are made in moderate amounts. A picture of the different amounts of carbon monoxide that the test fuels gave off is shown in Fig. 7. It is clear that when the engine is running at full load, it produces much more pollution than when it is running at part load. When the engine is going at full load, more fuel is injected, which makes it more likely that fuel-rich zones will form. This is because more fuel is released when the engine works full load.

Another problem that worsens is that there is less time for CO to change into CO2. When diesel, DHO, and DHOME run at full load, their CO emissions are 0.212%, 0.284%, and 0.214%, respectively. The B60’s CO emissions are also 0.212%. The higher viscosity of Deccan hemp oil stops the fuel molecules from breaking into smaller pieces during the pumping process. Because of this, these molecules won’t be able to burn at the start of the combustion process. This will cause intermediates like carbon monoxide to be made. There aren’t enough of these molecules for them to break down into water and CO2. Since the intermediaries will have less time and less air to burn as the flame moves forward, they cannot oxidise. This is because less air will reach the area as the flame moves. With DHOME and B60, the pollution can be lowered, and the results are the same as with diesel. Since these fuels don’t have as much volatility as DHO, the molecules in the fuel may break apart into smaller pieces very quickly. DHO is thicker than both fuels, which is why this is the case. This means the fuel molecules have enough air to burn, releasing less pollution.

It was adding n-butanol to the intake manifold cut down on the carbon monoxide output. When the vehicles carried the most weight, the B60Bu10, B60Bu20, and B60Bu30, all had lower CO emissions than diesel vehicles by 13.67%, 16.98%, and 19.34%, respectively. The lower CO emissions were caused by almost full combustion because the charge had more oxygen. The sample had more oxygen because n-butanol and biodiesel have small amounts of molecular oxygen. Because n-butanol cooled things down, the air in the intake manifold was denser than normal. This made it possible to add more air to the combustion chamber with each turn, raising the amount of oxygen there. Lower CO emissions were also caused by the alcohol fuel used instead of the blend because it had a low carbon level42. And this was one of the things that helped make the decrease possible.

Hydrocarbon emission

For B60, DHOME, DHO, diesel, and a few different premixed amounts of n-butanol input, Fig. 8shows the unburned hydrocarbon emissions. In the test, these amounts were used. Unburned hydrocarbon emissions are made when the fuel molecules inside the cylinder can’t get oxygen to burn when the temperature inside the cylinder is low or when the fuel molecules are close to the walls of the combustion chamber. The walls cool the flame out51. It is when fuels are burned incompletely that these pollutants are released. One of the loads that caused the most pollution was DHO, with 95 parts per million (ppm) of particulate matter in its releases, as shown in Fig. 8. This is always the case, no matter what load was used. The next one is DHOME, with a ppm of 76, then B60, with a ppm of 74, and finally diesel, with a ppm of 72.

As was already said, the molecule of Deccan hemp oil can’t break up into smaller pieces because the spray isn’t atomizing it enough. They can’t be broken up into smaller pieces, which is why this is the case. Because the molecule can’t be broken down into its bits, this is what happens. Because of this, less fuel is ready to be burned in the first part of combustion. This slows down the reaction, which slows down the rate at which heat is made. In this case, the temperature of the burning drops, which is an important step that needs to happen before the reaction can happen. The unburned fuel released into the air can’t be used during combustion. This increases the total amount of fumes that come from the burning process. Even though it burns better than DHO and makes less pollution, the methyl ester and its mix still pollute more than diesel. This is still the case, even though it is clear that burning is better than doing so with DHO. There is no difference between this and DHO regarding how well it burns, so this is always the case. At full load, the B60Bu10, B60Bu20, and B60Bu30 all released 71ppm, 67ppm, and 63ppm of unburned hydrocarbons.

After adding n-butanol, the molecules of the biodiesel mix have plenty of time to mix with the air and make a solid substance because the combustion process starts later. This is because the process of burning starts more slowly. This is because it takes longer for the process of burning to start. Once the burning process starts, the molecules in the air can mix with the oxygen in the air more quickly and easily. This makes heat. More heat will come out because of this, which directly results from what has happened. The flame moves faster after the alcohol is injected, which shows that it can quickly get to the cracks in the combustion chamber52,53. When n-butanol was added to the mixture, the average number of carbon atoms sent into the combustion chamber each cycle went down54,55. This was another important result. What we found was interesting and important. This happened because the n-butanol was involved in the process. There are several reasons why this discovery is so important, some of which are stated in the last sentence. All of these things have affected the reduction of the amount of unburned hydrocarbons found in the emissions, which has cut the total carbon footprint.

Oxides of nitrogen emission

When a vehicle runs on dual fuel, Fig. 9 shows how the levels of oxides of nitrogen emissions change based on the load for diesel, DHO, DHOME, B60, and different butanol-premixed ratios. This is true even if the car is running on butanol, which has already been mixed. Because of lean burn conditions, there is extra oxygen in the air, and the contents of the combustion chamber are exposed to high temperatures for a long time during burning. Both of these factors influence the release of oxides of nitrogen. Diesel (1738ppm), B60 (1725ppm), DHOME (1713ppm), and DHO (1588ppm) are the pollution levels when only one type of fuel is used. The premixed fuel burned more slowly, releasing less heat. This made the burning temperature lower. Since this was the case, NOx pollution decreased when DHO was used. More heat was released during the premixed phase when DHOME was used than when DHO was used. This led to a higher temperature during the burning process. The heat during the premixed process is even higher when mixed with 60% DHOME and diesel. Adding the DHOME increases the calorific value and the fuel’s cetane index. This is because there is more fuel available during this time because of the improvement.

Dual fuel mixtures release more nitrogen oxides (NOx) than diesel fuel. The rise is related to the amount of n-butanol in B60, which is true when the engine is part-loaded and fully loaded. These results came from the fact that diesel fuel gives off more nitrogen oxides (NOx) than dual-fuel mixtures. The B60Bu10, B60Bu20, and B60Bu30 engines all gave off 1784 ppm, 1842 ppm, and 1892 ppm of NOx running at full speed. The spark delay was longer because n-butanol with a low cetane index was added to the combustion chamber. In the premixed setting, more fuel can be burned, which raises the combustion temperature. In the beginning, when the gases burn, they squeeze the charge to a higher pressure, which causes the temperature to rise. It’s easy to get air, making NOx more likely to form. Molecular oxygen, which is found in biofuel and alcohol, is a form of oxygen that is easy to get. Gas at a high temperature is mixed with burning gas at a lower temperature in the growth process. Unfortunately, this causes NOx to freeze, making it less likely to break down. The results of more recent studies56,57,58, which also came to the same conclusions, back up these results.

Smoke emission

Figure 10 shows how the amount of smoke released changes with load for different n-butanol to B60 ratios. Figure 10 also shows these changes in a single fuel mode, with diesel, DHO, DHOME, and B60 as the fuels. At full load, the diesel, DHO, DHOME, B60, B60Bu10, B60Bu20, and B6Bu30 had smoke opacity levels of 48%, 67%, 42%, 44%, 39.2%, 36.6%, and 33.2%, in that order. They show the amounts of opacity for diesel, DHO, and DHOME in that order. The amount of opacity is much higher when the engine is in single-fuel mode than when it is in dual-fuel mode. The fuel is fed into the combustion chamber simply when the engine is running on a single fuel. This makes it more likely that rich zones will form, which will eventually cause fuel molecules to break down because there isn’t enough oxygen in the room.

The injection process can’t break up fuels with a higher viscosity into smaller pieces because they don’t flow as easily as fuels with a lower viscosity. This means there are times during the combustion process when the reaction between the fuel and oxygen molecules is very slow. This causes the combustion only partially to finish. In some areas, though, the fuel molecules are surrounded by the byproducts of their burning. These molecules are thermally broken without oxygen because of the high temperature, which makes soot59. The n-butanol and air are mixed evenly before being burned together in a dual-fuel combustion process. The burning process starts when the mixture is put into the room where it will happen. However, because n-butanol slightly cools the charge, the combustion process starts a little later than usual in normal circumstances. It burns cleanly because n-butanol starts the burning process already mixed with air. This means less soot is produced overall as the other molecules in the mixture look for oxygen to burn. Because n-butanol cools things down, the air becomes denser. These changes mean that more air is sucked in, which lowers pollution60, as does the fuel having oxygen in it. The numbers also show that the amount of n-butanol replacement and the level of emissions are related in a way that can’t be imagined. The fact that the association was negative showed this to be true. More fuel that has already been mixed is being put into the combustion area, reducing the amount of smoke made.

Cylinder pressure

When you can’t change how the fuel burns, the rate at which pressure rises inside the combustion chamber is directly related to the fuel’s amount. It would help if you looked into this feature to know more about a CI engine’s burning process. In Fig. 11, you can see how the pressure inside the cylinder changes when fully loaded. All of the different fuel samples that were tried showed this effect61,62,63,64,65. The cylinder pressure was the lowest of all the tried fuels because DHO caused the fuel to burn poorly. It can also be demonstrated that DHO combustion starts later than gasoline and DHOME combustion. As a result, the peak pressure moves farther away from TDC. DHO has less energy per unit volume than gasoline and DHOME. Unrefined Deccan hemp oil has a low cetane number and a low calorific value. It’s very thick and doesn’t flow easily. It takes longer for the burning process to start because of this, and there will be less fuel to burn when it does. There will be less fuel that can be burned, in other words. Also, less heat will be released because the calorific value has decreased. This will cause the peak pressure to go down no matter how much fuel is burned. The high pressure will go down because of this. Peak pressure goes up when the transesterification process is done on the oil. Also, the time it took for the burning process to begin was longer than usual, which is more typical of diesel. Diesel, DHOME, and B60 engines all had cylinder peak pressures of 71.91 bar at full load. DHO and B60 engines had pressures of 70 bar, and B60 engines had pressures of 66 bar.

When the engine was running in the dual fuel mode, the pressure inside the cylinder went up. This rise was followed by another rise in pressure as the amount of alcohol added rose. For the B60Bu10, the highest pressure in the cylinder was 74.45 bar; for the B60Bu20, it was 75.07 bar; and for the B60Bu30, it was 75.92 bar. This was when the engines were going full speed. Since n-butanol cools things down and has a smaller cetane number than other alcohols, it takes longer for the combustion process to start. This is because some alcohols have a bigger cetane number. It will take longer for this effect to wear off if there is more alcohol in the mix. Additionally, this means that the pumped biodiesel blend has more time to mix, leading to a quick release of energy and, ultimately, a rise in peak cylinder pressure. The high oxygen level in the combustion chamber makes the fuel burn faster, which raises the highest cylinder pressure60.

Heat release rate

It is one of the most important things to consider when understanding how burning works inside an internal combustion engine. You can get the desired result by applying the rules of thermodynamics to the pressure inside the cylinder. The differences in how fast each test fuel sample gives off heat when the engine is fully loaded are shown in Fig. 12, along with the crank angle. It happens when the engine is being used to its fullest capacity. As you can see, both diesel and Deccan hemp oil biodiesel can get rid of heat in the same way. One could say that the burning process starts a lot earlier with DHOME than with DHO. This might be because DHOME has a higher cetane number than DHO but a smaller calorific value.

Another thing is that adding n-butanol in dual fuel mode slowed down the spark because this alcohol has a low cetane number. Because of this delay, more fuel could be burned during the premixed combustion phase, which released more energy. With all of them running at full load, these engines give off heat at the following rates: 41.31 J/°CA for diesel, 32.82 J/°CA for DHO, 41.09 J/°CA for B60, 42.01 J/°CA for B60Bu10, 52.58 J/°CA for 58.59 J/°CA for B60Bu30, and 64.11 J/°CA for B60Bu1066,67,68,69.

In this study, a compression ignition engine was run in dual fuel mode with three different rates of n-butanol injection and a 60% Deccan hemp oil methyl ester blend. Here is a table that shows the results of this study. Compared to diesel in normal combustion mode, the BTE increased by 0.1% for the B60Bu10, 4.71% for the B60Bu20, and 8.1% for the B60Bu30 when running at full load. BSFC dropped 7.3% in B60Bu20 when running at full load compared to diesel, and it dropped 5% in B60Bu30 when the same conditions were used. Whenever the driver decided to drive the car in dual fuel mode, the exhaust gas temperature (EGT) dropped quickly. Compared to diesel, B60Bu10 had 13.67% less CO pollution, 16.98% less for B60Bu20, and 19.34% less for B60Bu30. When the B60 engine was run on n-butanol, it was discovered that the vehicle’s hydrocarbon (HC) emissions went down by 7.94–16.69% when fully loaded. When the engine was running at full load, B60Bu30 caused 8.86% more NOx to be released than diesel fuel. More pressure and heat were released from the cylinder for B60Bu10, B60Bu20, and B60Bu30 fuel amounts than diesel. The higher the butanol share, the more pressure and heat were released. It was found that these effects were better than those of diesel. Based on the results, it’s safe to say that green fuels can be used instead of traditional fuels when the engine is in dual-fuel mode. This makes the engine run better and cuts down on exhaust emissions by a significant amount.