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February 10, 2020
What is Octane Number? How rating of SI Engines (Spark ignition engines) is done using an octane number?

The hydrocarbon fuels used in spark ignition (S.I.) engine have a tendency to cause engine knock when the engine operating conditions become severe. The knocking tendency of a fuel in S. I. engines is generally expressed by its octane number. The percentage, by volume, of iso-octane in a mixture of iso-octane and normal heptane, which exactly matches the knocking intensity of a given fuel, in a standard engine, under given standard operating conditions, is termed as the octane number rating of that fuel. Thus, if a mixture of 50 percent iso-octane and 50 percent normal heptane matches the fuel under test, then this fuel is assigned an octane number rating of 50. If a fuel matches in knocking intensity a mixture of 75 percent iso-octane and 25 percent normal heptane, then this fuel would be assigned an octane number rating of 75. This octane number rating is an expression which indicates the ability of a fuel to resist knock in a spark ignition engine.

Since iso-octane is a very good anti-knock fuel, therefore it is assigned a rating of 100 octane number. On the other hand, normal heptane has a very poor anti-knock qualities, therefore, it is given a rating of zero octane number. These two fuels, i.e., iso-octane and normal heptane are known as primary reference fuels. It may be noted that higher the octane number rating of a fuel, the greater will be its resistance to knock and higher will be the compression ratio. Since the power output and specific fuel consumption are functions of compression ratio, therefore we may say that these are also functions of octane number rating. This fact indicates the extreme importance of the octane number rating in fuels for S. I. engines.

Note: The octane number of petrol, generally available, is 80 to 100.
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November 27, 2019
The primary difference between Petrol and Diesel engines is that the Petrol engine works on the Otto cycle whereas the Diesel engine works on the Diesel cycle. Other differences can be attributed to the structure, types, and uses of these engines. The main parameter they are classified on is the type of fuel they use. Generally, Engines run on the principle of heat transfer.

Petrol Engine

●      Petrol engines are internal combustion engines which have spark-ignition. They run on relatively volatile fuels such as petrol.
●      In these engines, air and fuel are generally mixed post-compression.
●      Petrol engines work on the Otto cycle, which consists of two isochoric processes and two isentropic processes.
●      In petrol engines, air and petrol are usually mixed in a carburettor before being introduced to the cylinder.
●      Once the air and petrol are compressed, the fuel is ignited via an electric spark.Difference Between Petrol and Diesel Engine

Diesel Engine

●      The Diesel engine is also an internal combustion engine which is also known as the compression-ignition engine. It is named after Rudolf Diesel.
●      In these engines, the fuel is injected into a combustion chamber and is then ignited by the high temperature of the air in the chamber.
●      The high temperature of the air in the cylinder is due to the adiabatic compression. These engines only compress the air and not the fuel.
●      When injected into the combustion chamber, the Diesel fuel undergoes spontaneous ignition.
●      These engines work on the Diesel cycle, which consists of a constant pressure process, a constant volume process, and two isentropic processes. Difference Between Petrol and Diesel Engine Diagram

Difference between Petrol and Diesel Engine

Apart from the type of fuel used, the engines are also divided on the basis of a lot of things, such as the presence of a spark plug in Petrol engines and a fuel injector in Diesel engines. We also know that lighter vehicles such as motorcycles, scooters, and cars typically use petrol in their engines whereas Diesel is used in much heavier machinery such as tractors, trucks, and buses. Thus, the types of fuel used also plays a major role in defining the major difference between Petrol and Diesel engines. More differences between these types of engines are listed in the tabular column below.


S.no
Petrol Engines
Diesel Engines
1
A petrol engine draws a mixture of petrol and air during the suction stroke.
A diesel engine draws only air during the suction stroke.
2
The carburetor is installed in petrol engines to mix air and petrol in the required proportion and to supply it to the engine during the suction stroke.
The injector or atomizer is installed in diesel engines to inject the fuel at the end of the compression stroke.
3
The pressure at the end of the compression is about 10 bar.
The pressure at the end of the compression is about 35 bar.
4
The charge (i.e. petrol and air mixture) is ignited with the help of spark plug.
The fuel is injected in the form of a fine spray. The temperature of the compressed air is about 600° C at a pressure of about 35 bars.
5
A petrol engine has compression ratio approximately from 6 to 10.
A diesel engine has compression ratio approximately from 15 to 25.
6
The combustion of fuel takes place approximately at constant volume. In other words, it works on Otto cycle.
The combustion of fuel takes place approximately at constant pressure. in other words, it works on Diesel cycle.
7
The thermal efficiency is up to about 26%.
The thermal efficiency is up to about 40%.
8
Overheating trouble is more in petrol engine due to low thermal efficiency.
Overheating trouble is less in diesel engine due to high thermal efficiency.
9
The starting of petrol engine is easy due to low compression ratio.
The starting of the diesel engine is slightly difficult due to higher compression ratio compared to a petrol engine.
10
As the compression ratio is low, the petrol engines are cheaper and lighter in weight.
As the compression ratio is high, the diesel engines are costlier and heavier in weight.
11
The running cost of petrol engine is high because of the higher cost of petrol fuel.
The running cost of the diesel engine is low because of the lower cost of diesel fuel.
12
The maintenance cost is less.
The maintenance cost is more.
13
Petrol engines are high-speed engines.
Diesel engines are relatively low-speed engines.
14
The petrol engines are are installed in light duty vehicles such as scooters, motorcycles, cars. These are also used in airplanes.
The diesel engines are are installed in heavy-duty vehicles such as buses, trucks, tractors, earth moving machines, etc.



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July 30, 2019
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:
Bad fuel mix - A bad fuel mix can occur in several ways:
· You are out of gas, so the engine is getting air but no fuel.
· The air intake might be clogged, so there is fuel but not enough air.
· The fuel system might be supplying too much or too little fuel to the mix, meaning that combustion does not occur properly.
· There might be an impurity in the fuel (like water in your gas tank) that makes the fuel not burn.
Lack of compression - If the charge of air and fuel cannot be compressed properly, the combustion process will not work like it should. Lack of compression might occur for these reasons:
· Your piston rings are worn (allowing air/fuel to leak past the piston during compression).
· The intake or exhaust valves are not sealing properly, again allowing a leak during compression.
·  There is a hole in the cylinder.
The most common "hole" in a cylinder occurs where the top of the cylinder (holding the valves and spark plug and also known as the cylinder head) attaches to the cylinder itself. Generally, the cylinder and the cylinder head bolt together with a thin gasket pressed between them to ensure a good seal. If the gasket breaks down, small holes develop between the cylinder and the cylinder head, and these holes cause leaks.
Lack of spark - The spark might be nonexistent or weak for a number of reasons:
· If your spark plug or the wire leading to it is worn out, the spark will be weak.
· If the wire is cut or missing, or if the system that sends a spark down the wire is not working properly, there will be no spark.
· If the spark occurs either too early or too late in the cycle (i.e. if the ignition timing is off), the fuel will not ignite at the right time, and this can cause all sorts of problems.

Many other things can go wrong. For example:
·If the battery is dead, you cannot turn over the engine to start it.
·If the bearings that allow the crankshaft to turn freely are worn out, the crankshaft cannot turn so the engine cannot run.
·If the valves do not open and close at the right time or at all, air cannot get in and exhaust cannot get out, so the engine cannot run.
·If someone sticks a potato up your tailpipe, exhaust cannot exit the cylinder so the engine will not run.
·If you run out of oil, the piston cannot move up and down freely in the cylinder, and the engine will seize.
In a properly running engine, all of these factors are within tolerance.

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October 01, 2016
IMPOSSIBLE_QUANTUM_SPACE_ENGINE

A couple of years ago, researchers at NASA’s Johnson Space Centre discovered a thruster system which actually generates thrust, despite requiring absolutely no propellant. The implications of this discovery are far-reaching; applications for space flight and other technologies which require propulsion could one day become far cheaper, allowing space exploration to expand exponentially. The existence of this technology also further validates the fact that energy can be derived from tapping into the quantum vacuum, also known as “zero-point.”
Bottom line is that space is not empty, and the energy which lies within it can be used. This was experimentally confirmed when  the Casimir Effectillustrated zero point or vacuum state energy, which predicts that two metal plates close together attract each other due to an imbalance in the quantum fluctuations(source)(source).
The propellant-less thruster is called the Cannae Drive, invented by Guido Fetta, and was tested by NASA over an eight day testing campaign that took place in August of 2013. It’s also known as the EM drive.  It showed that a small amount of thrust was achieved inside a container, again, without the use of any fuel. The results were then presented at the 50th Joint Propulsion Conference in Cleveland, Ohio in July the next year.
You can access the paper (titled “Numerical and Experimental Results for a Novel Propulsion Technology Requiring no On-Board Propellant”) that was presented at the conference here and inventor Guido Fetta’s paper here.
Now, it’s about to be launched into spacee, and, according to many, like ScienceAlert.com,  the EM “is as controversial as it gets, because while certain experiments have suggested that such an engine could work, it also goes against one of the most fundamental laws of physics we have.
It’s a law that Issac Newton derived, called the law of conservation of momentum, which states that an equal and opposite reaction must stem from an action.  In order for something to gain momentum it must expel some kind of propellent in the opposite direction, but not the EM drive, this invention taps into the ‘zero-point’ field of energy/electromagnetic waves, creating thrust by microwave photons bouncing around inside a cone shaped metal cavity. The cone shaped mental cavity is what accelerates it into the opposite direction.
This is exciting, because it basically proves that we have a limitless resource of energy to tap into and utilize for space travel.  This is currently the biggest barrier for modern day space travel and exploration.

It’s Time For The Laws Of Physics To Be Changed

We knew the Earth was flat, we knew that we were the centre of the universe, we knew that a man made heavier than air peace of machinery could not take flight. Through out human history, intellectual authorities have pronounced their supremacy by ridiculing or surpressing elements of reality that simply didn’t fit within the framework of accepted knowledge  – Terje Toftenes (taken from the film, The Day Before Disclosure)
Science needs to be careful and stray for from getting  caught up in the grip of scientific dogma. History has constantly shown us, especially within the realms of science, that what we accept as real always changes at another point in time. Our understanding and knowledge regarding the nature of our reality is constantly changing.
“There is nothing new to be discovered in physics now. All that remains is more and more precise measurement.” This statement (worldview statement) was made by Lord Kelvin in 1900, which was shattered five years later when Einstein published his paper on special relativity. This one great, out of many.
Today, engineers are inventing power generators that utilize these concepts, like Paramahamsa Tewari .
These laws need to be refined to account for the fact that space is not empty,
What we currently accept as fact is going to have to change, and developments like the EM drive, or electrical generators that used these concepts, are going to have to be acknowledged soon. Throughout history, new developments in fields such as energy have always taken their time to find it into the market place. In today’s world, there’s always a lot of Red Tape you’re going to have to go through, unfortunately.
Below is a short clip of former NASA astronaut and Princeton Physics Professor Dr. Brian O’leary speaking about these energy concepts:

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