Kinetic Energy Recovery Systems - KERS.
2011 sees the return of KERS to F1. This article is to explain just what Kinetic energy is and how it is recovered and used in F1 or any vehicle for that matter. Kinetic energy and its use is not something new, it has been utilised by man for centuries. An example, windmills are powered by the kinetic energy in the wind.
All of the above pictures are examples of kinetic energy.
Water wheels and hydro electric power stations are both powered by the kinetic energy provided by water movement. Kinetic energy is quite simply the power of motion. Nothing more complicated than that. Any object that is moving generates kinetic energy. Be it a car, truck, train, or simply someone running.
What is so misrepresented by the F1 press and misunderstood is how that energy is harvested and then reused to power the vehicle.
Calculating the kinetic energy of any mass that is moving is a relatively simple equasion.
· Step 1
Figure out what object on which you want to calculate the kinetic energy.
· Step 2
Determine the mass of the object that is in motion. The mass of an object is the measure of how much matter is in an object.
· Step 3
Determine the velocity of the object that is in motion. The velocity of an object is the speed of that object.
· Step 4
Multiply the object's velocity to itself in order to obtain the square of the velocity (velocity times velocity).
· Step 5
Kinetic Energy Formula
Multiply the value you calculated in Step 5 (mass) by the value you calculated in Step 4 (velocity). You now have the kinetic energy of the object.
There are various methods of calculating kinetic energy but for this article this is the simplest method.
Now, how that energy is harvested and stored? This is what is so badly reported and misunderstood. Kinetic energy is not recovered from the brakes. Indeed the brakes do what they have always done which is convert the kinetic energy into heat which is then dissipated into the atmosphere.
The engine plays no part at all in recovering kinetic energy. At the time you are recovering the kinetic energy the engine is doing nothing. It is on a closed throttle and producing no power at all. In fact it is assisting in the braking process by providing additional braking power generated by its compression.
Try pushing your car in gear. That’s engine braking.
The only relationship between braking and harvesting kinetic energy is that at that time you are trying to dissipate kinetic energy and instead of converting it all to heat via the brakes, you could use it to power a generator and produce electricity.
When the driver applies the brakes he simply engages a switch, to all intents and purposes exactly the same as the stop light switch on your car. That engages the generator and electricity is generated which is then stored in a power cell. This is actually a battery, but it bears no resemblance to the huge black lead acid battery in your car, or the batteries used in the current range of hybrid vehicles which occupy a great deal space and are also very heavy.
The electrical resistance of the generator does provide some braking effect but the remainder is still converted to heat by the traditional braking system.
Initially, the regulations limit the power of the KERS systems to 60kw (around 80 horsepower) and the storage capacity of the energy is 400kJ (kilojoules) per lap. What in effect this means is an extra 80 horsepower available for 6.7s per lap.
The system pictured below is the Magnetti Marelli system as fitted to Ferrari.
In 2009 the battery was located below the fuel tank which is not really possible in 2011.
This of course is due to the much larger fuel tanks required for the no refuelling regulations still in place for 2011.
To accommodate all of this for 2011 is a major technical challenge to the chassis builders and the systems designers..