KINETIC ENERGY RECOVERY SYSTEM

 KINETIC ENERGY RECOVERY SYSTEM

A kinetic energy recovery system (often known simply as KERS) is an automotive system for recovering a moving vehicle's kinetic energy under braking. The recovered energy is stored in a reservoir (for example a flywheel or high voltage batteries) for later use under acceleration. Formula One has stated that they support responsible solutions to the world's environmental challenges, and the FIA allowed the use of 60 kW (82 PS; 80 bhp) KERS in the regulations for the 2009 Formula One seasonTeams began testing systems in 2008: energy can either be stored as mechanical energy (as in a flywheel) or as electrical energy (as in a battery or supercapacitor). Kimi Räikkönen took the lead of the 2009 Belgian Grand Prix with a KERS-aided overtake and subsequently won the race. With the introduction of KERS in the 2009 season, only four teams used it at some point in the season: Ferrari, Renault, BMW and McLaren. Eventually, during the season, Renault and BMW stopped using the system. Vodafone McLaren Mercedes became the first team to win a F1 GP using a KERS equipped car when Lewis Hamilton won the Hungarian Grand Prix on July 26, 2009. Their second KERS equipped car finished fifth. At the following race, Lewis Hamilton became the first driver to take pole position with a KERS car, his team mate, Heikki Kovalainen qualifying second. This was also the first instance of an all KERS front row. On August 30, 2009, Kimi Räikkönen won the Belgian Grand Prix with his KERS equipped Ferrari. It was the first time that KERS contributed directly to a race victory, with second placed Giancarlo Fisichella claiming "Actually, I was quicker than Kimi. He only took me because of KERS at the beginning"

TYPES OF KERS

There are two basic types of KERS systems:

Electrical and Mechanical. The main difference between them is in the way they convert the energy and how that energy is stored within the vehicle

WORKING PRINCIPLE

ELECTRICAL KERS

In electrical KERS, braking rotational force is captured by an electric motor / generator unit (MGU) mounted to the engines crankshaft. This MGU takes the electrical energy that it converts from kinetic energy and stores it in batteries. The boost button then summons the electrical energy in the batteries to power the MGU. The most difficult part in designing electrical KERS is how to store the electrical energy. Most racing systems use a lithium battery, which is essentially a large mobile phone battery.

Batteries become hot when charging them so many of the KERS cars have more cooling ducts since charging will occur multiple times throughout a race. Super-capacitors can also be used to store electrical energy instead of batteries; they run cooler and are debatably more efficient.

MECHANICAL KERS

The concept of transferring the vehicle’s kinetic energy using flywheel energy storage was postulated by physicist Richard Feynman in the 1950. The mechanical KERS system has a flywheel as the energy storage device and it does away with MGUs by replacing them with a transmission to control and transfer the energy to and from the driveline. The kinetic energy of the vehicle ends up as kinetic energy of a rotating flywheel through the use of shafts and gears. Unlike electrical KERS, this method of storage prevents the need to transform energy from one type to another. Each energy conversion in electrical KERS brings its own losses and the overall efficiency is poor compared to mechanical storage. To cope with the continuous change in speed ratio between the flywheel and road-wheels, a continuously variable transmission (CVT) is used, which is managed by an electro-hydraulic control system. A clutch allows disengagement of the device when not in

Braking at the wheels dissipates the kinetic energy of the vehicle that is therefore completely lost. Conversely, KERS may store the kinetic energy of the vehicle during braking and return it under acceleration. The system utilises a flywheel as the energy storage device and a Continuously Variable Transmission (CVT) to transfer energy to and from the driveline to the rotating flywheel. The transfer of the vehicle kinetic energy to the flywheel kinetic energy reduces the speed of the vehicle and increases the speed of the flywheel. The transfer of the flywheel kinetic energy to the vehicle kinetic energy reduces the speed of the flywheel and increases the speed of the vehicle. The CVT is used because the ratios of vehicle and flywheel speed are different during a braking or an acceleration event. can change steplessly through an infinite number of effective gear ratios between maximum and minimum values. This contrasts with other mechanical transmissions that offer

ADVANTANGE OF MECHANICAL KERS OVER ELECTRICAL KERS

 Battery-based electric hybrid systems require a number of energy conversions each with corresponding efficiency losses. On reapplication of the energy to the driveline, the global energy conversion efficiency is 31–34%. The mechanical hybrid system storing energy mechanically in a rotating fly wheel eliminates the various energy conversions and provides a global energy conversion efficiency exceeding 70%, more than twice the efficiency of an electric system.