Braking energy

Electrochemical capacitors have been studied for many years. The first patents date back to 1957, where a capacitor based on high surface area carbon was described by Becker. Later in 1969 first attempts to market such devices were undertaken by Standard Oil Company of Ohio (SOHIO). However, only in the 1990s did electrochemical capacitors become famous in the context of hybrid electric vehicles. The electrochemical capacitor (EC) was supposed to boost the battery or the fuel cell in the hybrid electric vehicle to provide the necessaiy power for acceleration, and additionally allow for recuperation of brake energy (Viswanathan, 2006). 

Braking energy is preferably recovered in supercapacitors with an efficiency of 90%. 

Toyota s Prius uses the heavy, range-limited nickel-metal hydride battery, basically because it is safe. The Prius recaptures the braking energy (instead of wasting it in friction) and runs on electric power in stop-and-start traffic, but its all-electric mode of operation is limited. Toyota s Prius is also available in a version that has been converted to hydrogen by Quantum Fuel Systems. Toyota is planning to have a hybrid version of all its 2010 models. 

The fabrication of supercapacitors and electrochemical actuators that could be used as artificial muscles is another alternative for nanotube applications. Supercapacitors already were built on hybrid vehicles because this could provide rapid acceleration and store braking energy electrically. When using sheet electrodes with SWNT and MWNTs, it is possible to obtain specific capacitance of 180 and 102 F/g and power densities of 20 and 8kW/kg, respectively. 

NVH As mentioned in the section on Tribology, some braking energy is converted into vibration and sound energy. Just as in the tests used for wear characterization, several dynamometer and vehicle tests have been developed to characterize the NVH-generating tendency of brake systems. Dynamometer tests are conducted with the brake corner or a whole vehicle mounted in a controlled environmental chamber. 

Consideration of new technology elements (e.g. variable valve timing, exhaust gas recovery, brake energy recovery, etc.). 

Considering the evaluation of the life time of elastomer, Samay et al. pointed out that tensile strength has the same importance as ultimate elongation has. They proposed Braking Energy (BE) to estimate the life time of elastomer (J). Equation 1 defined BE. 

By means of clever combinations of mechanical drive-trains with appropriate gearing and clutches, a single electrical engine may operate for propulsion/ acceleration assist of the ICE, for recuperation of braking energy, and for battery recharge. This would save both weight and cost. The battery may supply electrical... 

In the future, the role of the ICE may be taken by a fuel cell that directly provides electrical energy for driving. This will not, however, remove the need for a battery, as a fuel cell is normally not able to operate as an electrolyzer. An electrical-storage device will still be required for recovery of braking energy as well as for peak power shaping and for supplying auxiliaries ( consumers ) at stand still. 

As a part of an interdisciplinary study [2] we are working on emission control catalysis for an extended hybrid concept (fig. 1). The heart of this hybrid system is a flywheel, equipped with a continuous variable transmission. This permits the flywheel to be accelerated with the intermittently operated combustion engine or the electrical engine independently of the speed of the vehicle. The flywheel is then used to accelerate the car and to store braking energy. The fl)nvheel concept allows the recuperation of... 

Application Normal braking energy absorbed kJ kg Emergency braking energy absorbed kJ kg ... 

Ni-MH batteries have application in hybrid electric vehicles and portable electronic devices, such as cameras, shavers, toothbrushes, etc. The Ni-MH battery is also used in hybrid cars to improve stop-start and acceleration performance. It absorbs braking energy to assist the breaking operations and during the acceleration, returns that energy to supplement the gas engine. 

RESS designs are modularized for broader industry adoption and include programmable power control hardware and software and interfaces. The RESS can be optimized for diverse bus applications and routes and is placed usually on the bus roof, although it is liquid cooled. Some are LIB-based, while others include ucaps and, if needed, blended options [33] of batteries with ucaps able to rapidly store and deliver on demand energy from either an APU or from saved regenerative braking energy. 

Brake energy regeneration (possibility of recovering part of the braking energy). 

Brake energy regeneration (as in mild and medium hybrids). 

Kinetic Energy and 40% Regenerative Braking Energy Recovery... 

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