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The paper presents a comprehensive analysis to identify the brake energy recovery potential of different technical solutions and physical principles, relative to the mechanical principle, based on a flywheel. The study considers the stored energy capacity, the energy density and the time response, both during braking and accelerating conditions. The flywheel solution is considered working under open air conditions and under vacuum conditions. It is emphasized to identify the influence of air resistance as energy dissipation source of flywheels for different vacuum parameters. The analysis is performed using an analytical model and a CFD model, based on the Lattice – Bolzmann method for different rotational speeds and mass. Limitation of the mass / speed correlation is the mechanical strength of the flywheel, for three different flywheel designs. The recovery potential is analyzed considering three braking and accelerating events with different intensities. The study is applied to a mini-mobile vehicle, having a mass of 250 kg. The reference parameters are recovered energy for the different scenarios, complexity and total mass identifying the energy density of the adopted solution and its parameter sensitivity. Finally different recovery principles, like mechanical electrical battery, electrical ultracapacitor and hydro-pneumatic solution are compared in terms of stored energy, time response and mass.

Automotive Engineering