One of the key requisites for a sustained mobility development is to have an efficient public transport system. Fuel efficiency and emission control are extremely important in this respect. By the very nature of city driving, it is obvious that city traffic results in frequent vehicle start and stops; which involves huge waste of vehicle kinetic energy. Every time vehicle moving from idle, needs a bigger input of power and every time the brakes are applied, all energy built up disappears again, wasted in the brake pads as heat.
An effort has been taken to recuperate vehicle kinetic energy, hydraulically during braking events and utilize it to assist the vehicle during acceleration. Hydraulic based hybrid vehicle working on the principle of regenerative braking is one of the most fuel-efficient technologies for city application. Parallel hydraulic hybrid vehicle has been developed and optimized for fuel efficiency gain at vehicle level.
Objective of this paper is to study behavior, performance and optimization of hydraulic hybrid vehicle in city application. This paper deals with evaluation of simulation, integration, calibration and performance tests carried out at real world usage conditions. As a final proof of concept and performance, the hydraulic hybrid bus was tested back to back with conventional city bus of same configuration and results were analyzed and compared. This paper also deals on the scope of engine downsizing and major challenges faced in developing hydraulic hybrid system for extremely hot weather conditions such as South Asian countries.