Waste Heat Recovery on a Diesel-Electric Hybrid Bus Using a Turbogenerator 2012-01-1945
An increase in global oil consumption, coupled with a peak in oil production, has seen the price of fuel escalate in recent years, and consequently the transport sector must take measures to reduce fuel consumption in vehicles. Similarly, ever-tightening emissions legislation is forcing automotive manufacturers to invest in technology to reduce toxic emissions.
In response to these concerns, this project aims to address one of the fundamental issues with the Internal Combustion Engine - approximately one third of the fuel energy supplied to the engine is lost as heat through the exhaust system. The specific aim of this project is to reduce the fuel consumption of a diesel-electric hybrid bus by recovering some of this waste heat and converting it to useful power.
This report details how turbocompounding can be applied to the engine, via the inclusion of a turbogenerator, and assesses its waste heat recovery performance. A brief state of the art of turbocompounding is presented along with an evaluation of its suitability for a hybrid bus application.
A one-dimensional engine model was developed using WAVE, and was validated against extensive experimental data. Subsequently, a turbogenerator was included in the model and the effects on fuel consumption are investigated. The size of the turbogenerator turbine was optimised to study the power output and fuel consumption benefit at various engine load and speed points, while a plan to further improve the overall configuration is also presented.