Assessment of Future Scope of Waste Heat Recovery System for IC Engine Powertrain Vehicles of Highway and Off-Highway Applications

In this article we summarize the major types of waste heat recovery ( WHR) systems developed and tested. The primary use of WHR system is to increase the fuel economy by minimum 3% from the energy recovery from the exhaust system ( 300-400 deg C ) instead of released to environment, which has heat energy about 18 ~ 25% of total fuel energy. There are 3 types of energy recovery system is discussed in detail, namely (1) thermoelectric devices (TED) to generate electrical energy directly, (2) Turbo-compound system and (3) Rankine cycle-based systems used to generate mechanical energy and that is transferred to crankshaft. Depend on these different technical approaches, there is a potential for up to 5% improvement in fuel economy and CO2 reduction , which can be achieved by generating mechanical or electrical power from exhaust energy using WHR system. However, the payback period for introduction of this WHR system to be taken into consideration while developing new system for the highway and off-highway applications. This paper concludes the benefits of each type of system with its limitations and scope of future potential for heady duty applications.