On Handling Waste Heat from Waste Heat Recovery Systems in Heavy-Duty Vehicles 2015-01-2792

The automotive industry have become more and more interested in recovering waste heat from internal combustion engines, especially with future, tighter fuel and CO2 emission regulations in sight.

In this study, we consider an automotive Rankine Waste Heat Recovery System on a long-haulage truck. This system transforms some of the combustion engine's waste heat into useful energy, but it still needs to return remaining heat to the surrounding, either through a direct condenser or from an indirect condenser via a Low Temperature Radiator, and this in the regular cooling module of the vehicle.

We focus on the integration of WHR-dedicated LTR or condenser into a generic, conventional truck-cooling module with an AC condenser, a cross-flow Charge Air Cooler, a down-flow High Temperature Radiator, and a fan. WHR cooling concepts considered are an indirect system with LTR; either in front or back of CAC, a direct system with condenser either in front or back of CAC. In addition, there is a discussion on various modeling problems on the 0D- and component sizing tools used.

The results show that it is important to consider when the WHR system is engaged and when it should be bypassed, how to maintain charge air- and coolant cooling needs, and when the fan need to be engaged. It is very dependent on where the LTR or condenser is placed, but at higher loads (∼75%) one should expect that additional fan work could easily be as much as 40% of the regained Rankine system work.