Combining a Diesel Particulate Filter and Heat Exchanger for Waste Heat Recovery and Particulate Matter Reduction

Significant progress towards reducing diesel engine fuel consumption and emissions is possible through the simultaneous Waste Heat Recovery (WHR) and Particulate Matter (PM) filtration in a novel device described here as a Diesel Particulate Filter Heat Exchanger (DPFHX). This original device concept is based on the shell-and-tube heat exchanger geometry, where enlarged tubes contain DPF cores, allowing waste heat recovery from engine exhaust and allowing further energy capture from the exothermic PM regeneration event. The heat transferred to the working fluid on the shell side of the DPFHX becomes available for use in a secondary power cycle, which is an increasingly attractive method of boosting powertrain efficiency due to fuel savings of around 10 to 15%. Moreover, these fuel savings are proportional to the associated emissions reduction after a short warm-up period, with startup emissions relatively unchanged when implementing a WHR system. Due to the absence of prior DPFHX research and the unique heat transfer process present, this effort describes construction of a prototype DPFHX and subsequent WHR experiments in a single cylinder diesel engine test cell with a comparison between heat exchanger performance with and without DPF cores installed. Furthermore, the paper discusses the implications of installing the DPFHX within a diesel engine exhaust stream, including the effects on engine performance and the sequencing of aftertreatment devices, as well as several other practical considerations. Finally, this paper discusses alternative DPFHX designs from the perspectives of performance and manufacturing.