Abstract
Signifcant progress towards reducing diesel engine fuel
consumption and emissions is possible through the
simultaneous Waste Heat Recovery (WHR) and Particulate
Matter (PM) fltration 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 fuid 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 effciency 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.
Introduction
Over the past few decades, periods of high fuel costs along
with concerns over imported oil have gone alongside the
emphasis to lower hazardous engine emissions including
greenhouse gases. As a result, the reduction of fuel
consumption and emissions have emerged as the two main
avenues to advance engine technology. Conventional
approaches to improve thermal effciency include Variable
Valve Timing (VVT), intake charge boosting, and direct
injection technology for spark ignition engines [1]. Moreover,
signifcant research is underway in the area of advanced
combustion regimes such as Homogeneous Charge
Compression Ignition (HCCI) and Pre-mixed Charge
Compression Ignition (PCI) that have the potential for high
thermal effciencies. These techniques require increasingly
complex engine designs and control architectures where
further decreases in fuel consumption are burdened by
signifcant hardware costs. Furthermore, the Low Temperature
Combustion (LTC) regimes of HCCI and PCI can only be
employed at lower loads because of the signifcant pressure
rise that occurs [2]. In addition, incremental lowering of
emission levels are causing engine manufacturers to limit
combustion temperatures and pressures, decreasing potential
effciency gains.
Among the exhaust species subject to Environmental
Protection Agency (EPA) regulations under the Clean Air Act
are particulate matter (PM), hydrocarbons (HC), carbon
monoxide (CO), and nitrogen oxides (NO
x
) [3], with future
legislation targeting carbon dioxide (CO
2
) on the horizon. To
meet these standards, Compression Ignition (CI) engine
manufacturers are utilizing signifcant levels of cooled Exhaust
Gas Recirculation (EGR) along with multiple in-cylinder fuel
injection events in order to decrease combustion temperatures
since NO
x
increases exponentially with temperature through
the thermal NO mechanism [4]. This method subsequently
diminishes the effciency of CI engines because of the reduced
work available due to lower combustion pressures along with a
reduced heat release rate through a longer combustion event.
Combining a Diesel Particulate Filter and Heat
Exchanger for Waste Heat Recovery and Particulate
Matter Reduction
2014-01-0673
Published 04/01/2014
Charles Sprouse III
Benedictine College; University of Kansas
Christopher Depcik
University of Kansas
CITATION: Sprouse III, C. and Depcik, C., "Combining a Diesel Particulate Filter and Heat Exchanger for Waste Heat
Recovery and Particulate Matter Reduction," SAE Technical Paper 2014-01-0673, 2014, doi:10.4271/2014-01-0673.
Copyright © 2014 SAE International
Downloaded from SAE International by Christopher Depcik, Friday, March 21, 2014 10:45:24 AM