Pilot-Scale Combined Reduction of Accumulated Particulate Matter and NO<i> <sub>x</sub> </i> Using Nonthermal Plasma for Marine Diesel Engine
Takuya Kuwahara, Keiichiro Yoshida, Tomoyuki Kuroki, Kenichi Hanamoto, Kazutoshi Sato, Masaaki Okubo
Abstract
An effective NOx-reduction aftertreatment system for a marine diesel engine that employs combined nonthermal plasma (NTP) and adsorption is investigated. The system can also treat particulate matter (PM) that employs a diesel particulate filter (DPF) and its regeneration by NTP-induced ozone. The effect of the combined reduction of accumulated PM and NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> is studied. The marine diesel engine of interest provides an output power of 1 MW at 100% of the engine load. The NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> reduction is composed of repeated adsorption and desorption flow processes using NTP combined with NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> adsorbents. With a view toward practical use, experiments on a higher number of cycles are carried out. The amount of adsorbents is 105 kg, which is greater than that in the authors' previous study. As a result, NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> reduction efficiency by NTP is higher than in the previous study and is greater at higher amounts of adsorbents owing to higher NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> desorption. Furthermore, DPF regeneration with plasma-induced O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> injection is achieved simultaneously. This aftertreatment system demonstrates an excellent energy efficiency of 114 g(NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> )/kWh. The present after-treatment can generate a synergistic effect of PM and NOx reduction.