Andreas Mayer

TL;DR: In this article, a complex 3D cellular model of the human airway epithelium in vitro by exposing the cells at the air-liquid interface was assessed and the induction of pro-apoptotic and necrotic cell death, cellular morphology, oxidative stress, and pro-inflammatory responses were assessed.

Abstract: By means of catalysts, either coatings or fuel-borne, the temperature level for triggering the combustion of soot stored in particulate traps can be lowered from 600°C to 300°C, in case of CRT even to 250°C; but even that may fail, if in dense traffic application of a city-bus only 150 200°C are attained similar situations of low load duty cycles exist in most other applications too. Mere passive regeneration may then not be sufficient, active support is needed. This paper presents an "active" method applicable to any Diesel engine to increase the exhaust temperature whenever required: load of Diesel engines is controlled by the fuel flow only; consequently, excess of air above stochiometric requirement is increasing from 'A = 1.5 to 'A= 8 with decreasing load, which is in fact the principal cause of the low temperature at light loads. By throttling the air flow simultaneously with the fuel flow, 'A is reduced leading to an increased temperature of the exhaust gas, which can be as high as 300 Centigrade. The paper reports an investigation of intake air-flow throttling as an active tool to increase the exhaust temperature whenever needed for regeneration of a particulate filter by means of a computational simulation as well as an experimental verification concluding that throttling downstream of the turbocharger compressor will be the most advisable method. Influence on fuel economy remains negligible because of the very short operation time. Fast responding actuators are required to take care of rapid load changes. Operation strategy can be electronically based on engine map data, but also more simple solutions are possible which are well suited to retrofit engines of older pure mechanical design. It is recommended to use air intake throttling in combination with catalytic coating of particle filters or fuel borne catalysts to cover a very wide range of engine applications and operation conditions.

TL;DR: The copper-catalyzed DPF system was not approved for workplace applications, whereas the iron system fulfilled all the specifications of the Swiss procedures for DPF approval (VERT).