Heat and mass transfer limitations in pre-turbocharger catalysts

Abstract

The use of the Diesel engine is increasing, while at the same time emission limits are becoming more stringent. To reduce emissions, novel catalyst converter designs have been proposed, including the placement of a small converter before the turbocharger. The role of this catalyst is to provide some reduction of the pollutant level prior to the main catalyst. This catalyst is typified by high flow rates. In this paper the performance of small catalytic converters operated at high flowrate is examined using computer simulation. The oxidation of CO is used as a model reaction. It is shown that for a typical oxidation catalyst, conversions of the order of 30% can be achieved at typical temperatures and a GHSV of 5 million h )1 .

Microstructured Reactor as a Pre-Turbo Catalytic Converter

“…In fact, velocity suggested in [1] exceeds many times that commonly applied in chemical reactors and to our knowledge there is no information on the functioning the structured reactors in the literature.…”

“…Therefore, novel methods of controlling CO/NO x emissions are still proposed to enhance the effectiveness of classic monolithic converters. For example, More et al [1] suggested preliminary pollution reduction in a small converter placed before the turbocharger. Assumed gas velocity may reach 100 m/s.…”

“…Assumed gas velocity may reach 100 m/s. The authors [1] postulated that up to 70 % of pollution may be neutralized within this small reactor. The above idea is a challenge for all: catalysis, material and chemical engineering.…”

“…Few years ago, Kołodziej and Łojewska [2] and Kołodziej et al [3] designed and modeled metallic shortchannel structures, which base on the assumption of developing laminar flow [4]. The short monolith proposed in [1] follows the idea of the short-channel reactor [2,3] for much higher flow velocities with possibility to reach the transition or even turbulent flow regime. For this reason, heat and mass transfer coefficients should be much higher than in classic monolithic converters.…”

“…The purpose of this work was to test the short-channel structures described in [2,3] for very high gas velocities, about 50 m/s, to meet and experimentally check the demands presented in [1].…”