Concepts for Hydrogen Internal Combustion Engines and Their Implications on the Exhaust Gas Aftertreatment System

Hydrogen as carbon-free fuel is a very promising candidate for climate-neutral internal combustion engine operation. In comparison to other renewable fuels, hydrogen does obviously not produce CO2 emissions. In this work, two concepts of hydrogen internal combustion engines (H2-ICEs) are investigated experimentally. One approach is the modification of a state-of-the-art gasoline passenger car engine using hydrogen direct injection. It targets gasoline-like specific power output by mixture enrichment down to stoichiometric operation. Another approach is to use a heavy-duty diesel engine equipped with spark ignition and hydrogen port fuel injection. Here, a diesel-like indicated efficiency is targeted through constant lean-burn operation. The measurement results show that both approaches are applicable. For the gasoline engine-based concept, stoichiometric operation requires a three-way catalyst or a three-way NOX storage catalyst as the primary exhaust gas aftertreatment system. For the diesel engine-based concept, state-of-the-art selective catalytic reduction (SCR) catalysts can be used to reduce the NOx emissions, provided the engine calibration ensures sufficient exhaust gas temperature levels. In conclusion, while H2-ICEs present new challenges for the development of the exhaust gas aftertreatment systems, they are capable to realize zero-impact tailpipe emission operation.

DETERMINATION OF ACOUSTIC FEATURES OF CATALYTIC CONVERTERS OF ESHAUST SYSTEMS

The object of the presented work are ceramic blocks and diesel particulate filters manufactured by CORNING and applied in the development and serial production of the exhaust gas aftertreatment systems for cars and trucks, providing the required emission standards and noise regulations. The purpose of the work is the definition of acoustic parameters of the blocks for the further use of these data in the design of the system components applying finite-element modeling. A set of the blocks with different model parameters (diameter, length, and the cell density) was tested on acoustic stand using previously developed methods. Acoustic wave parameters have been identified for each block (namely, the comprehensive speed of sound and comprehensive density). The technique of the test preparation on acoustic test bench, the methodology and results of testing, the methodology and the processing of the results are presented. The estimation of measurement and calculation of errors are presented.

Assessment of the Internal Catalyst Efficiency in a Diesel Engine of a Vehicle under the Conditions Simulating Real Driving

The application of a catalyst on a surface inside a combustion chamber is known as a supplementary method of exhaust gas aftertreatment. The efficiency of this method in the reduction in exhaust emissions as well as its influence on other engine properties has been analyzed in multiple scientific works. Most often, these works present the results of investigations carried out on dynamometers under engine stationary conditions. There are no results of the catalyst investigations performed under dynamic states, particularly on-going real time analyses during engine operation. Therefore, the authors set out to explore the efficiency of the in-cylinder catalyst of a diesel engine under dynamic conditions simulating actual vehicle operation. A unique methodology was applied. The investigations were carried out in road conditions in a test simulating the New European Driving Cycle (NEDC) homologation test in compliance with the similarity criteria of the zero-dimensional characteristics of vehicle speed during the investigations and in the homologation test. For the research, the authors used portable exhaust emissions measurement equipment. A unique method of test results analysis was also applied (a continuous method in the time domain). As a result of the tests being repeated several times, it was observed that the application of an internal catalyst under different operating engine conditions repeatedly results in: an approx. 2% reduction in the emissions of carbon monoxide, hydrocarbons, and carbon dioxide; a similar increase in the emission of nitrogen oxides; and a significant (over 10%) reduction in the particle number. The obtained results substantiate the purpose of actions aiming at improving the efficiency of the internal catalyst.

Influence of the Length of a Catalyst-Coated Glow Plug on Exhaust Emissions

This paper discusses the application of an in-cylinder catalyst in reducing the exhaust emissions from a diesel engine. This is an additional method of exhaust gas aftertreatment; yet the placement of a catalyst in the combustion chamber (i.e., the closest location to the process of combustion) allows a reduction of the emissions ‘at source’ (the catalyst applied on the glow plugs). For the investigations, we used an engine dynamometer to reproduce the traffic conditions of a homologation test carried out on a chassis dynamometer. We carried out the investigations on a Euro 4 1.3 JTD MultiJet diesel engine. The selection of the research object was followed by an analysis of the number of engines used in the EU meeting individual emission standards. We present results (measurement of carbon monoxide, hydrocarbons, nitrogen oxides, particle number, and carbon dioxide) related to the assessment of the applicability of the in-cylinder catalyst for three types of glow plugs: standard, catalyst-covered, and a prototype plug with an elongated catalyst-covered heating part. Prototype catalytic glow plugs ensure a few percent reduction in the emission of carbon monoxide, hydrocarbons, carbon dioxide, and particle number. The use of such a solution (glow plug replacement) in most diesel engines (easy to retrofit) would improve the environmental performance of combustion engines. It is of particular importance that in-cylinder catalysts are most efficient during cold start and warm-up, which is often the case in urban driving.

Lean-Burn Natural Gas Engines: Challenges and Concepts for an Efficient Exhaust Gas Aftertreatment System

High engine efficiency, comparably low pollutant emissions, and advantageous carbon dioxide emissions make lean-burn natural gas engines an attractive alternative compared to conventional diesel or gasoline engines. However, incomplete combustion in natural gas engines results in emission of small amounts of methane, which has a strong global warming potential and consequently makes an efficient exhaust gas aftertreatment system imperative. Palladium-based catalysts are considered as most effective in low temperature methane conversion, but they suffer from inhibition by the combustion product water and from poisoning by sulfur species that are typically present in the gas stream. Rational design of the catalytic converter combined with recent advances in catalyst operation and process control, particularly short rich periods for catalyst regeneration, allow optimism that these hurdles can be overcome. The availability of a durable and highly efficient exhaust gas aftertreatment system can promote the widespread use of lean-burn natural gas engines, which could be a key step towards reducing mankind’s carbon footprint.