Tim Franken

Brandenburg University of Technology Cottbus - Senftenberg | BTU · Institute of Thermodynamics and Thermal Process Engineering

Use of numerical simulations at early stage of engine and aftertreatment systems development helps in evaluating their different concepts and reducing the need for costly building of prototypes. In this work, we explore the feasibility of fully physical and chemical-based tool-chain for co-simulating engine in-cylinder and aftertreatment processes....

The production of green gases using power-to-gas in industry and the energy sector is essential for reducing the carbon footprint. In this process, green H2 and CO2 are converted into synthetic methane using nickel catalysts. The carbon dioxide can be obtained from the environment or from point sources such as waste-to-energy plants, combined heat...

This work presents a numerical investigation of oxyfuel combustion of methane in a gas engine with passive pre-chamber. A three-dimensional (3-D) computational fluid dynamics (CFD) solver with detailed chemistry in Converge v3.1.8 is used to predict the ignition and turbulent flame propagation in the engine. The reaction kinetic model for methane o...

div class="section abstract"> Worldwide, there is the demand to reduce harmful emissions from non-road vehicles to fulfill European Stage V+ and VI (2022, 2024) emission legislation. The rules require significant reductions in nitrogen oxides (NO_x), methane (CH₄) and formaldehyde (CH₂O) emissions from non-road vehic...

div class="section abstract"> In more or less all aspects of life and in all sectors, there is a generalized global demand to reduce greenhouse gas (GHG) emissions, leading to the tightening and expansion of existing emissions regulations. Currently, non-road engines manufacturers are facing updates such as, among others, US Tier 5 (2028), European...

Simulations under transient driving conditions can be used to optimize engine performance parameters by identifying the areas of improvements and testing different engine configurations, and hence reduce development cost and time-to-market for new vehicles. This work presents real-time simulations of engine-out emissions from a compression ignition...

div class="section abstract"> During cold start of natural gas engines, increased methane and formaldehyde emissions can be released due to flame quenching on cold cylinder walls, misfiring and the catalyst not being fully active at low temperatures. Euro 6 legislation does not regulate methane and formaldehyde emissions. New limits for these two p...

div class="section abstract"> In contrast to the currently primarily used liquid fuels (diesel and gasoline), methane (CH₄) as a fuel offers a high potential for a significant reduction of greenhouse gas emissions (GHG). This advantage can only be used if tailpipe CH₄ emissions are reduced to a minimum, since the GHG impact of...

Today ethanol is already blended by 10vol-% in gasoline and a further increase of the ethanol content to 20vol-% is discussed. During the ethanol production process, distillation and molecular sieving are required to remove the water concentration to achieve high-purity ethanol. However, hydrous ethanol can be beneficial to suppress the knock of sp...

The increasing requirements to further reduce pollutant emissions, particularly with regard to the upcoming Euro 7 (EU7) legislation, cause further technical and economic challenges for the development of internal combustion engines. All the emission reduction technologies lead to an increasing complexity not only of the hardware, but also of the c...

In this study, an engine and fuel co-optimization is performed to improve the efficiency and emissions of a spark ignition engine utilizing detailed reaction mechanisms and stochastic combustion modelling. The reaction mechanism for gasoline surrogates, ethanol, and methanol is validated for experiments at different thermodynamic conditions. Liquid...

The use of chemical kinetic mechanisms in computer aided engineering tools for internal combustion engine simulations is of high importance for studying and predicting pollutant formation of conventional and alternative fuels. However, usage of complex reaction schemes is accompanied by high computational cost in 0-D, 1-D and 3-D computational flui...

State of the art spark ignited gasoline engines achieve thermal efficiencies above 46 % e.g. due to friction optimized crank trains, high in-cylinder tumble flow and direct fuel injection. Further improvements of thermal efficiency are expected from lean combustion, higher compression ratio and new knock-resistant fuel blends. One of the limitation...

This work presents the assessment of direct water injection in spark-ignition engines using single cylinder experiments and tabulated chemistry-based simulations. In addition, direct water injection is compared with cooled low-pressure exhaust gas recirculation at full load operation. The analysis of the two knock suppressing and exhaust gas coolin...

div class="section abstract"> Water injection can be applied to spark ignited gasoline engines to increase the Knock Limit Spark Advance and improve the thermal efficiency. The Knock Limit Spark Advance potential of 6 °CA to 11 °CA is shown by many research groups for EN228 gasoline fuel using experimental and simulation methods. The influence of w...

Water injection is investigated for turbocharged spark-ignition engines to reduce knock probability and enable higher engine efficiency. The novel approach of this work is the development of a simulation-based optimization process combining the advantages of detailed chemistry, the stochastic reactor model and genetic optimization to assess water i...

The prediction of local heat transfer and thermal stratification in the 0D stochastic reactor model (SRM) is compared to direct numerical simulation (DNS) published by Schmitt et al. in 2015. DNS solves the Navier-Stokes equations without incorporating model assumptions for turbulence and wall heat transfer. Therefore, it can be considered as numer...

The oxidation chemistry in the unburned zone is modelled using the Ethanol Toluene Reference Fuel (ETRF) reactions scheme by Seidel [1] that allows for a flexible surrogate definition. This scheme was developed taking the core model from Seidel et al. [3], and reduced following the methodology in [3]. Netzer et al. [4, 5] showed that the prediction...

The 0D DI-SRM with tabulated chemistry is successfully applied for a multi-objective optimization of fuel consumption and NO x emissions in a direct injection Diesel engine. The approach highlighted its strength to account for physical and chemical effects in a 0D model framework with a lesser extent of computational costs. The optimization results...

The general knowledge from SI engine development could be confirmed by the QD SRM optimization. The reduction of fuel consumption is favored by increased compression ratio and earlier spark timing. In contrast, the lower knock probability is influenced by low compression ratios and later spark timings. The presence of water is beneficial for reduci...

Water injection is investigated for turbocharged spark ignition engines to limit knock probability and therefore enable higher engine efficiency. This work presents an integrated simulation-based optimization process to assess water injection. The fast running quasi-dimensional stochastic reactor model is coupled with tabulated chemistry to account...

Highly fuel-efficient Diesel engines, combined with effective exhaust aftertreatment systems, enable an economic and low-emission operation of heavy-duty vehicles. The challenge of its development arises from the present engine complexity, which is expected to increase even more in the future. The approved method of test bench measurements is stret...

Today numerical models are a major part of the diesel engine development. They are applied during several stages of the development process to perform extensive parameter studies and to investigate flow and combustion phenomena in detail. The models are divided by complexity and computational costs since one has to decide what the best choice for t...

A novel 0-D Probability Density Function (PDF) based approach for the modelling of Diesel combustion using tabulated chemistry is presented. The Direct Injection Stochastic Reactor Model (DI-SRM) by Pasternak et al. has been extended with a progress variable based framework allowing the use of a pre-calculated auto-ignition table. Auto-ignition is...

Stringent exhaust emission limits and new vehicle test cycles require sophisticated operating strategies for future diesel engines. Therefore, a methodology for predictive combustion simulation, focused on multiple injection operating points is proposed in this paper. The model is designated for engine performance map simulations, to improve predic...