Wyniki wyszukiwania - BazTech

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Numerical evaluation of urea-mixing devices for close-coupled selective catalytic reduction systems

Kaźmierski Bartosz Grzegorz, Kapusta Łukasz Jan

Combustion Engines

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2023

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R. 62, nr 2

84--93

EN

The following research presents a numerical evaluation of existing and conceptual urea-mixing devices used in close-coupled (to the engine) selective catalytic reduction (SCR) systems. The analysis was aimed at the assessment of urea-mixing devices that could considerably enhance the reduction of nitrogen oxides from the diesel-engine combustion process under a wide range of operating conditions, including cold starts. The analysis showed that replacing blade-equipped static mixers with perforated stationary mixing devices may provide a more uniform spatial distribution of ammonia at the inlet to the SCR catalyst and reduce pressure drops generated by mixing devices. Moreover, the conceptual mixing devices, based on combinations of the blade and perforated mixers to develop intensive turbulence, enabled the increase of the mixing length leading to effective decomposition of the urea-water solution (UWS), and provided uniform spatial distribution of ammonia, even for the small-sized mixing systems. However, the intensive mixing was often associated with a significant rise in the pressure drop.

2

Analysis of the structure of the atomized fuel spray with marine diesel engine injector in the early stage of injection

Grochowalska Joanna, Jaworski Piotr, Kapusta Łukasz Jan

Combustion Engines

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2023

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R. 62, nr 4

97--103

EN

This paper presents the results of the experimental research of the atomized fuel spray with the marine diesel engine injector in the constant volume chamber. The specificity of the phenomena occurring in the marine engine cylinder was the reason to use the optical visualisation method in the studies - the Mie scattering technique. This work presents an analysis of the influence of different geometry of outlet orifice and opening pressures of marine diesel injector on the macrostructure of the fuel spray. In the results, it was observed that the increased L/D ratio of the outlet orifice of the injector caused: an increase in the spray cone angle and a decrease in the spray tip penetration in the early stage of injection. Furthermore, it was defined that the characteristic of spray tip penetration over time was power, whereas the spray cone angle over time was a logarithmic function.

3

Numerical analysis of the flow rig for UWS spray examination in exhaust system-relevant conditions

Górka Krzysztof, Kaźmierski Bartosz, Kapusta Łukasz Jan

Combustion Engines

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2021

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R. 60, nr 3

103--112

EN

In the present study, a flow rig with optical access intended for spray investigations in exhaust system-relevant conditions was analysed in terms of flow and temperature in the spray area using numerical simulations. The operation of the rig was examined for a wide range of exhaust mass flow rates, temperatures and various forms of UWS (urea-water solution) spray plumes. The locations of the injector and thermocouple were verified. Both conventional and flash-boiling injections were considered to assess the effect of the interaction of sprays with a gas flow. The results showed a highly uniform flow in the visualisation area, with only minor fluctuations near the walls. A similar observation was carried out for the temperature distribution. It was found that the extreme operating conditions caused substantial deformations of the spray plumes. However, the selected injector location allowed us to properly observe the spray formation regardless of the flow conditions. The study showed that the examined test rig enabled reliable spray investigations for a wide range of operating points.

4

A conceptual design and numerical analysis of the mixerless urea-SCR system

Kaźmierski Bartosz, Górka Krzysztof, Kapusta Łukasz Jan

Combustion Engines

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2021

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R. 60, nr 4

12--20

EN

In the present study, an innovative design of a urea-selective catalytic reduction (SCR) system without conventional mixing elements was developed. The aim was to obtain a high degree of urea decomposition, and uniform ammonia distribution at the inlet to the catalyst, while minimising the liquid film deposition and keeping the compact design. The concept of the design was based on creating high turbulence and elongating the flow paths of the droplets. The design was verified through a series of numerical simulations based on the Reynolds-averaged Navier-Stokes (RANS) approach and a discrete droplet model (DDM) spray representation. The analysis included various operating conditions as well as subcooled and superheated sprays. A uniform ammonia distribution was achieved regardless of the operating points and spray properties. Additionally, in the case of a flash-boiling injection, a further reduction of the wall film was observed.

5

The gas-air mixing systems for the industrial gas engine fuelled with low quality gas

Sutkowski Marek, Kapusta Łukasz Jan, Pilarska Paulina

Combustion Engines

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2019

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R. 58, nr 4

182--185

EN

Modifications of standard fuel system for an industrial gas engine and an analysis of the engine operation on low quality fuel have been described in this paper. The implemented fuel system modifications aim to overcome the challenges which arise when standard fuel gas is replaced by low quality one. Analysis focuses on stability of mixture formation esp. on variations in gas distribution for each cylinder of the engine. The results and discussion include also emissions optimization impact on efficiency as well as the efficiency and emissions level dependency on fuel type.