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2 2018

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Numerical investigation of the back pressure influence on urea-water-solution mixing performance in close coupled SCR system

Rogóż R., Bachanek J., Boruc Ł., Teodorczyk A.

Journal of KONES

2018

Vol. 25, No. 3

377--383

The upcoming Euro 6d emission standard puts more even stringent requirements for diesel engine cars, especially in the case of nitrogen oxides (NOx) emission. The most widely used technique to meet tight standards is Selective Catalytic Reduction (SCR) with urea-water-solution (UWS) injection. One of the crucial factors is even ammonia distribution at the catalyst inlet; hence, very often product development is focused around this issue. The product development is supported by both experimental and numerical work. The common approach to measure cross section ammonia distribution on the SCR is using sampling system at catalyst outlet. Very often exhaust layout is opened just after the SCR catalyst, cutting off the rest part for instance tailpipe or Clean-up Catalyst. Therefore, a backpressure at SCR outlet resulting from the downstream part is also eliminated. This could significantly affect flow parameters as the density changes, thus ammonia distribution and wall film deposition may vary as well. Within this work, the influence of the backpressure at SCR outlet on the ammonia distribution and wall wetting was numerically investigated. The simulations were run under various boundary conditions for the Close Coupled SCR architecture. It was shown that depending on the operating point the boundary pressure affects both factors on the different level.

Evaluation of the possibilities of adapting a constant volume combustion chamber for research on ignition of hypergolic propellants under low and high-pressure conditions

Krzesicki M., Boruc Ł., Kapusta Ł. J.

Combustion Engines

2018

R. 57, nr 2

9--13

In this study, the adaptation possibilities of a constant volume combustion chamber (CVCC) for research on the ignition of hypergolic propellants are presented. The application of hypergolic bipropellants and crucial parameters regarding their ignition behaviour are discussed. The initial studies on ignition delay measurements presented here does not cover the whole range of conditions present in practical systems where hypergolic ignition occurs. In the study, a need for an evaluation of the influence of pressure on the ignition delay was indicated as the reason to conduct research on hypergolic ignition in low and high-pressure environments. Moreover, the study reviews the state-of-the-art experimental methods of investigating the ignition under atmospheric, low and high-pressure conditions, including those utilizing a constant volume combustion chamber. The drop test was pointed out as the most commonly used method; this makes it advantageous in terms of comparing the results with those obtained by other researchers. Therefore, the drop test was selected as a method to be used in a CVCC. The test rig developed here was designed based on a CVCC initially designed for diesel sprays’ visualization in high-pressure conditions. All the required modifications, especially the design of the oxidizer dosing unit, are presented in the study.