Mixing in the NETmix Reactor

NETmix is a static mixing reactor composed of a network of mixing chambers interconnected by channels. The repetitive mixing pattern inside the reactor enables the use of reduced geometries to represent the NETmix network, such as the ExtendedNUB model, used in this work. Mixing in NETmix is based on the impingement of jets, issuing from channels. Inside the chambers, the jets are engulfed by dynamic vortices which can be quantified using Lagrangian techniques. Batch Lagrangian Mixing Simulation (BLMS) is based on successive injections of particles to measure the fraction of the fluids at the outlet of the mixing chambers. The distribution of the outlet fraction of particles indicates that it is possible to have nearly perfect mixing inside the NETmix chambers, depending on the dimensions of the channels and chambers. The NETmix design is here optimized in relation to the chamber diameter to channel width ratio, D/d. Results from BLMS show that best performance in NETmix occurs for 6.65≤D/d≤6.85.

Numerical Investigation on the Performance of Two-Throat Nozzle Ejectors with Different Mixing Chamber Structural Parameters

In this study, the effects of the mixing chamber diameter (Dm), mixing chamber length (Lm) and pre-mixing chamber converging angle (θpm) were numerically investigated for a two-throat nozzle ejector to be utilized in a CO2 refrigeration cycle. The developed simulated method was validated by actual experimental data of a CO2 ejector in heat pump water heater system from the published literature. The main results revealed that the two-throat nozzle ejectors can obtain better performance with Dm in the range of 8–9 mm, Lm in the range of 64–82 mm and θpm at approximately 60°, respectively. Deviation from its optimal value could lead to a poor operational performance. Therefore, the mixing chamber structural parameters should be designed at the scope around its optimal value to guarantee the two-throat nozzle ejector performance. The following research can be developed around the two-throat nozzle geometries to strengthen the ejector performance.

Research on the Influence of Euro VI Diesel Engine Assembly Consistency on NOx Emissions

The assembly consistency of a diesel engine will affect its nitrogen oxides (NOx) emission variation. In order to improve the NOx emissions of diesel engines, a study was carried out based on the assembly tolerance variation of the diesel engine’s combustion system. Firstly, a diesel engine which meets the Euro VI standards together with the experimental data is obtained. The mesh model and combustion model of the engine combustion system are built in the Converge software (version 2.4, Tecplot, Bellevue, DC, USA), and the experimental data is used to calibrate the combustion model obtained in the Converge software. Then, the four-factor and three-level orthogonal simulation experiments are carried out on the dimension parameters that include nozzle extension height, throat diameter, shrinkage diameter and combustion chamber depth. Through mathematical analysis on the experimental data, the results show that the variation of nozzle extension height and combustion chamber depth have a strong influence on NOx emission results, and the variation of combustion chamber diameter also has a weak influence on NOx production. According to the regression model obtained from the analysis, there is a quadratic function relating the nozzle extension height and NOx emissions and the amount of NOx increases with increasing nozzle extension height. The relationship between emission performance and size parameters is complex. In the selected size range, the influence of the variation of the chamber diameter on NOx is linear. The variation of the chamber depth also has an effect on NOx production, and the simulation results vary with the change of assembly tolerance variation. Thus, in the engine assembly process, it is necessary to strictly control the nozzle extension height and combustion chamber depth. The research results are useful to improve the NOx emission of diesel engine and provide a basis for the control strategy of selective catalytic reduction (SCR) devices.

An attempt to increase technological capabilities of laboratory vibratory mills by changing the construction of chamber

The paper presents the issues related to the grinding process in the vibration mills with low vibration frequency. These mills are rated among devices with high energy of impacts with much wider potential of industrial use than the classic gravitation mills. In vibratory mills there is an unfavorable decrease in the intensity of the grinding process along with the increase in the chamber diameter, which makes it impossible to achieve high performance of such devices. One of the ways to reduce or eliminate this occurrence is to intensify the load movement inside the chamber – this is the subject of this article. The article shows that in a vibrating mill of periodic action it is possible to increase its technological capabilities by application of an appropriate cylindrical component permanently installed inside the milling chamber. The paper also presents an attempt to increase the technological capabilities of a laboratory continuous vibratory mill.

Cardiac Magnetic Resonance Imaging and Transthoracic Echocardiography: Investigation of Concordance between the Two Methods for Measurement of the Cardiac Chamber

Background and objectives: Cardiac magnetic resonance (CMR) imaging is the gold standard method for the detection of ventricular volumes and myocardial edema/scar. Transthoracic echocardiography (TTE) imaging is primarily used in the evaluation of cardiac functions and chamber dimensions. This study aims to investigate whether the chamber diameter measurements are concordant with each other in the same patient group who underwent TTE and CMR. Materials and Methods: The study included 41 patients who underwent TTE and CMR imaging. Ventricular and atrial diameter measurements from TTE-derived standard parasternal long axis and apical four-chamber views and CMR-derived three- and four-chamber views were recorded. The concordance between the two methods was compared using intra-class correlation coefficients (ICC) and Bland–Altman plots. Results: Of the patients, 25 (61%) were male and the mean age was 48.12 ± 16.79. The mean ICC for LVDD between CMR observers was 0.957 (95% CI: 0.918–0.978), while the mean ICC between CMR and TTE measurements were 0.849 (95% CI: 0.709–0.922) and 0.836 (95% CI: 0.684–0.915), respectively. The mean ICC for the right ventricle between CMR observers was 0.985 (95% CI: 0.971–0.992), while the mean ICC between CMR and TTE measurements were 0.869 (95% CI: 0.755–0.930) and 0.892 (95% CI: 0.799–0.942), respectively. Passing–Bablok Regression and Bland–Altman plots indicated high concordance between the two methods. Conclusions: TTE and CMR indicated high concordance in chamber diameter measurements for which the CMR should be considered in patients for whom optimal evaluation with TTE could not be performed due to their limitations.

Simulation and experiment study of the self-excited oscillating mixer with abrasive jet used for the descaling of rusty steel

A novel self-excited oscillating mixer is developed for the descaling of strip steel, which synthesizes the post-mixed abrasive water jet and self-excited oscillation. The realizable k-ɛ model is selected to investigate the effects of different abrasive entrance, inlet pressure, mixing chamber diameter, and length on the jet characteristics. Meanwhile, the effects of different inlet pressure and target distance on the outlet velocities for two kinds of mixers (including the developed mixer and conventional post-mixing mixer) with or without abrasive jet are investigated through simulation. Experiment as well as simulation results exhibited: (1) The oblique abrasive entrance can accelerate the mixture of water and abrasive due to its larger turbulent kinetic energy, and its outlet velocity is larger than that of radial and axial abrasive entrances. (2) For the developed mixer, the outlet velocity is preferable when the mixing chamber diameter is about 40–50 mm and the mixing chamber length is 20 mm. (3) The descaling efficiency of the developed mixer is superior to that of conventional post-mixing mixer. The research will lay foundation to optimize the structure of self-excited oscillating mixer for the descaling of rusty steel.

Influence of fineness level and applied agglomeration pressure of peppermint herb (Mentha piperita L.) on the mechanical properties of the obtained product

The objective of the conducted study was to evaluate the impact of the pressure agglomeration process of peppermint herb on the mechanical properties of the obtained product. The separated fractions of peppermint with 0.5-2.5 and 2.5-5 mm particles were compacted using a hydraulic press Fritz Heckert EU 20, with pressure 50, 100, 150 and 200 MPa. A closed matrix with the compression chamber diameter of 15.6 mm was used. Every time, a 2-g herb sample (corresponding to the weight of tea used for the production of tea bags) was poured into the matrix. Thus, compacted herb in the form of a straight cylinder was obtained. When producing the agglomerate compaction work was determined. Strength tests of the obtained agglomerate were conducted using the MTS Insight 2 testing machine. The density of the produced agglomerate, its compaction level and strength in the Brazilian test was calculated. The obtained results indicate that the values of the tested parameters increase with the increase of pressure in the tested range, yet differences occur between the tested herb fractions. Typically, the agglomerate produced from 0.5-2.5 mm fraction is characterized by a greater density, and the higher level of agglomerate compaction is obtained using 2.5-5 mm herb fraction. The highest strength determined using Brazilian test was determined for agglomerate produced from 0.5-5 mm peppermint herb fraction at 200 MPa pressure and 0.5-2.5 mm fraction using 150 and 200 MPa pressure.