Turbulent Energy Dissipation Rate and Turbulence Scales in the Blade Region of a Self-Aspirating Disk Impeller

Instantaneous radial and axial velocitieques of water in the tank with a self-aspirating disk impeller operating without gas dispersion were measured by the PIV method. A comparison of mean square velocity pulsations confirmed previous observations that the area in which turbulence is non-isotropic is small and extends about 3 mm above and under the impeller and radially 12,5 mm from the impeller blade tip. Based on velocity measurements, the distributions of energy dissipation rates were determined using the dimensional equation = C•u’3/D and Smagorinsky model. Adoption of the results of the dimensional equation as a reference value allowed us to determine the Smagorinsky constant value. This value appeared to be smaller than the values given in the literature. It has been shown that eddies in a small space near the impeller had sufficient energy to break up gas bubbles flowing out of the impeller. Based on the obtained energy dissipation rate distributions, appropriate turbulence scales were determined

CFD Simulation of a shell and multiple tubes condensing heat exchanger in a modified microwave plant applied for reprocessing End of Life Tires (ELTs)

Data Availability Statement: The data that support the findings of this study are openly available in BURA at https://bura.brunel.ac.uk/.Copyright © 2023 The Authors. The condensation heat exchanger has a critical role in the microwave reduction process to separate and capture valuable by-products after the microwave reactor. This study aims to perform a computational fluid dynamics (CFD) simulation of a condenser to assess the heat transfer performance of the heat exchanger comprehensively. The type of heat exchanger used for this study is based upon an existing industrial-scale condenser taken from a conventional thermal pyrolysis end of tires (ELT) reprocessing plant and repurposed for integration into a 1500 kg/h ELT microwave reduction process. The condenser is a shell-and-multiple-tube heat exchanger in which the syngas passes through the tubes while cold water from a cooling tower is placed inside the shell. After the simulation, the effects of inlet temperatures and mass flow rates of the gas and water are investigated. The results show that the heat transfer rate is 58 kW for the inlet air velocity of 0.25 m/s and increases due to the convective heat transfer by 32% and 55% when the air velocity rises to 0.5 and 1 m/s, respectively, for the inlet gas and water temperatures of 80 and 15°C, respectively. Additionally, because the outlet air temperature and the inlet water temperature are strongly correlated with convective heat transfer, the outlet air temperature is equivalent to 17.2, 22.3, and 29.5°C when the inlet water temperature is 15, 20, and 25°C, respectively

SNOSite: Exploiting Maximal Dependence Decomposition to Identify Cysteine S-Nitrosylation with Substrate Site Specificity

S-nitrosylation, the covalent attachment of a nitric oxide to (NO) the sulfur atom of cysteine, is a selective and reversible protein post-translational modification (PTM) that regulates protein activity, localization, and stability. Despite its implication in the regulation of protein functions and cell signaling, the substrate specificity of cysteine S-nitrosylation remains unknown. Based on a total of 586 experimentally identified S-nitrosylation sites from SNAP/L-cysteine-stimulated mouse endothelial cells, this work presents an informatics investigation on S-nitrosylation sites including structural factors such as the flanking amino acids composition, the accessible surface area (ASA) and physicochemical properties, i.e. positive charge and side chain interaction parameter. Due to the difficulty to obtain the conserved motifs by conventional motif analysis, maximal dependence decomposition (MDD) has been applied to obtain statistically significant conserved motifs. Support vector machine (SVM) is applied to generate predictive model for each MDD-clustered motif. According to five-fold cross-validation, the MDD-clustered SVMs could achieve an accuracy of 0.902, and provides a promising performance in an independent test set. The effectiveness of the model was demonstrated on the correct identification of previously reported S-nitrosylation sites of Bos taurus dimethylarginine dimethylaminohydrolase 1 (DDAH1) and human hemoglobin subunit beta (HBB). Finally, the MDD-clustered model was adopted to construct an effective web-based tool, named SNOSite (http://csb.cse.yzu.edu.tw/SNOSite/), for identifying S-nitrosylation sites on the uncharacterized protein sequences

Edge detection of bubble images

W pracy dokonano porównania czterech wybranych metod gradientowych do określania krawędzi obrazów pęcherzyków gazu uzyskanych na fotografiach. Dla użytych obrazów testowych i rzeczywistych najlepsze rezultaty otrzymano metodami Sobela i Canny'ego. Jednak ostateczny wynik jest zależny od wartości parametrów danej metody.In this paper a comparison of four gradient methods for gas bubbles edge detection was made. For the test and real images used in investigations the best results were obtained in case of Sobel and Canny methods. However the final result is dependent upon values of method parameters

Application of autocorrelation for determination of gas bubble velocity on double exposure photographs

W pracy zbadano możliwość określania wielkości pęcherzyków w układzie dwufazowym ciecz - gaz przez analizę zdjęć uzyskanych z podwójną ekspozycją. Stosując metodę autokorelacji oraz znając odstęp czasowy i przesunięcie na środka pęcherzyka na ekranie można było na tej podstawie określić prędkość i kierunek poruszania się pęcherzyka. Wykonane badania doświadczalne dla napowietrzania w mieszalniku potwierdziły możliwość zastosowania tej metody w praktyce wskazując jednocześnie no konieczność lepszego dopracowania proponowanej metody.In the study a possibility to determine gas bubble size in the two-phase gas - liquid system was investigated via analysis of double exposure photo- graphs. Based on the autocorrelation method and knowing the time interval ; and displacement from the middle of bubble, it was possible to determine the velocity and direction of bubble movement. The experimental investigations performed for aeration in the mixer confirmed a possibility to apply this method in practice, indicating simultaneously the necessity of its further elaboration

Characteristics of eddy structures generated by a self-aspirating impeller

Na podstawie pomiarów wykonanych przy użyciu anemometru laserowego w mieszalniku z samozasysającym mieszadłem tarczowym wykonano obliczenia wielkości skal długości, czasu i prędkości dla wirów z zakresu Kolmogurtncu, Taylora i Brodkcy'a.Based on measurements carried out using a laser anemometer in an agitator with a self-aspirating impeller the calculations of'length. time and velocity scales for eddies in the Kolmtigorov, Taylor and Brodkey range were made

Method of convective velocity determination from dissipative range of energy spectrum

In the study a new proposal of convective velocity determination necessary for eddy size determination from the dissipative range in a turbulent flow in a mixer was made. The proposed quantity depends on all the mean and fluctuating velocity components. By applying convective velocity one may determine the distribution of time and linear Taylor microscale in a stirred vessel

Impeller selection for a bioreactor

Porównano pracę dwóch mieszadeł o działaniu osiowym, tzn. sześciołopatkowego mieszadła turbinowego o łopatkach pochylonych oraz mieszadła TX535 podczas mieszania układu dwufazowego ciało stałe-ciecz. Po uwzględnieniu zapotrzebowania mocy do napędu obu mieszadeł stwierdzono, że mieszadło TX535 jest bardziej efektywne od mieszadła turbinowego. Jest to wynik bardziej opływowych kształtów mieszadła TX535. Przedstawiono również zastosowanie przemysłowe mieszadła TX535.Comparison of two axial agitators, i.e. six-blade turbine agitator with inclined blades and TX535 impeller during the mixing of two-phase solidliquid system is presented in the paper. After considering the power requirements to drive two impellers, it was found that TX535 impeller is more efficient than a turbine one. This effect results from a more streamline shapes of TX535 stirrer. The industrial application of TX535 impeller is also shown