Effects of mixing on the course of fast chemical reactions are relatively well understood, especially in homogeneous systems. This enables to design and operate chemical reactors with the goal to achieve a high yield of a desired product and use systems of complex reactions as a chemical probe (chemical test reactions) to identify progress of mixing and quality of mixture. Recently, a number of studies have focused on the application of chemical test reactions to identify energy efficiency of mixing, being a convenient way of comparing mixers and reactors in terms of their mixing efficiency. This review offers a presentation of chemical test reactions available in the literature and methods of applications of test reactions to identify the energy efficiency of mixing. Also methods to assess the extent of micromixing by measuring product distribution or segregation index, and to determine the time constant for mixing are presented for single phase homogeneous systems and two-phase liquid-liquid systems.
In this work a concept of energetic efficiency of mixing is presented and discussed; a classical definition of mixing efficiency is modified to include effects of the Schmidt number and the Reynolds number. Generalization to turbulent flows is presented as well. It is shown how the energetic efficiency of mixing as well as efficiencies of drop breakage and mass transfer in twophase liquid-liquid systems can be identified using mathematical models and test chemical reactions. New expressions for analyzing efficiency problem are applied to identify the energetic efficiency of mixing in a stirred tank, a rotor stator mixer and a microreactor. Published experimental data and new results obtained using new systems of test reactions are applied. It has been shown that the efficiency of mixing is small in popular types of reactors and mixers and thus there is some space for improvement.
Energetic efficiency depicting the fraction of energy dissipation rate used to perform processes of drop breakup and mass transfer in two-phase, liquid-liquid systems is considered. Results of experiments carried out earlier in two types of high-shear mixers: an in-line rotor-stator mixer and a batch rotor-stator mixer, have been applied to identify and compare the efficiency of drop breakage and mass transfer in both types of mixers. The applied method is based on experimental determination of both: the product distribution of chemical test reactions and the drop size distributions. Experimental data are interpreted using a multifractal model of turbulence for drop breakage and the model by Favelukis and Lavrenteva for mass transfer. Results show that the energetic efficiency of the in-line mixer is higher than that of the batch mixer; two stator geometries were considered in the case of the batch mixer and the energetic efficiency of the device equipped with a standard emulsor screen (SES) was higher than the efficiency of the mixer equipped with a general purpose disintegrating head (GPDH) for drop breakup but smaller for mass transfer.
Obtaining a pure product by mixing together raw materials, so as to carry out a chemical reaction at high selectivity, is a difficult part of manufacturing chemical products. How can we test reactors and mixers to ensure the efficient use of energy?
The measured rate of release of intercellular protein from yeast cells by ultrasonication was applied for evaluating the effects of sonication reactor geometry on cell disruption rate and for validation of the simulation method. Disintegration of two strains of Saccharomyces cerevisiae has been investigated experimentally using a batch sonication reactor equipped with a horn type sonicator and an ultrasonic processor operating at the ultrasound frequency of 20 kHz. The results have shown that the rate of release of protein is directly proportional to the frequency of the emitter surface and the square of the amplitude of oscillations and strongly depends on the sonication reactor geometry. The model based on the Helmholtz equation has been used to predict spatial distribution of acoustic pressure in the sonication reactor. Effects of suspension volume, horn tip position, vessel diameter and amplitude of ultrasound waves on the spatial distribution of pressure amplitude have been simulated. A strong correlation between the rate of protein release and the magnitude of acoustic pressure and its spatial distribution has been observed. This shows that modeling of acoustic pressure is useful for optimization of sonication reactor geometry.
Debata toczy się wokół dwóch kluczowych momentów życia pary, jakimi są zamieszkanie i ślub oraz związane z nimi praktyki. Według uczestniczek i uczestników debaty, mimo że związek może trwać i bez tych wydarzeń, to z badań nad parami wynika, że stanowią one ważne punkty zwrotne. W prezentowanej rozmowie zebrano wnioski o kondycji par w Polsce, z uwzględnieniem różnic i podobieństw pomiędzy parami jedno i dwupłciowymi, a także różnic związanych z wiekiem, wykształceniem i pochodzeniem (zarówno narodowym, jak i klasowym).
Przedmiotem artykułu jest program teoretyczno-badawczy ujmujący parę intymną jako formę praktykowania bliskości, miłości i troski, zakorzenionych w praktykach życia codziennego. W ramach tego programu proponujemy analizę o charakterze: relacyjnym, nienormatywnym, intersekcjonalnym oraz procesualnym. Najpierw wyjaśniamy, dlaczego kategoria pary intymnej jest użyteczna, uzupełniając, a także zastępując takie kategorie, jak rodzina, jednostka i gospodarstwo domowe. Druga część tekstu jest poświęcona korzyściom, które wnoszą do badań par intymnych teorie praktyk społecznych, z ich naciskiem na wiedzę milczącą i habitualną, cielesność i emocjonalność, materialność oraz symbolikę i kontekst działań. Proponowany program teoretyczno-badawczy stanowi syntezę kilku nurtów teoretycznych i został przepracowany w toku szeregu zrealizowanych w Polsce projektów badawczych.
The scope of work included the launch of the process of refining slag suspension in a gas oven using a variety of technological additives. After the refining process (in the context of copper recovery), an assessment of the effect of selected reagents at the level of the slag refining suspension (in terms of copper recovery). Method sieve separated from the slag waste fraction of metallic, iron - silicate and powdery waste. Comparison of these photographs macroscopic allowed us to evaluate the most advantageous method of separating metallic fraction from the slag. After applying the sample A (with KF2 + NaCl) we note that in some parts of the slag are still large amounts of metallic fraction. The fraction of slag in a large majority of the elements has the same size of 1 mm, and a larger portion of the slag, the size of which is from 2 to 6 mm. Definitely the best way is to remove the copper by means of the component B (with NaCl ) and D (with KF2 ). However, as a result of removing the copper by means of component C (with CaO) were also obtained a relatively large number of tiny droplets of copper, which was problematic during segregation. In both cases we were able to separate the two fractions in a fast and simple manner.
O b j e c t i v e s: To evaluate the properties of natural sweetener solutions in whole organ preservation and assess their influence on the dimension, weight and shape of cardiac tissue samples in stated time intervals, up to a one-year period of observation. B a c k g r o u n d: Tissue fixation is essential for biological sample examination. Many negative toxic effects of formaldehyde-based fixatives have forced us to seek alternatives for formaldehyde based solutions. It has been demonstrated that natural sweeteners can preserve small tissue samples well and that these solutions can be used in histopathological processes. However, their ability to preserve whole human organs are unknown. M e t h o d s: A total of 30 swine hearts were investigated. Th ree study groups (n = 10 in each case) were formed and classifi ed on the type of fixative: (1) 10% formaldehyde phosphate-buffered solution (FPBS), (2) 10% alcohol-based honey solution (ABHS), (3) 10% water-based honey solution (WBHS). Samples were measured before fi xation and in the following time points: 24 hours, 72 hours, 168 hours, 3 months, 6 months and 12 months. R e s u l t s: The WBHS failed to preserve heart samples and decomposition of tissues was observed one week after fixation. In half of the studied parameters, the ABHS had similar modifying tendencies as compared to FPBS. Th e overall condition of preserved tissue, weight, left ventricular wall thickness, right ventricular wall thickness and the diameter of the papillary muscle differed considerably. C o n c l u s i o n s: The ABHS may be used as an alternative fi xative for macroscopic studies of cardiac tissue, whereas the WBHS is not suited for tissue preservation.