21 research outputs found

    Isobars for the types of wood used as biofuel

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    W pracy zostały przedstawione równowagi sorpcyjne wybranych gatunków drewna, które są przydatne do projektowania procesu suszenia a także schematy aparatur do badania izobar i izoterm sorpcji. Zbadano próbki wierzby z gatunku Salix viminalis (2 i 3 letnie pędy), brzozy, sosny i dębu w temperaturach do 125°C i wyniki porównano z danymi literaturowymi dla różnych gatunków drewna. Głównym celem pracy była próba opisu własnych danych eksperymentalnych i danych literaturowych w szerokim zakresie temperatur i wilgotności za pomocą jednego uogólnionego równania. Dopasowano równanie pozwalające przewidywać równowagę sorpcyjną drewna w szerokim zakresie temperatur i wilgotności. Dopasowane równanie jest uniwersalne zarówno dla procesu suszenia parą przegrzaną jak i gorącym powietrzem. Znajomość tych równowag umożliwia wyznaczenie wilgotności krytycznej, charakteryzującej przejście z I do II okresu suszenia, i równowagowej wilgotnego materiału stwarzając jednocześnie możliwość prawidłowego zamodelowania procesu suszenia.This paper presents sorption equilibrium for some wood varieties that is necessary for designing drying processes. In that article set-up for isotherm and isobar sorption determination are shown. Samples of willow Salix viminalis (2 and 3-year stems), birch, pine and oak were examined in temperature range up to 125°C. The results were compared with data available in literature for different wood species. The main aim of that paper was an attempt to describe our own experimental data and literature data in a wide range of temperatures and moisture contents by one, generalized equation. The generalized equation describing sorption equilibrium in a wide range of temperatures and moisture content was fitted. The fitted equation is universal and can be used for both air drying and superheated steam drying. The knowledge about sorption equilibrium enables to determine critical (characterizes the transition between I and II drying period) and equilibrium moisture content of wet material. It gives the possibility for proper designing of drying processes

    Characteristic of Cast Zn-Al-Cu Alloy Microstructure after Modification

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    Cast zinc alloys have similar properties to aluminium alloys. The differences are due to the lower melting point and higher density. Zinc has a density of 7.14 g/cm3, a melting point of 419.5°C and the boiling temperature of 906º C. In the temperature range from 150 to 200°C, zinc has good susceptibility to plastic deformation. It is also resistant to atmospheric factor influence, but is not resistant to acids. The main use of zinc alloy, is the production of thin-walled casts that require high precision. Zinc alloys are also used for die casting moulds, housings and covers as well as a variety of devices that are used in the precision industry, electrical engineering, automotive and construction industry. Properly performed chemical modification leads to improve of properties of the produced castings. Therefore it is very important to know how the cast structure with the change of the chemical composition by adding metallic modifiers to the liquid metal. In this work there was studied the effect of chemical modification of cast zinc alloy on the properties and microstructure of the alloys before and after modification. Modified alloys were prepared by adding modifiers in the range of 0.1% to 1% in form of Ti- Sr and B as aluminium master alloy and then cast into the metal moulds. Next the thermo-derivative analysis was performed of the modified Zn-Al-Cu alloy, the microstructure investigation was carried out using light microscopy and scanning electron microscopy with EDS X-ray microanalysis usage as well as hardness was measured of the modified Zn-Al-C alloys

    Influence of Mg Addition on Crystallisation Kinetics and Structure of the Zn-Al-Cu Alloy

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    In this work the effect of Mg addition on structure as well as kinetics of crystallisation of Zn-Al-Cu cast alloy was presented. To the zinc alloy was added 0.1% mass of Mg. The alloy was cast into a metal mould. Thermo-derivative analysis was performed using the UMSA platform (Universal Metallurgical Simulator and Analyzer). The investigated alloys were freely cooled down with a rate of 0.1°C s-1. For the structure analysis were used results obtained using light microscopy, scanning and transmission electron microscopy

    Improvement of Mathematical Model for Sedimentation Process

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    In this article, the fractional-order differential equation of particle sedimentation was obtained. It considers the Basset force’s fractional origin and contains the Riemann–Liouville fractional integral rewritten as a Grunwald–Letnikov derivative. As a result, the general solution of the proposed fractional-order differential equation was found analytically. The belonging of this solution to the real range of values was strictly theoretically proven. The obtained solution was validated on a particular analytical case study. In addition, it was proven numerically with the approach based on the S-approximation method using the block-pulse operational matrix. The proposed mathematical model can be applied for modeling the processes of fine particles sedimentation in liquids, aerosol deposition in gas flows, and particle deposition in gas-dispersed systems

    Influence of Spray Nozzle Operating Parameters on the Fogging Process Implemented to Prevent the Spread of SARS-CoV-2 Virus

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    This article reports the results of a study into the effect of operating parameters on the occurrence and course of gas–liquid two-phase phenomena during the fogging process carried out with the use of a conical pressure-swirl nozzle. Four alternatives of the stub regulation angles and four values of pressure of air supply to the nozzle were tested as part of the current research. The range of the investigated variables was common for the operation of fumigators used to prevent the spread of SARS-CoV-2 virus. The liquid flow rate (weighting method), the field of velocity, and turbulent flow intensity factor, as well as velocity profiles over the section of 1 m from the nozzle were determined using the particle image velocimetry (PIV) technique. The obtained results were correlated with the measurements of the diameters of spray droplets using the laser light scattering (LLS) technique. On the basis of this research, a dependence between the nozzle parameters and the spray cone pattern was identified in terms of dynamics and droplet diameter distribution. As a result of the research, a wide range of parameters were identified in which the fogging process was carried out in a stable and repeatable manner. There were exceptions to this rule only in the cases when there was a deficiency of the liquid necessary to generate a two-phase mixture
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