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    Wyświetlanie 1-11 z 11
    Tytuł:
    Effect of elevated pressure on gas-solid flow properties in a powder feeding system
    Autorzy:
    Ren, Guanlong
    Sun, Haijun
    Xu, Yihua
    Li, Chao
    Powiązania:
    https://bibliotekanauki.pl/articles/2174817.pdf
    Data publikacji:
    2022
    Wydawca:
    Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
    Tematy:
    Powder engine
    Pressure effect
    Dense gas-solid two-phase flow
    Euler-Euler two-fluid model
    Numerical simulation
    Opis:
    In view of the powder feeding system, a multi-physical coupling model of the gas-powder-piston was established based on the Euler-Euler two-fluid model. The numerical simulation method was applied to explore the effects of dense gas-solid flow characteristics under different operating pressures. The results show that gas-solid pulsations at different operating pressures are mainly concentrated in the upper part of the powder tank. An elevated operating pressure efficiently decreases the powder layer area (εp = 0.1) fluctuation. As the operating pressure increases from 0.5 MPa to 3.0 MPa, the rising time and fluctuation rate of pressure are reduced by 71.4% and 62.3%, respectively, and the pressure in the tank has a long stabilization period. Meanwhile, the variation of the instantaneous powder flow rate is more stable and its average value is closer to the theoretical. A high-pressure environment is more conducive to the stable transportation of powder.
    Źródło:
    Polish Journal of Chemical Technology; 2022, 24, 3; 41--52
    1509-8117
    1899-4741
    Pojawia się w:
    Polish Journal of Chemical Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Are the Heat Capacities of Liquids Calculated from Speeds of Sound and pρT Relationships Reliable? A Comparison with the Reference Values and a Discussion of the Uncertainties
    Autorzy:
    Szpaczek, Sylwia
    Marczak, Wojciech
    Powiązania:
    https://bibliotekanauki.pl/articles/31339956.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    speed of sound
    density
    compressibilt
    expansibility
    calorimetr
    elevated pressure
    Opis:
    Recent advances in the construction of speed of sound meters made high-accuracy routine measurements possible in laboratories non-specialized in physical acoustics. Reliable values of the isentropic compressibility can be obtained from speeds of sound and densities of liquids using the Laplace formula. Strict thermodynamic relationships connect the isentropic compressibility of a medium and its density as a function of temperature and pressure with the heat capacity. These relationships result from the principles of thermodynamics and require no approximations or molecular models. In this study, the heat capacities of twelve liquids: hydrocarbons, acetonitrile, and ionic liquids were calculated from the speeds and densities taken from the literature sources. The agreement of the calculation results with the reference heat capacities, either critical values or measured calorimetrically, was satisfactory. The relative uncertainty of the calculated heat capacities was rather conservatively estimated for 5%. If the measurement procedures were optimized for heat capacity determination, better results would be attained, with the uncertainty probably smaller than 1%. Thus, the speed-and-density method is a potential alternative to classical calorimetry.
    Źródło:
    Archives of Acoustics; 2022, 47, 4; 547-554
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Otrzymywanie nanosrebra na drodze jednoetapowej redukcji chemicznej w środowisku wodnym w warunkach podwyższonego ciśnienia
    Preparation of nanosilver via one-step chemical reduction in aqueous medium at elevated pressure
    Autorzy:
    Banach, M.
    Pulit, J.
    Tymczyna, L.
    Chmielowiec-Korzeniowska, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/142265.pdf
    Data publikacji:
    2014
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Przemysłu Chemicznego. Zakład Wydawniczy CHEMPRESS-SITPChem
    Tematy:
    nanosrebroredukcja chemicznazielona chemia
    zielona chemia
    nanosilverchemical reductiongreen chemistry
    green chemistry
    Opis:
    Otrzymywanie nanosrebra przeprowadzone zostało na drodzejednoetapowej redukcji chemicznej. Jako środek redukujący jonysrebra i stabilizujący nanocząstki zastosowano odpowiednio kwasaskorbinowy i żelatynę. Otrzymano zawiesinę nanosrebra charakteryzującąsię monomodalnym rozkładem wielkości cząstek i średnimich rozmiarem 5–125 nm.
    Nanosilver synthesis was carried out by a one-step chemicalreduction. Ascorbic acid and gelatin were used as reducing agentof silver ions and stabilizing factor of nanoparticles. Obtainednanosilver suspensions were characterized by monomodalparticle size distribution with their average size of 5–125 nm.
    Źródło:
    Chemik; 2014, 68, 2; 111-116
    0009-2886
    Pojawia się w:
    Chemik
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Trace muscovite dissolution separation from vein quartz by elevated temperature and pressure acid leaching using sulphuric acid and ammonia chloride solutions
    Autorzy:
    Lin, M.
    Pei, Z.-Y.
    Lei, S.-M.
    Liu, Y.-Y.
    Xia, Z.-J.
    Xie, F.-X.
    Powiązania:
    https://bibliotekanauki.pl/articles/110755.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    vein quartz
    muscovite
    sulphuric acid
    ammonium chloride
    acid leaching
    Opis:
    Effects of sulphuric acid and ammonia chloride on muscovite dissolution were studied in acid leaching of vein quartz under elevated temperature and pressure. The leaching processes have been studied in detail by analyzing sources of impurity minerals, optimizing leaching process, analyzing leaching kinetics of Al in muscovite and charactering leaching mechanism of muscovite. The results showed that elements of Al and K mainly occurred in muscovite, and 98.10% or more of muscovite could be removed by acid leaching, while the process had limited influence on the particle size of quartz sand. Leaching of Al in the quartz ore was mainly controlled by chemical reaction. A calcination process and ammonia chloride were used for reducing chemical reaction resistance by damaging crystal structure of muscovite and providing stable acid leaching environment. Combined with the calcination process, muscovite, as a main gangue mineral, was effectively extracted during acid leaching of vein quartz at elevated temperature and pressure.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2018, 54, 2; 448-458
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fenomen górnej granicy wybuchowości (GGW) paliw w powietrzu i tlenie w warunkach podwyższonego ciśnienia i temperatury
    The phenomenon of upper explosion limit of fuels in air and oxygen at elevated temperature and pressure
    Autorzy:
    Rarata, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/213416.pdf
    Data publikacji:
    2010
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
    Tematy:
    Instytut Techniki Cieplnej (PW)
    górna granica wybuchowości paliw w powietrzu i tlenie
    warunki podwyższonego ciśnienia i temperatury
    EPATS Europejski System Transportu Małymi Samolotami
    Institute of Heat Engineering at Warsaw University of Technology
    upper explosion limit of fuels in air and oxygen
    elevated temperature and pressure
    EPATS European Personal Air Transportation System
    Opis:
    Przedstawiona paca doświadczalna została wykonana w laboratoriach Instytutu Techniki Cieplnej PW. Artykuł zawiera wyniki serii pomiarów, których celem było ustalenie wpływu wybranych parametrów fizycznych na wartość ciśnienia wybuchu dla mieszanin gazowych alkanów z tlenem. Dane takie, łącznie z wyznaczoną wartością górnej granicy wybuchowości (GGW) dla poszczególnych mieszanin, mają podstawowe znaczenie dla ustalania odpowiednich norm bezpieczeństwa w przemyśle chemicznym. Badaniom poddano gazowe alkany, a więc metan, etan, propan oraz n-butan. Wyniki, prezentowane w postaci sumarycznych danych (tabel), zostały uzyskane w wyniku przeprowadzenia pomiarów w stalowym naczyniu kulistym o objętości 2,3 dm3. Jako źródło zapłonu użyto tzw. eksplodujący drucik (exploding wire), który uwalniał około 0,1 J energii za każdym razem. Przebieg zmian ciśnienia w czasie rejestrowano przy użyciu szybkiego czujnika piezoelektrycznego. Zbadano wpływ temperatury początkowej mieszanin testowych, w zakresie od 20°C do 200°C. Przeprowadzono również pomiary w zakresie wzrastającego ciśnienia początkowego mieszanin. Na ich podstawie autor wyznaczył wyraźne zależności GGW od początkowej wartości T oraz p badanych mieszanin.
    The presented research work has been done in the Institute of Heat Engineering laboratories at Warsaw University of Technology. The explosive range of chosen gases is determined by specific conditions of temperature and pressure. These values also depend on different factors, such as the shape of the explosion vessel, ignition energy or the presence of other substances which may, for instance, have catalytic properties. The obtained results relate the influence of chosen physical parameters on the value of the Upper Explosive Limit (UEL). Other research data is also presented in the paper. This was obtained from specially designed spherical explosion chamber of a volume of 2.3 dm3. Exploding wire was used as the ignition source. It released about 0.1 J energy each time. The influence of the increased initial temperatures of those mixtures on their value of UEL was also investigated in the range of 20°C up to 200°C. Further experiments on the influence of elevated conditions, as well as the position of ignition source and residence time, were carried out as well. A number of higher alkanes were examined (up to n-butane), both in air and oxygen mixtures. These experiments allowed the author to find distinct dependencies in the values of UEL under the investigation conditions. The results have been compared and validated with literature data and numerical code, according to the experimental conditions, methodology and adopted criteria of UEL determination. Some of the effects found were possible to explain only by acceptance of such phenomenon as cool flames appearing in the regions close to UEL. This seems to be particularly important when safety parameters or numerical modelling standards for UEL are sought.
    Źródło:
    Prace Instytutu Lotnictwa; 2010, 2 (204); 1-70
    0509-6669
    2300-5408
    Pojawia się w:
    Prace Instytutu Lotnictwa
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experiments on the upper explosion limits of gaseous alkanes-oxygen mixtures at elevated conditions of T and P in a spherical vessel
    Autorzy:
    Rarata, G.
    Szymczyk, J.
    Wolański, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/242309.pdf
    Data publikacji:
    2009
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    explosive limit
    flammability limit
    elevated conditions
    explosion pressure
    Opis:
    This experimental work has been completed in the Institute of Heat Engineering Laboratories of Warsaw University of Technology. The article reports on the explosion pressure data and the influence of chosen physical parameters on the value of the Upper Explosive Limit (UEL) of gaseous alkanes-oxygen mixtures. Such explosion behavior data of common gases for different initial conditions are essential for a quantitative risk assessment in many industrial environments. A number of higher alkanes-oxygen mixtures were examined (up to n-butane). Summarized research data is presented in the paper. All the presented data have been obtained from the experiments conducted in a 2.3 dm3 spherical, steel vessel. Exploding wir e was used as the mean of ignition source. It released approx. 0.1 J energy each time. The pressure histories in the combustion vessel have been recorded by means of piezoelectric pressure transducer. The influence of the increased initial temperatures of the tested mixtures on their value of UEL was investigated in the range of 20°C up to 200°C. Further experiments on the influence of elevated pressure, as well as the position of the ignition source, were carried out too. The experiments allowed the authors to find distinct dependencies in the values of obtained UEL under elevated conditions of pressure and temperature.
    Źródło:
    Journal of KONES; 2009, 16, 2; 393-399
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experiments on the upper explosion limits of gaseous alkanes-oxygen mixtures at elevated conditions of T and P in a spherical vessel
    Badania górnej granicy wybuchowości (GGW) mieszanin gazowych alkanów w tlenie w naczyniu kulistym w warunkach podwyższonej temperatury T praz ciśnienia p
    Autorzy:
    Rarata, G.
    Szymczyk, J.
    Wolański, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/213842.pdf
    Data publikacji:
    2009
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
    Tematy:
    górna granica wybuchowości (GGW)
    naczynie kuliste
    warunki podwyższonej temperatury
    warunki podwyższonego ciśnienia
    flammability
    explosive limits
    flammability limits
    elevated conditions
    explosion pressure
    Opis:
    This experimental work has been completed in the Institute of Heat Engineering Laboratories of Warsaw University of Technology. The article reports on the explosion pressure data and the influ-of chosen physical parameters on the value of the Upper Explosive Limit (UEL) of gaseous alkanes-oxygen mixtures. Such explosion behavior data of common gases for different initial con-ditions are essential fora quantitative risk assessment in many industrial environments. A number of higher alkanes-oxygen mixtures were examined (up to n-butane). Summarized research data is presented in the paper. All the presented data have been obtained from the experiments conducted in a 2.3 dm' spherical, steel vessel. Exploding wire was used as the mean of ignition source. It released about 0.1 J energy each time. The pressure histories in the combustion vessel have been recorded by means of piezoelectric pressure transducer. The influence of the increased initial temperatures of the tested mixtures on their value of UEL was investigated in the range of 20°C up to 200°C. Further experiments on the influence of elevated pressure, as well as the position of the igignition source, were carried out too. The experiments allowed the authors to find a distinct dependencies in the values of obtained UEL under elevated conditions of pressure and temperature.
    Przedstawiona praca doświadczalna została wykonana w laboratoriach Instytutu Techniki Cieplnej Politechniki Warszawskiej. Artykuł zawiera wyniki serii pomiarów, których celem bylo ustalenie wpływu wybranych parametrów fizycznych na wartość ciśnienia wybuchu dla mieszanin gazowych alkanów z tlenem. Dane takie, łącznie z wyznaczoną wartością górnej granicy wybuchowości (GGW) dla poszczególnych mieszanin, mają podstawowe znaczenie dla ustalania odpowiednich norm bezpieczeństwa w przemyśle chemicznym. Badaniom poddano gazowe alkany, a więc metan, etan, propan oraz n-butan. Wyniki, prezentowane w postaci sumarycznych danych (tabel) zostały uzyskane w wyniku przeprowadzenia pomiarów w stalowym naczyniu kulistym o objętości 2,3 dm3. Jako źródło zapłonu użyto tzw. eksplodujacy drucik (exploding wire), który uwalniał za każdym razem okolo 0,1J energii. Przebieg zmian ciśnienia w czasie rejestrowano przy użyciu szybkiego czujnika piezoelektrycznego. Zbadano wpływ ternperatury początkowej mieszanin testowych, w zakresie od 20°C do 200°C. Przeprowadzono również pomiary w zakresie wzrastajacego ciśnienia początkowego mieszanin. Na ich podstawie autorzy wyznaczyli wyraźne zależności GGW od początkowej wartaści T oraz p badanych mieszanin.
    Źródło:
    Prace Instytutu Lotnictwa; 2009, 5 (200); 160-167
    0509-6669
    2300-5408
    Pojawia się w:
    Prace Instytutu Lotnictwa
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The impact of sleeping in an elevated upper body position during acclimatization to high altitude on acute mountain sickness and pulmonary artery systolic pressure
    Autorzy:
    Graß, Maren
    Apel, Christian
    Bertsch, Daniela
    Cerfontaine, Carina
    van der Giet, Michael
    van der Giet, Simone
    Haunolder, Miriam
    Hundt, Nina
    Jäger, Julia
    Kühn, Christian
    Museol, Sonja
    Timmermann, Lisa
    Wernitz, Knut
    Gieseler, Ulf
    Morrison, Audry
    Schöffl, Volker
    Küpper, Thomas
    Powiązania:
    https://bibliotekanauki.pl/articles/34671004.pdf
    Data publikacji:
    2024-02-28
    Wydawca:
    Akademia Tarnowska
    Tematy:
    acute mountain sickness
    pulmonary artery systolic pressure
    sleeping positions
    acclimatization
    Opis:
    Background: The effect of sleeping positions during acclimatization to high altitude on Acute Mountain Sickness (AMS) and High Altitude Pulmonary Edema (HAPE) is unknown. We tested whether sleeping with the upper body raised by 5° reduces prevalence and severity of symptoms of AMS as well as of elevated pulmonary artery systolic pressure (PASP) values as a risk factor of HAPE. Methods: Randomly assigning trekking tourist volunteers n = 44 (25 m, 19 f; mean age 42.9 yr) sleeping at 4280 m or 5170 m to the experimental group (upper body elevated by 5°), or to the control group. After exclusion of other reasons for AMS-like symptoms those assumed to be related to AMS were rated by Lake Louise Score questionnaire in the evening and the following morning of the study. Transthoracic echocardiography was performed on both occasions to estimate PASP. Results: In the study group, symptoms of AMS were significantly reduced in younger subjects (p = 0.021), prevalence of AMS was reduced in women (p = 0.156), and PASP values were significantly reduced in older subjects and men (p = 0.032; p = 0.031 respectively). Conclusion: Results suggest that sleeping with the upper body in elevated position during a high altitude ascent may benefit those suffering from AMS or at risk of HAPE due to elevated PASP values.
    Źródło:
    Health Promotion & Physical Activity; 2023, 25, 4; 1-8
    2544-9117
    Pojawia się w:
    Health Promotion & Physical Activity
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Speed of Ultrasound and Internal Pressure of Propanediol and Butanediol Isomers under Elevated Pressures
    Autorzy:
    Zorębski, E.
    Piotrowska, M.
    Dzida, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1811570.pdf
    Data publikacji:
    2008-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    82.30.Rs
    62.50.-p
    Opis:
    Speed of ultrasound and internal pressure of 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, and 1,3-butanediol at the temperatures ranging from 293.15 to 318.15 K and pressures up to 101 MPa are analyzed and discussed in terms of molecular structure and ability to form inter- and intramolecular hydrogen bonds.
    Źródło:
    Acta Physica Polonica A; 2008, 114, 6A; A-265-A-270
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of increased temperature on dimensional and shape accuracy of castings produced from the EN AC-AlSi11 alloy by pressure die casting process
    Autorzy:
    Jarco, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/353899.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    high pressure die casting
    Al-Si alloy
    blistering
    dimensional accuracy
    shape accuracy
    elevated temperature behavior
    Opis:
    The present work discusses results of increased temperature on shape-dimensional changes of a 110 type hose coupling, produced from EN AC-AlSi11 alloy with the use of pressure die casting technology. The castings were soaked for 3.5 h at temperatures 460°C, 475°C and 490°C. The verification of shape-dimensional accuracy of the elements after soaking treatment, in relation to raw casting, was carried out by comparing the 3D models received from 3D scanning. Soaking temperature of about 460°C-475°C results in no significant changes in the shapes and dimensions of the castings, or surface defects in the form of blisters, which can be seen at a temperature of 490°C.
    Źródło:
    Archives of Metallurgy and Materials; 2019, 64, 1; 325-328
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Temperature effect on explosion parameters of hydrogen-air deflagrations in presence of water vapor
    Autorzy:
    Grabarczyk, M.
    Żbikowski, M.
    Mężyk, Ł.
    Teodorczyk, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/115947.pdf
    Data publikacji:
    2016
    Wydawca:
    Fundacja na Rzecz Młodych Naukowców
    Tematy:
    explosion pressure
    hydrogen
    closed vessel
    elevated temperature
    water vapor
    deflagration
    ciśnienie wybuchu
    wodór
    naczynie zamknięte
    podwyższona temperatura
    para wodna
    deflagracja
    Opis:
    Results of investigation of hydrogen-air deflagrations phenomenon in closed vessel in various initial temperatures and volume fraction of water vapor are presented in following paper. Tests were performed in apparatus which construction complies with EN 15967 recommendations—20-litre sphere. Studied parameters were explosion pressure (Pex) and maximum explosion pressure (Pmax). Defining the influence of the initial conditions (temperature and amount of water vapor) on the maximum pressure of the hydrogen-air deflagration in a constant volume was the main aim. Initial temperatures were equal to 373K, 398K and 413K. Initial pressure was ambient (0.1 MPa). Hydrogen volume fraction differed from 15% to 80%, while humidity volume fraction from 0% to 20%. Ignition source was placed in geometrical center of testing chamber and provided energy between 10-20J from burnout of fuse wire with accordance to abovementioned standard. Common features of all experimentally obtained results were discussed. Maximum explosion pressure (Pmax) decreases with increasing the initial temperature. Furthermore, addition of the water vapor for constant initial temperature decreases value of Pmax and shifts the maximum peak to the direction of lean mixtures. Data provided in paper can be useful in assessment of explosion risk of industry installations working with hydrogen-air atmospheres with high water vapor addition.
    Źródło:
    Challenges of Modern Technology; 2016, 7, 3; 39-44
    2082-2863
    2353-4419
    Pojawia się w:
    Challenges of Modern Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-11 z 11

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