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Wyniki wyszukiwania dla: thermodynamics
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Theoretical methods in thermodynamics of condensed phases
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The lows of thermodynamics: cell energy transfer
PublikacjaW pracy przedstawiono zasady termodynamiki i wymiany ciepła w organizmach żywych i urządzeniach technicznych. Przedstawiono zasady stosowania praw fizycznych związanych z konwersją energii w organizmach żywych.
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Singular Surface Curves in the Resultant Thermodynamics of Shells
PublikacjaWithin six-parameter shells theory we discuss the governing equations of shells with material or non-material singular curves. By singular curve we mean a surface curve where are discontinuities in some surface fields. As an example we consider shells with junctions and shells undergoing stress-induced phase transitions.
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Duhem and Natanson: Two Mathematical Approaches to Thermodynamics
PublikacjaIn this article, the previously unrecognized contributions of Pierre Duhem and Ladislavus Natanson in thermodynamics are shown. The mathematical remodelling of a few of their principal ideas is taken into consideration, despite being neglected in the literature. To emphasize these ideas in an appropriate epistemological order, it would be crucial to first revalue and reconstruct some underrepresented parts of the proceedings process...
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Chapter 7: Engineering Thermodynamics and the Carnot Cycle
PublikacjaThe chapter presents information about thermodynamics and thermodynamic cycles, especially the history and meaning of Carnot Cycle as well as P-v and T-s Diagrams
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1.21 Computation of Structure, Dynamics, and Thermodynamics of Proteins
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Thermodynamics of solid phases containing rare earth oxides
PublikacjaRare earth elements (RE) are incorporated into a large variety of complex oxide phases to provide tailored mechanical, electrical, optical, and magnetic properties. Thermodynamics control phase stability, materials compatibility in use, corrosion, and transformation. This review presents, in one compilation, the thermodynamic properties of a large number of such materials and discusses systematic trends in energetics and the factors...
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On coertia and inertia in aspects of Natanson’s nonlinear extended thermodynamics
PublikacjaIn this article, the previously underrepresented contributions of Natanson to the field of thermodynamics have been presented. In order to identify a source of irreversibility at Nature, Natanson introduced the concept of Coertia, which is similar to inertia. Natanson’s Coertia is a fundamental property of space that is responsible for every irreversible phenomena in matter, as well as in the electromagnetic and gravitational fields....
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Thermodynamics aspects of interactions between acridine derivatives and DNA
PublikacjaDNA is a molecular target for many anticancer and antiviral drugs. Therefore, a clear understanding of the interaction of small molecules with DNA is important in the rational design of ligands that can bind to DNA with high affinity and selectivity. There are several methods to investigate interactions between drug and DNA. Some of them measure changing into DNA structures, such as lengthening and untwisting of helix of DNA. Other...
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Thermodynamics of micellization of imidazolium ionic liquids in aqueous solutions
PublikacjaPodobieństwo pomiędzy strukturami niektórych cieczy jonowych, a surfaktamtami jonowymi wskazuje na możliwość wykazywania, przez te związki, tendencji do agregacji i adsorpcji na powierzchniach międzyfazowych. Mierząc w różnych temperaturach przewodnictwo elektryczne w funkcji stężenia oznaczono temperaturę Kraffta i zależność temperaturową krytycznego stężenia micelizacji (CMC) dla czterech, różniących się długościami łańcucha,...
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The laws of thermodynamics: entropy, free energy, information and complexity
PublikacjaW rozdziale przedstawiono podstawowe Zasady Termodynamiki. Omówiono zagadnienia związane z pojęciem entropii, energii Gibbsa, egzergii oraz systemami złożonymi.
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New Insights into Thermodynamics of Solutes in Neat and Complex Solvents
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Conductivity, structure, and thermodynamics of Y2Ti2O7–Y3NbO7 solid solutions
PublikacjaThe defect fluorite yttrium niobate Y3NbO7 and pyrochlore yttrium titanate Y2Ti2O7 solid solutions have been synthesized via a solid state synthesis route. The resulting stoichiometry of the oxides is Y2+xTi2−2xNbxO7, where x = 0 to x = 1. All of the samples were single-phase; however, for those with a predominant fluorite phase, a small amount of additional pyrochlore phase was detected. The volume of the solid solution unit cells...
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Numerical modelling of thermodynamics and dynamics of sea ice in the Baltic Sea
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Thermodynamics of the thermal decomposition of calcium oxalate monohydrate examined theoretically
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Neoclassical Navier–Stokes Equations Considering the Gyftopoulos–Beretta Exposition of Thermodynamics
PublikacjaThe seminal Navier-Stokes equations were stated even before the creation of the foundations of thermodynamics and its first and second laws. There is a widespread opinion in the literature on thermodynamic cycles that the Navier-Stokes equations cannot be taken as a thermodynamically correct model of a local "working fluid", which would be able to describe the conversion of "heating" into "working" (Carnot's type cycles) and vice...
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Thermodynamics of aggregation of 1-methyl-3-tetradecylimidazolium chloride in an aqueous solution
PublikacjaZbadano zależność agregacji chlorku 1-metylo-3-tetradecyloimidazoliowego w środowisku wodnym od temperatury. Wyznaczono krytyczne stężenie agregacji (CAC) oraz stopień jonizacji metodą pomiaru przewodnictwa właściwego. Otrzymane wyniki wykorzystano do predykcji parametrów termodynamicznych - entalpii swobodnej, entalpii i entropii, stosując phase separation model. Wykazano, że krzywa zależności CAC od temperatury jest U-kształtna...
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Thermodynamics of Chemical Processes in the System of Nanocrystalline Iron–Ammonia–Hydrogen at 350 °C
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Irreversible thermodynamics model equations for heterogeneous solute flows in a double-membrane system
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Removal of diphenols using pine biochar. Kinetics, equilibrium, thermodynamics, and mechanism of uptake
PublikacjaThermal pyrolysis synthesized activated biochar from the Pinus elliottii sawdust (PS) at 600° C. The obtained activated biochar (PB600) was used for the removal of three diphenols, catechol (CAT), resorcinol (RES), and hydroquinone (HYD), which are utilized mainly in different industries. The PB600 was characterized by several analytical techniques. The BET surface area of 1473 m2.g−1 and a total pore volume of 0.707 cm3 g−1 was...
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Thermodynamics and kinetics of amphotericin B self-association in aqueous solution characterized in molecular detail
PublikacjaAmphotericin B (AmB) is a potent but toxic drug commonly used to treat systemic mycoses. Its efficiency as a therapeutic agent depends on its ability to discriminate between mammalian and fungal cell membranes. The association of AmB monomers in an aqueous environment plays an important role in drug selectivity, as oligomers formed prior to membrane insertion – presumably dimers – are believed to act differently on fungal (ergosterol-rich)...
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Thermodynamics, size, and dynamics of zwitterionic dodecylphosphocholine and anionic sodium dodecyl sulfate mixed micelles
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UNRES server for physics-based coarse-grained simulations and prediction of protein structure, dynamics and thermodynamics
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Scale-consistent approach to the derivation of coarse-grained force fields for simulating structure, dynamics, and thermodynamics of biopolymers
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Adsorption of cationic dyes onto Fe@graphite core–shell magnetic nanocomposite: Equilibrium, kinetics and thermodynamics
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Thermodynamics and Intermolecular Interactions of Nicotinamide in Neat and Binary Solutions: Experimental Measurements and COSMO-RS Concentration Dependent Reactions Investigations
PublikacjaIn this study, the temperature-dependent solubility of nicotinamide (niacin) was measured in six neat solvents and five aqueous-organic binary mixtures (methanol, 1,4-dioxane, acetonitrile, DMSO and DMF). It was discovered that the selected set of organic solvents offer all sorts of solvent effects, including co-solvent, synergistic, and anti-solvent features, enabling flexible tuning of niacin solubility. In addition, differential...
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Function and Frustration of Multi-Drug ABC Exporter Protein and Design of Model Proteins for Drug Delivery Using Protein Hydration Thermodynamics
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Kinetics and thermodynamics of the reaction of iminodiacetate copper(II) complexes with 1,10-phenanthroline and 2,2′-bipyridine in aqueous, anionic, cationic and nonionic surfactants solutions
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Adsorption of anionic dye Direct Red 23 onto magnetic multi-walled carbon nanotubes-Fe3C nanocomposite: Kinetics, equilibrium and thermodynamics
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Implementation of Molecular Dynamics and Its Extensions with the Coarse-Grained UNRES Force Field on Massively Parallel Systems: Toward Millisecond-Scale Simulations of Protein Structure, Dynamics, and Thermodynamics
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Experiences from operation of different expansion devices for application in domestic micro CHP
PublikacjaW pracy opisano doświadczenia zdobyte podczas badań trzech różnych urządzeń ekspansyjnych, możliwych do zaimplementowania w mikrosiłowni CHP. Przebadano ekspander wykonany na bazie sprężarki spiralnej oraz dwojakiego rodzaju silniki pneumatyczne. Wykazano "wyższość" maszyn pneumatycznych nad ekspanderem typu scroll, uzyskując sprawności wewnętrzne w zakresie 61-82%. Dodatkowo, mniejsza objętość i masa urządzeń pneumatycznych stanowi...
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Experimental and theoretical study of dryout in annular flow in small diameter channels
PublikacjaW pracy zaprezentowano badania eksperymentalne kryzysu wrzenia II rodzaju w kanałach o małej średnicy. Badania prowadzone były w rurach pionowych o średnicy 1.15 i 2.3 mm, w których badanym czynnikiem były płyny niskowrzące, takie jak SES36 i R123. W badaniach zastosowano nowoczesne techniki pomiarowe do określania lokalizacji kryzysu wrzenia na ściance kanału, np. kamerę termowizyjną. Na podstawie pozyskanych punktów eksperymentalnych...
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Parametric study of fluid flow and heat transfer over louvered fins of air heat pump evaporator
PublikacjaTwo-dimensional numerical investigations of the fluid flow and heat transfer have been carried out for the laminar flow of the louvered fin-plate heat exchanger, designed to work as an air-source heat pump evap- orator. The transferred heat and the pressure drop predicted by simulation have been compared with the corresponding experimental data taken from the literature. Two dimensional analyses of the louvered fins with varying...
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Experimental investigation of domestic micro-CHP based on the gas boiler fitted with ORC module
PublikacjaThe results of investigations conducted on the prototype of vapour driven micro-CHP unit integrated with a gas boiler are presented. The system enables cogeneration of heat and electric energy to cover the energy demand of household. The idea of such system is to produce electricity for own demand or for selling it to the electric grid – in such situation the system user will became the prosumer. A typical commercial gas boiler,...
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Comparative study of selected fluids for use in supercritical Organic Ranking Cycles
PublikacjaIn view of increasing interest in improving energy efficiency of energy conversion devices, there is an increasing requirement of combined production of heat and electricity as well as demand for increased implementation of renewable energy resources. The micro cogenerative units utilizing the Organic Rankine Cycle are focusing the attention of many research centres around the world. In the present paper calculations of ORC cycles...
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Dryout in annular flow - theoretical analysis
PublikacjaW pracy zaprezentowano model kryzysu wrzenia w przepływie pierścieniowym, obowiązujący dla wysokich wartości stopnia suchości i stanowiący modyfikację wcześniejszej wersji modelu zaproponowanego przez Sedlera i Mikielewicza. Model ten uwzględnia bilans masy w filmie cieczowym i bilans masy dla kropel cieczy w rdzeniu przepływu oraz zawiera dodatkowy człon odpowiedzialny za odparowanie filmu na ściance kanału. Rozwiązanie układu...
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Investigation of the influence of capilary effect on operation of the loop heat pipe
PublikacjaIn the paper presented are studies on the inestigation of the capillary forces effect inducted in the porous structure of a loop heat pipe using water and ethanol ad test fluids. The potential application of such effects is for example in the evaporator of the domestic micro-CHP unit, where the reduction of pumping power could be obtained. Preliminary analysis of the results indicates water as having the best potential for developing...
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Comparitive study of heat transfer and pressure drop during flow boiling and flow condensation in minichannels
PublikacjaIn the paper a method developed earlier by authors is applied to calculations of pressure drop and heat transfer coefficient for flow boiling and also flow condensation for some recent data collected from literature for such fluids as R404a, R600a, R290, R32,R134a, R1234yf and other. The modification of interface shear stresses between flow boiling and flow condensation in annular flow structure are considered through incorporation...
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Pool boiling of nanofluids on rough and porous coated tubes: experimental and correlation
PublikacjaThe paper deals with pool boiling of water-Al2O3 and water- Cu nanofluids on rough and porous coated horizontal tubes. Commercially available stainless steel tubes having 10 mm outside diameter and 0.6 mm wall thickness were used to fabricate the test heater. The tube surface was roughed with emery paper 360 or polished with abrasive compound. Aluminium porous coatings of 0.15 mm thick with porosity of about 40% were produced by...
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Increase of power and efficiency of the 900 MW supercritical power plant through incorporation of the ORC
PublikacjaThe objective of the paper is to analyse thermodynamical and operational parameters of the supercritical power plant with reference conditions as well as following the introduction of the hybrid system incorporating ORC. In ORC the upper heat source is a stream of hot water from the system of heat recovery having temperature of 90 °C, which is additionally aided by heat from the bleeds of the steam turbine. Thermodynamical analysis...
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Revalorization of the Szewalski binary vapour cycle
PublikacjaThe aim of the paper is to revalorizate of the Szewalski binary vapour cycle by analysing thermodynamical and operational parameters of this cycle. This was carried by accessible numerical CFM (Computational Flow Mechanics) codes type, by step-by-step modeling of separates apparatus. The binary vapour cycle is providing steam as the working fluid in the high temperature part of the cycle, while another fluid - a low boiling point...
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Pressure drop related to flow maldistribution in a model minichannel plate heat exchanger
PublikacjaThe paper describes the issues related to the pressure drop that accompanies the phenomenon of maldistribution of working fluid between the channels of a model minichannel plate heat exchanger. The research concerns a single exchanger's plate containing 51 (in every geometry) parallel rectangular minichannels of hydraulic diameters 461 µm, 571 µm, 750 µm and 823 µm. In addition, the more complex geometry has been investigated,...
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The use of liquid crystal thermography TLC and particle image velocimetry PIV in selected technical applications
PublikacjaNowadays, the energy cost is very high and this problem is carried out to seek techniques for improvement of the aerothermal and thermal (heat flow) systems performances in different technical applications. The transient and steady-state techniques with liquid crystals for the surface temperature and heat transfer coefficient or Nusselt number distribution measurements have been developed. The flow pattern produced by transverse...
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Dynamic characteristics of the proton exchange membrane fuel cell module
PublikacjaThe paper describes a fuel cell based system and its performance. The system is based on two fuel cell units, DC/DC converter, DC/AC inverter, microprocessor control unit, load unit, bottled hydrogen supply system and a set of measurement instruments. In the study presented in the paper a dynamic response of the proton exchange membrane (PEM) fuel cell system to unit step change load as well as to periodical load changing cycles...
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Performance analyses of helical coil heat exchangers. The effect of external coil surface modification on heat exchanger effectiveness
PublikacjaThe shell and coil heat exchangers are commonly used in heating, ventilation, nuclear industry, process plant, heat recovery and air conditioning systems. This type of recuperators benefits from simple construction, the low value of pressure drops and high heat transfer. In helical coil,centrifugal force is acting on the moving fluid due to the curvature of thetube results in the development. It has been long recognized that the...
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Determination of dryout localization using a five-equation model of annular flow for boiling in minichannels
PublikacjaDetailed studies have suggested that the critical heat flux in the form of dryout in minichannels occurs when the combined effects of entrainment, deposition, and evaporation of the film make the film flow rate go gradually and smoothly to zero. Most approaches so far used the mass balance equation for the liquid film with appropriate formulations for the rate of deposition and entrainment respectively. It must be acknowledged...
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Heat transfer in plate heat exchanger channels: experimental validation of selected correlation equations
PublikacjaThis study is focused on experimental investigation of selected type of brazed plate heat exchanger. The Wilson approach was applied in order to estimate heat transfer coefficients for the PHEx passages. The main aim of the paper was to experimentally check ability of several correlations published in the literature to predict heat transfer coefficients by comparison experimentally obtained data with appropriate predictions. The...
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Comparison of Downdraft and Updraft Gasification of Biomass in a Fixed Bed Reactor
PublikacjaThe aim of this study was to compare and analyze the gasification process of beech wood. The experimental investigation was conducted inside a gasifier, which can be operated in downdraft and updraft gasification system. The most important operating parameter studied in this paper was the influence of the amount of supply air on the temperature distribution, biomass consumption and syngas calorific value. The results show that...
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Selected studies of flow maldistribution in a minichannel plate heat exchanger
PublikacjaAnalysis of the state of-the-art in research of minichannel heat exchangers, especially on the topic of flow maldistribution in multiple channels, has been accomplished. Studies on minichannel plate heat exchanger with 51 parallel minichannels with four hydraulic diameters, i.e., 461 μm, 574 μm, 667 μm, and 750 μm have been presented. Flow at the instance of filling the microchannel with water at low flow rates has been visualized. The...
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Investigations on mixture preparation for two phase adiabatic pressure drop of R134a flowing in 5 mm diameter channel
PublikacjaThe article presents detailed two-phase adiabatic pressure drops data for refrigerant R134a. Study cases have been set for a mass flux varying from 200 to 400 kg/m2 s, at the saturation temperature of 19.4 ◦C. Obtained experimental data was compared with the available correlations from the literature for the frictional pressure drop during adiabatic flow. Influence of mixture preparation on pressure drop was investigated, for...
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The performance of H2O, R134a, SES36, ethanol, and HFE7100 two-phase closed thermosyphons for varying operating parameters and geometry
PublikacjaIn this study, the influences of different parameters at performance two-phase closed thermosiphon (TPCT) was presented. It has been confirmed that the working fluid, as well as operating parameters and fill ratio, are very important factors in the performance of TPCT. The article shows characteristics of gravitational tube geometr ies, as well as the technical characteristic of the most important system components, i.e., the evaporator/condenser....
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Recuperator with microjet technology as a proposal for heat recovery from low-temperature sources
PublikacjaA tendency to increase the importance of so called dispersed generation, based on the local energy sources and the working systems uti- lizing both the fossil fuels and the renewable energy resources is observed nowadays. Generation of electricity on industrial or domestic scale together with production of heat can be obtained for example through employment of the ORC systems. It is mentioned in the EU directive 2012/27/EU for...
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MEASUREMENT OF TEMPERATURE-DEPENDENT VISCOSITY AND THERMAL CONDUCTIVITY OF ALUMINA AND TITANIA THERMAL OIL NANOFLUIDS
PublikacjaIn this study results of simultaneous measurements of dynamic viscosity, thermal conductivity, electrical conductivity and pH of two nanofluids, i.e. thermal oil/Al2O3 and thermal oil/TiO2 are presented. Thermal oil is selected as a base liquid because of possible application in ORC systems as an intermediate heating agent. Nanoparticles were tested at the concentration of 0.1%, 1% and 5% by weight within temperature range from...
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Utilisation of bleed steam heat to increase the upper heat source temperature in low-temperature ORC
PublikacjaW pracy przedstawiono możliwość dogrzewu obiegu ORC za pomocą pary upustowej.
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A semi-empirical method for calculation of heat transfer coefficient in flow boiling for conventional tubes and minichannels
PublikacjaW pracy przedstawiono zagadnienia które należy uwzględnić podczas modelowania wymiany ciepła z wrzeniem w przepływie w kanałach o małej średnicy. Uzyskano dobrą zgodność z wynikami badań eksperymentalnych.
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Horizontal flow boiling of R22, R134a and their mixtures with oil in smooth and enhanced tubes
PublikacjaOpisano stanowisko i procedurę badawczą. Przedstawiono wyniki badań wrzenia czynników R 22 i R 134a oraz ich mieszanin z olejem wewnątrz dwóch rur gładkich i dwóch rur o rozwiniętej powierzchni. Zweryfikowno wybrane korelacje współczynnika przejmowania ciepła podczas wrzenia czystych czynników chłodniczych w rurach gładkich.
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Comparative study of flow condensation in conventional and small diameter tubes
PublikacjaFlow boiling and flow condensation are often regarded as two opposite or symetrical phenomena. Their description however with a single correlation has yet to be suggested.In the case of flow boiling in minichannels there is mostly encountered the annular flow structure, where the buble generetion is not present. Similar picture holds for the case of inside tube condensation, where annular flow structure predominates. In such case...
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Optimal boiling temperature for ORC installation
PublikacjaW pracy przedstawiono oryinalne kryterium wyznaczania optymalnej temperatury odparowania czynnika w obiegu ORC w postaci równań analitycznych. Pokazano przykład obliczeniowy na bazie R134a, wody i etanolu.
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Thermal-hydraulic issues of flow boiling and condensation in organic Rankine cycle heat exchangers
PublikacjaW pracy przedstawiono szereg zagadnień cieplno-przepływowych podczas wrzenia i kondensacji w przepływie w wymiennikach ciepła obiegu ORC. Uwzględniono przemiany fazowe. Analizowano zagadnienia stabilności pracy wymienników oraz ich dynamikę
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Determination of the thermal conductivity of material dividing the metallic core elements of the bi-calorimeter using modified theory
PublikacjaW pracy przedstawiono zmodyfikowaną teorię bikalorymetru z dzielonym metalowym rdzeniem. Pomiędzy dwiema częściami rdzenia umieszczano próbki badanego ciała stałego lub gazu. Ogrzewano jedną stronę rdzenia. Mierzono temperaturę obu części rdzenia w funkcji czasu. Uzyskane wyniki umożliwiły wyznaczenie różnicy temperatur i strumienia ciepła, przepływającego przez próbkę. Z zastosowaniem prawa Fouriera obliczano współczynnik przewodności...
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Improved model of void fraction distribution in two-phase flow in the boundary layer
PublikacjaPraca skupiona jest na eksperymentalnej weryfikacji sił działających na pęcherzyk gazowy przepływający wzdłuż ścianki kanału, a następnie implementacji uzyskanych wyników do zaproponowanego wczesniej przez jednego z współautorów modelu rozkładu stopnia zapełnienia w warstwie przyściennej przepływu dwufazowego. Podczas badań pęcherzyk modelowany był sztywną kulą podwieszoną na strunie. Autorzy przekonują, że pokazany model dobrze...
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Cogenerative micro power plants - a new direction for development of power engineering?
PublikacjaW pracy przedstawiono rozważania dotyczące perspektywy mikrosiłowni domowych w gospodarce rozproszonej. Przedstawiono oryginalne kryterium doboru czynnika roboczego w mikrosiłowni oraz przedstawiono sprawności cieplne i egzergetyczne obiegów Clausiusa-Rankina realizujących pracę mikrosiłowni.
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A study of flow boiling heat transfer in minichannels
PublikacjaW pracy przedstawiono badania eksperymentalne wrzenia w przepływie w minikanale o średnicy wewnętrznej 2.3mm i długości 38cm. Uzyskano rozłady temperatury wzdłuż ścianki kanału oraz lokalne współczynniki przejmowania ciepła. Dane skorelowano z korelacją półempiryczną uzyskując zadowalającą zgodność.
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Design and computational fluid dynamics analysis of the last stage of innovative gas-steam turbine
PublikacjaResearch regarding blade design and analysis of flow has been attracting interest for over a century. Meanwhile new concepts and design approaches were created and improved. Advancements in information technologies allowed to introduce computational fluid dynamics and computational flow mechanics. Currently a combination of mentioned methods is used for the design of turbine blades. These methods enabled us to improve flow efficiency...
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Analysis of start energy of Stirling engine type alpha
PublikacjaThe Stirling engine type alpha is composed of two cylinders (expansion space E and compression space C), regenerator that forms the space between the cylinders and the buffer space (under the pistons). Before the start-up and as a result of long-term operation, the average pressure in the working space (above the pistons) and in the buffer space is the same. However, in the initial phase of operation, the average pressure in the...
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Modeling of the internal combustion engine cooling system
PublikacjaThe article concerns computer modelling of processes in cooling systems of internal combustion engines. Modelling objectives and existing commercial programs are presented. It also describes Author’s own method of binding graphs used to describe phenomena in the cooling system of a spark ignition engine. The own model has been verified by tests on the engine dynamometer. An example of using a commercial program for experimental...
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Hydraulic resistance analyses of selected elements of the prototype Stirling engine
PublikacjaThe paper presents the results of simulation tests of hydraulic resistance and temperature distribution of the prototype Stirling alpha engine supplied with waste heat. The following elements were analyzed: heater, regenerator and cooler. The engine uses compressed air as a working gas. Analyses were carried out for three working pressure values and different engine speeds. The work was carried out in order to optimize the configuration...
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Mathematical modeling of hydrogen production performance in thermocatalytic reactor based on the intermetallic phase of Ni3Al
PublikacjaThe main goal of the following work is to adjust mathematical modelling for mass transfer, to specific conditions resulting from presence of chemical surface reactions in the flow of the mixture consisting of helium and methanol. The thermocatalytic devices used for decomposition of organic compounds incorporate microchannels coupled at the ends and heated to 500 oC at the walls regions. The results of the experiment were compared...
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Computational fluid dynamics simulation of heat transfer from densely packed gold nanoparticles to isotropic media
PublikacjaThis work aims to determine and compare heat generation and propagation of densely packed gold nanoparticles (Au NPs) induced by a resonant laser beam (532 nm) according to the Mie theory. The heat flux propagation is transferred into the materials, which here are: silica glass; soda-lime-silica glass; borosilicate glass; polymethyl methacrylate (PMMA); polycarbonate (PC); and polydimetylosiloxane (PDMS). This analysis aims to...
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Challenges in operating and testing loop heat pipes in 500–700 K temperature ranges
PublikacjaThe potential applications of loop heat pipes (LHPs) are the nuclear power space systems, fuel cell thermal management systems, waste heat recovery systems, medium temperature electronic systems, medium temperature military systems, among others. Such applications usually operate in temperature ranges between 500–700 K, hence it is necessary to develop an LHP system that will meet this requirement. Such a thermal management device...
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Prediction of flow boiling heat transfer data for R134a, R600a and R290 in minichannels
PublikacjaIn the paper presented is the analysis of the results of calculations using a model to predict flow boiling of refrigerants such as R134a, R600a and R290. The latter two fluids were not used in development of model semiempirical correction. For that reason the model was verified with present experimental data. The experimental research was conducted for a full range of quality variation and a relatively wide range of mass velocity....
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Power enhancement of the Brayton cycle by steam utilization
PublikacjaThe paper presents thermodynamic analysis of the gas-steam unit of the 65 MWe combined heat and power station. Numerical analyses of the station was performed for the nominal operation conditions determining the Brayton and combined cycle. Furthermore, steam utilization for the gas turbine propulsion in the Cheng cycle was analysed. In the considered modernization, steam generated in the heat recovery steam generator unit is directed...
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EFFECT OF NANOFLUID CONCENTRATION ON TWO-PHASE THERMOSYPHON HEAT EXCHANGER PERFORMANCE
PublikacjaAn approach – relaying on application of nanofluid as a working fluid, to improve performance of the two-phase thermosyphon heat exchanger (TPTHEx) has been proposed. The prototype heat exchanger consists of two horizontal cylindrical vessels connected by two risers and a downcomer. Tube bundles placed in the lower and upper cylinders work as an evaporator and a condenser, respectively. Distilled water and nanofluid water-Al2O3...
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Prediction of flow boiling heat transfer coefficient for carbon dioxide in minichannels and conventional channels
PublikacjaIn the paper presented are the results of calculations using authors own model to predict heat transfer coefficient during flow boiling of carbon dioxide. The experimental data from various resea rches were collected. Calculations were conducted for a full range of quality variation and a wide range of mass velocity. The aim of the study was to test the sensitivity of the in-house model. The results show the importance of taking into...
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Exergy analysis of the Szewalski cycle with a waste heat recovery system
PublikacjaThe conversion of a waste heat energy to electricity is now becoming one of the key points to improve the energy efficiency in a process engineering. However, large losses of a low-temperature thermal energy are also present in power engineering. One of such sources of waste heat in power plants are exhaust gases at the outlet of boilers. Through usage of a waste heat regeneration system it is possible to attain a heat rate of approximately...
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Performance of cryogenic oxygen production unit with exhaust gas bleed for sewage sludge gasification and different oxygen purities
PublikacjaThe paper presents a thermodynamic analysis of the integration of a cryogenic air separation unit into a negative CO2 emission gas power plant. The power cycle utilizes sewage sludge as fuel so this system fits into the innovative idea of bioenergy with carbon capture and storage. A cryogenic air separation unit integrated with the power plant was simulated in professional plant engineering and thermodynamic process analysis software....
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Formation of bubbles from a single nucleation site.
PublikacjaPrzedstawiono wyniki systematycznych badań eksperymentalnych wrzenia wody destylowanej i metanolu z pojedynczego, sztucznego centrum nukleacji. Jako centra nukleacji służyły otwory wywiercone na czołowej powierzchni miedzianego pręta. Średnice otworów wynosiły: 0.25 mm, 0.60 mm oraz 1.0 mm. Do pomiaru częstotliwości odrywania się pęcherzyków zastosowano układ laser diodowy-fotodioda. Sygnał z fotodiody był rejestrowany za...
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Thermal and hydraulic phenomena in boundary layer of minijets impingement on curved surfaces
PublikacjaPresented work considers flow and thermal phenomena occurring during the single minijet impingement on curved surfaces, heated with a constant heat flux, as well as the array of minijets. Numerical analyses, based on the mass, momentum and energy conservation laws, were conducted, regarding single phase and two-phase simulations. Focus was placed on the proper model construction, in which turbulence and boundary layer modeling...
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Design and investigations of the ethanol microturbine
PublikacjaThe paper presents the results of the design analysis and experimental investigations of the microturbine set consisting of the microturbine with partial admission and permanent magnet generator. The microturbine was designed for operation with the vapour of ethanol as a working fluid. Microturbine unit was tested for different parameters of the working fluid and varying the electrical load. The examples and the comparison between...
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Optimisation of turbine shaft heating process under steam turbine run-up conditions
PublikacjaAn important operational task for thermal turbines during run-up and run-down is to keep the stresses in the structural elements at a right level. This applies not only to their instantaneous values, but also to the impact of them on the engine lifetime. The turbine shaft is a particularly important element. The distribution of stresses depends on geometric characteristics of the shaft and its specific locations. This means a groove manufactured...
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Thermal and economic investigation of straight and U-bend double tube heat exchanger with coiled wire turbulator
PublikacjaExperimental research has been carried out for four individual heat exchanger constructions, i.e., plain double tube, turbulized double tube, plain U-bend and U-bend with turbulator. Tests were made for the water-water system. The study covered a wide measuring range, i.e., Re = 800–9000 – on the shell side, for a constant cold water temperature of 9 ◦C and hot water of 50 ◦C. The heat exchangers were made from copper tubes with...
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Model of heat transfer in the stagnation point of rapidly evaporating microjet
PublikacjaThe paper presents investigation into the single water microjet surface cooling producing evaporating film. Reported tests were conducted under steady state conditions. Experiments were conducted using the nozzle size of 70 and 100 mikrometer respectively. In the course of investigations obtained were experimental relations between heat flux and wall superheating. It was proved that the phenomenon is similar to that of pool boiling...
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Thermodynamic analysis of the double Brayton cycle with the use of oxy combustion and capture of CO2
PublikacjaIn this paper, thermodynamic analysis of a proposed innovative double Brayton cycle with the use of oxy combustion and capture of CO2, is presented. For that purpose, the computation flow mechanics (CFM) approach has been developed. The double Brayton cycle (DBC) consists of primary Brayton and secondary inverse Brayton cycle. Inversion means that the role of the compressor and the gas turbine is changed and firstly we have expansion...
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Heat transfer and pressure drop characteristics of the silicone-based plate heat exchanger
PublikacjaThe paper presents an experimental investigation of a silicone based heat exchanger, with passive heat transfer intensification by means of surface enhancement. The main objective of this paper was to experimentally investigate the performance of a heat exchanger module with the enhanced surface. Heat transfer in the test section has been examined and described with precise measurements of thermal and flow conditions. Reported...
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The effect of temperature difference on heat transport in solar cells
PublikacjaW pracy omówiono wpływ wzrostu temperatury i mechanizm transportu ciepła na drodze przewodzenia w układach hybrydowych PV/T. Wyznaczono współczynniki przewodzenia krystalicznego krzemu typu n i p oraz gęstość strumienia ciepła w zakresie temperatur od 0 do 100 st. C.
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Nonlinear resultant theory of shells accounting for thermodiffusion
PublikacjaThe complete nonlinear resultant 2D model of shell thermodiffusion is developed. All 2D balance laws and the entropy imbalance are formulated by direct through-the-thickness integration of respective 3D laws of continuum thermodiffusion. This leads to a more rich thermodynamic structure of our 2D model with several additional 2D fields not present in the 3D parent model. Constitutive equations of elastic thermodiffusive shells...
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Apparent molar volumes and compressibilities of tetrabutyl-ammonium bromide in organic solvents
PublikacjaW oparciu o pomiary gęstości i szybkości rozchodzenia się dźwięku w niewodnych roztworach bromku czterobutyloamoniowego obliczono pozorne objętości molowe w przedziale temperatur od 288,15 K do 323,15 K oraz pozorne ściśliwości w temperaturze 298,15 K. Graniczne wielkości pozornej objętości molowej i ściśliwości wyznaczono w oparciu o równanie Massona, jak i równanie Redlicha, Rosenfelda i Mayera oraz z wykorzystaniem teorii Pitzera....
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Excess molar volume and viscosity deviation for binary mixtures of gamma-butyrolactone with dimethyl sulfoxide
PublikacjaThe densities of binary liquid mixtures of dimethyl sulfoxide and gamma-butyrolactone at (293.15, 298.15, 303.15 and 313.15) K and viscosity at T=298.15 K have been measured at atmospheric pressure over theentire range of concentration. From these data the excess molar volumes VE at (293.15, 298.15, 303.15 and 313.15) K and the viscosity deviation, the excess entropy, and the excess Gibbs energy of activation for viscous flow at...
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Studies on the solid-liquid equilibria and intermolecular interactions Urea binary mixtures with Sulfanilamide and Sulfacetamide
PublikacjaThe binary phase diagrams of Sulfanilamide-Urea (SN-U) and Sulfacetamide-Urea (SC-U) were measured using differential scanning calorimetry technique (DSC). Both examined mixtures were found to form simple binary eutectics. The limited miscibility in the solid state observed by DSC, proving inability of co-crystallization in new multi-molecular form, was also confirmed using PXRD and FTIR-ATR measurements of solid dispersions...
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Solvation of multivalent cations in methanol - apparent molar volumes, expansibilities, and isentropic compressibilities
PublikacjaWyznaczono gęstości roztworów trifluorometanosulfonianów galu, itru, lantanu, gadolinu i lutetu w metanolu w zakresie temperatur (283.15 to 313.15) K. Zmierzono prędkości dźwięku dla tych układów w temperaturze T = 298.15 K. Z uzyskanych danych wyznaczono standardowe cząstkowe objętości molowe i ich pochodne temperaturowe oraz standardowe cząstkowe molowe ściśliwości adiabatyczne badanych jonów. Wyniki omówiono stosując klasyczny...
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Densimetric and ultrasonic characterization of pentaerythritol in water and in aqueous NaCl and MgCl2 solutions at different temperatures
PublikacjaZmierzono gęstości dla serii roztworów pentaerytritolu w czystej w wodzie jak i w wodnych roztworach NaCl i MgCl2 zawierających stałą ilość soli. Pomiary wykonano dla trzech różnych zawartości NaCl i MgCl2 w sześciu rożnych temperaturch w przedziale od 20oC do 40oC. Ponadto wyznaczono szybkości rozchodzenia się dźwięku w przygotowanych roztworach dla dwóch temperatur (25 i 37oC). W oparciu o uzyskane wielkości obliczono pozorne...
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Apparent molar volumes and compressibilities of electrolytes and ions in gamma-butyrolactone
PublikacjaW oparciu o zmierzone wartości gęstości roztworów i rozpuszczalnika w temperaturach od 15 do 40oC wyznaczono pozorne molowe objętości bromku litu, nadchloranu litu, nadchloranu sodu, tetrafenyloboranu sodu oraz bromku tetrafenylofosfoniowego w gamma-butyrolaktonie. Ponadto, wyznaczone prędkości rozchodzenia się dźwięku w 25oC w badanych układach pozwoliły obliczyć pozorne molowe ściśliwości wybranej grupy soli. Uzyskane (w wyniku...
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Excess volumes of mixing in (N,N-Dimethylacetamide+methanol+water) and (N,N-Dimethylacetamide+ethanol+water) at the temperature 313.15 K
PublikacjaW pracy podane są rezultaty precyzyjnych pomiarów namiarowych objętości molowych dla dwóch układów trójskładnikowych zawierających wodę, amid alifatyczny (N,N-dimetyloacetamid) oraz alkohol: metanol lub etanol. Dla wszystkich badanych układów obserwowane są duże i ujemne wartości nadmiarowych objętości mieszania, wskazujące na obecność silnych oddziaływań międzycząsteczkowych.
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Densimetric and ultrasonic characterization of urea and its derivatives in water
PublikacjaW oparciu o pomiary gęstości dla serii roztworów jak i rozpuszczalnika wykonanych w temperaturach 15, 20, 25, 30 i 35oC wyznaczono pozorne molowe objętości mocznika, N-metylomocznika, N,N'-dimetylomocznika, N,N,N',N'-tetrametylomocznika, N-etylomocznika, N,N'-dietylomocznika jak i N-butylomocznika w wodzie. Dodatkowe pomiary szybkości dźwięku przeprowadzone w temperaturze 25oC pozwoliły obliczyć ściśliwości adiabatyczne, pozorne...
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Apparent molar volumes and compressibilities of lanthanum, gadolinium, lutetium and sodium trifluoromethanesulfonates in N,N-dimethylformamide and N,N-dimethylacetamide
PublikacjaZmierzono gęstości roztworów trifluorometanosulfonianów lantanu, gadolinu i lutetu w N,N-dimetyloformamidzie i N,N-dimetyloacetamidzie w szerokim zakresie temperatur. W oparciu o uzyskane wartości gęstości wyznaczono pozorne objętości molowe, cząstkowe objętości molowe oraz rozszerzalności izobaryczne. Dodatkowo zmierzono szybkości rozchodzenia się dźwięku w badanych roztworach w 298,15 K i wyznaczono pozorne ściśliwości molowe...
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Apparent Molar Volumes and Compressibilities of Lanthanum, Gadolinium and Lutetium trifluoromethanesulfonates in Dimethylsulfoxide
PublikacjaZmierzono gęstości roztworów trifluorometanosulfonianów lantanu, gadolinu i lutetu w dimetylosulfotlenku w zakresie temperatur 293,15 -333,15 K. W oparciu o uzyskane wartości gęstości wyznaczono pozorne objętości molowe, cząstkowe objętości molowe oraz rozszerzalności izobaryczne. Dodatkowo zmierzono szybkości rozchodzenia się dźwięku w badanych roztworach w 298,15 K i wyznaczono pozorne ściśliwości molowe trifluorometanosulfonianów...
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Copper(II) coordination properties of GxG peptides: Key role of side chains of central residues on coordination of formed systems; combined potentiometric and ITC studies
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(Vapour + liquid) equilibrium in (n,n-dimethylacetamide + ethanol + water) at the temperature 313.15 K
PublikacjaW pracy prezentowane są pomiary całkowitej prężności pary dla tytułowego układu trójskładnikowego oraz dla składowych układów binarnych. Uzyskane w pracy wyniki porównane zostały z wcześniejszymi danymi dla podobnych układów. Znaleziono w przybliżeniu liniową zależność pomiędzy wartościami nadmiarowej entalpii swobodnej Gibbsa a objętością molową amidu, spełnianą w układach dwuskładnikowych: amid + alkohol alifatyczny.
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Limiting partial molar volumes and expansibilities of ammonium perchlorate, tetraalkylammonium perchlorates, and tetrabutylammonium tetraphenylborate in N,N-dimethylformamide
PublikacjaWyniki pomiarów gęstości i szybkości rozchodzenia się dźwięku w roztworach nadchloranu amonu, nadchloranów alkiloamoniowych i tetrafenyloboranu tetrabutylomoniowego w N,N-dimetyloformamidzie wyznaczono wartości graniczne cząstkowych molowych objętości i rozszerzalności. Dokonano rozdziału tych wartości na udziały jonowe. Przeanalizowano wpływ temperatury oraz długości łańcucha na te wielkości.
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Limiting Partial Molar Volumes of Tetra-n-Alkylammonium Perchlorates in N,N-dimethylacetamide, Triethylphosphate and Dimethyl Sulfoxide at 298.15 K
PublikacjaThe densities of tetraalkylammonium perchlorates R4NClO4(R = methyl, or ethyl, or propyl, or butyl) and ammonium perchlorate solutions in N, N - dimethylacetamide, dimethyl sulfoxide, and triethylphosphate have been measured over the whole composition range atT = 298.15 K. From these densities, apparent and limiting partial molar volumes of the electrolytes and ions...