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Analysis of heat transfer in a coated bed of an adsorption chiller
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Selected aspects of heat recovery simulation in houseboat installations
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Heat Source Models in Numerical Simulations of Laser Welding
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New trends in development of micro heat exchangers for ORC's
PublicationIn the paper, new trends in development of micro heat exchangers for CHP are presented. Main attention is concentrated on the question, how channels size and thermal development lenght affect the heat transfer. New types of micro heat exchangers developed at the Institute of Fluid-Flow Machinery PAS and the methoda of their design are presented. The new experimental testing methods of the micro-channel heat exchangers, new algorithms...
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Thermal Analysis Of Hybrid Microchannel-Microjet Heat Exchanger
PublicationThe paper presents the numerical investigation of a microjet- microchannel cooling module. In which microjets of water are impinging into the microchannels and forming a liquid film on the impingement surface. Applied technology takes benefits from two very attractive heat removal techniques. When laminar jets are impinging on the surface have a very high kinetic energy at the stagnation point, also in microchannels boundary layer...
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HIGH TEMPERATURE HEAT PUMPS – PERSPECTIVE HEATING SYSTEMS?
PublicationIn the paper presented are authors own concepts of high temperature compressor heat pumps for the utilisation of medium and low temperature sources of heat. Working fluids for use in high temperature heat pumps are discussed, as well as the criteria for their selection. Analyses are presented for the production of in the upper steam source at 130 °C. One-stage systems and cascade systems were analyzed. An analysis of the coefficient...
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CFD analysis of fluid flow through the labyrinth seal
PublicationSteam and gas turbines are some of the fundamental means of power generation. The energy efficiency of the turbines, however, is not satisfactory. Ever since the start-up of the first turbine in the world, engineers have been striving for their increased efficiency. Multiple solutions to the problem of steam loss in an operating turbine are available. The use of seals is one of them. Empirical methods or numerical calculations...
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Microwave heat treatment application to pasteurization of human milk
PublicationA prototype of microwave pasteurizer has been proposed as an alternative for holder pasteurization (HP) routinely used in Human Milk Bank (HMB), ensuring microbiological safety of human milk (HM). It was shown that the time of heat generation was about 15–16 min shorter by applying the microwave than in HP. Total inactivation of heat-sensitive bacteria Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus...
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Flow maldistribution and its mitigation in mini heat exchangers
PublicationIn the present paper, a detailed numerical investigation has been carried out to analyze the flow maldistribution in 50 parallel 1 mm x 1 mm rectangular minichannels and 1 mm depth minigap section with rectangular, trapezoidal, triangular or concave mani-folds in Z-type flow configuration (16 different cases). The working medium was ethanol and the mass flow rate was 5×10-4 kg/s. Both sections was heated from the bottom side. Heat...
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Gas boiler as a heat source for the domestic micro-CHP
PublicationIn the presented analysis a commercially available domestic gas boiler as a heat source for domestic ORC is considered. The applicability of the gas boiler (De Dietrich with thermal power 25 kW) coupled with the laboratory prototype micro ORC setup has experimentally studied. The main aim of the study is to determine the working fluid temperature, attainable heat rates and efficiencies of the whole system. Preliminary investigations...
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Nuclear power plant as a source of electrical energy and heat
PublicationIn this paper certain issues concerning usage of nuclear power plants as sources of not only electric power but also thermal energy will be discussed. For such a solution appeals most of all the need to limit harmful emissions of gases (including CO2) and ashes, which come from the process of burning fossil fuels, as well as the raising demand for network heat and chill. Additionally combined heat and power production brings measurable...
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The impact of environmentally friendly refrigerants on heat pump efficiency
PublicationThis paper discusses the issue of heat pump simulation. Lower operating costs can be achieved through good equipment design and appropriate operation. Detailed technical and economic analysis inform the selection of system components with the highest possible efficiency and lower energy demand. The use of systems based on environmentally friendly refrigerants can deliver long product life, which is associated with a shorter payback...
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Gas boiler as a heat source for the domestic micro-CHP
PublicationThis analysis considers a commercially available domestic gas boiler as a heat source for a domestic organic Rankine cycle system. An experimental study was made into the applicability of the gas boiler (De Dietrich with thermal power 25 kW) coupled with the laboratory prototype micro ORC setup. The main aim of the study is to determine the working fluid temperature, attainable heat rates and effciencies of the whole system. Preliminary...
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Heat Dissipation from the Power Cable in the Casing Pipe
PublicationThe current carrying capacity of a power cable determines its ability to carry a specific current and is related to the efficiency of dissipation of heat generated in the cable laid in a specific environment. The studies were conducted in order to determine how the characteristics of the medium around the cable affected its temperature, and thus the ability of the cable to transmit electricity. The experimentation in the lab and...
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Convective heat transfer inside hemispherical reflective concentrator.
PublicationW pracy przedstawiono uproszczone rozwiązanie analityczne, obliczenia numeryczne wykonane za pomocą programu FLUENT/UNS i wyniki badań eksperymentalnych swobodnej konwekcyjnej wymiany ciepła wewnątrz izotermicznej powierzchni kołowej w przestrzeni nieograniczonej. Wykonane obserwacje bezpośrednie konwekcyjnych struktur przepływu, jak i wyniki obliczeń numerycznych otrzymane w postaci pola prędkości i linii prądu wewnątrz...
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Geothermal heating plant with a combustion engine heat pump.
PublicationPrzedstawiono koncepcję ciepłowni geotermalnej zagospodarowującej zasoby energii zawarte w nisko i średniotemperaturowej wodzie termalnej. W tym celu zaproponowano zastosowanie pompy grzejnej napędzanej silnikiem spalinowym.
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Hydrodynamics and heat transfer in bubbly flow in the turbulent boundarylayer
PublicationW pracy przedstawiono oryginalne podejście do modelowania przepływu pęcherzykowego w warstwie przyściennej i w kanale. Podejście oparte jest na sumowaniu energii dyssypacji pochodzącej od przepływu ścinającego w kanale oraz dyssypacji pochodzącej od obecności pęcherzyków. W wyniku otrzymuje się naprężenia styczne ekwiwalentnego przepływu jednofazowego. Zaproponowano własne podejście do modelowania stopnia zapełnienia opisane równaniem...
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Thermochromic liquid crystals applied for heat transfer research
PublicationAutorzy opisali własne wieloletnie doświadczenia z badań wymiany ciepła, w których wykorzystali termochromatyczne ciekłe kryształy. Obejmowały one badania przepływów w kanałach o różnorakiej konfiguracji, badania w przestrzeniach zamkniętych oraz podczas zmiany stanu skupienia badanego płynu.
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The use of thermochromic liquid crystals in heat transfer research
PublicationW ostatnich latach ciekłe kryształy zostały z powodzeniem zastosowane do wizualizacji pola temperatury w stanach ustalonych i przejściowych na różnych powierzchniach. Analiza otrzymanych obrazów początkowo była skomplikowana, ale dzięki zastosowaniu obróbki komputerowej pomiary stały się o wiele dokładniejsze i szybsze. W opracowaniu przedstawiono przegląd badań, w których zastosowano automatyczną technikę analizy obrazów, a prowadzone...
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Natural convective heat transfer from isothermal cuboids
PublicationPrzestawiono rozważania teoretyczne i wyniki badań eksperymentalnych konwekcyjnej wymiany ciepła od powierzchni izotermicznego prostopadłościanu. W rozwiązaniu analitycznym uwzględniono pełną długość warstwy przyściennej i sposób jej rozchodzenia się wzdłuż powierzchni prostopadłościanu. W celu zweryfikowania otrzymanego rozwiązania przeprowadzono badania eksperymentalne w trzech możliwych położeniach bryły. Zaproponowano uniwersalną...
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The effect of temperature difference on heat transport in solar cells
PublicationW 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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Natural convective heat transfer from isothermal cuboids
PublicationThe paper presents results of theoretical and experimental investigations of the convective heat transfer from isothermal cuboid. The analytical solution was performed taking into account complete boundary layer length and the manner of its propagation around isothermal cuboid. It arises at horizontal bottom surface and grows on vertical lateral surface of the block. After changing its direction, the boundary layer occurs above...
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Investigations of welded joints of dissimilar heat resistant steels.
PublicationPrzeprowadzono badania metalograficzne połączeń spawanych różnorodnych stali żarowytrzymałych rur o przekroju 31,8x7,1 mm ze stali 10H2M z blachą ze stali 20H23N18. Badania makro- i mikrostruktury złączy spawanych wykazały, że istotnym czynnikiem wpływającym na właściwości mechaniczne złącza jest obecność wad takich jak pory lub wtrącenia żużla. Te nieciągłości w materiale powodują koncentrację naprężeń i powstawanie mikropęknięć.
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Heat and mass exchange in the process of condensation on critical droplets.
PublicationSformułowano model wzrostu kropli krytycznej podając równania zmiany masy i temperatury kropli. Pokazano formę zlinearyzowaną tych równań dobrze aproksymującą wzrost kropli w poblizu wymiaru krytycznego. Podano rozwiązanie układu zlinearyzowanego uzależniając zmianę temperatury od zmiany masy kropli i czasu charakterystycznego.
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THE USE OF MORPHOLOGICAL FILTERS AND GRANULOMETRIC METHOD TO ANALYZE THE MOVEMENT OF THE MOLECULES IN THE SEA WATER OF THE SOUTHERN BALTIC SEA
PublicationModern granulometry opens a new way of analysing images by means of morphological filters. In this paper a closer look has been presented on the problem of interpreting information about the features and conditions of marine environment from images taken at the sea coast and shallow water. Using this method allows for example selection of the objects on the image according to the differences in shape. Processes occurring in the...
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Revista Chilena de Pediatria-Chile
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Cuadernos de historia (Santiago, Chile)
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Applied Set-Valued Analysis and Optimization
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Southeast European and Black Sea Studies
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Recent advances of selected passive heat transfer intensification methods for phase change material-based latent heat energy storage units: A review
PublicationThe following article overviews recent studies regarding heat transfer enhancement methods, explicitly focusing on fins and coils utilization, in phase change material-based latent heat thermal energy storage systems. It discusses the influence of various geometrical and material parameters on the melting and solidification processes, as well as the orientation of the heat transfer surface within the storage tank. Additionally,...
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Dimension of the solution set for differential inclusions
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Hydrofoil craft motions in rough sea
PublicationW pracy przedstawiono, bardziej od dotychczas znanych, matematyczny, liniowy model ruchów wodolotu na wzburzonym morzu. Fala jest wiatrową o zadanym widmie a kurs wodolotu względem głównego kierunku biegu fal może być dowolny. Wodolot może być jednokadłubowcem lub katamaranem, podpartym układem dwóch lub trzech płatów nośnych, przy czym co najmniej jego płaty dziobowe przecinają niezakłóconą powierzchnię wody. Płaty nośne mogą...
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Propagation of Acoustic Disturbances in Shallow Sea
PublicationPropagation of acoustic waves in shallow sea differs fundamentally from the same phenomenon occurring in deep sea in view of non-negligible distance from the sea bottom in the first case, where presence of two regions limiting the water layer results in the acoustic pressure distribution induced by a harmonic source has an interferential nature as a result of multi-path propagation of the acoustic signal. These interferential properties...
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Age management in the Baltic Sea Region
PublicationThis chapter takes a broader view on the issues connected with age management. In its first part, some demographic processes in the European Union countries are described. Those processes contribute to the ageing of the society and an increasing need for age management at various levels. Furthermore, situation in selected Baltic Sea Region countries is presented. In the next section, age management from organizational perspective...
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On residualities in the set of Markov operators on C1
PublicationDowodzi się, że zbiór operatorów Markowa na klasie Schattena 1, które są mieszające w normie, jest normowo gęsty, otwarty. Natomiast w topologii mocno operatorowej operatory Markowa mocno mieszające są zbiorem I kategorii.
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Small wood waste fired combined heat and power plant. Possible use of wood biomass for the generation of electric and heat energy as an alternative to fossil fuels
PublicationThis article discusses the possibility of burning wood biomass instead of fossil fuels in boilers. It describes the properties of wood biomass, including the variation of its calorific value depending on the moisture content of wood. The article proposes several variants of a combined heat and power plant (CHP) system burning wood biomass for the generation of electric and heat energy, using the energy contained in exhaust gases...
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Phosphorylation‐mediated regulation of heat shock response in Escherichia coli
PublicationEscherichia coli has two heat shock regulons under the transcriptional control of Esigma(32) and Esigma(E) RNA polymerases. These polymerases control the expression of genes, the products of which are needed for correct folding of proteins in the cytoplasm and the extracytoplasm respectively. In this study, we report that mutations in a tyrosine phosphatase-encoding gene led to decreased activity of these heat shock regulons. The...
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Jeffreys heat conduction in coupled semispaces subjected to interfacial heating
PublicationA Jeffreys heat conduction problem for coupled semispaces subjected to the action of an interfacial heat source was defined. An analytical solution of the problem was derived for a polynomial specific power of the heat source using the Laplace transform approach. The asymptotic and parametric analysis was performed for different ratios of thermal conductivities , thermal diffusivities , thermal relaxation times and coefficients...
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Additive Manufacturing as a Solution to Challenges Associated with Heat Pipe Production
PublicationThe aim of this review is to present the recent developments in heat pipe production, which respond to the current technical problems related to the wide implementation of this technology. A novel approach in HP manufacturing is to utilise hi-tech additive manufacturing techniques where the most complicated geometries are fabricated layer-by-layer directly from a digital file. This technology might be a solution to various challenges...
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Beeswax And Palmitic Acid Utilization With Heat Pipes For Electronics Cooling
PublicationThis paper presents an experimental study of heat pipes supported by phase change materials (PCMs) coated at their adiabatic sections in application for electronics cooling. The PCMs investigated in this research were palmitic acid and beeswax, the latter being considered as a more cost-effective alternative. The study focused on three powers: 20W, 25W, and 30W. The experimental results revealed that the incorporation of palmitic...
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Numerical Study of Turbulent Flow and Heat Transfer of Nanofluids in Pipes
PublicationIn this work, Nusselt number and friction factor are calculated numerically for turbulent pipe flow (Reynolds number between 6000 and 12000) with constant heat flux boundary condition using nanofluids. The nanofluid is modelled with the single-phase approach and the simulation results are compared with experimental data. Ethylene glycol and water, 60:40 EG/W mass ratio, as base fluid and SiO2 nanoparticles are used as nanofluid...
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Optimization of the geometry of the crankshaft for an internal combustion engine with heat regeneration
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Numerical analysis of high temperature minichannels heat exchanger performance
PublicationNowadays, the most difficult technological challenge in energy sector is connected with the gas micro-CHP units, dedicated to the distributed power generation. They are expected to be of high efficiency and at the same time of compact in size. Regarding the first reason, significant increase in microturbine efficiency can only be achieved by increase in the engine operating temperature. Therefore, one of the critical elements in...
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Modelling heat transfer in heterogeneous media using fractional calculus
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Modeling Heat Transfer in Heterogeneous Media Using Fractional Calculus
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A Comparison of the Exergy Efficiencies of Various Heat-Integrated Distillation Columns
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Numerical heat transfer model in skin burn depth simulations
PublicationW artykule przedstawiono numeryczny model wymiany ciepła zachodzącej w tkance skórnej . Wyniki symulacji na modelu zostały porównane z wynikami pomiarów In vivo na zwierzętach.
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Measurements of heat transfer enhanced by the use of transverse vortex generators
PublicationArtykuł dotyczy badań eksperymentalnych wymiany ciepła w modelowym wymienniku ciepła z turbulizatorami przepływu dla różnej geometrii turbulizatorów. Badania wykonano przy użyciu termografii ciekłokrystalicznej i cyfrowej anemometrii obrazowej.
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Ring thruster - a preliminary optimisation study of ferrofluid seal and propeller
PublicationThe article reports the course of preliminary examination of a ferrofluid seal applied in liquid environment.A newly built research rig is described, and results of pressure tests performed for different shaft rotationsare discussed. Other studies carried out in the past only referred to the gas environment, while the presentexamination aims at finding an answer to the question whether magnetic liquids can be successfully used...
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Model of heat transfer in the stagnation point of rapidly evaporating microjet
PublicationThe paper presents investigation in the single water microjet surface cooling producing evaporating film. Reported tests were conducted under steady state conditions. It was proved that the phenomenon is similar to that of pool boiling. Results of experiments were compared with predictions by the model showing a good consistency.