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Wyniki wyszukiwania dla: flow system
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A simplified energy dissipation based model of heat transfer for subcooled flow boiling
PublikacjaIn the paper a model is presented based on energetic considerations for subcooled flow boiling heat transfer. The model is the extension of authors own model developed earlier for saturated flow boiling and condensation. In the former version of the model we used the heat transfer coefficient for the liquid single-phase as a reference level, due to the lack of the appropriate model for heat transfer coefficient for the subcooled...
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Numerical simulation of temperature distribution of heat flow on reservoir tanks connected in a series
PublikacjaThe flow of temperature distribution through a medium in thermodynamic studies plays an important role in understanding physical phenomena in chemical science and petroleum engineering, while temperature distribution indicates the degree of reaction that must be undergone to obtain the final product. Therefore, this paper aims to present and apply the exponential matrix algorithm (EMA), differential transformation algorithm (DTA),...
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Cylindrical orifice testing in laminar flow with the orifice diameter ratio β = 0.5
PublikacjaThe paper presents the results of an experimental study of a cylindrical orifice with the orifice diameter ratio β = 0.5 and the flow opening length‑to‑diameter ratio L/d = 1, with hydraulic oil flowing in the DN50 measuring channel. The measurements of the values characterising the oil flow were made in the laminar flow regime, for the Reynolds numbers ranging between Re = 100 to 950. Based on the experimental tests, standard...
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Numerical investigation of multiphase blood flow coupled with lumped parameter model of outflow
PublikacjaPurpose The purpose of this paper is the application of the computational fluid dynamics model simulating the blood flow within the aorta of an eight-year-old patient with Coarctation of Aorta. Design/methodology/approach The numerical model, based on commercial code ANSYS Fluent, was built using the multifluid Euler–Euler approach with the interaction between the phases described by the kinetic theory of granular flow (KTGF). Findings A...
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Numerical Analysis of Turbulent Flow over a Backward-facing Step in an Open Channel
PublikacjaComputational examinations of the flow field in an open channel having a single Backward--Facing Step (BFS) with a constant water depth of 1.5 m were performed. The effects of the expansion ratio, and the flow velocity along the reattachment length, were investigated by employing two different expansion ratios of 1.5 and 2, and eight various flow velocities of 0.5, 1, 2, 3, 4, 5, 7.5 and 10 m/sec in the Computational Fluid Dynamic...
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Wpływ liczby mieszkańców na obliczenia ilości ścieków w projektowaniu kanalizacji sanitarnej
PublikacjaZmiana sposobu rozliczania zużycia wody, promocja wodooszczędnych technologii oraz uszczelnienie kanałów wyraźnie wpłynęły na ilość odprowadzanych do kanalizacji ścieków. Obecnie stwierdzić można, że opracowania z lat 70-tych XX wieku podają zawyżone wskaźniki odpływu ścieków, skutkiem czego są problemy eksploatacyjne. Bez wątpienia, prawidłowe zaprojektowanie kanalizacji sanitarnej to zadanie trudne, wymagające między innymi prawidłowego...
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MONTE CARLO MODELING OF OPTICAL SENSOR FOR POST-OPERATIVE FREE FLAP MONITORING
PublikacjaAfter a preliminary study of the currently employed methods in vitality monitoring of the tissue flaps (TRAM, DIEP, SIEA), a usefulness of optical techniques is discussed. It seems that one of the most promising in monitoring tissue flaps blood flow is a near infrared spectrometry (NIRS). However, a special design of a measurement sensor has to be developed. First, basing on the literature study an optical “window” is characterized....
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Cargo ships heat demand - operational experiment
PublikacjaThe paper presents the results of an experiment conducted on two cargo ships – a 5300 TEU container with a steam heating system and a 7500 dwt general cargo ship with a thermal oil system. On both ships research has been carried out using specially designed measuring equipment. After gathering data about flow velocity and temperatures (steam/ cooling water/ thermal oil/ seawater/ outside air), calculations have been done, resulting...
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Insights Into Hydrodynamics of Spinning Fluids Reactor
PublikacjaSpinning fluids reactor (SFR) is one of the most efficient gas-liquid contacting system with high potential of application in many fields. The unique solution of SFR is the contacting of two spinning fluids which generated centrifugal force. The aim of this study was to investigate the pressure field distribution on the inner surface of reactors dispersing element. Obtained results confirm the high heterogeneity of the field pressure...
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Operational problems of constructed wetland for landfill leachates treatment: case study
PublikacjaIn the paper the quality fluctuations of leachate from municipal landfill in Gdansk (Poland) over the last 5 years and evaluation of a wetland system designed for treatment of the leachate are discussed.The research has been conducted during the 5 years period. The constructed wetland for leachate treatment, consisting of 2 horizontal subsurface flow reed beds, working in parallel was built in 2001. In the period 2005-06 it underwent...
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A modelling approach to the transport support for the harvesting and transportation complex under uncertain conditions
PublikacjaThe article proposes a modelling approach based on structural and parametric identification of the transport support of the harvesting and transportation complex. The efficiency and effectiveness of the proposed methods of structural and parametric identification for the development of a system for harvesting and transportation complex operation has been proved. A mathematical model based on fuzzy logic has been developed. It reflects...
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Experimental research on helical coil biomass boiler with oil as a heating fluid
PublikacjaThis paper presents an experimental research of helical coil biomass boiler with thermal oil heating agent. Heat exchanger consists of two coaxial helical coils swept by the flue gases. The burner is a single vertical retort connected to the fuel tank (wooden pellets). The boiler is a part of micro-power plant in which the heat from the boiler is exchanged with low-boiling HFE7100 to produce steam for a custom steam turbine. The...
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Considerations about the applicability of the Reynolds equation for analyzing high-speed near field levitation phenomena
Publikacjaequation for analyzing near field levitation (NFL) phenomena. Two separate approaches were developed, experimentally verified, and applied to meet the research objective. One was based on the Reynolds equation and the other was based on general conservation equations for fluid flow solved using computational fluid dynamic (CFD). Comparing the calculation results revealed that, for certain operating conditions, differences in the...
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Structural optimization of microjet array cooling system
PublikacjaThe single phase heat transfer from an upward facing, horizontal copper surface to arrays of impinging water jets was experimentally investigated. Experimental configuration allows for a free-surface unconfined jets flow. Square nozzles 50 × 100 μm arranged in four different geometries were used. Additionally, for the set of two jets array geometry was varied by adjusting the nozzle to nozzle distance. The area averaged heat transfer...
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Treatment of landfill leachate by constructed wetlands: three case studies
PublikacjaThe performance of three CW systems treating landfill leachate, two located in northern Poland (Szadółki near Gdańsk and Gatka near Miastko) and one in southern Sweden (Örebro), is discussed. The CWs differ in size, hydraulic regime, type of hydrophytic plants and type of leachate pre-treatment before discharging to the CW. The CW in Szadółki consists of two parallel beds with sub-surface, horizontal flow of leachate (HSSF) planted...
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Flexible syngas-biogas-hydrogen fueling spark-ignition engine behaviors with optimized fuel compositions and control parameters
PublikacjaThis paper presents the results research on the optimal fuel compositions and the control parameters of the spark ignition engine fueled with syngas-biogas-hydrogen for the purpose of setting up a flexible electronic control unit for the engine working in a solar-biomass hybrid renewable energy system. In syngas-biogas-hydrogen mixture, the optimal content of hydrogen and biogas is 20% and 30%, respectively. Exceeding these thresholds,...
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Recent advances in hydrogen production from biomass waste with a focus on pyrolysis and gasification
PublikacjaThis paper presents the results research on the optimal fuel compositions and the control parameters of the spark ignition engine fueled with syngas-biogas-hydrogen for the purpose of setting up a flexible electronic control unit for the engine working in a solar-biomass hybrid renewable energy system. In syngas-biogas-hydrogen mixture, the optimal content of hydrogen and biogas is 20% and 30%, respectively. Exceeding these thresholds,...
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The advanced monitoring as a key factor for appropriate optimization and control of full-scale activated sludge systems – case study Debogorze WWTP.
PublikacjaComputer simulation has become a helpful tool in wastewater treatment systems performance and effectiveness analysis. Advanced monitoring, by using appropriate software, enables to create a mathematical model of a real wastewater treatment plant (WWTP), run a simulation and subsequently interpret results under various conditions. An operation of WWTP is usually controlled by global parameters such as flow, solids retention time,...
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Influence of geometry and surface morphology of the U-tube on the fluid flow in the range of various velocities
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Close-Distance Optical Flow Fusion Using EKF for Multirotor UAV Position Estimation
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Estimation of the River Flow Synchronicity in the Upper Indus River Basin Using Copula Functions
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Flow Cytometric Assessment of Endothelial and Platelet Microparticles in Patients With Atrial Fibrillation Treated With Dabigatran
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Possibility of exact determination of thermal and flow degradation symptoms in on-line power objects diagnostics
PublikacjaPrzedyskutowano problem dokładności tworzenia symptomów degradacji dotyczących sprawności urządzeń składowych dużych obiektów energetycznych. W referacie zajęto się szczególnie metodami tworzenia wzorców sprawnej pracy w przypadku określania sprawności w układzie on-line i porównano ją z określeniem w systemie off-line. Do odtwarzania stanu referencyjnego zastosowano sieć neuronową statystyczną (SSN, ang. ANN) o nieskokowych funkcjach...
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Removal of organic matter and nitrogen in an horizontalsubsurface flow (HSSF) constructed wetland undertransient loads
PublikacjaA monitoring campaign in a horizontal subsurface flow constructed wetland under the influence of transient loads of flow-rate, organic matter, nitrogen and suspended solids showed an irregular removal of COD and TSS and lower both removal efficiencies and mass removal rates than the ones observed in other studies for similar operating conditions. This circumstance is associated to the presence of large amount of particulate organic...
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Experimental investigation of the flow pattern and wall pressure distribution in a silo with double-cone insert
PublikacjaArtykuł opisuje przeprowadzone badania przepływów silosowych i naporu materiałów sypkich podczas napełniania i opróżniania silosu o średnicy 2.5 m wyposażonego we wkładkę "podwójny stożek". Badania przeprowadzane były w Instytucie Badawczym Tel-Tek w Norwegii. Materiałem użytym był suchy piasek. Napór na ścianę mierzony był bezpośrednio za pomocą 10 czujników wbudowanych w ścianę. Badania eksperymentalne pokazały duży wpływ wkładki...
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Free surface flow modeling in numerical estimation of flood risk zones: a case study
PublikacjaNa przykładzie doliny Wisły w Warszawie przedstawiono metodę wyznaczenia stref zagrożenia powodziowego. Symulowana numerycznie powódź wywołana została potencjalnym przerwaniem obwałowania rzeki w okolicach Saskiej Kępy. Do obliczeń zastosowano opracowany w Katedrze Hydrotechniki Wydziału Inżynierii Lądowej i Środowiska Politechniki Gdańskiej model dwuwymiarowego, płaskiego przepływu wody ze swobodną powierzchnią.
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Simulation of water flow in double -porosity soils on unstructured grids with the finite element method.
PublikacjaRozważa sie model przepływu wody w gruntowym ośrodku o podwójnej porowatości. Model matematyczny uzyskano poprzez zastosowanie teorii homogenizacji zastosowanej do gruntów o bardzo dużej różnicy przepuszczalności.
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The influence of a cone-in-cone insert on flow pattern and wall pressure in a full-scale silo
PublikacjaArtykuł opisuje przeprowadzone badania przepływów silosowych i naporu materiałów sypkich podczas napełniania i opróżniania silosu o średnicy 2.5 m wyposażonego we wkładkę "stożek w stożku''. Badania przeprowadzane były w Instytucie Badawczym Tel-Tek w Norwegii. Materiałem użytym był suchy piasek. Napór na ścianę mierzony był bezpośrednio za pomocą 10 czujników wbudowanych w ścianę. Badania eksperymentalne pokazały duży wpływ wkładki...
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Numerical and physical modeling of water flow over the ogee weir of the new Niedów barrage
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Numerical modeling of cross-flow heat exchanger for air-conditioning purposes in preliminary study.
PublikacjaPraca przedstawia wyniki obliczeń numerycznych krzyżowego płytowo-rurowego wymiennika ciepła przeznaczonego do celów klimatyzacyjnych w początkowym etapie jego projektowania.
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Application of vertical flow constructed wetlands for highly contaminated wastewater treatment: preliminary results
PublikacjaBasing on quantitative and qualitative characteristics of reject waters (RWC) generated during dewatering of digested sewage sludge on centrifuges in conventional WWTP and municipal landfill leachate (LL), the pilot constructed wetlands for treatment of both types wastewater were designed and built. In the paper the conception, design and assumed treatment efficiencies of the pilot plants are presented. The water balance of the...
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Tome-lapse X-ray tomography imaging of flow patterns in versatile silo model
PublikacjaThe paper introduces a new versatile silo model that was especially designed for in situ X-ray tomography studies of silo discharge for various flow conditions, namely concentric and eccentric. The presented work focuses on organic granular materials where low fraction of short-grain white rice is mixed with spheroidal sorghum particles. The high-quality tomography images combined with adequate image processing strategy allows...
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A simplified energy dissipation based model of heat transfer for post-dryout flow boiling
Publikacjamodel for post dryout mist flow heat transfer is presented based on considerations of energy dissipation in the flow. The model is an extension of authors own model developed earlier for saturated and subcooled flow boiling. In the former version of the model the heat transfer coefficient for the liquid singlephase convection as a reference was used, due to the lack of the appropriate model for heat transfer coefficient for the...
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Numerical Modeling of Water and Ice Dynamics for Analysis of Flow Around the Kiezmark Bridge Piers
PublikacjaThis paper presents the results of a numerical model study on the effect of ice on the proposed bridge piers in the Vistula River outlet and its effect on flow conditions in the river. The model DynaRICE is used in this study, which is a two-dimensional hydro-ice dynamic numerical model developed for dynamic ice transport and jamming in rivers. To simulate river hydrodynamics in the vicinity of the bridge piers, 2-dimensional numerical...
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Modelling of subarachnoid space width changes in apnoea resulting as a function of blood flow parameters
PublikacjaDuring apnoea, the pial artery is subjected to two opposite physiological processes: vasoconstriction due to elevated blood pressure and vasorelaxation driven by rising pH in the brain parenchyma. We hypothesized that the pial artery response to apnoea may vary, depending on which process dominate. Apnoea experiments were performed in a group of 19 healthy, non-smoking volunteers (9 men and 10 women). The following parameters...
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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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A semi-empirical model for flow boiling heat transfer with account of the reduced pressure effect
PublikacjaIn the present study the attention was focused on the influence of reduced pressure on the predictions of heat transfer during flow boiling at the extensive range of pressures. The results of calculations were to test the sensitivity of the in-house flow boiling model with respect to the selection of the appropriate two-phase flow multiplier, which is one of the distinctive elements of that model. For this purpose a few two-phase...
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Determination of the uncertainty of mass flow measurement using the orifice for different values of the Reynolds number
PublikacjaStandard orifice flowmeters are widely used in the chemical and energy industry. Therefore, it is essential to know how accurate the measurements made with these instruments are. The paper presents an estimation of measurement uncertainty of a liquid mass flow using the orifice plate. The authors will present the influence of ranges of the Reynolds number on the estimated uncertainty, obtained on the basis of simulation and laboratory...
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Signals features extraction in radioisotope liquid-gas flow measurements using wavelet analysis
PublikacjaKnowledge of the structure of a flow is significant for the proper conduct of a number of industrial processes. In this case, a description of a two-phase flow regimes is possible by use of the time-series analysis in time, frequency and state-space domain. In this article the Discrete Wavelet Transform (DWT) is applied for analysis of signals obtained for water-air flow using gamma ray absorption. The presented method was illustrated...
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Effect of the North Atlantic Thermohaline Circulation on changes in climatic conditions and river flow in Poland
Publikacja: The purpose of this study is to find connections between the North Atlantic Thermohaline Circulation (NA THC), climate elements, such as cloud cover, precipitation, air temperature, sunshine duration, and relative humidity, and flow of rivers in Poland. The intensity of NA THC was characterized by the DG3L index, which was established to assess changes in the amount of heat transported by NA THC along with the transport of water...
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Experimental study and comparison with predictive methods for flow boiling heat transfer coefficient of HFE7000
PublikacjaThis article describes an experimental study of flow boiling of HFE7000 inside a smooth vertical channel. The investigation has been carried out in a circular stainless-steel tube with an inner diameter of 2.3 mm. The data have been collected for the applied heat fluxes q ranging from 61 to 205 kW/m2, the mass flux G ranging from 214 to 1006 kg/(m2 s), the saturation temperature Tsat ranging from 30 to 54 °C and the full range...
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Signal Processing in the Investigation of Two-phase Liquid-gas Flow by Gamma-ray Absorption
Publikacjan this paper, the use of the gamma-absorption method applied in the investigation of the two-phase liquid-gas flow in the pipeline is described. An example of its application to the air transported by water in a horizontal pipeline is evaluated. In the measurements, Am-241 radioactive sources and probes with Nal (Tl) scintillation crystals have been used. The signals from the radiometric set were used to determine the velocity...
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Prediction of flow boiling heat transfer coefficient for carbon dioxide in minichannels and conventional channels
PublikacjaIn the paper are presented the results of calculations using authors own model to predict heat transfer coefficient during flow boiling for carbon dioxide. The experimental data from various researches were scrutinised conducted for a full range of quality variation and wide range of mass velocity. The aim of the study was to test the sensitivity of the in-house model. The work shows the importance of taking into account surface...
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Electrohydrodynamic flow patterns and collection efficiency in narrow wire-cylinder type electrostatic precipitator
PublikacjaRecently, narrow electrostatic precipitators (ESPs) have become a subject of interest because of their possible application for the cleaning of the exhaust gases emitted by diesel engines. Diesel engines emit fine particles, which are harmful to human and animal health. There are several methods for decrease particulate emission from a diesel engines, but up to now, these methods are not enough effective or very expensive. Therefore,...
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Determination of pressure drop in flow condensation of HFE7000 in minichannels with account of non-adiabatic effects
PublikacjaFlow boiling and flow condensation are often regarded as two opposite or symmetrical phenomena involving the change of phase. There is a temptation to describe both these phenomena with one only correlation, however such method has yet to be suggested. From amongst the structures present in flow boiling and flow condensation at least the annular flow structure seems to be mostly appropriate to the common modeling. However, the shear...
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PRESSURE DROP OF HFE7000 AND HFE7100 IN FLOW CONDENSATION IN MINICHANNELS WITH ACCOUNT OF NON-ADIABATIC EFFECTS
PublikacjaFlow boiling and flow condensation are often regarded as two opposite or symmetrical phenomena involving the change of phase. There is a temptation to describe both these phenomena with one only correlation. From amongst the structures present in flow boiling and flow condensation at least the annular flow structure seems to be mostly appropriate to the common modeling. However, the shear stress acting between vapor phase and liquid...
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Influence of heterogeneous air entry pressure on large scale unsaturated flow in porous media
PublikacjaThe paper presents numerical simulations of water infiltration in unsaturated porous media containing coarse-textured inclusions embed- ded in fine-textured background material. The calculations are performed using the two-phase model for water and air flow and a simplified model known as the Richards equation. It is shown that the Richards equation cannot correctly describe flow in the presence of heterogeneities. How- ever, its...
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Unstructured finite-volume meshes for two-dimensional flow in variably saturated porous media
PublikacjaW pracy opisano rozwiązanie równania przepływu nienasyconego w ośrodkach porowatych z wykorzystaniem metody objętości skończonych. Przedstawiono różne sposoby tworzenia siatki numerycznej. Przeprowadzono analizę wpływu sposobu uśredniania współczynnika filtracji między sąsiednimi objętościami skończonymi na dokładność wyników.
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Space-mapping-based design flow of miniaturized broadband matching transformer with perforated metallization
PublikacjaA fast design procedure of unconventional passive components has been presented and experimentally validated on the basis of a wideband microstrip four-section matching transformer (50:6 OHm). A classic impedance matching circuit has been miniaturized by means of compact microstrip resonant cells (CMRCs) leading to a considerable length reduction (34%) together with minor degradation in its performance. The spacemapping-based design...
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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...