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1
Content available remote Przyczyny zawilgacania budynków
PL
Przedmiotem artykułu są zagadnienia dotyczące hydroizolacji budynków. Omówiono w nim warunki gruntowo-wodne rzutujące na dobór odpowiednich do nich izolacji. Przeanalizowano magazynowanie i transport wody w materiałach porowatych, a także zjawiska sorpcji, kondensacji powierzchniowej i dyfuzji pary wodnej.
EN
This paper concerns the issues related with waterproof insulation of buildings. It also describes the soil and water conditions that affect the selection of proper insulation materials. Storage and transfer of water in porous materials, as well as sorption, surficial condensation and water vapour diffusion have been analysed.
PL
W artykule przedstawiono model matematyczny kondensacyjnego wymiennika ciepła typu spaliny-woda, służącego do odzysku niskotemperaturowego ciepła odpadowego ze spalin bloku energetycznego węglowego. Model ten bazuje na modyfikacji modelu Colburna-Hougena, przedstawionej w pracach [17, 24, 33]. W modelu założono, że część wykroplonej pary wodnej reaguje z częścią strumienia dwutlenku siarki w spalinach, wskutek czego powstaje kwas siarkowy (IV). Przy pomocy powyższego modelu przeprowadzono analizę porównawczą wyników obliczeń dla spalin pochodzących z węgla kamiennego i brunatnego. Przeprowadzono optymalizację wymiennika ciepła pod względem wybranych parametrów.
EN
The aim of the article is to present a mathematical model of flue gases-water condensing heat exchanger used for the recovery of low temperature waste heat of coal-fired power unit. This model is based on the modification of the Colburn-Hougen model, presented in [17, 24, 33]. In addition, it was assumed that some of the condensed water vapor reacts with a portion of the sulfur dioxide stream in exhaust, resulting in formation of sulfuric acid (IV). With this model, a comparative analysis of calculation results for flue gases derived from lignite and bituminous coal was performed. The heat exchanger has been optimized for selected parameters.
EN
In this paper, the steady three-dimensional problem of condensation film on an inclined rotating disk is considered. The governing nonlinear partial differential equations are reduced to the nonlinear ordinary differential equations system by a similarity transform. The equation system is solved by the variation of parameters method (VPM) which is rather used to solve nonhomogeneous linear differential equations but can also be used to solve nonlinear differential equations. This method has not previously been used to solve a nonlinear condensation problem. The dimensionless velocity and temperature profiles are shown, and the influence of Prandtl number and rotation ratio on the flow field and the Nusselt number are discussed in detail. In order to assess the accuracy of the solutions obtained by this method, the problem is also solved numerically using the Matlab bvp4c solver. The validity of our solutions is verified by the numerical results.
EN
Helical coil heat exchangers are widely used in a variety of industry applications such as refrigerationsystems, process plants and heat recovery. In this study, the effect of Reynolds number and theoperating temperature on heat transfer coefficients and pressure drop for laminar flow conditions wasinvestigated. Experiments were carried out in a shell and tube heat exchanger with a copper coiledpipe (4 mm ID, length of 1.7 m and coil pitch of 7.5 mm) in the temperature range from 243 to 273 K.Air – propan-2-ol vapor mixture and coolant (methylsilicone oil) flowed inside and around the coil,respectively. The fluid flow in the shell-side was kept constant, while in the coil it was varied from 6.6to 26.6 m/s (the Reynolds number below the critical value of 7600). Results showed that the helicalpipe provided higher heat transfer performance than a straight pipe with the same dimensions. Theconvective coefficients were determined using the Wilson method. The values for the coiled pipe werein the range of 3–40 W/m2·K. They increased with increasing the gas flow rate and decreasing thecoolant temperature.
EN
The image analysis consists in extracting from the information which is available to the observer of the part that is important from the perspective of the investigated process. This process usually accompanies a considerable reduction in the amount of information from the image. In the field of two-phase flows, computer image analysis can be used to determine flow and geometric parameters of flow patterns. This article presents the possibilities of using this method to determine the void fraction, vapor quality, bubble velocity and the geometric dimensions of flow patterns. The use of computer image analysis methods is illustrated by the example of HFE 7100 refrigerant methoxynonafluorobutane condensation in a glass tubular minichannel. The high speed video camera was used for the study, and the films and individual frames received during the study were analyzed.
6
Content available Wilgoć w budynkach zabytkowych
PL
Wilgoć jest głównym zagrożeniem dla zabytków. Prowadzi bezpośrednio do degradacji substancji zabytkowej oraz uruchamia procesy niszczące niewystępujące bez jej udziału. Poprawne rozpoznanie źródeł zawilgocenia pozwala na podjęcie odpowiednich kroków w stronę skutecznej i trwałej renowacji. Jednak właściwa diagnoza często nie jest łatwa, a z pozoru oczywiste obserwacje mogą owocować sformułowaniem błędnych wniosków i wdrożeniem działań, które przyniosą więcej szkody niż pożytku. Artykuł opisuje najczęstsze przyczyny powstawania zawilgoceń w budynkach zabytkowych oraz zwraca uwagę na podstawowe czynniki, które należy wziąć pod uwagę, chcąc uniknąć nieskutecznych i kosztownych napraw. Szczególnie podnosi problem tzw. wilgoci wstępującej od gruntu, zdecydowanie zbyt często i łatwo wskazywanej jako główny powód zawilgocenia.
EN
Dampness is considered to be one of the most serious threats to heritage buildings. It leads directly to degradation of historical fabric and triggers damaging processes that would not appear without it. Correct diagnosis of the source of damp is necessary for implementing appropriate measures that will lead to effective and lasting renovation. But making a correct diagnosis is not easy, and what appears obvious from observation can lead to formulating incorrect conclusions and actions, which do more harm than good. The paper describes the most common causes of dampness in heritage buildings and draws attention to the basic factors, which need to be taken into account, in order to avoid ineffective and costly repairs. Special attention is devoted to the so-called damp rising from the ground, which is too often and too easily implicated as the main cause of dampness.
PL
Kondensacja magiczne słowo powodujące, że nagle kotły mają sprawność 109%, czyli dają więcej niż dostały. Z fizyki na poziomie szkoły podstawowej wiadomo, że nie można zrobić perpetuum mobile, czyli urządzenia, które wytworzy więcej energii niż się do niego włożyło. Zatem czy producenci kotłów oszukują swoich klientów?
8
EN
Proposed is the analysis of steam condensation in the presence of inert gases in a power plant condenser. The presence of inert, noncondensable gases in a condenser is highly undesirable due to its negative effect on the efficiency of the entire cycle. In general, thermodynamics has not provided an explicit criterion for assessing the irreversible heat transfer process. The method presented here enables to evaluate precisely processes occurring in power plant condensers. This real process is of particular interest as it involves a number of thermal layers through which heat transfer is observed. The analysis was performed using a simple, known in the literature and well verified Berman’s model of steam condensation in the presence of non-condensable gases. Adapted to the geometry of the condenser, the model enables, for instance, to recognise places where non-condensable gases are concentrated. By describing with sufficient precision thermodynamic processes taking place in the vicinity of the heat transfer area segment, it is possible to determine the distributions of thermodynamic parameters on the boundaries between successive layers. The obtained results allow for the recognition of processes which contribute in varying degrees to irreversible energy degradation during steam condensation in various parts of the examined device.
EN
In this study, a new damage detection method is developed which directly uses input–output data of a forced vibration of a structure. For this, the dynamic vibration formulation of an FE model has been integrated within the time domain of the vibration of the structure. Also, the static condensation scheme is used to reduce required measured degrees of freedom (DOF's). Hence, the main characteristic of the proposed method is that it just uses translational time history response of a structure at specified nodes corresponding to the finite element model of that structure. Also, the only required data from the original FE model of the structure is its stiffness matrix. To assess the capability of the proposed method in damage detection in beam type structures a cantilever beam is studied. Not only can the method locate damaged elements, but also the quantity of damage in every damaged element is computed successfully. Also, it has been shown that as the frequency of the applied load in simulated experiment approaches to the first natural frequency of the beam, the accuracy dwindles significantly. Hence, for obtaining more reliable results, the frequency of the applied load shall be far enough from the first natural frequency of the free vibration of the beam. The results demonstrate that the integrated displacements in specified nodes through the time of vibration carry enough information about damages in elements and the proposed method can be successfully used for damage detection in beam type structures.
10
Content available remote Hexahydroquinoline derivatives : synthesis and anti-hepatoma cancer activity
EN
Arom. aldehydes were condensed in EtOH under boiling, pptd. by cooling to the room temp., sepd. by filtration, dried under vacuum and studied for anticancer activity against 3 human hepatoma tumor cell lines (SMMC-7721, BEL-740 and HCCLM3). Normal fibroblast cells WI 38 were also used. Fluorouracil was used as a ref. anticancer agent. One of the synthesized comps. showed a high inhibitory effect against 3 tumor cell lines (higher than the ref. agent). The compd. was non-cytotoxic to normal cells (IC50 values higher than 100 μg/mL).
PL
Przedstawiono syntezę i charakterystykę 4 pochodnych heksahydrochinoliny. Związki te zsyntetyzowano w reakcji kondensacji różnych aldehydów aromatycznych i oceniono pod kątem właściwości antyrakowych na podstawie badania 3 ludzkich linii komórkowych raka wątrobowokomórkowego (SMMC-7721, BEL-740 i HCCLM3). W badaniu wykorzystano także komórki WI 38 jako normalne fibroblasty. Najlepsze wyniki uzyskano dla związku 4, który wykazał najskuteczniejsze działanie hamujące rozwój 3 linii komórek rakowych. Działanie to okazało się skuteczniejsze niż w przypadku referencyjnego fluorouracylu. Ponadto związek ten nie działał cytotoksycznie na normalne komórki (IC₅₀ > 100 μg/mL).
EN
In the present paper, an attempt was made to model the periodic hydrodynamic instabilities of the condensation process of a refrigerant in pipe minichannels. For this purpose, a homogenous thermodynamic model with an equilibrium condition on both sides was used, which was based on the equations of the balance of the mass, momentum and energy. These equations were used for numerical modeling of flow disturbances with a phase change. This model takes into account the complexity of multiphase flows. The accuracy of the model calculations was verified by means of the experimental results obtained. A satisfactory compliance was found for this comparison, which confirms the usefulness of the computational model proposed for the determination of the influence of periodically generated hydrodynamic disturbances on the condensation process of R134a and R404A refrigerants in pipe minichannels.
12
Content available Flow structures during refrigerants condensation
EN
For several years, in the world are carried out studies on the refrigerants condensation in minichannels. These studies are aimed at understanding the condensation process and facilitate the design of mini heat exchangers. It is very important to optimize heat transfer and drive power consumption of the is the knowledge of the processes occurring during refrigerants condensation in pipe minichannels. It is important in this case to make a individual flow structures maps for the refrigerants, due to the significant effect of flow structured formed in the minichannel on the heat transfer and flow resistance. Unfortunately, in relation to the number of publications about condensation in minichannels, the number of published flow maps is relatively small. Due to the fact that the condensation process takes place differently in the minichannels and conventional channels, there is no possibility of using the flow maps for conventional channels to identification flow patterns in minichannels. One of the most popular flow maps for the condensation in minichannels is the map created by Colleman and Garimella, which was made for the R134a refrigerant. The authors conducted their own experimental studies of refrigerants R134a, R404A and R407C condensation in pipe minichannels with an internal diameter d = 3.3 - 0.31 mm. These studies results were subjected to calculation identification of flow structures using the map of Colleman and Garimella. These results are compared with the criteria published on Thome and Cavallini flow maps.
PL
Celem pracy było zbadanie procesów odpowiedzialnych za powstawanie i właściwości aerozoli uwalnianych z elektronicznych papierosów. Wykorzystując dyfraktometr laserowy określono podstawowe parametry objętościowego rozkładu wielkości kropel aerozolu uwalnianego z czterech modeli e-papierosów różniących się wewnętrznym oporem aerodynamicznym. Aerozole zostały wytworzone w warunkach odpowiadającym fizjologicznym wartościom przepływu powietrza z płynów zawierających składniki powszechnie występujące w e-liquidach. Stwierdzono, że jakość uwalnianego aerozolu zależy przede wszystkim od konstrukcji urządzenia, ale także od składu i właściwości e-liquidów.
EN
The aim of this work was to investigate the processes responsible for generation and properties of aerosols released from electronic cigarettes. Based on the laser diffraction method the primary parameters of droplet size distribution of aerosols released from four e-cigarette models with different internal aerodynamic resistance were determined. Aerosols were generated at physiological flow rates from e-liquids with different composition and properties. It was stated that the quality of aerosol depends mainly on device construction but it is also related to e-liquid composition and properties.
EN
Investigations of refrigerant condensation in pipe minichannels are very challenging and complicated issue. Due to the multitude of influences very important is mathematical and computer modeling. Its allows for performing calculations for many different refrigerants under different flow conditions. A large number of experimental results published in the literature allows for experimental verification of correctness of the models. In this work is presented a mathematical model for calculation of flow resistance during condensation of refrigerants in the pipe minichannel. The model was developed in environment based on conservation equations. The results of calculations were verified by authors own experimental investigations results.
15
Content available Modeling of KERENA emergency condenser
EN
KERENA is an innovative boiling water reactor concept equipped with several passive safety systems. For the experimental verification of performance of the systems and for codes validation, the Integral Test Stand Karlstein (INKA) was built in Karlstein, Germany. The emergency condenser (EC) system transfers heat from the reactor pressure vessel (RPV) to the core flooding pool in case of water level decrease in the RPV. EC is composed of a large number of slightly inclined tubes. During accident conditions, steam enters into the tubes and condenses due to the contact of the tubes with cold water at the secondary side. The condensed water flows then back to the RPV due to gravity. In this paper two approaches for modeling of condensation in slightly inclined tubes are compared and verified against experiments. The first approach is based on the flow regime map. Depending on the regime, heat transfer coefficient is calculated according to specific semi-empirical correlation. The second approach uses a general, fully-empirical correlation. The models are developed with utilization of the object-oriented Modelica language and the open-source OpenModelica environment. The results are compared with data obtained during a large scale integral test, simulating loss of coolant accident performed at Integral Test Stand Karlstein (INKA). The comparison shows a good agreement. Due to the modularity of models, both of them may be used in the future in systems incorporating condensation in horizontal or slightly inclined tubes. Depending on his preferences, the modeller may choose one-equation based approach or more sophisticated model composed of several exchangeable semi-empirical correlations.
EN
The pressure of wet water vapor inside a condenser has a great impact on the efficiency of thermal cycle. The value of this pressure depends on the mass share of inert gases (air). The knowledge of the spots where the air accumulates allows its effective extraction from the condenser, thus improving the conditions of condensation. The condensation of water vapor with the share of inert gas in a model tube bank of a condenser has been analyzed in this paper. The models include a static pressure loss of the water vapor/air mixture and the resultant changes in the water vapor parameters. The mass share of air in water vapor was calculated using the Dalton’s law. The model includes changes of flow and thermodynamic parameters based on the partial pressure of water vapor utilizing programmed water vapor tables. In the description of the conditions of condensation the Nusselts theory was applied. The model allows for a deterioration of the heat flow conditions resulting from the presence of air. The paper contains calculations of the water vapor flow with the initial mass share of air in the range 0.2 to 1%. The results of calculations clearly show a great impact of the share of air on the flow conditions and the deterioration of the conditions of condensation. The data obtained through the model for a given air/water vapor mixture velocity upstream of the tube bank allow for identification of the spots where the air accumulates.
EN
Neptunian sills at Rocca Busambra, a fragment of the Trapanese/Saccense Domain in western Sicily, host the most abundant ammonite and gastropod fauna which has ever been recorded from the Jurassic of the western Tethys. The fauna is dominated by parautochthonous organisms which were swept into the sills by gentle transport. Ammonites are characterized by perfect preservation and small size, a feature which is due to the predominance of microconchs but also of stunting. The most complete sill is 0.7 m thick and could be separated into 17 levels which range in age from the early Toarcian into the late Kimmeridgian, thus representing the most extreme case of palaeontologically and depositionally documented stratigraphic condensation in Earth history. The unique feature of the Rocca Busambra sills is due to the interaction of three processes: extreme stratigraphic condensation on the sea floor, weak tectonic fracturing of the host rock and repeated reopening on top of already existing sills. Contrasting percentages of gastropods in individual levels reflect sea-level oscillations which correspond to long known low- and highstands during the Jurassic of the western Tethys. Comparisons with other ammonite-bearing sill faunas reveal several similarities, but represent only short-timed phases of tectonic pulses and deposition.
PL
Celem artykułu jest przedstawienie dwóch modeli matematycznych kondensacyjnego wymiennika ciepła oraz porównanie wyników obliczeń przeprowadzonych przy pomocy tych modeli. Pierwszy model matematyczny jest jednowymiarowy i ustalony i bazuje na modyfikacji modelu Colburna-Hougena kondensacyjnego wymiennika ciepła, opisanej w [8, 9, 10]. Drugi model jest trójwymiarowy (CFD). Jest to model przepływu wielofazowego, rozszerzony o model kondensacji pary wodnej w spalinach. Przy pomocy obu modeli przeprowadzono analizę porównawczą wyników obliczeń i stwierdzono bardzo dobrą zgodność wyników.
EN
The aim of the article is to present two mathematical models of condensing heat exchanger and to compare the results of calculations by using these models. The first model is one-dimensional and steady and bases on Colburn-Hougen model modification, described in [8, 9, 10]. Second model is three-dimensional (CFD). It is a model of multiphase flow, developed of model of water vapor condensation in flue gases. Using these models authors performed a comparative analysis of calculations results and found very good agreement of results.
19
Content available remote Modelowanie procesu kondensacji gazu w kominach przemysłowych
PL
W artykule przedstawiono wyniki modelowania procesu kondensacji gazu w przewodzie kominowym. Analiza dotyczyła dwóch modeli geometrycznych połączenia czopucha z przewodem kominowym. Omówiono wyniki analizy charakteru przepływu oraz porównano intensywność wydzielania się kondensatu.
EN
The paper contains numerical analysis of the condensation process in industrial stack. The analysis was carried out for two models which differ by flue inlet geometry. The results show the character of flow and condensate quantity comparison.
EN
The paper deals with the condensation method used for inertial filtering separation process. It is a new alternative method in comparison with traditionally used technologies for gas condensate systems depuration using devices for prior condensation. The developed and presented here mathematical model of separation process by coupled heat transfer in the inertial filtering gas separator-condenser can also estimate fluid phase amount condensed during the separation process and the main factors of heat and mass transfer (during the same process).
PL
Przedstawiono nowy sposób inercyjno-filtrującej separacji podczas kondensacji, alternatywny dla tradycyjnie stosowanych technologii procesu oczyszczania z wykorzystaniem urządzeń wstępnej kondensacji. Opracowany model matematyczny separacji z dopasowaną wymianą ciepła w inercyjno-filtracyjnym separatorze-skraplaczu pozwala określić ilość fazy ciekłej, która skrapla się podczas procesu oraz podstawowe wskaźniki wymiany ciepła i masy w analizowanym układzie.
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