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Wyniki wyszukiwania dla: HIGH MODULUS LOW TEMPERATURE TRANSVERSE CRACKING HARD BITUMEN
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Investigation of low-temperature cracking in newly constructed high-modulus asphalt concrete base course of a motorway pavement
PublikacjaThe paper presents the issue of low-temperature transverse cracks which have developed in newly constructed base courses made of high-modulus asphalt concrete mix (HMAC). Numerous transverse cracks developed in the analysed HMAC base during the winter season before the pavement was actually completed, both at the transverse joint locations and in the areas between them. This had not happened so far on such a scale during road construction...
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Właściwości niskotemperaturowe betonów asfaltowych o wysokim module sztywności (AC-WMS) w badaniach trzypunktowego zginania
PublikacjaArtykuł przedstawia właściwości niskotemperaturowe betonów asfaltowych o wysokim module sztywności. Przedstawione wyniki zostały uzyskane w dwóch badaniach zginania trzypunktowego próbek belkowych: ze stałą prędkością przemieszczenia oraz pod stałym obciążeniem. Obie te metody są od dawna stosowane na Politechnice Gdańskiej do oceny właściwości niskotemperaturowych betonów asfaltowych. Badaniu poddano pięć betonów asfaltowych –...
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Wpływ zbrojenia polimerowymi włóknami rozproszonymi na wybrane właściwości mieszanek mineralno-asfaltowych
PublikacjaW artykule przedstawiono wybrane wyniki badań mieszanek mineralno-asfaltowych zbrojonych polimerowymi włóknami rozproszonymi. Ocenie poddano mieszankę włókien zbrojących aramidowo-poliolifenowych pod kątem wpływu ich zastosowania na właściwości niskotemperaturowe i odporności na deformacje trwałe mieszanek mineralno-asfaltowych. Właściwości niskotemperaturowe oceniano na podstawie testu zginania próbek belkowych oraz na podstawie...
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The Impact of Homogeneity of High Modulus Asphalt Concrete Layer on Low-Temperature Cracking
PublikacjaDuring winter season of 2012 numerous transverse cracks developed in high-modulus asphalt concrete (HMAC) base of newly constructed motorway. Pavement cracked both in transverse joint locations and in the area between them. Research which was conducted during investigation of the causes and mechanisms of cracking consisted of: field examination, laboratory testing of specimens cored out of the existing pavement, computational analyses...
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Field Evaluation of High Modulus Asphalt Concrete Resistance to Low-Temperature Cracking
PublikacjaHigh-modulus asphalt concrete has numerous advantages in comparison to conventional asphalt concrete, including increased resistance to permanent deformations and increased pavement fatigue life. However, previous studies have shown that the construction of road pavements with High Modulus Asphalt Concrete (HMAC) may significantly increase the risk of low-temperature cracking. Those observations were the motivation for the research...
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Field investigation of low-temperature cracking and stiffness moduli on selected roads with conventional and high modulus asphalt concrete
PublikacjaHigh Modulus Asphalt Concrete (HMAC) was introduced in Poland as a one of the solutions to the problem of rutting, type of deterioration common in the 1990s. After first encouraging trials in 2002 HMAC was widely used for heavily loaded national roads and motorways. However some concerns were raised about low-temperature cracking of HMAC. This was the main reason of the studies presented in this article were started. The article...
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Comparison of low-temperature cracks intensity on pavements with high modulus asphalt concrete and conventional asphalt concrete bases
PublikacjaHigh modulus asphalt concrete (HMAC) base courses provide very good resistance to rutting and fatigue but they can increase the risk of low-temperature cracking as compared with conventional asphalt concrete (AC). The article presents the comparison of these two road materials in terms of low-temperature cracking. The statistical method based on the ordered logistic regression model was used. The analysis was based on results of...
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Influence of Bitumen Type and Asphalt Mixture Composition on Low-Temperature Strength Properties According to Various Test Methods
PublikacjaIn regions with low-temperatures, action transverse cracks can appear in asphalt pavements as a result of thermal stresses that exceed the fracture strength of materials used in asphalt layers. To better understand thermal cracking phenomenon, strength properties of different asphalt mixtures were investigated. Four test methods were used to assess the influence of bitumen type and mixture composition on tensile strength properties...
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Low-Temperature Requirements for Bitumen in Central East European Road Construction
PublikacjaThe paper presents the proposition of special assessment of lowtemperature requirements for bitumens in the region of Central and Eastern Europe where there is a moderate transitional area from sea to the continental type of climate. The results of the research program conducted on the road neat bitumens, Styrene-Butadiene-Styrene polymer and polymer-rubber modified bitumen, and multigrade bitumen types were presented and discussed....
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Influence of bitumen type on cracking resistance of asphalt mixtures used in pavement overlays
PublikacjaCracking is one of the predominant distresses occurring in flexible pavements, especially in old pavements that were rehabilitated with an asphalt overlay. In such cases asphalt mixtures should be designed to ensure high resistance to reflective cracking because new asphalt layers are exposed to existing cracks of the old pavement. The nature of these cracks can be various (transverse, longitudinal as well as crazy cracking). One...
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Factors affecting low-temperature cracking of asphalt pavements: analysis of field observations using the ordered logistic model
PublikacjaAccurate identification of factors that primarily affect the number of low-temperature cracks is crucial for selection of road materials and planning of pavement maintenance. Field investigations of lowtemperature cracks were performed in the years 2014 and 2020 on the same 68 road sections being in service in typical traffic conditions. The collected data were statistically analysed using the ordered logistic regression model....
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Evaluation of Low Temperature Properties of Rubberized Asphalt Mixtures
PublikacjaThe paper presents low-temperature test results of asphalt mixtures designed with use of bitumen modified by crumb rubber and also SBS polymer. Laboratory tests were conducted on two types of asphalt mixtures for wearing course – stone matrix asphalt (SMA 8) and porous asphalt (PA 8). This paper presents results of the following laboratory tests at low temperatures: TSRST test, three point bending creep test, fracture toughness...
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Effect of bitumen characteristics obtained according to EN and Superpave specifications on asphalt mixture performance in low-temperature laboratory tests
PublikacjaThe paper aims to identify those characteristics of bitumen which have the greatest impact on asphalt mixture low-temperature performance. It was observed that stiffness and m-value of bitumen from BBR test were moderately related to stiffness and m-value of asphalt mixture obtained from 3 PB test. Simultaneously those rheological properties significantly impact on cryogenic stresses induced during TSRST test. The multiple regression...
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Evaluation of Asphalt Mixture Low-Temperature Performance in Bending Beam Creep Test
PublikacjaLow-temperature cracking is one of the most common road pavement distress types in Poland. While bitumen performance can be evaluated in detail using bending beam rheometer (BBR) or dynamic shear rheometer (DSR) tests, none of the normalized test methods gives a comprehensive representation of low-temperature performance of the asphalt mixtures. This article presents the Bending Beam Creep test performed at temperatures from −20...
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Evaluation of thermal cracking probability for asphalt concretes with high percentage of RAP
PublikacjaThe paper presents determination of the probability of thermal cracking of asphalt mixtures with different reclaimed asphalt pavement (RAP) content on the basis of laboratory tests and analytical evaluation using thermal stress development method. Probability was evaluated taking into consideration: the type and gradation of the mixture and the quality and content of RAP. Thermal stresses were determined using two models: elastic and...
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Influence of Bitumen Type and Asphalt Mixture Composition on Low-temperature Strength Properties
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Performance of the very high-temperature heat pump with low GWP working fluids
PublikacjaTraditional heat pumps are a very attractive pro-ecological solutions for a number of applications, including providing of heating or heat recovery from industrial processes. The application range of heat pumps could be greatly enlarged when the operating temperature would be increased to 130-150°C and/or the temperature lift can be increased to 50-100 K. In the paper, the very high temperature vapour-compressor based single stage...
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Investigation of transverse cracking of asphalt pavements in the north-eastern Poland
PublikacjaSpękania poprzeczne są jednym z najczęstszych typów uszkodzeń występujących na polskich drogach. Artykuł przedstawia wyniki badań spękań poprzecznych dróg zlokalizowanych w Polsce północno-wschodniej. Na podstawie badań terenowych podjęto próbę wyznaczenia związków pomiędzy częstotliwością spękań, zdefiniowaną indeksem spękań, a wybranymi cechami nawierzchni. Analizowane były następujące cechy nawierzchni: typ podbudowy (podbudowa...
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Low-temperature high-pressure cryogelation of nanooxides
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Modeling of low calorific gas burning in a deficient oxygen environment and high-temperature oxidizer
PublikacjaThe experimental research will be performed using the experimental facility with a combustion chamber. The oxygen concentration in combustion oxidizers will be varied from 21% by volume (normal) air to 2%. The test combustion chamber will be fed with propane or methane as the reference fuel, then with low calorific fuels as test gases obtained by mixing various combustible components, e.g. H2, CH4, CO, and neutral gases, e.g. N2,...
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Cold Cracking Of Underwater Wet Welded S355G10+N High Strength Steel
PublikacjaWater as the welding environment determines some essential problems influencing steel weldability. Underwater welding of high strength steel joints causes increase susceptibility to cold cracking, which is an effect of much faster heat transfer from the weld area and presence of diffusible hydrogen causing increased metal fragility. The paper evaluates the susceptibility to cold cracking of the high strength S355G10+N steel used,...
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Influence of High Temperature Oxidation on Hydrogen Absorption and Degradation of Zircaloy-2 and Zr 700 Alloys
PublikacjaThe present research was aimed at determining the effects of the oxide layers on hydrogen absorption, microstructure and mechanical properties of the Zircaloy- 2 and Zr 702 alloys. The oxidation was made at 350 °C, 700 °C and 900 °C for 10 to 30 min in laboratory air, followed by hydrogen cathodic charging for 72 h and annealing at 400 °C for 4 h. The slow strain rate tests were carried out on oxidized, charged and annealed specimens. The...
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Influence of cooling rate and additives on low-temperature properties of asphalt mixtures in the TSRST
PublikacjaThe paper presents the results and analysis of low-temperature properties of asphalt mixtures according to Thermal Stress Restrained Specimen Test (TSRST) and Indirect Tensile Test methods. Different groups of bitumen were investigated: neat, SBS-modified and highly SBS-modified. Influence of cooling rates (1 C/h, 3 C/h, 5 C/h and 10 C/h) and additives (aramid fibres and crumb rubber) was identified as well. Moreover, for each...
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High-Energy-Low-Temperature Technologies for the Synthesis of Nanoparticles: Microwaves and High Pressure
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Investigating the combined impact of plasticizer and shear force on the efficiency of low temperature reclaiming of ground tire rubber (GTR)
PublikacjaIn the present work, ground tire rubber (GTR) was mechano-chemically reclaimed at ambient temperature using two-roll mills. Road bitumen and styrene-butadiene-styrene (SBS)-modified bitumen at variable content (in range: 2.5–20 phr) were applied as reactive plasticizers to enhance reclaiming of GTR. For better understanding the plasticizing effect of bitumen on the quality of obtained reclaimed rubber, mechano-chemically reclaimed...
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Testing of low temperature behaviour of asphalt mixtures in bending creep test
PublikacjaThe paper presents a method of bending beam test and its importance for evaluation of asphalt mixtures behaviour at low temperatures. Two types of asphalt mixtures: asphalt concrete AC with normal paving grade bitumen and stone mastic asphalt SMA with SBS-modified bitumen were tested. Long-term oven ageing (LTOA) test was also used in the laboratory according to SHRP procedure. The Burgers model was applied and rheological parameters...
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Asphalt concrete subjected to long-time loading at low temperatures – Deviations from the time-temperature superposition principle
PublikacjaThe article presents the observed deviations from the time-temperature superposition principle of asphalt concretes, tested in the bending beam creep test at low temperatures for a long time of loading. In almost all tested asphalt concretes, deviations appeared after 500 s of loading at the temperature of -10 C. Some types of bitumen presented deviations at other temperatures – usually the harder the grade of the bitumen, the...
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HIGH TEMPERATURE HEAT PUMPS – PERSPECTIVE HEATING SYSTEMS?
PublikacjaIn 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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Impact of low-temperature sintering on the Fe-based amorphous coatings
PublikacjaBulk metallic glasses (BMGs) have gained a lot of attention in recent years due to their outstanding properties such as high hardness and excellent wear and corrosion resistance. However, they are restricted in industrial applications due to their extreme brittleness. Iron based amorphous coatings from BMGs are the best solution to use them by overcoming the problem of extreme brittleness. The coatings can be sprayed by various...
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High temperature corrosion of evaporator tubes in low-emission steam boilers
PublikacjaW artykule opisano zjawisko korozji wysokotemperaturowej rur ekranowych kotłów parowych niskoemisyjnych. Przeprowadzono badania rur po eksploatacji. Wykonano badania składu chemicznego zgorzelin. Stwierdzono, że główną przyczyną pocienienia rur na wyższych poziomach jest korozja siarkowa, natomiast na poziomach niższych oddziaływanie stopionych soli.
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High temperature corrosion of steel equipment in modern rafinery environments with high and low sulphur content
PublikacjaPrzedstawiono charakterystykę i mechanizmy procesów wysokotemperaturowej korozji elementów ze stali we współczesnych rafineriach ropy naftowej podczas eksploatacji we frakcjach węglowodorowych o niskiej i wysokiej zawartości siarki. Zwrócono uwagę na procesy korozji siarkowej w obecności wodoru i bez obecności wodoru oraz proces pylenia metalu pod wpływem węgla ze środowiska - w wypadku niskiej zawartości siarki w środowisku.
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Effect of Chitosan Solution on Low-Cohesive Soil’s Shear Modulus G Determined through Resonant Column and Torsional Shearing Tests
PublikacjaIn this study the effect of using a biopolymer soil stabilizer on soil stiffness characteristics was investigated. Chitosan is a bio-waste material that is obtained by chemical treatment of chitin (a chemical component of fungi or crustaceans’ shells). Using chitosan solution as a soil stabilizer is based on the assumption that the biopolymer forms temporary bonds with soil particles. What is important is that these bonds are biodegradable,...
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Hard carbon derived from rice husk as low cost negative electrodes in Na-ion batteries
PublikacjaHere, we report the synthesis of hard carbon materials (RH) made from natural rice husk through a single pyrolysis process and their application as an anode in sodium-ion batteries. The studies show that the electrochemical properties of RHs are affected by the treatment temperatures, which determine the materials morphology, in particular, their degree of graphitization and extent of continuous channels (nanovoids). The latter...
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Weldability of S460ML High Strength Low Alloy Steel in Underwater Conditions
PublikacjaThe paper presents experimental evaluation of susceptibility of the high strength S460ML steel to cold cracking in the conditions of wet welding with the use of covered electrodes. From the results of Tekken tests it was found out that the investigated steel was characterised, in the conditions of the carried out experiments (underwater wet welding and air welding with rutile electrodes), of high susceptibility to cold cracking....
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The Influence of Thin Gold Electrodes on the High-Temperature Impedance of Oxide Glasses
PublikacjaThe influence of thin gold electrodes on the electrical measurements of glasses at high temperatures was studied using impedance spectroscopy. The impedance was measured several times over a wide frequency range from 10 mHz to 1 MHz and the temperature ranged from 213 to 673 K under air and nitrogen atmospheres. The results showed a drop in the conductivity of more than an order of magnitude at a temperature around 603 K during...
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High temperature corrosion resistance of porous hastelloy alloy
PublikacjaTo further understand the suitability of Ni-Cr-base alloy for solid oxide fuel cell (SOFC), a commercial Ni-Cr-Fe-Mo alloy, Hastelloy X was selected and evaluated for oxidation behaviour under high temperature conditions. HastelloyX was chosen due to its unusual resistance to oxidizing, reducing and neutral atmospheres. For long term stability of metal supported fuel cell, the corrosion resistance plays a vital role and must be...
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Influence of the low ambient temperature on the start-up process of hydraulic pumps
PublikacjaStarting hydraulic pumps in low ambient temperatures may cause: decreased hydraulic-mechanical efficiency, larger vibration of hydraulic installation, faster wear and more frequent damage to the elements of pumps, change of material properties of elements, increase of pressure drop. As a result of pressure drop in the suction pipe, large underpressure may be experienced, causing incomplete filling of pump working chambers with...
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Combustion of low calorific fuel at room and high temperature and at different oxygen content in the oxidizer
PublikacjaPraca przedstawia wyniki badań spalania paliwa niskokalorycznego powstałego w wyniku gazyfikacji biomasy. Badania prowadzono w temperaturze pokojowej oraz w warunkach typowych dla technologii HiTAC, tj. w temperaturze powyżej samozapłonu paliwa i przy różnej zawartości tlenu w utleniaczu. Wykazano możliwość wykorzystania technologii HiTAC do spalania takich paliw.
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Low temperature CVD growth of graphene nano-flakes directly on high K dielectrics
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Hydrogen delayed cracking of high-strength weldable steels
PublikacjaOceniano podatność na niszczenie wodorowe stali 14HNMBCu o wysokiej wytrzymałości i jej połączeń spawanych przy obciążeniu stałym w wodzie morskiej. Badania przeprowadzono w powietrzu, oraz w środowisku wody morskiej przy potencjale korozyjnym i przy polaryzacji katodowej. Obecność lub brak opóźnionych pęknięć próbek z karbem przyjęto za miarę odporności na niszczenie wodorowe przy stałym obciążeniu.
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The selected effects of high temperature air-steam mixture wood drying
PublikacjaThe results of properties change of beech wood after drying process are presented. The wood taken to experiments was from northern part of Pomeranian region in Poland. Before the main high temperature drying process using air-steam mixture, wood was initially dried in an open air conditions. The high temperature drying process was conducted at temperature 120oC, humidity 48%, flow rate of drying medium 2.5m/s and atmospheric pressure....
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PROBLEMS OF THE STARTING AND OPERATING OF HYDRAULIC COMPONENTS AND SYSTEMS IN LOW AMBIENT TEMPERATURE (PART IV) MODELLING THE HEATING PROCESS AND DETERMINING THE SERVICEABILITY OF HYDRAULIC COMPONENTS DURING THE STARTING-UP IN LOW AMBIENT TEMPERATURE
PublikacjaDesigners of hydraulically driven machines and devices are obliged to ensure during design process their high service life with taking into account their operational conditions. Some of the machines may be started in low ambient temperature and even in thermal shock conditions (due to delivering hot working medium to cold components). In order to put such devices into operation appropriate investigations, including experimental...
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Deposition and Electrical and Structural Properties of La0.6Sr0.4CoO3 Thin Films for Application in High-Temperature Electrochemical Cells
PublikacjaLow-temperature deposition of electroceramic thin films allows the construction of new devices and their integration with existing large-scale fabrication methods. Developing a suitable low-cost deposition method is important to further advance the development of microdevices. In this work, we deposited a 1-lm-thick La0.6Sr0.4CoO3d (LSC) perovskite with high electrical conductivity on sapphire substrates at 400C and analyzed its...
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Experimental study of the fuel jet combustion in high temperature and low oxygen content exhaust gases
PublikacjaPrzeprowadzono badania eksperymentalne spalania pojedynczego strumienia paliwa gazowego. Paliwo podawano współosiowo do generowanych przez konwencjonalny palnik gazowy spalin o wysokiej temperaturze i niskiej zawartości tlenu. Badano wpływ zawartości tlenu w utleniaczu na widzialność płomienia i skład produktów spalania.
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High Temperature Air Combustion and Gasification (HTAC; HTAG)
PublikacjaCombustion and gasification technology utilizing high-cycle regenerative air/steam preheater has drawn increased attention in many application areas. The process is to be realized at temperature level above ash melting point using highly preheated agent. The use of highly preheated media above 900oC provides additional energy in to conversion processes and results in considerable changes to the design of combustion and gasification...
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Analysing selection of low-temperature medium for cogeneration micro power plant
PublikacjaThe article analyses the ORC system working with dry and wet low-boiling media which are most frequently used in installations of this type. Two types of cycles were examined, which were the cycle with heat regeneration for dry media: fc72, hfe7100, R227ea, R245fa, R423a and R600a, and the cycle without heat regeneration for wet media: R11, R12, R134a, R718 and 507a. The calculations were performed for the assumed required thermal...
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Analysing selection of low-temperature medium for cogeneration micro power plant
PublikacjaThe article analyses the ORC system working with dry and wet low-boiling media which are most frequently used in installations of this type. Two types of cycles were examined, which were the cycle with heat regeneration for dry media: fc72, hfe7100, R227ea, R245fa, R423a and R600a, and the cycle without heat regeneration for wet media: R11, R12, R134a, R718 and 507a. The calculations were performed for the assumed required thermal...
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Management of low-temperature heat source by ORC aided by additional heat source
PublikacjaThe presented work is aimed at utilisation of waste heat in the manner to produce electricity in ORC installation. Therefore the precondition of the study was to use the waste heat available in the form of a stream of hot water at 90°C. Such low enthalpy heat source is rather insufficient to produce a good quality vapour to feed the ORC turbine. That was the incentive to search for the ways of increasing the temperature of the...
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Management of low-temperature heat source by ORC aided by additional heat source
PublikacjaIn the paper presented is a concept to utilize waste heat from the power plant with the aid of the low-temperature ORC cycle. The ORC system is heated from two heat sources, the first one being the flow rate of waste heat obtained from the exhaust gases. Subsequently, the working fluid in the cycle is additionally heated by the condensing steam from the low pressure turbine extraction points increasing in such way the level of...
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High temperature drying of beech with content of tension wood
PublikacjaThe presented artcle is focused on comparison of tension and normal wood of beech (Fagus sylvatica L.) in a high-temperature drying process. Samples of 26 mm thickness were selected from sapwood zone with different angle of growth rings. The article evaluated properties of tension and normal wood before and after drying process. Properties which are monitored were moisture, moisture gradients, covering tests, colour changes and...