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Search results for: COOLING
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Improved energy management technique in pipe-embedded wall heating/cooling system in residential buildings
PublicationEffective and environmentally responsive techniques of energy management in residential buildings are desirable for the resulting reduction of energy costs and consumption. In this paper, an improved and efficient technique of energy management in pipe-embedded wall heating/cooling systems, called the Thermal Barrier, is described. Specifically, the Thermal Barrier is a technique focused on the management and control of heat...
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Improved energy management technique in pipe-embedded wall heating/cooling system in residential buildings
PublicationEffective and environmentally responsive techniques of energy management in residential buildings are desirable for the resulting reduction of energy costs and consumption. In this paper, an improved and efficient technique of energy management in pipe-embedded wall heating/cooling systems, called the Thermal Barrier, is described. Specifically, the Thermal Barrier is a technique focused on the management and control of heat supply...
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Implementation of Fluidized Bed Concept to Improve Heat Transfer in Ecological Adsorption Cooling and Desalination Systems
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Evaluation of Performance and Power Consumption of a Thermoelectric Module-Based Personal Cooling System—A Case Study
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Influence of the engine cooling down period during short car stops on the average fuel consumption
PublicationW publikacji przedstawiono wpływ schłodzenia silnika podczas krótkich postojów pomiędzy jazdami na średnie zużycie paliwa. Przeprowadzono własne pomiary w czasie jazd miejskich w Gdańsku. Użyto samochodu osobowego z silnikiem o objętości skokowej 2 dm^3 z zapłonem siskrowym. Mierzono zużycie paliwa na trasach o długości 3-10 km. Krótko opisano sposoby wstępnego podgrzania silnika przed rozruchem.
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Heat transfer to car engine cooling system - influence of coolant flow through engine block
PublicationW artykule przedstawiono wyniki badań doświadczalnych nad wpływem nastawianej wydajności pompy cieczy na strumień odbieranego ciepła w silniku spalinowym. Wykorzystano hamownię silnikową z silnikiem o zapłonie iskrowym o objętości skokowej 1.8 dm^3. Przyjęto obciążenia silnika oporami ruchu samochodu na biegu bezpośrednim.
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Organic Rankine cycle turbogenerator cooling – Optimization of the generator water jacket heat exchange surface
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The features of steel surface hardening with high energy heating by high frequency currents and shower cooling
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Design, fabrication, and investigations of prototype supersonic micro-ejector for innovative cooling system of electronic components
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Structural and Microhardness Changes After Turning of the AISI 1045 Steel for Minimum Quantity Cooling Lubrication
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Improvement of machinability of Ti and its alloys using cooling-lubrication techniques: a review and future prospect
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Comparison of heat transfer characteristics in surface cooling using microjets with water, ethanol and HFE7100 as test fluids
PublicationAccurate control of cooling parameters is required in ever wider range of technical applications. It is known that reducing the dimensions of the size of nozzle leads to an increase in the economy of cooling and improves its quality. Present study describes research related to the design and construction of the nozzles and microjet study, which may be applied in many technical applications such as in metallurgy, electronics, etc....
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Instantaneous Heating and Cooling Caused by Periodic or Aperiodic Sound of Any Characteristic Duration in a Gas with Vibrational Relaxation
PublicationThermodynamic relaxation of internal degrees of a molecule's freedom in a gas occurs with some characteristic time. This makes wave processes in a gas behave differently depending on the ratio of characteristic duration of perturbations and the relaxation time. In particular, generation of the secondary non-wave modes by intense sound in a nonlinear flow dependens on frequency. These kinds of interaction are considered in this...
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Modern design solutions of cooling systems, as an example of energy efficiency rationing, operational safety and environmental protection
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Integration of Active Clothing with a Personal Cooling System within the NGIoT Architecture for the Improved Comfort of Construction Workers
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Experimental investigation on the effect of dry and multi-jet cryogenic cooling on the machinability and hole accuracy of CFRP composites
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Cooling System with PCM Storage for an Office Building: Experimental Investigation Aided by a Model of the Office Thermal Dynamics
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Polymer journal bearings behaviour research under limited lubrication and cooling conditions conducted on high torque test rig
PublicationPolymer journal bearings are frequently used as a water-lubricated bearings of small marine units’ propeller shafts . Choice of these bearings is based on their simple construction and relatively low purchase and maintenance costs. Although properly designed and installed water lubricated bearings may well last for over a decade, rapid wear or failure of these bearings can be observed...
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An optimized controlled rate slow cooling protocol for bovine ovarian tissue cryopreservation by means of X-ray computed tomography
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Adaptable management for cooling cyclic air in ship power plants by heat conversion – Part 1: Downsizing strategy for cogeneration plants
PublicationThe ship power plants (SPP) are generally based on Diesel engines. Their fuel efficiency is gradually sensible to cyclic air temperatures and drops with their rise. A sustainable performance of ship engines with high fuel efficiency is possible by cooling intake and charge air as two objects in waste heat conversion chillers. The peculiarities of marine engine application are associated with constrained space of machine room. Whereas,...
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Experimental research on water lubricated marine stern tube bearings in conditions of improper lubrication and cooling causing rapid bush wear
PublicationWater lubricated bearings are popular in sliding bearings of marine propeller shafts, turbines and pump shafts. Such popularity is partly due to their simple construction which also means a relatively affordable price. In practical experience one may also observe cases of rapid wear or even malfunctions of this bearings, some of which may be caused by insufficient flow of lubricant leading to overheating. The conducted...
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Beyond the helium buffer: 12C−2 rotational cooling in cold traps with H2 as a partner gas: interaction forces and quantum dynamics
Publicationabstract = { The scattering cross-sections and corresponding rate coefficients for rotationally inelastic collisions of $^{12}$C$_2$^-$ ($^2 \Sigma_g^+$) with H$_2$ ($^1 \Sigma_g^+$) are presented over a broad range of cold-trap temperatures. They have been calculated using quantum scattering theory that employs a new ab initio potential energy surface. The rate coefficients for the inelastic processes in the anionic partner are...
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Thermal, electrical, and magnetic properties of Fe2O3–PbO–SiO2 glass prepared by traditional melt-quenching and twin roller fast-cooling methods
PublicationIn this study, Fe–Pb–Si oxide glasses containing between 12.5 and 17.5 mol% Fe2O3 were prepared using two different methods comprising traditional melt-quenching and twin roller fast-cooling techniques. The topography and structure of the materials obtained were characterized by X-ray powder diffraction and scanning electron microscopy. All of the materials were found to be amorphous. The topography of most of the glasses comprised...
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The Influence of the Application of EP Additive in the Minimum Quantity Cooling Lubrication Method on the Tool Wear and Surface Roughness in the Process of Turning 316L Steel
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Thermal cooling process by nanofluid flowing near stagnating point of expanding surface under induced magnetism force: A computational case study
PublicationThis paper is dedicated to the exam of entropy age and research of the effect of mixing nanosolid additives over an extending sheet. In this review, Newtonian nanofluid version turned into researched at the actuated appealing field, heat radiation and variable heat conductivity results. With becoming modifications, the proven PDEs are moved into popular differential situations and paintings mathematically making use of a specific...
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Analysis of Cutting Force and Power Under the Conditions of Minimized Cooling in the Process of Turning AISI-1045 Steel with the Use of the Parameter Space Investigation Method
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Obliczanie czasów chłodzenia spawanych łukowo złączy stali odpornych na korozję = Cooling times calculation for stainless steels arc welded joints.
PublicationPrzedstawiono wpływ właściwości cieplnych i parametrów spawania stali odpornych na korozję na czas chłodzenia złącza w zakresie temperatur 800-500oC. Przedstawiono analityczne obliczenia tego czasu. W oparciu o wyniki badań rzeczywistych cykli cieplnych spawania stali typu duplex 2205 opracowano wzór do obliczania czasów chłodzenia złącza 800-500 C.
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Enhancing Internal Cooling Channel Design in Inconel 718 Turbine Blades via Laser Powder Bed Fusion: A Comprehensive Review of Surface Topography Enhancements
PublicationInconel 718, a widely utilized Ni-based superalloy in the aerospace industry, is renowned for its exceptional mechanical properties, high-temperature corrosion resistance, and thermal stability, making it an ideal material for turbine blades operating under extreme conditions of up to 2200 °C and high-pressure. Traditional single crystal casting, the prevalent manufacturing method for turbine blades, poses inflexibility challenges....
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Research on water lubricated main shaft bearings in conditions of improper lubrication and cooling conducted on high torque real-life scale bush test rig
PublicationWater lubricated polymer bushes find increasingly popular use in the sliding bearings of marine propellers, water turbines and pump shafts. Such popularity is partly due to their simple construction which also means relatively affordable price. In addition, properly designed and installed water lubricated bearings may well last for over a decade. However, in practical experience one may also observe cases of rapid wear...
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Negative CO2 Emission Gas Power Plant As Technology for Utilization of Sewage Sludge, Production of Electrical Energy, and CO2 Capture - Case of Chamber Under Transpiration Cooling
PublicationThis work focuses on the concept developed in the nCO2PP project, which aims to demonstrate a technology that allows to achieve negative CO2 emissions through Carbon Capture and Storage (CCS) applied to sewage sludge. A feedstock is first gasified, then the resulting syngas is burned in a semi-closed oxy-fuel gas turbine with pure oxygen and water, using the advantages of oxy-combustion, to ease the capture of CO2 in the resulting...
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Comparative study of a bottoming SRC and ORC for Joule–Brayton cycle cooling modular HTR exergy losses, fluid-flow machinery main dimensions, and partial loads
PublicationEnergy conversion efficiency increase in power plants with high-temperature gas-cooled reactors via implementation of the bottoming cycle was investigated under nominal and minimal thermal load of a high-temperature reactor (HTR). Heat transfer surface area and turbine outlet volumetric flow rate in bottoming cycles was also investigated. Water and two low-boiling point working fluids (ammonia and ethanol) were analyzed. Analyzed...
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Bond graph modeling of the new generation engine cooling systems = Zastosowanie metody grafów wiązań do modelowania nowej generacji układów chłodzenia silników spalinowych
PublicationW referacie szczegółowo opisano modele wymiany ciepła i przepływów w układzie chłodzenia. Metoda grafów wiązań okazała się szczególnie użyteczną dla modelowania skomplikowanych systemów energetycznych o różnych postaciach energii. Jako przykładu użyto obiegu chłodzenia silnika badawczego na hamowni silnikowej.
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Effect of rPET Content and Preform Heating/Cooling Conditions in the Stretch Blow Molding Process on Microcavitation and Solid-State Post-Condensation of vPET-rPET Blend: Part I—Research Methodology and Results
PublicationPolyethylene terephthalate (PET) is widely used in bottle production due to its costeffectiveness and low environmental impact. The first part of this article describes the research and statistical analysis methodology of the influence of the virgin PET (vPET) and recycled PET (rPET) content in the vPET-rPET blend, as well as the preform heating/cooling conditions in the stretch blow molding (SBM) process on the microscopic bottle...
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Effect of the Cooling Time in Annealing at 350°C on the Phase Transformation Temperatures of a Ni<sub>5</sub><sub>5</sub>Ti<sub>4</sub><sub>5</sub> wt. Alloy
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Effect of rPET Content and Preform Heating/Cooling Conditions in the Stretch Blow Molding Process on Microcavitation and Solid-State Post-Condensation of vPET-rPET Blend: Part II—Statistical Analysis and Interpretation of Tests
PublicationThis research explores how varying proportions of virgin polyethylene terephthalate (vPET) and recycled polyethylene terephthalate (rPET) in vPET-rPET blends, combined with preform thermal conditions during the stretch blow molding (SBM) process, influence PET bottles’ microscopic characteristics. Key metrics such as viscosity, density, crystallinity, amorphous phase relaxation, and microcavitation were assessed using response...
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Wojciech Litwin prof. dr hab. inż.
People1992÷1996 - study on Mechanical Department at Gdansk University of Technology1996 – employed in the Faculty of Ocean Engineering and Ship Technology at the Gdansk University of Technology2004 – PhD2014 – habilitation2016 - vice dean for science at Faculty of Ocean Engineering2020 - dean of the Faculty of Ocean Engineering2021 - head of Institute of Naval Architecture He participated in a number of designing and research programs...
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A novel degree-hour method for rational design loading
PublicationCooling degree-hours (CDH) received the broadest application in evaluation of the ambient air cooling efficiency in power engineering (engine intake air cooling systems) and air conditioning. The current CDH numbers are defined as a drop in air temperature multiplied by associated time duration of performance and their summarized annual number is used to estimate the annual effect achieved due to sucked air cooling in power plants...
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THERMAL ANALYSIS AND DESIGN OF HYBRID MICROCHANNEL -MICROJET TEST PROBE
PublicationAccurate control of cooling parameters is required in ever wider range of technical applications. It is known that reducing the flow hydraulic diameter to an increase in the economy of cooling and improves its quality (Mikielewicz and Muszyński 2009). Present study describes research results related to the design and construction of the test stand for hybrid microjet- microchannel cooling modules study, which may be applied in...
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Air-cooled photovoltaic roof tile as an example of the BIPVT system – An experimental study on the energy and exergy performance
PublicationThe air-cooled photovoltaic tile is a subject of presented investigations, which focused on improving the overall system efficiency of PV tiles with heat recovery. The operational efficiency of a PV roof tile, together with the construction optimising the air cooling efficiency, were the main points of plans realized at this research stage. The article describes the experimental research consisting of the assessment of electrical,...
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The unstable thermoelectric effect in non-stoichiometric Cu2Se during the non-equilibrium phase transition
PublicationThe superionic α ↔ β phase transition in Cu1.96Se thermoelectric material is investigated by means of thermal analysis (DSC) and measurements of Seebeck coefficient and electrical conductivity. Results of the DSC measurements with 1–10 K/min heating and cooling rates show that the material is close to the equilibrium phase composition during the transformation. However, the kinetic limitation of the process exists, which is indicated...
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Flow visualization and heat transfer investigations on the flat plate with streamwise pressure gradient
PublicationPaper presents experimental investigations results for film cooling on a flat plate. The main objective of the design is the streamwise pressure distribution on the flat plate as in the blade cascade. The transient and steady-state technique with liquid crystals for the surface temperature distribution with film cooling has been used in experiments in a low speed wind tunnel.
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Selektywne chłodzenie mózgu noworodka po niedotlenieniu okołoporodowym. Cześć 3. Hybrydowy system selektywnego chłodzenia mózgu noworodka
PublicationZapoczątkowane brakiem tlenu procesy biochemiczne mają zgubne skutki dla układu nerwowego, w szczególności rozwijającego się. Hipotermia, czyli stan oziębienia poniżej pewnych wartości temperatur, spowalnia znacznie lub całkowicie wyhamowuje poszczególne reakcje, i to leży u podstaw jej własności neuroprotekcyjnych. Powyższe twierdzenie poparte licznymi faktami naukowymi leży u podstaw koncepcji selektywnego chłodzenia mózgu i...
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Simplified method of water cooled exhaust system design.
PublicationThe water cooled exhaust systems are not often used onboard ships. Prime goal is to lower temperature of exhaust gas from main propulsion and auxiliary engines to the defined limit. The design of such systems require detailed analysis of propulsion system operational parameters to meet designer expectations. The paper outlines the cooled exhaust system design problems in specific application. The simplified method of evaluation...
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A new viscoelastic method of calculation of low-temperature thermal stresses in asphalt layers of pavements
PublicationThe paper presents a new method of calculation of thermal stresses in asphalt layers of pavements induced by cooling or heating. The method, developed by the author, is based on the analytical solution for the linear viscoelastic Burgers model extended numerically for the case of asphalt layers whose rheological parameters are strongly dependent on temperature. The coefficient of thermal expansion and Poisson’s ratio may optionally...
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Selektywne chłodzenie mózgu noworodka po Niedotlenieniu okołoporodowym. Część 1. Medyczne fakty oraz przegląd dostępnych rozwiązań systemów selektywnego chłodzenia mózgu
PublicationMózg ludzki jest organem delikatnym, dlatego tak ważne jest zadbanie o to, aby już w momencie przyjścia na świat noworodek miał zapewnioną, w razie konieczności możliwość minimalizacji uszkodzeń neurologicznych, spowodowanych niedotlenieniem okołoporodowym. Niedotlenienie to w dramatyczny sposób zaburza homeostazę mózgu, który jako organ najbardziej energochłonny potrzebuje najwięcej tlenu. Zapoczątkowane brakiem tlenu procesy...
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Friction and Lubrication of Large Tilting-Pad Thrust Bearings
PublicationFluid film bearings have been extensively used in the industry because of their unbeatable durability and extremely low friction coefficient, despite a very low coefficient of friction dissipation of energy being noticeable, especially in large bearings. Lubricating systems of large tilting pad thrust bearings utilized in large, vertical shaft hydrogenerators are presented in this paper. A large amount of heat is generated due...
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Propagation of initially sawtooth periodic and impulsive signals in a quasi-isentropic magnetic gas
PublicationThe characteristics of propagation of sawtooth periodic and impulsive signals at a transducer are analytically studied in this work. A plasma under consideration is motionless and uniform at equilibrium, and its perturbations are described by a system of ideal magnetohydrodynamic equations. Some generic heating/cooling function, which in turn depends on equilibrium thermodynamic parameters, may destroy adiabaticity of a flow and...
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The effect of laser on metal surfaces for multidisciplinary usage in material and thermal engineering
PublicationThe subject of heat transfer and cooling systems is still a matter of contention in many different fields of science and industry. Infrigidation is much more difficult than warming, and so, much more needed in more and more different devices, starting from massive industrial machinery and air conditioning in commercial buildings, up to micro and nano-surgery tools. In fact, the size of many cooling systems is still a problem. It...
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Dariusz Mikielewicz prof. dr hab. inż.
PeopleProfessor Dariusz Mikielewicz – born on February 6, 1967. in Gdansk. Here in 1974 he enrolled first to the Elementary School No. 17, and then in the Grammar School No. 5, named after Stefan Żeromski in Gdansk-Oliwa. After graduating from the Secondary School, with honors, in 1985 he successfully passed the entrance exams to the Faculty of Mechanical Engineering of Technical University of Gdansk, where he graduated with a very good...
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WSPÓŁCZESNE OCHŁODZENIE REJONU SZETLANDÓW POŁUDNIOWYCH I PÓŁNOCO-ZACHODNICH KRAŃCÓW PÓŁWYSPU ANTARKTYCZNEGO
PublicationThe paper discusses changes of hydro-climatic conditions occurring in the South Shetland Islands and in NW parts of the Antarctic Peninsula in the 1979–2016 years period. These changes are important for evaluation of the transformation of marine and coastal ecosystems. The general feature of these changes was a transition from the strong warming phase to the cooling phase, which took place around the year 2000. The paper presents...