Filters
total: 5106
-
Catalog
- Publications 3788 available results
- Journals 58 available results
- Conferences 1 available results
- Publishing Houses 1 available results
- People 118 available results
- Inventions 4 available results
- Projects 13 available results
- Research Teams 1 available results
- Research Equipment 1 available results
- e-Learning Courses 160 available results
- Events 5 available results
- Open Research Data 956 available results
displaying 1000 best results Help
Search results for: POOL BOILING, NANOFLUID, CHF
-
INFLUENCE OF NANOPARTICLE CONCENTRATION ON THERMAL PROPERTIES OF THERMAL OIL-MWCNT NANOFLUID
PublicationThis paper deals with measurements of dynamic viscosity, thermal conductivity, electrical conductivity and pH of thermal oil-MWCNT (TO-MWCNT) nanofluid. Nanoparticles were tested at the concentration of 0.001%, 0.005%, 0.01%, 0.05%, and 0,1% by weight. Ultrasonic vibration was used in order to stabilize the dispersion of the nanoparticles. Thermal oil (TO) was selected as a base liquid, because of possible application in ORC systems...
-
Influence of concentration on contact angle of water-Cu nanofluid on glass substrate
PublicationIn the paper the results of an experimental investigation of influence of nanoparticle concentration on contact angle of water-Cu nanofluid on glass substrate have been presented. Nanoparticles were tested at the concentration of 0.01%, 0.1%, and 1% by weight. In the present study copper was applied as nanoparticle while distilled, deionized water was used as a base fluid. The mean diameter of nanoparticle is estimated to be 50...
-
Influence of nanoparticle concentration on thermal properties of thermal oil-MWCNT nanofluid
PublicationResults of the measurements of dynamic viscosity, thermal conductivity, electrical conductivity and pH of thermal oil-MWCNT (TO-MWCNT) nanofluid have been presented. Nanoparticles were tested at the concentration of 0.001%, 0.005%, 0.01%, 0.05%, and 0,1% by weight. Thermal oil (TO) was selected as a base liquid, because of possible application in ORC systems as an intermediate heating agent. Multi-walled carbon nanotubes were used...
-
Performance of the flat plate solar collector operated with water-Al2O3 nanofluid
PublicationThe paper discusses the effect of application of water-Al2O3 nanofluid, as a working fluid, on the efficiency of a flat plate solar collector. The mass concentration of nanoparticles was 0.1%, 0.2% and 0.4%. The tests were conducted for two values of radiation of about 1050 W/m2 and 400 W/m2, and volume flow rates of 60 l/h, 120 l/h and 170 l/h. The efficiency was calculated according to recommendations of the Polish Standard....
-
EFFECT OF NANOFLUID CONCENTRATION ON TWO-PHASE THERMOSYPHON HEAT EXCHANGER PERFORMANCE
PublicationAn approach – relaying on application of nanofluid as a working fluid, to improve performance of the two-phase thermosyphon heat exchanger (TPTHEx) has been proposed. The prototype heat exchanger consists of two horizontal cylindrical vessels connected by two risers and a downcomer. Tube bundles placed in the lower and upper cylinders work as an evaporator and a condenser, respectively. Distilled water and nanofluid water-Al2O3...
-
Free convection of water-Al2O3 nanofluid from horizontal porous coated tube
PublicationNanofluids are expected to enhance heat transfer in many thermal systems. Present efforts are concentrated on boiling heat transfer of nanofluids, although single phase convection is of key importance in various appliances such as car radiators or heating systems. This paper presents experimental results of heat transfer during free convection of water-Al3O3 nanofluid from horizontal tube covered with metallic porous coating. Contrary...
-
BUILDING AND ENVIRONMENT
Journals -
Peptide bond modification. I. Simple and efficient method of Boc-Gly[CH(OH)CH2]Gly-OH synthesis.
PublicationZaprezentowano prostą i efektywną metodę syntezy obu enancjomerów t-butoksykarbonylo chronionego pseudo dipeptydu (R) oraz (S)-Boc-Gly[CH(OH)CH2]Gly-OH.
-
Size-exclusion chromatography for the determination of the boiling point distribution of high-boiling petroleum fractions
PublicationThe paper describes a new procedure for the determination of boiling point distribution of high-boiling petroleum fractions using size exclusion chromatography with refractive index detector. Thus far, the determination of boiling range distribution by chromatography has been accomplished using simulated distillation with gas chromatography with the flame ionization detection. This study revealed that in spite of substantial differences...
-
Boiling crisis - danger or a must?
PublicationW artykule przedstawiono zjawisko kryzysu wrzenia w przepływie. W głównej mierze skupiono się na zjawisku dryout'u podczas przepływu pierścieniowego. W pracy przedstawiono teoretyczny model wysychania filmu cieczowego na ściance wraz z jego modyfikacją w oparciu o model dwurównaniowy zaprezentowany przez Sedlera i Mikielewicza (1981). Model ten opiera się na bilansie cieczy w rdzeniu przepływu i w filmie cieczowym, gdzie głównym...
-
An Improved Method of Minimizing Tool Vibration during Boring Holes in Large-Size Structures
PublicationThe paper presents a thoroughly modified method of solving the problem of vibration suppression when boring large-diameter holes in large-size workpieces. A new approach of adjusting the rotational speed of a boring tool is proposed which concerns the selection of the spindle speed in accordance with the results of the simulation of the cutting process. This streamlined method focuses on phenomenological aspects and involves the...
-
Free convection of water-Al2O3 nanofluid from horizontal porous coated tube
PublicationThe main aim of the present study was to investigate the influence of nanoparticles on heat transfer coefficients during free convection of water-Al2O3 nanofluid from horizontal porous coated tube under atmospheric pressure for nanoparticle concentration of 0.01% by weight. Contrary to published data present study concerns on free convection of nanofluids in extensive, quiescent fluid.
-
Experimental investigation of free convection of glycol-Al2O3 nanofluid from horizontal tube
PublicationNanofluids came to be seen as a new generation of coolants, both in single- and two phase systems. Furthermore, nanofluids or nanocomposites may be used as a media in a thermal energy storage (TES) in such systems as sensible heat storage (SHS) and phase change materials (PCM). In the SHS systems the dominating mechanism of the heat transfer is natural convection. However, in the literature only a few investigations of free convection...
-
EXPERIMENTAL INVESTIGATION OF FREE CONVECTION OF GLYCOL-Al2O3 NANOFLUID FROM HORIZONTAL TUBE
PublicationNanofluids came to be seen as a new generation of coolants, both in single- and two phase systems. Furthermore, nanofluids or nanocomposites may be used as a media in a thermal energy storage (TES) in such systems as sensible heat storage (SHS) and phase change materials (PCM). In the SHS systems the dominating mechanism of the heat transfer is natural convection. However, in the literature only a few investigations of free convection...
-
UHF ESPAR antenna for simple Angle of Arrival estimation in UHF RFID applications
PublicationAn electronically switched beam antenna for localization of passive UHF RFID tags based on a simple Angle of Arrival (AoA) technique is proposed‥ Detailed antenna design and realization are presented together with corresponding simulations and measurement results. Experimental tests with passive UHF RFID tag show the validity of theoretical assumptions for application of the antenna in UHF RFID based localization systems.
-
Modelling of heat transfer in flow boiling
PublicationW pracy przedstawiono zagadnienia związane z modelowaniem wrzenia w przepływie w kanałach o małej średnicy. Przedstawiono modyfikację rozwijanej przez autorów korelacji umożliwiającej wyznaczanie współczynnika przejmowania ciepła podczas wrzenia w przepływie.
-
Visualization of water boiling in tube bundle
PublicationW pracy przedstawiono wyniki wizualizacji, za pomocą systemu laserowego noża świetlnego (PIV), wrzenia cieczy w pęku rur. Wykorzystanie systemu PIV umożliwiło analizę skomplikowanej struktury przepływu cieczy podczas wrzenia, a także wzajemnego oddziaływania pomiędzy sekcją grzejną a wrzącą cieczą.
-
Optimal boiling temperature for ORC installation
PublicationW pracy przedstawiono oryinalne kryterium wyznaczania optymalnej temperatury odparowania czynnika w obiegu ORC w postaci równań analitycznych. Pokazano przykład obliczeniowy na bazie R134a, wody i etanolu.
-
Heat transfer enhancement through nanofluids with applications in automobile radiator
Publication -
Numerical study of turbulent flow and heat transfer of nanofluids in pipes
PublicationIn this work, Nusselt number and friction factor are calculated numerically for turbulent pipe flow (6 000 < Re < 12 000) with constant heat flux boundary condition using nanofluids. The nanofluid is modelled with the single-phase approach and the simulation results are compared with experimental data of Vajjha et al. [1]. Ethylene glycol and water, 60:40 EG/W mass ratio, as base fluid and SiO2 nanoparticles are used as nanofluid...
-
INFLUENCE OF SURFACE CURVATURE ON SESSILE DROPLET CONTACT ANGLE OF NANOFLUIDS
PublicationThis paper deals with change in contact angle of droplets of three nanofluids, i.e. water-Al2O3, water-TiO2 and water-Cu. Nanoparticles were tested at the concentration of 0.01%, 0.1%, and 1% by weight. Although dispersants were not used to stabilize the suspension, the solutions tested exhibited satisfactory stability. Ultrasonic vibration was used in order to stabilise the dispersion of the nanoparticles. Experimental measurements...
-
Numerical Study of Turbulent Flow and Heat Transfer of Nanofluids in Pipes
PublicationIn this work, Nusselt number and friction factor are calculated numerically for turbulent pipe flow (Reynolds number between 6000 and 12000) with constant heat flux boundary condition using nanofluids. The nanofluid is modelled with the single-phase approach and the simulation results are compared with experimental data. Ethylene glycol and water, 60:40 EG/W mass ratio, as base fluid and SiO2 nanoparticles are used as nanofluid...
-
Computational examination of Jeffrey nanofluid through a stretchable surface employing Tiwari and Das model
Publication -
Experiment-aided virtual prototyping to minimize tool-workpiece vibration during boring of large-sized structures
PublicationThe paper presents the author's method of solving the problems of vi-bration suppression during boring of large-sized workpieces by means of an in-novative method of adjusting the rotational speed of the boring bar. It consists in selecting the spindle speed in accordance with the results of the cutting process simulation. The method includes identification of the model of the finite element method of the boring bar. The Root Mean...
-
WOOL TECHNOLOGY AND SHEEP BREEDING
Journals -
Numerical single-phase modeling of turbulent flow and heat transfer of nanofluids
PublicationIn this work, Nusselt number and friction factor are calculated numerically for turbulent pipe flow (6 000< Re < 12 000) with constant heat flux boundary condition using nanofluids. The nanofluid is modelled with the single-phase approach and the simulation results are compared with published experimental data.
-
Numerical Modelling of Forced Convection of Nanofluids in Smooth, Round Tubes: A Review
PublicationA comprehensive review of published works dealing with numerical modelling of forced convection heat transfer and hydrodynamics of nanofluids is presented. Due to the extensive literature, the review is limited to straight, smooth, circular tubes, as this is the basic geometry in shell-and-tube exchangers. Works on numerical modelling of forced convection in tubes are presented chronologically in the first part of the article....
-
Effect of Temperature and Nanoparticle Concentration on Free Convective Heat Transfer of Nanofluids
PublicationA theoretical analysis of the influence of temperature and nanoparticle concentration on free convection heat transfer from a horizontal tube immersed in an unbounded nanofluid was presented. The Nusselt (Nu) number and heat transfer coefficient were parameters of the intensity of the convective heat transfer. For free convection, the Nu number was a function of the Rayleigh (Ra) number and Prandtl (Pr) number. The Rayleigh (Ra)...
-
Sensitivity study of correlation for flow boiling in tubes.
PublicationW referacie skupiono uwagę na szczegółowym zbadaniu wpływu wybranych typów modeli, opisujących współczynnik oporu przepływu oraz współczynnik przejmowania ciepła dla wrzenia w przepływie na korelację dla wrzenia w przepływie ( wyprowadzoną dla rur o konwencjonalnych wymiarach -półempiryczny model Mikielewicza ). Otrzymane wyniki porównano z danymi eksperymentalnymi.
-
Modelling of convective heat transfer in flow boiling.
PublicationW pracy przedstawiono rozważania dotyczące modelowania przepływu z wrzeniem w zastosowaniu do kanałów o małej średnicy. Stwierdzono,że stosowanie korelacji obowiązujących dla średnic konwencjonalnych nie sprawdza się z praktyką w przypadku małych średnic.
-
Flow boiling of R22 and R134 a in enhanced tubes.
PublicationPrzedstawiono wyniki badań wrzenia R22 oraz R134a w rurkach gładkich i o rozwiniętej powierzchni: mikrożebrowanej i śrubowo-formowanej. Podano opis stanowiska badawczego, procedury pomiarowej oraz metody obliczania średniego współczynnika przejmowania ciepła. Omówiono wyniki badań eksperymentalnych na tle danych cytowanych w literaturze, a także w porównaniu do wybranych korelacji.
-
A study of flow boiling heat transfer in minichannels
PublicationW pracy przedstawiono badania eksperymentalne wrzenia w przepływie w minikanale o średnicy wewnętrznej 2.3mm i długości 38cm. Uzyskano rozłady temperatury wzdłuż ścianki kanału oraz lokalne współczynniki przejmowania ciepła. Dane skorelowano z korelacją półempiryczną uzyskując zadowalającą zgodność.
-
Rheology of Variable Viscosity‐Based Mixed Convective Inclined Magnetized Cross Nanofluid with Varying Thermal Conductivity
PublicationCross nanofluid possesses an extraordinary quality among the various fluidic models to explore the key characteristics of flowing fluid during very low and very high shear rates and its viscosity models depend upon shear rate. The current study establishes the numerical treatment regarding variable viscosity‐based mixed convective inclined magnetized Cross nanofluid with var‐ ying thermal conductivities over the moving permeable...
-
Numerical simulation of natural convection of Glycol-Al2O3 nanofluids from a horizontal cylinder
PublicationThis paper deals with natural convection around a circular cylinder with constant heat flux in a cavity using computational fluid dynamics. As fluids ethylene glycol and a mixture of ethylene glycol with Al2O3 nanoparticles (mass concentrations of nanoparticles: 0.1% and 1%) are chosen. Rayleigh number ranges from 3104 to 3105. The nanofluids are modeled with single-phase approach. For the investigated range of nanoparticle concentration, the...
-
Experimental Investigations of Forced Convection of Nanofluids in Smooth, Horizontal, Round Tubes: A Review
PublicationA comprehensive review of published works dealing with experimental studies of forced convection heat transfer of nanofluids is presented. The survey is limited to straight, smooth, and round tubes. Moreover, only mono nanofluids exhibiting Newtonian behaviour are considered. Works on experimental research of forced convection in tubes are presented in a chronological order in the first part of the article. In this part, attention...
-
Experimental Investigation of Free Convection Heat Transfer from Horizontal Cylinder to Nanofluids
PublicationThe results of free convection heat transfer investigation from a horizontal, uniformly heated tube immersed in a nanofluid are presented. Experiments were performed with five base fluids, i.e., ethylene glycol (EG), distilled water (W) and the mixtures of EG and water with the ratios of 60/40, 50/50, 40/60 by volume, so the Rayleigh (Ra) number range was 3 104 Ra 1.3 106 and the Prandtl (Pr) number varied from 4.4 to 176....
-
Impact of Temperature and Nanoparticle Concentration on Turbulent Forced Convective Heat Transfer of Nanofluids
PublicationTheoretical analysis of the influence of nanoparticles and temperature on the average Nusselt (Nu) number and the average heat transfer coefficient (HTC) during the turbulent flow of nanofluid in a horizontal, round tube was carried out. The Nu number is a function of the Reynolds (Re) number and the Prandtl (Pr) number, which in turn are functions of the thermophysical properties of the liquid and the flow conditions. On the other...
-
Turbulence model evaluation for numerical modelling of turbulent flow and heat transfer of nanofluids
PublicationIn this work, Nusselt number and friction factor are calculated numerically for turbulent pipe flow (Reynolds number between 6000 and 12000) with constant heat flux boundary condition using nanofluids. The nanofluid is modelled with the single-phase approach and the simulation results are compared with experimental data. Ethylene glycol and water, 60:40 EG/W mass ratio, as base fluid and SiO2 nanoparticles are used as nanofluid...
-
Experimental investigation of forced convection of water/EGAl2O3 nanofluids inside horizontal tube
PublicationIn this paper, forced convection of water/EG-Al2O3 nanofluids inside horizontal stainless steel tube is studied experimentally. As base fluid served water/EG mixture of two ratios (60:50 and 50:50). Nanoparticle mass concentrations was 0.1% or and 1%. Transition and turbulent flow regimes were tested. Average heat transfer coefficient and pressure drop values were determined for nanofluids and compared to base fluids. Deterioration...
-
Experimental investigation of forced convection of water-Al2O3 nanofluids inside horizontal tubes,
PublicationIn this paper, forced convection of water–Al2O3 nanofluids inside horizontal copper tube is studied experimentally. Experiments were conducted for three, i.e. 0.1%, 1% and 5% nanoparticle mass concentrations under transition and turbulent flow regimes. Average heat transfer coefficients and pressure drop values were determined and compared to distilled water. Enhancement of heat transfer for lower nanoparticle concentration and...
-
Joining of tubular elements by internal rolling with use of burnishing tools.Łączenie elementów rurowych przez wewnętrzne rozpęczanie z użyciem nagniataków.
PublicationW referacie przedstawiono wyniki prac zmierzających do zastosowania nagniataków do łączenia rur aluminiowych przez ich rozgniatanie. Zaprezentowano analityczny szacunek wytrzymałości złącz i porównano z wynikami prób ich rozłączania na maszynie wytrzymałościowej.
-
Tackling Air Pollution in Cities with Modelling and Simulation: Remote Group Model Building as an Educational Tool Supporting System Dynamics Modelling
Publication -
Influence of lightweight structures used in swimming pools and water parks objects on their functionality, building form and spatial-visual effects indoors.
PublicationSpeaking about architecture of swimming facilities and water parks we have in mind their form, function , design and detail, texture and color. A particularly important element of the architecture of these buildings was and still is the structure.
-
Flow boiling of oil-refrigerant mixtures in smooth tubes
PublicationPrzedstawiono wyniki badań współczynnika przejmowania ciepła i spadku ciśnienia podczas wrzenia czynników R 22, R 134a i R 407C i ich mieszanin z olejem w rurach gładkich. Opisano procedurę badawczą. Udział masowy oleju w mieszaninie z czynnikiem wynosił 0,1% i 5%. Zaobserwowano negatywny wpływ obecności środka smarnego we wrzącym czynniku chłodniczym.
-
Modelling of flow boiling process in small diameter tubes.
PublicationW pracy zastosowano standardową korelację wrzenia w przepływie (wyprowadzoną dla rur o konwencjonalnych wymiarach) do przypadków wrzenia w rurach o małych średnicach. Porównanie wyników obliczeń z danymi literaturowymi wykazało nieużyteczność tej korelacji. Wykazano zatem potrzebę prowadzenia badań podstawowych celem uzyskania korelacji pozwalającej umiejętnie przewidywać warunki wymiany ciepła w kanałach o małych średnicach.
-
Experimental investigations of R22 flow boiling in enhanced tubes.
PublicationPrzedstawiono wyniki badań eksperymentalnych wrzenia R22 podczas wrzenia w przepływie wewnątrz rur o rozwiniętej powierzchni przejmowania ciepła: miedzianej rury niskożebrowanej wewnętrznie, stalowej rury formowanej śrubowo oraz stalowej rury z pokryciem porowatym. Przeprowadzono także badania na dwóch rurach gładkich, o średnicy odpowiadającej maksymalnej średnicy wewnętrznej rur o rozwiniętej powierzchni. Średnie wartości...
-
Boiling heat transfer performance of the thermosiphon heat exchanger
PublicationPrzedstawiono wyniki badań eksperymentalnych prototypowego, termosyfonowgo wymiennika ciepła. W szczególności określono wpływ geometrii pęku rur, stanu powierzchni rurek oraz poziomu cieczy w parowniku na wydajność cieplną wymiennika.
-
Simulation of temperature field in cylindrical boiling heating section
PublicationW pracy przedstawiono wyniki obliczeń cylindrycznej sekcji grzejnej. Biorąc pod uwagę geometrię i konstrukcję sekcji grzejnej zaprezentowano rozwiązania pola temperatury dla cylindrycznej sekcji grzejenej. W uzyskaniu rozwiązania posłużono się metodą elementów skończonych.
-
BUILDING ACOUSTICS
Journals -
Collection Building
Journals