Wyniki wyszukiwania dla: ITERATIVE PROCEDURE FOR HEAT TRANSFER MODELLING
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Thermodynamic and geometrical characteristics of mixed convection heat transfer in the shell and coil tube heat exchanger with baffles
PublikacjaThe article presents passive heat transfer enhancement method in the form of baffles to increase the energy efficiency of the shell coil heat exchanger. Conducted literature review shows that, despite numer- ous studies, there is little work on the intensification of heat transfer at the shell side. Most of the work focuses on the impact of geometrical parameters of the coil itself. This article successfully proves that it is possible...
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Effect of Temperature and Nanoparticle Concentration on Free Convective Heat Transfer of Nanofluids
PublikacjaA 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)...
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Hydrodynamics and heat transfer in bubbly flow in the turbulent boundarylayer
PublikacjaW pracy przedstawiono oryginalne podejście do modelowania przepływu pęcherzykowego w warstwie przyściennej i w kanale. Podejście oparte jest na sumowaniu energii dyssypacji pochodzącej od przepływu ścinającego w kanale oraz dyssypacji pochodzącej od obecności pęcherzyków. W wyniku otrzymuje się naprężenia styczne ekwiwalentnego przepływu jednofazowego. Zaproponowano własne podejście do modelowania stopnia zapełnienia opisane równaniem...
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Heat transfer characteristics of hybrid microjet – Microchannel cooling module
PublikacjaThe paper presents experimental investigation of heat transfer intensification in a microjet–microchannel cooling module. Applied technology takes benefits from two very attractive heat removal techniques. When jets are impinging on the surface, they have a very high kinetic energy at the stagnation point, also in microchannels boundary layer is very thin allowing to obtain very high heat fluxes. Main objective of this paper was...
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Heat transfer characteristics of hybrid microjet -microchannel cooling module
PublikacjaThe paper presents the experimental investigation of heat transfer intensification in a microjet- microchannel cooling module. Applied technology takes benefits from two very attractive heat removal techniques. When jets are impinging on the surface, they have a very high kinetic energy at the stagnation point, also in microchannels boundary layer is very thin allowing to obtain very high heat fluxes. Main objective of this paper...
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Modeling of Passive and Forced Convection Heat Transfer in Channels with Rib Turbulators
PublikacjaThe main goal of the research presented in this paper was the experimental and numerical analysis of heat enhancement and aerodynamic phenomena during air flow in a channel equipped with flow turbulators in the form of properly configured ribs. The use of ribs intensifies the heat transfer and at the same time increases not only the flow resistance but also the energy costs. Therefore, designing modern heat exchangers with optimal...
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Parametric study of fluid flow and heat transfer over louvered fins of air heat pump evaporator
PublikacjaTwo-dimensional numerical investigations of the fluid flow and heat transfer have been carried out for the laminar flow of the louvered fin-plate heat exchanger, designed to work as an air-source heat pump evap- orator. The transferred heat and the pressure drop predicted by simulation have been compared with the corresponding experimental data taken from the literature. Two dimensional analyses of the louvered fins with varying...
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Turbulence model evaluation for numerical modelling of turbulent flow and heat transfer of nanofluids
PublikacjaIn 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...
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Numerical investigation of conjugate heat transfer in the presence of two fluid separated by a rigid wall
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Study of free convective heat transfer from horizontal conic.
PublikacjaPrzedstawiono teoretyczne rozważania i badania eksperymentalne konwekcji swobodnej od izotermicznej powierzchni poziomego stożka w przestrzeni nieograniczonej. Rozwiązanie przeprowadzono dla wprowadzonego krzywoliniowego układu współrzędnych, opartego na krzywej linii prądu wokół powierzchni stożkowej.
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Free Convection Heat Transfer from Horizontal Cylinders
PublikacjaThe results of experimental investigation of free convection heat transfer in a rectangular container are presented. The ability of the commonly accepted correlation equations to reproduce present experimental data was tested as well. It was assumed that the examined geometry fulfils the requirement of no-interaction between heated cylinder and bounded surfaces. In order to check this assumption recently published correlation equations...
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Selected problems of heat and mass transfer
Kursy Online -
Selected problems of heat and mass transfer
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Cattaneo–Christov heat flow model for copper–water nanofluid heat transfer under Marangoni convection and slip conditions
PublikacjaThis report is devoted to the study of the flow of MHD nanofluids through a vertical porous plate with a temperature-dependent surface tension using the Cattaneo–Christov heat flow model. The energy equation was formulated using the Cattaneo–Christov heat flux model instead of Fourier’s law of heat conduction. The Tiwari–Das model was used to take into account the concentration of nanoparticles when constructing the momentum equation....
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Heat and mass transfer in lack of gravity
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Heat and mass transfer in lack of gravity
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Heat Transfer in Adsorption Chillers with Fluidized Beds of Silica Gel, Zeolite, and Carbon Nanotubes
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Effect of the inclination angle of the condenser on the heat transfer coefficient value – experimental study
PublikacjaWhen considering problem of the condensation of the refrigerant in a flow inside channel, one needs to pay attention to the shape of its cross-section, the hydraulic diameter, the channel length as well as the orientation of the channel axis in space (horizontal, vertical, inclined). This paper presents an experimental study concerning the effect of the inclination angle of the condenser with a single coil pipe on the heat transfer...
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An experimental investigation on the effect of new continuous core-baffle geometry on the mixed convection heat transfer in shell and coil heat exchanger
PublikacjaIn the article, the authors presented the influence of continuous core-baffle geometry at mixed convection heat transfer in shell and coil heat exchanger. Experiments were carried out for a large power range, i.e. from 100W to 1200W and mass flow rates ranging from 0.01 kg/s to 0.025 kg/s. During the experiments, the mass flow rate of cooling water, the temperature of water at the inlet and outlet as well as the wall temperature...
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Heat transfer enhancement of modular thermal energy storage unit for reversible heat pump cooperation
PublikacjaThe following article presents experimental comparison research on a hexagonal shelland-tube latent thermal energy storage (TES). Such shape of a shell was deliberately chosen instead of a cylindrical one due to its high modularity and with intent for future applications in automobiles (EV and PHEV) air conditioning systems (HVAC). Two geometries of helical coils, acting as tubes, were studied in this article. One was a simple...
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Characterisation of the interfacial heat transfer coefficient in hot stamping of titanium alloys
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Janusz Cieśliński prof. dr hab. inż.
OsobyUrodził się 15 kwietnia 1954 r. w Słupsku. Jest absolwentem Wydziału Budowy Maszyn Politechniki Gdańskiej (1978), z którą związał całe swoje życie zawodowe. W 1986 r. obronił doktorat, w 1997 r. – habilitację, w 2006 r. – uzyskał tytuł profesora. Pełnił funkcje prodziekana ds. nauki Wydziału Mechanicznego przez dwie kadencje (2002–2008) oraz kierownika: Katedry Maszyn Przemysłu Spożywczego (2002–2006), Katedry Ekoinżynierii i...
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An improved method for flow boiling heat transfer with account of the reduced pressure effect
PublikacjaIn the paper are presented the results using the authors own model to predict heat transfer coefficient during flow boiling. The model has been tested against a large selection of experimental data to investigate the sensitivity of the in-house developed model. In the work are presented the results of calculations obtained using the semi-empirical model on selected experimental flow boiling data of the refrigerants: R134a, R1234yf,...
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Numerical study of turbulent flow and heat transfer of nanofluids in pipes
PublikacjaIn 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...
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Heat Transfer-Asian Research
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Frontiers in Heat and Mass Transfer
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Interfacial Phenomena and Heat Transfer
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Metal-organic frameworks (MOF) based heat transfer: A comprehensive review
PublikacjaHigher than a standard level, the humidity provides a suitable environment for the pathogenic microorganisms to grow and increases energy consumption for cooling, increasing greenhouse gas emissions. Desiccant air-conditioning (DAC) is an effective method to reduce humidity and energy simultaneously. Conventional desiccants are not suitable for use as a desiccant in building air conditioners, mainly because of high regeneration...
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Heat Transfer
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Prediction of flow boiling heat transfer coefficient for carbon dioxide in minichannels and conventional channels
PublikacjaIn the paper presented are the results of calculations using authors own model to predict heat transfer coefficient during flow boiling of carbon dioxide. The experimental data from various resea rches were collected. Calculations were conducted for a full range of quality variation and a wide range of mass velocity. The aim of the study was to test the sensitivity of the in-house model. The results show the importance of taking into...
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Experimental Investigation of Free Convection Heat Transfer from Horizontal Cylinder to Nanofluids
PublikacjaThe 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....
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A new method for determination of flow boiling heat transfer coefficient in conventional diameter channels and minichannels
PublikacjaW pracy przedstawiono rozważania związane z modelowaniem wrzenia w przepływie w kanałach o średnicach konwencjonalnych, małych i minikanałach. Przedstawiono przegląd podejść do modelowania wymiany ciepła i w tym świetle przedstawiono oryginalne podejście autora. W przeciwieństwie do innych podejść metoda autora ma zastosowanie zarówno do kanałów o średnicach konwencjonalnych i minikanałach. Przedstawiono zadowalające porównania...
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Promising Nanoparticle-Based Heat Transfer Fluids—Environmental and Techno-Economic Analysis Compared to Conventional Fluids
PublikacjaProviding optimal operating conditions is one of the major challenges for effective heating or cooling systems. Moreover, proper adjustment of the heat transfer fluid is also important from the viewpoint of the correct operation, maintenance, and cost efficiency of these systems. Therefore, in this paper, a detailed review of recent work on the subject of conventional and novel heat transfer fluid applications is presented. Particular...
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A semi-empirical model for flow boiling heat transfer with account of the reduced pressure effect
PublikacjaIn the present study the attention was focused on the influence of reduced pressure on the predictions of heat transfer during flow boiling at the extensive range of pressures. The results of calculations were to test the sensitivity of the in-house flow boiling model with respect to the selection of the appropriate two-phase flow multiplier, which is one of the distinctive elements of that model. For this purpose a few two-phase...
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Inverse heat transfer problem solution of sounding rocket using moving window optimization
PublikacjaAn Inverse Heat Transfer Problem is solved for a sounding rocket module given its geometry and measured temperature profile. The solution is obtained via moving window optimization, a technique for solving inverse dynamics. An analysis is performed to modify the method to avoid oscillatory behavior of the resulting heat flux profile. The method parameters are tuned in relation to characteristic phases of the flight. Results are...
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Heat transfer intensification by jet impingement – numerical analysis using RANS approach
PublikacjaJet impingement is a method of the heat transfer enhancement applied in the engineering systems. The idea is to generate fast-flow fluid jet which impinge on the heated (or cooled) surface, causing significantly higher heat transfer rate. Although some flat surface jet impingement cases are described in the literature, the validated data is still limited. The reason is coming from the fact, that these flows are hydrodynamically...
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Analysis of Organic Rankine Cycle efficiency and vapor generator heat transfer surface in function of the reduced pressure
PublikacjaIn the paper presented is analysis of the influence of reduced pressure on efficiency and heat transfer area of vapor generator of Organic Rankine Cycle (ORC) in case of subcritical and supercritical parameters of operation. Compared are two cases of subcritical and supercritical ORC featuring a similar arrangement of heat source supply and heat removal, that is featuring the same temperatures of working fluid before the turbine,...
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Influence of nanoparticle concentration on convective heat transfer of water-Al2O3 nanofluids inside horizontal tubes
PublikacjaNanofluids came to be seen as a new generation of coolants, especially in single-phase systems. Conducted experiments indicate that the increase in thermal conductivity is not the only reason for the intensification of heat transfer when using nanofluids. Preliminary results of the experimental investigation of the forced convection heat transfer of water-Al2O3 nanofluids inside stainless steel tube with 8 mm internal diameter...
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Experimental study of boiling heat transfer in the stagnation point of water microjet
PublikacjaIn the paper presented is a comparison of computational model with experimental data. Numerical model of liquid film with phase change in the stagnation zone due to impingement of the microjet is more widely presented in authors previous work. The radius on which theevaporation process is taking place can be determined from the energy balance on the element of the plate. That radius has also been confirmed experimentally in the...
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[IMe] Selected problems of heat and mass transfer
Kursy Online{mlang pl} Dyscyplina: Inżynieria mechaniczna (PG + IMP PAN) Zajęcia obowiązkowe Prowadzący: prof. dr. hab. inż. Dariusz Mikielewicz Liczba godzin: 20 h Forma zajęć: wykład {mlang} {mlang en} Discipline: mechanical engineering (GUT + IFFM PAS) Obligatory course Academic teacher: prof. dr. hab. inż. Dariusz Mikielewicz Total hours of training: 20 teaching hours Course type: lecture {mlang}
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Pressure drop and heat transfer during boiling and condensation at subcritical region
PublikacjaMost of the data presented in the literature relate to saturation temperatures in the range - 20°C to 40°C due to the application in refrigeration technology. There is necessity to extend databases to higher values of saturation temperature due to new applications such as Organic Rankine Cycle and high temperature heat pumps. Only few papers contain data for high reduced pressure for low boiling point liquids. This paper focus...
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Impact of Temperature and Nanoparticle Concentration on Turbulent Forced Convective Heat Transfer of Nanofluids
PublikacjaTheoretical 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...
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Impact of the inclination angle of the condenser with refrigerant R410A on heat transfer coefficient – experimental study
PublikacjaIn the paper the authors present results of a laboratory test of the condenser with refrigerant R410A. The effect of the inclination of this condenser on the heat transfer coefficient value has been considered. The test has proved that there is an optimal inclination angle of the condenser which gives maximal value of this coefficient.
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Comparison of heat transfer characteristics in surface cooling using microjets with water, ethanol and HFE7100 as test fluids
PublikacjaAccurate 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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The effect of reduced pressure on carbon dioxide flow boiling heat transfer in minichannels
Publikacja. In the paper presented are the results of the study on the effect of reduced pressure on flow boiling heat transfer data in minichannels as well as conventional ones. That effect renders that most of heat transfer correlations fail to return appropriate results of predictions. Mostly they have been developed for the reduced pressures from the range 0.1-0.3. The special correction has been postulated to the in-house model of flow...
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Boiling heat transfer performance of the thermosiphon heat exchanger
PublikacjaPrzedstawiono 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.
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Heat Transfer of the Multicolor-Laser-Sources-Irradiated Nanoparticles in Reference to Thermal Processes
PublikacjaUnlike the standard materials, metallic nanoparticles offer enhancing the heat convertion rate which implies the maximum and average temperature boost significantly in the considered system. The work’s purpose is to examine heat transfer in the metallic nanoparticles which have been deposited on a glassy substrate, enabling the nanostructures thermoablation. Furthermore, the functionalized substrate is irradiated with multicolor-laser-sources,...
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Numerical analysis of the two‐phase steam‐air heat transfer flow induced in smooth and corrugated channel using the VOF model
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Experimental investigation of M-shape heat transfer coefficient distribution of R123 flow boiling in small-diameter tubes
PublikacjaW publikacji przedstawiono wyniki badań wrzenia czynnika R123 w srebrnych rurkach o małych średnicach (średnice wewnętrzne wynosiły odpowiednio 1.15 mm i 2.3 mm). Badania przeprowadzono w szerokim zakresie stopnia suchości pary (0.01-0.9), gęstości strumienia masy (650-3000 kg/(m2s)) oraz gęstości strumienia ciepła (40-80 kW/m2). W badaniach wykazano, że istnieją dwa lokalne maksima współczynnika przejmowania ciepła w jego profilu...
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A common method for calculation of flow boiling and flow condensation heat transfer coefficients in minichannels with account of nonadiabatic effects
PublikacjaW pracy przedstawiono metodę ogólną wyznaczania współczynników przejmowania ciepła podczas wrzenia w przepływie i kondensacji w przepływie w minikanałach z uwzględnieniem efektu nieadiabatycznego. Uwzględnia ona wpływ modyfikacji naprężeń stycznych na granicy ciecz-para na wymianę ciepła.