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Wyszukujesz frazę "Heat Transfer" wg kryterium: Temat


Wyświetlanie 1-14 z 14
Tytuł:
The effect of regulating elements on convective heat transfer along shaped heat exchange surfaces
Autorzy:
Cernecky, J.
Koniar, J.
Brodnianska, Z.
Powiązania:
https://bibliotekanauki.pl/articles/185818.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heat transfer
convection
holographic interferometry
przenikanie ciepła
konwekcja
interferometria holograficzna
Opis:
The paper deals with a study of the effect of regulating elements on local values of heat transfer coefficients along shaped heat exchange surfaces with forced air convection. The use of combined methods of heat transfer intensification, i.e. a combination of regulating elements with appropriately shaped heat exchange areas seems to be highly effective. The study focused on the analysis of local values of heat transfer coefficients in indicated cuts, in distances expressed as a ratio x/s for 0; 0.33; 0.66 and 1. As can be seen from our findings, in given conditions the regulating elements can increase the values of local heat transfer coefficients along shaped heat exchange surfaces. An optical method of holographic interferometry was used for the experimental research into temperature fields in the vicinity of heat exchange surfaces. The obtained values correspond very well with those of local heat transfer coefficients [alfa]x, recorded in a CFD simulation.
Źródło:
Chemical and Process Engineering; 2013, 34, 1; 5-16
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Methodology of heat transfer and flow resistance measurement for matrices of rotating regenerative heat exchangers
Autorzy:
Butrymowicz, D.
Karwacki, J.
Kwidziński, R.
Śmierciew, K.
Gagan, J.
Przybyliński, T.
Skiepko, T.
Łapin, M.
Powiązania:
https://bibliotekanauki.pl/articles/185740.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heat transfer
single blow technique
rotating heat exchanger
regenerator
przenikania ciepła
wymiennik ciepła
Opis:
The theoretical basis for the indirect measurement approach of mean heat transfer coefficient for the packed bed based on the modified single blow technique was presented and discussed in the paper. The methodology of this measurement approach dedicated to the matrix of the rotating regenerative gas heater was discussed in detail. The testing stand consisted of a dedicated experimental tunnel with auxiliary equipment and a measurement system are presented. Selected experimental results are presented and discussed for selected types of matrices of regenerative air preheaters for the wide range of Reynolds number of gas. The agreement between the theoretically predicted and measured temperature profiles was demonstrated. The exemplary dimensionless relationships between Colburn heat transfer factor, Darcy flow resistance factor and Reynolds number were presented for the investigated matrices of the regenerative gas heater.
Źródło:
Chemical and Process Engineering; 2016, 37, 3; 341-358
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Intensification of heat transfer between heat exchange surfaces at low RE values
Autorzy:
Cernecky, J.
Brodnianska, Z.
Koniar, J.
Powiązania:
https://bibliotekanauki.pl/articles/184897.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heat transfer
heat exchange surface
Colburn j-factor
interferometry
przenikanie ciepła
powierzchnia wymiany ciepła
interferometria
Opis:
This contribution deals with the heat transfer parameters and pressure losses in heat exchange sets with six geometrical arrangements at low Re values (Re from 476 to 2926). Geometrical arrangements were characterised by the h/H ratio ranging from 0.2 to 1.0. The experiments used the holographic interferometry method in real time. This method enables visible and quantitative evaluations of images of temperature fields in the examined heat exchange. These images are used to determine the local and mean heat transfer parameters. The obtained data were used to determine the Colburn j-factor and the friction coefficient f. The measured values show that by using the profiled heat exchange surfaces and inserting regulating tubes, an intensification of heat transfer (increase of Num, and/or j) was achieved. However, pressure losses recorded a significant increase (increase of f).
Źródło:
Chemical and Process Engineering; 2015, 36, 3; 331-344
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Maximization of generated electric power in the TEG module at various heat exchange conditions
Autorzy:
Poświata, Artur
Gierycz, Paweł
Powiązania:
https://bibliotekanauki.pl/articles/2034053.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
optimization
thermoelectric
TEG
heat transfer
electric power
optymalizacja
termoelektryczny
wymiana ciepła
energia elektryczna
Opis:
Thermoelectric generators using the Seebeck effect to generate electricity are increasingly used in various areas of human activity, especially in cases where a cheap high-temperature heat source is available. Despite many advantages, TEG generators have one major disadvantage: very low efficiency of heat conversion into electrical power which strongly depends on the applied load resistance. There is a maximum of generated power between the short and the open circuit in which it is zero. That is why optimization of TEG modules is particularly important. In this paper a method of maximization of generated power in a single TEG module is presented for two cases. The first case concerns a problem with fixed heat flux flow into the hot side of the module whereas the second one concerns a problem with fixed heat transfer parameters in hot heat exchanger i.e. supply gas temperature and heat transfer coefficient. A number of optimization results performed for various values of these parameters are presented and discussed.
Źródło:
Chemical and Process Engineering; 2020, 41, 4; 277-291
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Computational Fluid Dynamics and Experimental Studies of a New Mixing Element in a Static Mixer as a Heat Exchanger
Autorzy:
Konopacki, M.
Kordas, M.
Fijałkowski, K.
Rakoczy, R.
Powiązania:
https://bibliotekanauki.pl/articles/185462.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
mixing
heat transfer process
static mixer
CFD
process intensification
mieszanie
proces przenikania ciepła
mieszalnik statyczny
intensyfikacja
Opis:
The main aim of this work is to study the thermal efficiency of a new type of a static mixer and to analyse the flow and temperature patterns and heat transfer efficiency. The measurements were carried out for the static mixer equipped with a new mixing insert. The heat transfer enhancement was determined by measuring the temperature profiles on each side of the heating pipe as well as the temperature field inside the static mixer. All experiments were carried out with varying operating parameters for four liquids: water, glycerol, transformer oil and an aqueous solution of molasses. Numerical CFD simulations were carried out using the two-equation turbulence k-ω model, provided by ANSYS Workbench 14.5 software. The proposed CFD model was validated by comparing the predicted numerical results against experimental thermal database obtained from the investigations. Local and global convective heat transfer coefficients and Nusselt numbers were detrmined. The relationship between heat transfer process and hydrodynamics in the static mixer was also presented. Moreover, a comparison of the thermal performance between the tested static mixer and a conventional empty tube was carried out. The relative enhancement of heat transfer was characterised by the rate of relative heat transfer intensification.
Źródło:
Chemical and Process Engineering; 2015, 36, 1; 59-72
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Principles of modelling of slinky-coil groundheat exchangers
Autorzy:
Larwa, Barbara
Kupiec, Krzysztof
Powiązania:
https://bibliotekanauki.pl/articles/185834.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
slinky-coil ground heat exchangers
analytical model of heat transfer
gruntowe wymienniki ciepła typu slinky-coil
analityczny model wymiany ciepła
Opis:
The paper presents analytical relationships based on the theory of Green’s functions. The relationshipsrefer to instantaneous and continuous as well as point and ring heat sources which are discussed. Therelationship relating to continuous ring source is the basis for modelling and designing of spiral groundheat exchangers. Heat transfer in the infinite and semi-infinite body was considered. In the latter case,the image method was discussed. Using the results of measurements regarding heat transfer in theground with a heat exchanger in the form of a single coil installed, a comparison of calculated groundtemperatures with measured values was presented.
Źródło:
Chemical and Process Engineering; 2020, 41, 2; 81-93
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
CFD simulations of heat transfer in internally helically ribbed tubes
Autorzy:
Majewski, K.
Grądziel, S.
Powiązania:
https://bibliotekanauki.pl/articles/952677.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heat transfer coefficient
helically internally ribbed tube
power boiler
współczynnik przenikania ciepła
rura spiralna wewnątrz prążkowana
kocioł
Opis:
Heating surfaces in power boilers are exposed to very high hea t flux. For evaporator protection against overheating, internally helically ribbed tubes are used. The intensification of the heat transfer and the maintenance of the thin water layer in the intercostal space, using ribbed tubes, enables better protection of the power boiler evaporator than smooth pipes. Extended inner surface changes flow and thermal conditions by influencing the linear pressure drop and heat transfer coefficient. This paper presents equations that are used to determine the heat transfer coefficient. The results of total heat transfer, obtained from CFD simulations, for two types of internally ribbed and plain tubes are also presented.
Źródło:
Chemical and Process Engineering; 2016, 37, 2; 251-260
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Large Eddy Simulation of turbulent flowand heat transfer in a Kenics static mixer
Autorzy:
Murasiewicz, Halina
Zakrzewska, Barbara
Powiązania:
https://bibliotekanauki.pl/articles/185383.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heat transfer
turbulent flow
Large Eddy Simulation
CFD
static mixer
wymiana ciepła
przepływ turbulentny
Symulacja dużych wirów
mikser
Opis:
CFD modelling of momentum and heat transfer using the Large Eddy Simulation (LES) approach hasbeen presented for a Kenics static mixer. The simulations were performed with the commercial codeANSYS Fluent 15 for turbulent flow of three values of Reynoldsnumber,Re=5 000, 10 000 and18 000. The numerical modelling began in the RANS model, where standardk−εturbulence modeland wall functions were used. Then the LES iterations started from the initial velocity and temperaturefields obtained in RANS. In LES, the Smagorinsky–Lilly modelwas used for the sub-grid scalefluctuations along with wall functions for prediction of flowand heat transfer in the near-wall region.The performed numerical study in a Kenics static mixer resulted in highly fluctuating fields of bothvelocity and temperature. Simulation results were presented and analysed in the form of velocity andtemperature contours. In addition, the surface-averaged heat transfer coefficient values for the wholeinsert length were computed and compared with the literature experimental data. Good compliance ofthe LES simulation results with the experimental correlation was obtained.
Źródło:
Chemical and Process Engineering; 2019, 40, 1; 87--99
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
CFD Analysis of Heat Transfer in a Microtubular Solid Oxide Fuel Cell Stack
Autorzy:
Pianko-Oprych, P.
Kasilova, E.
Jaworski, Z.
Powiązania:
https://bibliotekanauki.pl/articles/185553.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
przenikanie ciepła
strata ciepła
rozkład temperatur
microtubular Solid Oxide Fuel Cell stack
heat transfer
heat losses
temperature distributions
computational fluid dynamics (CFD)
Opis:
The aim of this work was to achieve a deeper understanding of the heat transfer in a microtubular Solid Oxide Fuel Cell (mSOFC) stack based on the results obtained by means of a Computational Fluid Dynamics tool. Stack performance predictions were based on simulations for a 16 anodesupported mSOFCs sub-stack, which was a component of the overall stack containing 64 fuel cells. The emphasis of the paper was put on steadystate modelling, which enabled identification of heat transfer between the fuel cells and air flow cooling the stack and estimation of the influence of stack heat losses. Analysis of processes for different heat losses and the impact of the mSOFC reaction heat flux profile on the temperature distribution in the mSOFC stack were carried out. Both radiative and convective heat transfer were taken into account in the analysis. Two different levels of the inlet air velocity and three different values of the heat losses were considered. Good agreement of the CFD model results with experimental data allowed to predict the operation trends, which will be a reliable tool for optimisation of the working setup and ensure sufficient cooling of the mSOFC stack.
Źródło:
Chemical and Process Engineering; 2014, 35, 3; 293-304
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enhancement of heat transfer in helical coil heat exchangers using nano-fluids
Autorzy:
Parveez, Malik
Hanief, Mohammad
Powiązania:
https://bibliotekanauki.pl/articles/2173429.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
nano-fluids
heat transfer
Nusselt number
Prandtl number
volume fraction
nanopłyny
przenoszenie ciepła
liczba Nusselta
liczba Prandtla
ułamek objętościowy
Opis:
Investigation for heat transfer behaviour of Al2O3 and CuO nano-fluid in helical coil heat exchangers was carried out in this study. The thermo-physical properties of the fluids have temperature dependent nature. The main emphasis was to depict the influence of nano-particle concentration by volume on the characteristics of temperature, rate of heat transfer and heat transfer coefficients (convective). In order to enhance efficiency, density and thermal conductivity are considered to be the most important variables. In comparison to water and for equal flow rate, the rate of heat transfer of nano-fluid increases conspicuously. Efficiency of the helical coil heat exchanger increased by 38.80%.
Źródło:
Chemical and Process Engineering; 2022, 43, 2; 279--283
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of temperature distribution in the ground
Autorzy:
Larwa, Barbara
Kupiec, Krzysztof
Powiązania:
https://bibliotekanauki.pl/articles/185407.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heat transfer
temperature distribution in the ground
heat balance at the ground
surface
wymiana ciepła
rozkład temperatury w ziemi
bilans cieplny na ziemi
powierzchnia
Opis:
Knowledge of the temperature distribution in subsurface layers of the ground is important in thedesign, modelling and exploitation of ground heat exchangers. In this work a mathematical model ofheat transfer in the ground is presented. The model is based on the solution of the equation of transientheat transfer in a semi-infinite medium. In the boundary condition on the surface of the groundradiation fluxes (short- and long-wave), convective heat flux and evaporative heat flux are taken intoaccount. Based on the developed model, calculations were carried out to determine the impact ofclimatic conditions and the physical properties of the ground on the parameters of the Carslaw-Jeagerequation. Example results of calculated yearly courses of the daily average temperature of the surfaceof the ground and the amount of particular heat fluxes on the ground surface are presented. Thecompatibility of ground temperature measurements at different depths with the results obtained fromthe Carslaw–Jaeger equation is evaluated. It was found thatthe temperature distribution in the groundand its variability in time can be calculated with good accuracy.
Źródło:
Chemical and Process Engineering; 2019, 40, 1; 123--137
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bed-to-wall heat ransfer in a supercritical circulating fluidised bed boiler
Autorzy:
Błaszczuk, A.
Nowak, W.
Jagodzik, S.
Powiązania:
https://bibliotekanauki.pl/articles/185814.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
współczynnik przenoszenia ciepła
gęstość zawiesiny
temperatura pieca
kocioł CFB w stanie nadkrytycznym
heat transfer coefficient
suspension density
furnace temperature
circulating fluidised bed
supercritical CFB boiler
cluster renewal approach
Opis:
The purpose of this work is to find a correlation for heat transfer to walls in a 1296 t/h supercritical circulating fluidised bed (CFB) boiler. The effect of bed-to-wall heat transfer coefficient in a long active heat transfer surface was discussed, excluding the radiation component. Experiments for four different unit loads (i.e. 100% MCR, 80% MCR, 60% MCR and 40% MCR) were conducted at a constant excess air ratio and high level of bed pressure (ca. 6 kPa) in each test run. The empirical correlation of the heat transfer coefficient in a large-scale CFB boiler was mainly determined by two key operating parameters, suspension density and bed temperature. Furthermore, data processing was used in order to develop empirical correlation ranges between 3.05 to 5.35 m x s-1 for gas superficial velocity, 0.25 to 0.51 for the ratio of the secondary to the primary air, 1028 to 1137K for bed temperature inside the furnace chamber of a commercial CFB boiler, and 1.20 to 553 kg x m-3 for suspension density. The suspension density was specified on the base of pressure measurements inside the boiler’s combustion chamber using pressure sensors. Pressure measurements were collected at the measuring ports situated on the front wall of the combustion chamber. The obtained correlation of the heat transfer coefficient is in agreement with the data obtained from typical industrial CFB boilers.
Źródło:
Chemical and Process Engineering; 2014, 35, 2; 191-204
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Methods of Thermal Calculations for a Condensing Waste-Heat Exchanger
Autorzy:
Rączka, P.
Wójs, K.
Powiązania:
https://bibliotekanauki.pl/articles/185363.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
odzysk ciepła kondensacji
obliczanie transferu ciepła i masy
wymiennik ciepła
ciepło odpadowe
condensation heat recovery
calculation of heat and mass transfer
heat exchanger
waste heat
Opis:
The paper presents the algorithms for a flue gas/water waste-heat exchanger with and without condensation of water vapour contained in flue gas with experimental validation of theoretical results. The algorithms were used for calculations of the area of a heat exchanger using waste heat from a pulverised brown coal fired steam boiler operating in a power unit with a capacity of 900 MWe. In calculation of the condensing part, the calculation results obtained with two algorithms were compared (Colburn-Hobler and VDI algorithms). The VDI algorithm allowed to take into account the condensation of water vapour for flue gas temperatures above the temperature of the water dew point. Thanks to this, it was possible to calculate more accurately the required heat transfer area, which resulted in its reduction by 19 %. In addition, the influence of the mass transfer on the heat transfer area was taken into account, which contributed to a further reduction in the calculated size of the heat exchanger - in total by 28% as compared with the Colburn-Hobler algorithm. The presented VDI algorithm was used to design a 312 kW pilot-scale condensing heat exchanger installed in PGE Belchatow power plant. Obtained experimental results are in a good agreement with calculated values.
Źródło:
Chemical and Process Engineering; 2014, 35, 4; 447-461
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Agitation efficiency of different physical systems
Autorzy:
Karcz, Joanna
Szoplik, Jolanta
Major-Godlewska, Marta
Cudak, Magdalena
Kiełbus-Rąpała, Anna
Powiązania:
https://bibliotekanauki.pl/articles/2086781.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
agitated vessel
power consumption
mixing time
heat and mass transfer
gas hold-up
wzburzony statek
pobór energii
czas mieszania
wymiana ciepła i masy
zatrzymywanie gazu
Opis:
Efficiency of agitation was considered for different physical systems on the basis of our own experimental studies on homogenisation, heat and mass transfer as well as gas hold-up. Measurements were performed for different physical systems: Newtonian liquids of low and higher viscosity, pseudoplastic liquid, gas–liquid and gas–solid–liquid systems agitated in vessels of the working volume from 0.02 m3 to 0.2 m3. Agitated vessels of different design were equipped with a high-speed impeller (10 impellers were tested). Comparative analysis of the experimental results proved that energy inputs (power consumption) should be taken into account as a very important factor when agitation efficiency is evaluated in order to select a proper type of equipment. When this factor is neglected in the analysis, intensification of the process can be estimated only.
Źródło:
Chemical and Process Engineering; 2021, 42, 2; 139--156
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-14 z 14

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