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Wyświetlanie 1-15 z 56
Tytuł:
Experimental and theoretical studies on heat and mass transfer in anti-condensation coatings
Autorzy:
Grzebielec, A.
Rusowicz, A.
Powiązania:
https://bibliotekanauki.pl/articles/240246.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
powłoka antykondensacyjna
wymiana ciepła
wymiana masy
anti-condensation coating
heat transfer
mass transfer
Opis:
Anti-condensation coatings are widely used in refrigeration, air conditioning and ships technology. They can store a certain amount of water in its own volume, and then return it back in favorable conditions. Anti-condensation coatings are used also to protect structures from the moisture. This paper presents the results of experimental research on heat and mass transfer in an anti-condensation coating under natural and forced convection. Experimental results are obtained for horizontal and inclined plates. Experimental data are compared with different models of computation.
Źródło:
Archives of Thermodynamics; 2011, 32, 3; 45-56
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal and economic investigation of straight and U-bend double tube heat exchanger with coiled wire turbulator
Autorzy:
Andrzejczyk, Rafał
Muszyński, Tomasz
Powiązania:
https://bibliotekanauki.pl/articles/239983.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
NTU – number of transfer units
heat exchanger
heat transfer coefficient
energy efficiency
wymiennik ciepła
współczynnik wnikania ciepła
efektywność energetyczna
metoda NTU
Opis:
Experimental research has been carried out for four individual heat exchanger constructions, i.e., plain double tube, turbulized double tube, plain U-bend and U-bend with turbulator. Tests were made for the water-water system. The study covered a wide measuring range, i.e., Re = 800–9000 – on the shell side, for a constant cold water temperature of 9°C and hot water of 50°C. The heat exchangers were made from copper tubes with external diameter of 10 mm and 18 mm respectively and wall thickness of 1 mm. The helicoidal vortex generator was made from brass wire with a diameter of 2.4 mm, coil diameter of 13 mm and pitch of 11 mm. For these geometries, the values of pressure drop, heat flux and heat transfer coefficient were determined. Wire coil turbulator increased the heat transfer coefficient (HTC) over 100% and pressure drop up by 100%. The comparison of heat transfer efficiency was performed based on the number of transfer units-effectivenes (NTU-ε) method. The modified construction achieved a similar efficiency. Economic analysis of wire coil turbulator was made to validate its use in the system. It showed that a coiled wire turbulator can greatly decrease the investment cost of the double tube heat exchanger while maintaining transferred heat at a constant level.
Źródło:
Archives of Thermodynamics; 2019, 40, 2; 17-33
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Verification of heat flux and temperature calculation on the control rod outer surface
Autorzy:
Taler, J.
Cebula, A.
Powiązania:
https://bibliotekanauki.pl/articles/240728.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
strumień ciepła
temperatura
wymiana ciepła
metoda inwersji
CFD
heat flux
heat transfer
inverse method
temperature
Opis:
The paper presents heat transfer calculation results concerning a control rod of Forsmark Nuclear Power Plant (NPP). The part of the control rod, which is the object of interest, is surrounded by a mixing region of hot and cold flows and, as a consequence, is subjected to thermal fluctuations. The paper describes a numerical test which validates the method based on the solution of the inverse heat conduction problem (IHCP). The comparison of the results achieved by two methods, computational fluid dynamics (CFD) simulations and IHCP, including a description of the IHCP method used in the calculation process, shows a very good agreement between the methods.
Źródło:
Archives of Thermodynamics; 2011, 32, 3; 157-173
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigations on heat and momentum transfer in CuO-water nanofluid
Autorzy:
Dzido, G.
Drzazga, M.
Lemanowicz, M.
Gierczycki, A. T.
Powiązania:
https://bibliotekanauki.pl/articles/240561.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
nanofluids
fluid mechanics
heat transfer
nanopłyny
mechanika płynów
przenikanie ciepła
Opis:
This paper presents results of investigations on the application of CuO-water nanofluids for intensification of convective heat transfer. Performance of nanofluids with 2.2 and 4.0 vol.% CuO NPs (nanoparticles) content were examined with regard to heat transfer coefficient and pressure losses in case of turbulent flow in a tube. Negligible impact of examined nanofluid on heat transfer improvement was found. Moreover, measured pressure losses significantly exceeded those determined for primary base liquid. The observations showed that application of nanofluid for heat transfer intensification with a relatively high solid load in the examined flow range is rather controversial.
Źródło:
Archives of Thermodynamics; 2015, 36, 2; 49-59
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental investigation of single-phase microjet cooling of microelectronics
Autorzy:
Rusowicz, A.
Leszczyński, M.
Grzebielec, A.
Laskowski, R.
Powiązania:
https://bibliotekanauki.pl/articles/240614.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
cooling
heat transfer
microjets
microprocessor
chłodzenie
wymiana ciepła
mikrojety
mikroprocesor
Opis:
Development of electronics, which aims to improve the functionality of electronic devices, aims at increasing the packing of transistors in a chip and boosting clock speed (the number of elementary operations per second). While pursuing this objective, one encounters the growing problem of thermal nature. Each switching of the logic state at the elementary level of an integrated circuit is associated with the generation of heat. Due to a large number of transistors and high clock speeds, higher heat flux is emitted by the microprocessor to a level where the component needs to be intensively cooled, or otherwise it will become overheated. This paper presents the cooling of microelectronic components using microjets.
Źródło:
Archives of Thermodynamics; 2015, 36, 3; 139-147
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental research on the resistojet thruster heater
Autorzy:
Kindracki, J.
Mężyk, J.
Paszkiewicz, P.
Powiązania:
https://bibliotekanauki.pl/articles/240186.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
resistojet thruster
electric heater
heat transfer
grzałka elektryczna
transport ciepła
Opis:
The paper describes experimental research on a resistojet type rocket thruster which was built as an actuator in the Attitude Control System of a model space robotic platform. A key element of the thruster is the heater responsible for increasing the temperature of the working medium in the thruster chamber and hence the specific impulse. This parameter describes the performance of the thruster, increases providing – for lower propellant consumption – the same propulsion effect (thrust). A high performance thruster means either total launch mass can be reduced or satellite lifetime increased, which are key commercial factors. During the first phase of the project, 7 different heating chamber designs were examined. The heater is made of resistive wire with resistivity of 9Ω/m. Power is delivered by a dedicated supply system based on supercapacitors with output voltage regulated in the range of 20–70 V. The experimental phase was followed by designing the chamber geometry and the heating element able to deliver both: maximum increase of gas temperature and minimum construction dimensions. Experiments with the optimal design show an increase in temperature of the working gas (air) by about 300 °C giving a 40% increase in specific impulse. The final effect of that is a 40% reduction in mass flow rate while retaining thrust at a nominal level of 1 N.
Źródło:
Archives of Thermodynamics; 2018, 39, 3; 29-43
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical analysis of the steam flow field in shell and tube heat exchanger
Autorzy:
Bartoszewicz, J.
Bogusławski, L.
Powiązania:
https://bibliotekanauki.pl/articles/240429.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heat transfer
heat exchanger
shell and tube heat exchanger
przenikanie ciepła
wymiennik ciepła
wymiennik płaszczowo-rurowy
Opis:
In the paper, the results of numerical simulations of the steam flow in a shell and tube heat exchanger are presented. The efficiency of different models of turbulence was tested. In numerical calculations the following turbulence models were used: k-ε, RNG k-ε, Wilcox k-ω, Chen-Kim k-ε, and Lam-Bremhorst k-ε. Numerical analysis of the steam flow was carried out assuming that the flow at the inlet section of the heat exchanger were divided into three parts. The angle of steam flow at inlet section was determined individually in order to obtain the best configuration of entry vanes and hence improve the heat exchanger construction. Results of numerical studies were verified experimentally for a real heat exchanger. The modification of the inlet flow direction according to theoretical considerations causes the increase of thermal power of a heat exchanger of about 14%.
Źródło:
Archives of Thermodynamics; 2016, 37, 2; 107-120
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Parametric study of fluid flow and heat transfer over louvered fins of air heat pump evaporator
Autorzy:
Muszyński, T.
Kozieł, S. M.
Powiązania:
https://bibliotekanauki.pl/articles/240658.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heat exchangers
heat transfer intensification
CFD
convection
air source heat pump
wymienniki ciepła
intensyfikacja wymiany ciepła
konwekcja
powietrzne pompy ciepła
Opis:
Two-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 evaporator. 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 geometry have been conducted. Simulations have been performed for different geometries with varying louver pitch, louver angle and different louver blade number. Constant inlet air temperature and varying velocity ranging from 2 to 8 m/s was assumed in the numerical experiments. The air-side performance is evaluated by calculating the temperature and the pressure drop ratio. Efficiency curves are obtained that can be used to select optimum louver geometry for the selected inlet parameters. A total of 363 different cases of various fin geometry for 7 different air velocities were investigated. The maximum heat transfer improvement interpreted in terms of the maximum efficiency has been obtained for the louver angle of 16° and the louver pitch of 1.35 mm. The presented results indicate that varying louver geometry might be a convenient way of enhancing performance of heat exchangers.
Źródło:
Archives of Thermodynamics; 2016, 37, 3; 45-62
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative study of flow condensation in conventional and small diameter tubes
Autorzy:
Mikielewicz, D.
Andrzejczyk, R.
Powiązania:
https://bibliotekanauki.pl/articles/240398.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
kondensacja w przepływie
minikanały
wymiana ciepła
flow condensation
heat transfer
minichannels
Opis:
Flow boiling and flow condensation are often regarded as two opposite or symmetrical phenomena. Their description however with a single correlation has yet to be suggested. In the case of flow boiling in minichannels there is mostly encountered the annular flow structure, where the bubble generation is not present. Similar picture holds for the case of inside tube condensation, where annular flow structure predominates. In such case the heat transfer coefficient is primarily dependent on the convective mechanism. In the paper a method developed earlier by the first author is applied to calculations of heat transfer coefficient for inside tube condensation. The method has been verified using experimental data from literature on several fluids in different microchannels and compared to three well established correlations for calculations of heat transfer coefficient in flow condensation. It clearly stems from the results presented here that the flow condensation can be modeled in terms of appropriately devised pressure drop.
Źródło:
Archives of Thermodynamics; 2012, 33, 2; 67-83
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental determination of correlations for mean heat transfer coefficients in plate fin and tube heat exchangers
Autorzy:
Taler, D.
Powiązania:
https://bibliotekanauki.pl/articles/239992.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
model matematyczny
przenikanie ciepła
wymiennik ciepła
heat transfer correlations
mathematical model
tube and plate fin heat exchangers
Opis:
This paper presents a numerical method for determining heat transfer coefficients in cross-flow heat exchangers with extended heat exchange surfaces. Coefficients in the correlations defining heat transfer on the liquid- and air-side were determined using a nonlinear regression method. Correlation coefficients were determined from the condition that the sum of squared liquid and air temperature differences at the heat exchanger outlet, obtained by measurements and those calculated, achieved minimum. Minimum of the sum of the squares was found using the Levenberg-Marquardt method. The uncertainty in estimated parameters was determined using the error propagation rule by Gauss. The outlet temperature of the liquid and air leaving the heat exchanger was calculated using the analytical model of the heat exchanger.
Źródło:
Archives of Thermodynamics; 2012, 33, 3; 3-26
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Unsteady natural convection in micropolar nanofluids
Autorzy:
Rup, K.
Nering, K.
Powiązania:
https://bibliotekanauki.pl/articles/240090.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
micropolar fluid
nanofluid
heat transfer enhancement
płyn mikropolarny
nanopłyn
intensyfikacja wymiany ciepła
Opis:
This paper presents the analysis of momentum, angular momentum and heat transfer during unsteady natural convection in micropolar nanofluids. Selected nanofluids treated as single phase fluids contain small particles with diameter size 10-38.4 nm. In particular three water-based nanofluids were analyzed. Volume fraction of these solutions was 6%. The first of the analyzed nanofluids contained TiO2 nanoparticles, the second one contained Al2O3 nanoparticles, and the third one the Cu nanoparticles.
Źródło:
Archives of Thermodynamics; 2014, 35, 3; 155-170
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance analyses of helical coil heat exchangers. The effect of external coil surface modification on heat exchanger effectiveness
Autorzy:
Andrzejczyk, R.
Muszyński, T.
Powiązania:
https://bibliotekanauki.pl/articles/240706.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
effectiveness
heat transfer intensification
number of transfer unit
helical coil
skuteczność
intensyfikacja wymiany ciepła
liczba jednostek przesyłowych
spirala
Opis:
The shell and coil heat exchangers are commonly used in heating, ventilation, nuclear industry, process plant, heat recovery and air conditioning systems. This type of recuperators benefits from simple construction, the low value of pressure drops and high heat transfer. In helical coil, centrifugal force is acting on the moving fluid due to the curvature of the tube results in the development. It has been long recognized that the heat transfer in the helical tube is much better than in the straight ones because of the occurrence of secondary flow in planes normal to the main flow nside the helical structure. Helical tubes show good performance in heat transfer enhancement, while the uniform curvature of spiral structure is inconvenient in pipe installation in heat exchangers. Authors have presented their own construction of shell and tube heat exchanger with intensified heat transfer. The purpose of this article is to assess the influence of the surface modification over the performance coefficient and effectiveness. The experiments have been performed for the steady-state heat transfer. Experimental data points were gathered for both laminar and turbulent flow, both for co current- and countercurrent flow arrangement. To find optimal heat transfer intensification on the shell-side authors applied the number of transfer units analysis.
Źródło:
Archives of Thermodynamics; 2016, 37, 4; 137-159
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurement of heat flux density and heat transfer coefficient
Autorzy:
Taler, D.
Taler, J.
Grądziel, S.
Powiązania:
https://bibliotekanauki.pl/articles/240288.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
pomiar temperatury
strumień ciepła
współczynnik przenikania ciepła
zagadnienie odwrotne
heat flux
heat transfer coefficient
inverse problem
temperature measurement
Opis:
The paper presents the solution to a problem of determining the heat flux density and the heat transfer coefficient, on the basis of temperature measurement at three locations in the flat sensor, with the assumption that the heat conductivity of the sensor material is temperature dependent. Three different methods for determining the heat flux and heat transfer coefficient, with their practical applications, are presented. The uncertainties in the determined values are also estimated.
Źródło:
Archives of Thermodynamics; 2010, 31, 3; 3-18
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of radiative heat transfer impact in cross-flow tube and fin heat exchangers
Autorzy:
Hanuszkiewicz-Drapała, M.
Bury, T.
Widziewicz, K.
Powiązania:
https://bibliotekanauki.pl/articles/240216.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heat exchangers
radiative heat transfer
numerical model
experimental validation
wymienniki ciepła
radiacyjna wymiana ciepła
model numeryczny
weryfikacja doświadczalna
Opis:
A cross-flow, tube and fin heat exchanger of the water – air type is the subject of the analysis. The analysis had experimental and computational form and was aimed for evaluation of radiative heat transfer impact on the heat exchanger performance. The main element of the test facility was an enlarged recurrent segment of the heat exchanger under consideration. The main results of measurements are heat transfer rates, as well as temperature distributions on the surface of the first fin obtained by using the infrared camera. The experimental results have been next compared to computational ones coming from a numerical model of the test station. The model has been elaborated using computational fluid dynamics software. The computations have been accomplished for two cases: without radiative heat transfer and taking this phenomenon into account. Evaluation of the radiative heat transfer impact in considered system has been done by comparing all the received results.
Źródło:
Archives of Thermodynamics; 2016, 37, 1; 99-112
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Heat transfer and pressure drop characteristics of the silicone-based plate heat exchanger
Autorzy:
Muszyński, Tomasz
Andrzejczyk, Rafał
Park, Il Wong
Dorao, Carlos Alberto
Powiązania:
https://bibliotekanauki.pl/articles/240347.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heat transfer coefficient
heat exchangers
enhanced surface
Wilson plot method
współczynnik wnikania ciepła
wymienniki ciepła
czynnik chłodniczy
metoda Wilsona
Opis:
The paper presents an experimental investigation of a silicone based heat exchanger, with passive heat transfer intensification by means of surface enhancement. The main objective of this paper was to experimentally investigate the performance of a heat exchanger module with the enhanced surface. Heat transfer in the test section has been examined and described with precise measurements of thermal and flow conditions. Reported tests were conducted under steady-state conditions for single-phase liquid cooling. Proposed surface modification increases heat flux by over 60%. Gathered data presented, along with analytical solutions and numerical simulation allow the rational design of heat transfer devices.
Źródło:
Archives of Thermodynamics; 2019, 40, 1; 127-143
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 56

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