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Tytuł:
Diffusive–inertial droplet separation model from two-phase flow
Autorzy:
Mikielewicz, Jarosław
Dolna, Oktawia
Kwidziński, Roman
Powiązania:
https://bibliotekanauki.pl/articles/1955019.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
two-phase flow
diffusive-inertial droplet separation
stopping distance
Opis:
This paper concerns analytical considerations on a complex phenomenon which is diffusive-inertial droplet separation from the twophase vapour-liquid flow which occurs in many devices in the power industry (e.g. heat pumps, steam turbines, organic Rankine cycles, etc.). The new mathematical model is mostly devoted to the analysis of the mechanisms of diffusion and inertia influencing the distance at which a droplet separates from the two-phase flow and falls on a channel wall. The analytical model was validated based on experimental data. The results obtained through the analytical computations stay in a satisfactory agreement with available literature data.
Źródło:
Archives of Thermodynamics; 2021, 42, 3; 141-158
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Computer cooling using a two phase minichannel thermosyphon loop heated from horizontal and vertical sides and cooled from vertical side
Autorzy:
Bieliński, H.
Mikielewicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/240497.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
obieg termosyfonowy
przepływu dwufazowy
thermosyphon loop
two phase flow
Opis:
In the present paper it is proposed to consider the computer cooling capacity using the thermosyphon loop. A closed thermosyphon loop consists of combined two heaters and a cooler connected to each other by tubes. The first heater may be a CPU processor located on the motherboard of the personal computer. The second heater may be a chip of a graphic card placed perpendicular to the motherboard of personal computer. The cooler can be placed above the heaters on the computer chassis. The thermosyphon cooling system on the use of computer can be modeled using the rectangular thermosyphon loop with minichannels heated at the bottom horizontal side and the bottom vertical side and cooled at the upper vertical side. The riser and a downcomer connect these parts. A one-dimensional model of two-phase flow and heat transfer in a closed thermosyphon loop is based on mass, momentum, and energy balances in the evaporators, rising tube, condenser and the falling tube. The separate two-phase flow model is used in calculations. A numerical investigation for the analysis of the mass flux rate and heat transfer coefficient in the steady state has been accomplished.
Źródło:
Archives of Thermodynamics; 2010, 31, 4; 51-59
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The rectangular two-phase closed thermosyphon: A case study of two-phase internal flow patterns behaviour for heat performance
Autorzy:
Chompookham, Teerapat
Sichamnan, Surachet
Bhuwakietkumjohn, Nipon
Parametthanuwat, Thanya
Powiązania:
https://bibliotekanauki.pl/articles/240618.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
internal flow
flow pattern
rectangular two-phase closed thermosyphon
Opis:
This research explored different types of two-phase flow patterns that influenced heat transfer rate by assessing rectangular two-phase closed thermosyphon (RTPCT) made from glass with the sides of equal length of 25.2 mm, aspect ratio 5 and 20, evaporation temperature of 50, 70, and 90°C, working substance addition rate of 50% by volume of evaporator, and water inlet temperature at condensation of 20°C. Upon testing with aspect ratios 5, three flow patterns emerged which were: bubble flow, slug flow and churn flow respectively. As per the aspect ratio 20, four flow patterns were discovered which were: bubble flow, slug flow, churn flow and annular flow, respectively. Aspect ratio 5 pertains characteristic which resulted in a shorter evaporation rate of the RTPCT than that of the aspect ratio 20, thus, a shorter flow distance from the evaporator section to heat releaser was observed. Therefore, flow patterns at aspect ratio 5 exhibited a faster flow velocity than that of the aspect ratio 20. Furthermore, changes of flow pattern to the one that is important for heat transfer rate can be easily achieved. Churn flow was the most important type of the flow for heat transfer, followed by slug flow. Moreover, with aspect ratio 20, annular flow was the most important flow for the heat transfer, followed by churn flow, respectively. Throughout the test, average heat flux as obtained from the aspect ratio 5 were 1.51 and 0.74 kW/m2 which were higher than those of the aspect ratio 20. The highest heat flux at the operating temperature of the evaporator section was 90°C, which was equivalent to 2.60 and 1.52 kW/m2, respectively.
Źródło:
Archives of Thermodynamics; 2020, 41, 3; 223-254
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Validation of the generalized model of two-phase thermosyphon loop based on experimental measurements of volumetric flow rate
Autorzy:
Bieliński, H.
Powiązania:
https://bibliotekanauki.pl/articles/240528.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
thermosyphon loop
two-phase flow
minichannels
obieg termosyfonowy
przepływ dwufazowy
minikanały
Opis:
The current paper presents the experimental validation of the generalized model of the two-phase thermosyphon loop. The generalized model is based on mass, momentum, and energy balances in the evaporators, rising tube, condensers and the falling tube. The theoretical analysis and the experimental data have been obtained for a new designed variant. The variant refers to a thermosyphon loop with both minichannels and conventional tubes. The thermosyphon loop consists of an evaporator on the lower vertical section and a condenser on the upper vertical section. The one-dimensional homogeneous and separated two-phase flow models were used in calculations. The latest minichannel heat transfer correlations available in literature were applied. A numerical analysis of the volumetric flow rate in the steady-state has been done. The experiment was conducted on a specially designed test apparatus. Ultrapure water was used as a working fluid. The results show that the theoretical predictions are in good agreement with the measured volumetric flow rate at steady-state.
Źródło:
Archives of Thermodynamics; 2016, 37, 3; 109-138
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exergy analysis of operation of two-phase ejector in compression refrigeration systems
Autorzy:
Dudar, A.
Butrymowicz, D.
Śmierciew, K.
Karwacki, J.
Powiązania:
https://bibliotekanauki.pl/articles/240804.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
two-phase ejector
compression refrigeration system
COP
exergy
strumienica dwufazowa
egzergia
Opis:
Paper deals with theoretical analysis of possible efficiency increase of compression refrigeration cycles by means of application of a two-phase ejector. Application of the two phase ejector in subcritical refrigeration system as a booster compressor is discussed in the paper. Results of exergy analysis of the system operating with various working fluids for various operating conditions have been shown. Analysis showed possible exergy efficiency increase of refrigeration compression cycle.
Źródło:
Archives of Thermodynamics; 2013, 34, 4; 107-122
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Two-temperature theory for a heated semi-infinite solid by a pulsed laser radiation
Autorzy:
Zenkour, Ashraf M.
Abouelregal, Ahmed E.
Powiązania:
https://bibliotekanauki.pl/articles/240137.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
thermoelasticity
two-temperature
non-Gaussian laser pulse
laser intensity
phase lags
Opis:
In this paper, the two-temperature thermoelasticity model is proposed to a specific problem of a thermoelastic semi-infinite solid. The bounding plane surface of the semi-infinite solid is considered to be under a non-Gaussian laser pulse. Generalized thermoelasticity analysis with dual-phase-lags is taken into account to solve the present problem. Laplace transform and its inversion techniques are applied and an analytical solution as well as its numerical outputs of the field variables are obtained. The coupled theory and other generalized theory with one relaxation time may be derived as special cases. Comparison examples have been made to show the effect of dual-phase-lags, temperature discrepancy, laser-pulse and laser intensity parameters on all felids. An additional comparison is also made with the theory of thermoelasticity at a single temperature.
Źródło:
Archives of Thermodynamics; 2020, 41, 2; 85-101
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wave propagation in 2D between two elastic media in contact in theory of generalized two temperature thermoelasticity with gravity effect
Autorzy:
Lotfy, Khaled
Gabr, Mahmoud
El-Bary, Alaa Abd
Powiązania:
https://bibliotekanauki.pl/articles/240130.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
generalized thermoelasticity
surface waves
two temperatures
Lord-Shulman theory
influence of gravity
Opis:
The theory of generalized two-temperature thermoelasticity is used to solve the boundary value problems between two elastic media with two different types of temprature under the influence of gravity.The classical dynamical coupled theory and Lord-Şhulman theory are used to obtain the general solution of the governing equations and investigate the effect of surface waves in an isotropic elastic medium subjected to gravity field. The harmonic vibrations method is used to obtain the displacement components, stress tensor and temperature distribution in the considerd physical domain with comparison with the two theories. The obtained analytic solution of the problem is applied for special cases for which the effect of two temperatures is studied. The conductive and dynamical temperatures as well as stress and strain components are shown graphically for a suitable material. Some comparisons are also introduced in the absence and in the presence of gravity, and two-temperature parameter. The differences in the obtained results between the two theories are considered.
Źródło:
Archives of Thermodynamics; 2020, 41, 1; 219-243
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical simulation of thermal-hydraulic processes in the riser chamber of installation for clinker production
Autorzy:
Borsuk, G.
Dobrowolski, B.
Nowosielski, G.
Wydrych, J.
Duda, J.
Powiązania:
https://bibliotekanauki.pl/articles/240205.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
two-phase flow
precalcination
particle distribution
CFD
przepływ dwufazowy
rozkład wielkości cząstek
Opis:
Clinker burning process has a decisive influence on energy consumption and the cost of cement production. A new problem is to use the process of decarbonization of alternative fuels from waste. These issues are particularly important in the introduction of a two-stage combustion of fuel in a rotary kiln without the typical reactor-decarbonizator. This work presents results of numerical studies on thermal-hydraulic phenomena in the riser chamber, which will be designed to burn fuel in the system where combustion air is supplied separately from the clinker cooler. The mathematical model is based on a combination of two methods of motion description: Euler description for the gas phase and Lagrange description for particles. Heat transfer between particles of raw material and gas was added to the numerical calculations. The main aim of the research was finding the correct fractional distribution of particles. For assumed particle distribution on the first stage of work, authors noted that all particles were carried away by the upper outlet to the preheater tower, what is not corresponding to the results of experimental studies. The obtained results of calculations can be the basis for further optimization of the design and operating conditions in the riser chamber with the implementation of the system.
Źródło:
Archives of Thermodynamics; 2016, 37, 1; 127-142
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental investigation of the ecological hybrid refrigeration cycle
Autorzy:
Cyklis, P.
Kantor, R.
Ryncarz, T.
Górski, B.
Duda, R.
Powiązania:
https://bibliotekanauki.pl/articles/240899.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
hybrid refrigerating cycle
adsorption
two stage refrigerating
hybrydowy cykl chłodniczy
adsorpcja
dwustopniowe chłodzenie
Opis:
The requirements for environmentally friendly refrigerants promote application of CO2 and water as working fluids. However there are two problems related to that, namely high temperature limit for CO2 in condenser due to the low critical temperature, and low temperature limit for water being the result of high triple point temperature. This can be avoided by application of the hybrid adsorption-compression system, where water is the working fluid in the adsorption high temperature cycle used to cool down the CO2 compression cycle condenser. The adsorption process is powered with a low temperature renewable heat source as solar collectors or other waste heat source. The refrigeration system integrating adsorption and compression system has been designed and constructed in the Laboratory of Thermodynamics and Thermal Machine Measurements of Cracow University of Technology. The heat source for adsorption system consists of 16 tube tulbular collectors. The CO2 compression low temperature cycle is based on two parallel compressors with frequency inverter. Energy efficiency and TEWI of this hybrid system is quite promising in comparison with the compression only systems.
Źródło:
Archives of Thermodynamics; 2014, 35, 3; 145-154
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental investigation of the two-phase flow regimes and pressure drop in horizontal mini-size rectangular test section
Autorzy:
Elazhary, A.
Soliman, H.
Powiązania:
https://bibliotekanauki.pl/articles/239912.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
dwufazowy
minikanał
przepływ
spadek ciśnienia
flow regimes
mini channel
pressure drop
two-phase
Opis:
An experimental study was conducted in order to investigate two-phase flow regimes and fully developed pressure drop in a mini-size, horizontal rectangular channel. The test section was machined in the form of an impacting tee junction in an acrylic block (in order to facilitate visualization) with a rectangular cross-section of 1.87-mm height on 20-mm width on the inlet and outlet sides. Pressure drop measurement and flow regime identification were performed on all three sides of the junction. Air-water mixtures at 200 kPa (abs) and room temperature were used as the test fluids. Four flow regimes were identified visually: bubbly, plug, churn, and annular over the ranges of gas and liquid superficial velocities of 0.04 [ less than or equal to] JG [ less than or equal to] 10 m/s and 0.02 [ less than or equal to] JL [ less than or equal to] 0.7 m/s, respectively, and a flow regime map was developed. Accuracy of the pressure-measurement technique was validated with single-phase, laminar and turbulent, fully developed data. Two-phase experiments were conducted for eight different inlet conditions and various mass splits at the junction. Comparisons were conducted between the present data and former correlations for the fully developed two-phase pressure drop in rectangular channels with similar sizes. Wide deviations were found among these correlations, and the correlations that agreed best with the present data were identified.
Źródło:
Archives of Thermodynamics; 2012, 33, 2; 47-6
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of a two-phase thermosyphon loop with minichannels and a minipump in computer cooling
Autorzy:
Bieliński, H.
Mikielewicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/240132.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
thermosyphon loop
two phase flow
computer cooling
obieg termosyfonowy
przepływ dwufazowy
chłodzenie komputera
Opis:
This paper focuses on the computer cooling capacity using the thermosyphon loop with minichannels and minipump. The one-dimensional separate model of two-phase flow and heat transfer in a closed thermosyphon loop with minichannels and minipump has been used in calculations. The latest correlations for minichannels available in literature have been applied. This model is based on mass, momentum, and energy balances in the evaporator, rising tube, condenser and the falling tube. A numerical analysis of the mass flux and heat transfer coefficient in the steady state has been presented.
Źródło:
Archives of Thermodynamics; 2016, 37, 1; 3-16
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Novel model for emptying of a self-pressurised nitrous oxide tank
Autorzy:
Szymborski, Jakub
Kardaś, Dariusz
Powiązania:
https://bibliotekanauki.pl/articles/2134934.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
convective mass transfer
nitrous oxide
hybrid rocket engine
two-phase
flow
self-pressurisation
Opis:
Nitrous oxide is often used in the space industry, as an oxidiser or monopropellant, mostly in self-pressurised configurations. It has potential for growth in use due to the recent rising interest in green propellants. At the same time, modelling the behaviour of a self-pressurising nitrous oxide tank is a challenging task, and few accurate numerical models are currently available. Two-phase flow, heat transfer and rapid changes of mass and temperature in the investigated system all increase the difficulty of accurately predicting this process. To get a get better understanding of the emptying of a self-pressurised nitrous oxide tank, two models were developed: a phase equilibrium model (single node equilibrium), treating the control volume as a single node in equilibrium state, and a phase interface model, featuring a moving interface between parts of the investigated medium. The single node equilibrium model is a variation of equilibrium model previously described in the literature, while the phase interface model involves a novel approach. The results show that the models are able to capture general trends in the main parameters, such as pressure or temperature. The phase interface model predicts nitrous oxide as a liquid, a two-phase mixture, and vapour in the lower part of the tank, which is reflected in the dynamics of changes in pressure and mass flow rate. The models developed for self-pressurisation, while created for predicting nitrous oxide behaviour, could be adapted for other media in conditions near vapour– liquid equilibrium by adding appropriate state equations.
Źródło:
Archives of Thermodynamics; 2022, 43, 3; 141--173
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of nanofluid concentration on two-phase thermosyphon heat exchanger performance
Autorzy:
Cieśliński, J. T.
Powiązania:
https://bibliotekanauki.pl/articles/240904.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
two-phase thermosyphon
heat exchanger
nanofluid
Wilson method
termosyfon dwufazowy
wymiennik ciepła
metoda Wilsona
Opis:
An 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 solution were used as working fluids. Nanoparticles were tested at the concentration of 0.01% and 0.1% by weight. A modified Peclet equation and Wilson method were used to estimate the overall heat transfer coefficient of the tested TPTHEx. The obtained results indicate better performance of the TPTHEx with nanofluids as working fluid compared to distilled water, independent of nanoparticle concentration tested. However, increase in nanoparticle concentration results in overall heat transfer coefficient decrease of the TPTHEx examined. It has been observed that, independent of nanoparticle concentration tested, decrease in operating pressure results in evaporation heat transfer coefficient increase.
Źródło:
Archives of Thermodynamics; 2016, 37, 2; 23-40
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of thermodynamics of two-fuel power unit integrated with a carbon dioxide separation plant
Autorzy:
Kotowicz, J.
Bartela, Ł.
Mikosz, D.
Powiązania:
https://bibliotekanauki.pl/articles/240322.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
CO2 separation
thermodynamic analysis
two-fuel power unit
separacja CO2
analiza termodynamiczna
Opis:
The article presents the results of thermodynamic analysis of the supercritical coal-fired power plant with gross electrical output of 900 MW and a pulverized coal boiler. This unit is integrated with the absorption-based CO2 separation installation. The heat required for carrying out the desorption process, is supplied by the system with the gas turbine. Analyses were performed for two variants of the system. In the first case, in addition to the gas turbine there is an evaporator powered by exhaust gases from the gas turbine expander. The second expanded variant assumes the application of gas turbine combined cycle with heat recovery steam generator and backpressure steam turbine. The way of determining the efficiency of electricity generation and other defined indicators to assess the energy performance of the test block was showed. The size of the gas turbine system was chosen because of the need for heat for the desorption unit, taking the value of the heat demand 4 MJ/kg CO2. The analysis results obtained for the both variants of the installation with integrated CO2 separation plant were compared with the results of the analysis of the block where the separation is not conducted.
Źródło:
Archives of Thermodynamics; 2014, 35, 4; 55-68
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurements of two-phase flow patterns and local void fraction in vertical rectangular minichannel
Autorzy:
Kaniowski, R.
Poniewski, M.
Powiązania:
https://bibliotekanauki.pl/articles/240074.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
boiling
minichannel
two-phase flow pattern
void fraction
wrzenie
minikanał
model przepływu dwufazowego
udział objętościowy
Opis:
Technology advancements entail a necessity to remove huge amounts of heat produced by today’s electronic devices based on highly integrated circuits, major generators of heat. Heat transfer to boiling liquid flowing through narrow minichannels is a modern solution to the problem of heat transfer enhancement. The study was conducted for FC-72 boiling in a rectangular, vertical and asymmetrically heated minichannel that had depths of 0.5–1.5 mm, a width of 20 mm and a length of 360 mm. The heat flux increased and decreased within the range of 58.3–132.0 kWm-2, the absolute pressure ranged from 0.116 to 0.184 MPa and the mass flux was 185–1139.2 kgm-2s-1. The boiling process took place on a flat vertical heating surface made of Haynes-230 0.1 mm thick acid-proof rolled plate with the surface roughness of 121 μm.
Źródło:
Archives of Thermodynamics; 2013, 34, 2; 3-21
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
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