TY  - JOUR
AU  - Stevanović, Vladimir
AU  - Stanojević, Miroslav
AU  - Radić, Dejan
AU  - Jovanović, Milorad
PY  - 2008
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/819
AB  - Pressure changes in annular downward flows of condensing steam in vertical tubes are predicted with a three-fluid model. Several available correlations for the steam-liquid film interfacial friction are applied in the three-fluid model. Since discrepancies are obtained between calculated and measured pressure changes, a new correlation for the interfacial friction coefficient is proposed by taking into account the influence of the steam and liquid density ratio. The new correlation provides good agreement. The influence of the gravitational, frictional and acceleration pressure changes on the total pressure change is analysed, as well as the droplets entrainment from the liquid film surface to the steam core.
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - International Journal of Heat and Mass Transfer
T1  - Three-fluid model predictions of pressure changes in condensing vertical tubes
EP  - 3744
IS  - 15-16
SP  - 3736
VL  - 51
DO  - 10.1016/j.ijheatmasstransfer.2007.12.008
ER  - 

@article{
author = "Stevanović, Vladimir and Stanojević, Miroslav and Radić, Dejan and Jovanović, Milorad",
year = "2008",
abstract = "Pressure changes in annular downward flows of condensing steam in vertical tubes are predicted with a three-fluid model. Several available correlations for the steam-liquid film interfacial friction are applied in the three-fluid model. Since discrepancies are obtained between calculated and measured pressure changes, a new correlation for the interfacial friction coefficient is proposed by taking into account the influence of the steam and liquid density ratio. The new correlation provides good agreement. The influence of the gravitational, frictional and acceleration pressure changes on the total pressure change is analysed, as well as the droplets entrainment from the liquid film surface to the steam core.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "International Journal of Heat and Mass Transfer",
title = "Three-fluid model predictions of pressure changes in condensing vertical tubes",
pages = "3744-3736",
number = "15-16",
volume = "51",
doi = "10.1016/j.ijheatmasstransfer.2007.12.008"
}

Stevanović, V., Stanojević, M., Radić, D.,& Jovanović, M.. (2008). Three-fluid model predictions of pressure changes in condensing vertical tubes. in International Journal of Heat and Mass Transfer
Pergamon-Elsevier Science Ltd, Oxford., 51(15-16), 3736-3744.
https://doi.org/10.1016/j.ijheatmasstransfer.2007.12.008

Stevanović V, Stanojević M, Radić D, Jovanović M. Three-fluid model predictions of pressure changes in condensing vertical tubes. in International Journal of Heat and Mass Transfer. 2008;51(15-16):3736-3744.
doi:10.1016/j.ijheatmasstransfer.2007.12.008 .

Stevanović, Vladimir, Stanojević, Miroslav, Radić, Dejan, Jovanović, Milorad, "Three-fluid model predictions of pressure changes in condensing vertical tubes" in International Journal of Heat and Mass Transfer, 51, no. 15-16 (2008):3736-3744,
https://doi.org/10.1016/j.ijheatmasstransfer.2007.12.008 . .

TY  - JOUR
AU  - Stevanović, Vladimir
AU  - Milivojević, Sanja
AU  - Maslovarić, Blaženka
AU  - Zivković, Branislav
AU  - Nikodijević, Srđan
PY  - 2007
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/693
AB  - An efficient method for numerical simulation and analyses of the steady state hydraulics of complex pipeline networks is presented. It is based on the loop model of the network and the method of square roots for solving the system of linear equations. The procedure is presented in the comprehensive mathematical form that could be straightforwardly programmed into a computer code. An application of the method to energy efficiency analyses of a real complex district heating system is demonstrated. The obtained results show a potential for electricity savings in pumps operation. It is shown that the method is considerably more effective than the standard Hardy Cross method still widely used in engineering practice. Because of the ease of implementation and high efficiency, the method presented in this paper is recommended for hydraulic steady state calculations of complex networks.
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Energy Conversion and Management
T1  - Efficient numerical method for district heating system hydraulics
EP  - 1543
IS  - 5
SP  - 1536
VL  - 48
DO  - 10.1016/j.enconman.2006.11.018
ER  - 

@article{
author = "Stevanović, Vladimir and Milivojević, Sanja and Maslovarić, Blaženka and Zivković, Branislav and Nikodijević, Srđan",
year = "2007",
abstract = "An efficient method for numerical simulation and analyses of the steady state hydraulics of complex pipeline networks is presented. It is based on the loop model of the network and the method of square roots for solving the system of linear equations. The procedure is presented in the comprehensive mathematical form that could be straightforwardly programmed into a computer code. An application of the method to energy efficiency analyses of a real complex district heating system is demonstrated. The obtained results show a potential for electricity savings in pumps operation. It is shown that the method is considerably more effective than the standard Hardy Cross method still widely used in engineering practice. Because of the ease of implementation and high efficiency, the method presented in this paper is recommended for hydraulic steady state calculations of complex networks.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Energy Conversion and Management",
title = "Efficient numerical method for district heating system hydraulics",
pages = "1543-1536",
number = "5",
volume = "48",
doi = "10.1016/j.enconman.2006.11.018"
}

Stevanović, V., Milivojević, S., Maslovarić, B., Zivković, B.,& Nikodijević, S.. (2007). Efficient numerical method for district heating system hydraulics. in Energy Conversion and Management
Pergamon-Elsevier Science Ltd, Oxford., 48(5), 1536-1543.
https://doi.org/10.1016/j.enconman.2006.11.018

Stevanović V, Milivojević S, Maslovarić B, Zivković B, Nikodijević S. Efficient numerical method for district heating system hydraulics. in Energy Conversion and Management. 2007;48(5):1536-1543.
doi:10.1016/j.enconman.2006.11.018 .

Stevanović, Vladimir, Milivojević, Sanja, Maslovarić, Blaženka, Zivković, Branislav, Nikodijević, Srđan, "Efficient numerical method for district heating system hydraulics" in Energy Conversion and Management, 48, no. 5 (2007):1536-1543,
https://doi.org/10.1016/j.enconman.2006.11.018 . .

TY  - JOUR
AU  - Stevanović, Nevena
PY  - 2007
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/696
AB  - A two-dimensional, isothermal, compressible and subsonic gas flow in a microchannel with slowly varying cross-section is analytically investigated. The microchannel gas flow is described by the Burnett momentum equation that comprises the shear stress tensor of the second order. The application of the Burnett equation allows the introduction of the second-order boundary condition for the gas velocity slip on microchannel walls. The model solution is based on perturbation analysis. The analytical solution procedure incorporates the exact physical relation between Mach, Reynolds and Knudsen numbers, which enables the evaluation of the order of all terms within the balance equations and the boundary conditions and provides high accuracy of the model. It is shown that the Burnet equation has the same form as the Navier-Stokes equation for low Mach number flows in channels with slowly varying cross sections. The obtained analytical results are in excellent agreement with available measured data and numerical solutions of the Boltzmann equation. The presented analytical model is new since previous solutions are limited to microchannels with uniform cross sections, while here the presented solution is obtained for microchannels with varying cross sections. The presented model is a useful tool for the design and analysis of gas flows in microchannels, and it provides accurate benchmark results for the validation of the numerically obtained results.
PB  - IOP Publishing Ltd, Bristol
T2  - Journal of Micromechanics and Microengineering
T1  - A new analytical solution of microchannel gas flow
EP  - 1702
IS  - 8
SP  - 1695
VL  - 17
DO  - 10.1088/0960-1317/17/8/036
ER  - 

@article{
author = "Stevanović, Nevena",
year = "2007",
abstract = "A two-dimensional, isothermal, compressible and subsonic gas flow in a microchannel with slowly varying cross-section is analytically investigated. The microchannel gas flow is described by the Burnett momentum equation that comprises the shear stress tensor of the second order. The application of the Burnett equation allows the introduction of the second-order boundary condition for the gas velocity slip on microchannel walls. The model solution is based on perturbation analysis. The analytical solution procedure incorporates the exact physical relation between Mach, Reynolds and Knudsen numbers, which enables the evaluation of the order of all terms within the balance equations and the boundary conditions and provides high accuracy of the model. It is shown that the Burnet equation has the same form as the Navier-Stokes equation for low Mach number flows in channels with slowly varying cross sections. The obtained analytical results are in excellent agreement with available measured data and numerical solutions of the Boltzmann equation. The presented analytical model is new since previous solutions are limited to microchannels with uniform cross sections, while here the presented solution is obtained for microchannels with varying cross sections. The presented model is a useful tool for the design and analysis of gas flows in microchannels, and it provides accurate benchmark results for the validation of the numerically obtained results.",
publisher = "IOP Publishing Ltd, Bristol",
journal = "Journal of Micromechanics and Microengineering",
title = "A new analytical solution of microchannel gas flow",
pages = "1702-1695",
number = "8",
volume = "17",
doi = "10.1088/0960-1317/17/8/036"
}

Stevanović, N.. (2007). A new analytical solution of microchannel gas flow. in Journal of Micromechanics and Microengineering
IOP Publishing Ltd, Bristol., 17(8), 1695-1702.
https://doi.org/10.1088/0960-1317/17/8/036

Stevanović N. A new analytical solution of microchannel gas flow. in Journal of Micromechanics and Microengineering. 2007;17(8):1695-1702.
doi:10.1088/0960-1317/17/8/036 .

Stevanović, Nevena, "A new analytical solution of microchannel gas flow" in Journal of Micromechanics and Microengineering, 17, no. 8 (2007):1695-1702,
https://doi.org/10.1088/0960-1317/17/8/036 . .

TY  - JOUR
AU  - Tucaković, Dragan
AU  - Stevanović, Vladimir
AU  - Živanović, Titoslav
AU  - Jovović, Aleksandar
AU  - Ivanović, Vladan B.
PY  - 2007
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/742
AB  - Rifled evaporating tubes are applied in the steam boilers with the aim to increase the steam-water mixture turbulization and to prevent the burnout of tubes walls. The rifled evaporating tubes and the working fluid forced circulation are applied in the steam boiler at the Thermal Power Plant "Kolubara B" that is being built by the Electric Power Utility of Serbia. In order to investigate operating characteristics of the steam boiler of such an advanced design, a simulation and analysis of complex coupled thermal processes on the furnace gas side and thermal-hydraulics inside the evaporating tubes were performed for the whole range of plant operating loads. In this paper a methodology for hydraulic calculations of both forced and natural circulation loops is presented. The increased thermal safety margin of rifled tubes is predicted and compared with the safety margin of smooth tubes for uniform and variable heat loads among walls of the boiler furnace. The rifled tube provides an acceptable temperature of its wall even under a high void fraction of the coolant and prevents the occurrence of critical heat transfer conditions. The influence of the rifled tubes on an increase of the hydraulic resistance in the circulation loop is analyzed. Also, a range of operating conditions under which there is no need for the circulation pumps operation is determined.
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Applied Thermal Engineering
T1  - Thermal-hydraulic analysis of a steam boiler with rifled evaporating tubes
EP  - 519
IS  - 2-3
SP  - 509
VL  - 27
DO  - 10.1016/j.applthermaleng.2006.06.009
ER  - 

@article{
author = "Tucaković, Dragan and Stevanović, Vladimir and Živanović, Titoslav and Jovović, Aleksandar and Ivanović, Vladan B.",
year = "2007",
abstract = "Rifled evaporating tubes are applied in the steam boilers with the aim to increase the steam-water mixture turbulization and to prevent the burnout of tubes walls. The rifled evaporating tubes and the working fluid forced circulation are applied in the steam boiler at the Thermal Power Plant "Kolubara B" that is being built by the Electric Power Utility of Serbia. In order to investigate operating characteristics of the steam boiler of such an advanced design, a simulation and analysis of complex coupled thermal processes on the furnace gas side and thermal-hydraulics inside the evaporating tubes were performed for the whole range of plant operating loads. In this paper a methodology for hydraulic calculations of both forced and natural circulation loops is presented. The increased thermal safety margin of rifled tubes is predicted and compared with the safety margin of smooth tubes for uniform and variable heat loads among walls of the boiler furnace. The rifled tube provides an acceptable temperature of its wall even under a high void fraction of the coolant and prevents the occurrence of critical heat transfer conditions. The influence of the rifled tubes on an increase of the hydraulic resistance in the circulation loop is analyzed. Also, a range of operating conditions under which there is no need for the circulation pumps operation is determined.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Applied Thermal Engineering",
title = "Thermal-hydraulic analysis of a steam boiler with rifled evaporating tubes",
pages = "519-509",
number = "2-3",
volume = "27",
doi = "10.1016/j.applthermaleng.2006.06.009"
}

Tucaković, D., Stevanović, V., Živanović, T., Jovović, A.,& Ivanović, V. B.. (2007). Thermal-hydraulic analysis of a steam boiler with rifled evaporating tubes. in Applied Thermal Engineering
Pergamon-Elsevier Science Ltd, Oxford., 27(2-3), 509-519.
https://doi.org/10.1016/j.applthermaleng.2006.06.009

Tucaković D, Stevanović V, Živanović T, Jovović A, Ivanović VB. Thermal-hydraulic analysis of a steam boiler with rifled evaporating tubes. in Applied Thermal Engineering. 2007;27(2-3):509-519.
doi:10.1016/j.applthermaleng.2006.06.009 .

Tucaković, Dragan, Stevanović, Vladimir, Živanović, Titoslav, Jovović, Aleksandar, Ivanović, Vladan B., "Thermal-hydraulic analysis of a steam boiler with rifled evaporating tubes" in Applied Thermal Engineering, 27, no. 2-3 (2007):509-519,
https://doi.org/10.1016/j.applthermaleng.2006.06.009 . .

TY  - JOUR
AU  - Simović, Željko
AU  - Ocokoljić, Sanja
AU  - Stevanović, Vladimir
PY  - 2007
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/711
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - International Journal of Multiphase Flow
T1  - Interfacial friction correlations for the two-phase flow across tube bundle
EP  - 226
IS  - 2
SP  - 217
VL  - 33
DO  - 10.1016/j.ijmultiphaseflow.2006.08.003
ER  - 

@article{
author = "Simović, Željko and Ocokoljić, Sanja and Stevanović, Vladimir",
year = "2007",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "International Journal of Multiphase Flow",
title = "Interfacial friction correlations for the two-phase flow across tube bundle",
pages = "226-217",
number = "2",
volume = "33",
doi = "10.1016/j.ijmultiphaseflow.2006.08.003"
}

Simović, Ž., Ocokoljić, S.,& Stevanović, V.. (2007). Interfacial friction correlations for the two-phase flow across tube bundle. in International Journal of Multiphase Flow
Pergamon-Elsevier Science Ltd, Oxford., 33(2), 217-226.
https://doi.org/10.1016/j.ijmultiphaseflow.2006.08.003

Simović Ž, Ocokoljić S, Stevanović V. Interfacial friction correlations for the two-phase flow across tube bundle. in International Journal of Multiphase Flow. 2007;33(2):217-226.
doi:10.1016/j.ijmultiphaseflow.2006.08.003 .

Simović, Željko, Ocokoljić, Sanja, Stevanović, Vladimir, "Interfacial friction correlations for the two-phase flow across tube bundle" in International Journal of Multiphase Flow, 33, no. 2 (2007):217-226,
https://doi.org/10.1016/j.ijmultiphaseflow.2006.08.003 . .