Photographic Technique Application to the Determination of Void Fraction in Two-Phase Flow Boiling in Mini Channels

Płaczkowski, Krzysztof; Poniewski, Mieczysław E.; Grabowski, Mirosław; Alabrudziński, Sławomir

doi:10.4028/www.scientific.net/amm.797.299

Cited by 4 publications

(7 citation statements)

References 2 publications

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“…Observations of the two-phase flow structures helped determine the void fraction ( Figure 5). The method of determining the void faction was described in detail in Reference [20]. …”

Section: Resultsmentioning

confidence: 99%

“…Observations of the two-phase flow structures helped determine the void fraction ( Figure 5). The method of determining the void faction was described in detail in Reference [20]. This method is based on the script developed in a Matlab 2012 environment (MathWorks, Natick, MA, USA) that uses two toolboxes: Computer System Vision and Image Processing Toolbox 2012 (MathWorks, Natick, MA, USA).…”

Section: Resultsmentioning

confidence: 99%

“…Measurements of the insulating foil temperature based on the data from the thermal imaging camera (Figure 7a) were approximated by a third-degree polynomial (Figure 7b). The void fraction determined in the manner described in Reference [20] at distances of 0 mm, 20 mm, 40 mm, 80 mm from the mini-channel inlet was also approximated by a polynomial (Figure 7c).…”

Section: Resultsmentioning

confidence: 99%

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Heat Transfer Coefficient Identification in Mini-Channel Flow Boiling with the Hybrid Picard–Trefftz Method

et al. 2018

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This paper summarizes the results of the flow boiling heat transfer study with ethanol in a 1.8 mm deep and 2.0 mm wide horizontal, asymmetrically heated, rectangular mini-channel. The test section with the mini-channel was the main part of the experimental stand. One side of the mini-channel was closed with a transparent sight window allowing for the observation of two-phase flow structures with the use of a fast film camera. The other side of the channel was the foil insulated heater. The infrared camera recorded the 2D temperature distribution of the foil. The 2D temperature distributions in the elements of the test section with two-phase flow boiling were determined using (1) the Trefftz method and (2) the hybrid Picard-Trefftz method. These methods solved the triple inverse heat conduction problem in three consecutive elements of the test section, each with different physical properties. The values of the local heat transfer coefficients calculated on the basis of the Robin boundary condition were compared with the coefficients determined with the simplified approach, where the arrangement of elements in the test section was treated as a system of planar layers.

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“…Observations of the two-phase flow structures helped determine the void fraction ( Figure 5). The method of determining the void faction was described in detail in Reference [20]. …”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Heat Transfer Coefficient Identification in Mini-Channel Flow Boiling with the Hybrid Picard–Trefftz Method

et al. 2018

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“…The measurement procedure [2,3] included reading and recording of the following quantities: temperature and pressure at the channel inlet and outlet, differences in inlet and outlet pressures, volume flux of the flowing medium, current and voltage of the heater power supply. At the same time, structures of two-phase flow were filmed using high-speed video camera.…”

Section: Measurement Proceduresmentioning

confidence: 99%

Photographic Technique Application to the Determination of Void Fraction in Two-Phase Flow Boiling in Mini Channels

Płaczkowski

Poniewski

Grabowski

et al. 2015

AMM

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The study deals with experimental investigations into heat transfer flow boiling in rectangular, vertical and horizontal mini-channels. The dedicated measurement system was designed to observe flow boiling in the mini-channel. The main task of the system is to record images of two-phase flow with a high-speed video camera, which is equipped with the synchronous movement system. The data, in the form of the footage of two-phase flow structures, were subjected to the analysis with the scripts, developed for that purpose in the MathWorks Matlab 2010b environment. The scripts allowed the determination of void fraction for each pattern of two-phase flow structures observed, at various heat fluxes and various volume fluxes, for two spatial orientations of the mini-channel: vertical and horizontal.

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“…These parameters are in particular: temperature and pressure at characteristic points of the system, mass flux of the boiling fluid, heat flux and void fraction. The measurements of the void fraction were combined with photographic recording of boiling two-phase flow structures, characteristic for horizontal orientation of the minichannel [4,5].…”

Section: Introductionmentioning

confidence: 99%

Application of the 2-D Trefftz Method for Identification of Flow Boiling Heat Transfer Coefficient in a Rectangular MiniChannel

et al. 2020

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The study presents the experimental and numeric heat transfer investigations in flow boiling of water through an asymmetrically heated, rectangular and horizontal minichannel, with transparent side walls. A dedicated system was designed to record images of two-phase flow structures using a high-speed video camera with a synchronous movement system. The images were analyzed with Matlab 2019a scripts for determination of the void fraction for each pattern of two-phase flow structures observed. The experimental data measured during the experimental runs included inlet and outlet temperature, temperature at three internal points of the heater body, volume flux of the flowing water, inlet pressure, pressure drop, current and the voltage drop in the heater power supply. The flows were investigated at Reynolds number characteristic of laminar flow. The mathematical model assumed the heat transfer process in the measurement module to be steady-state with temperature independent thermal properties of solids and flowing fluid. The defined two inverse heat transfer problems were solved with the Trefftz method with two sets of T- functions. Graphs were used to represent: the boiling curves, the local void fraction values, the boiling heat transfer coefficients and the errors of both of them for selected mass fluxes and heat fluxes.

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Photographic Technique Application to the Determination of Void Fraction in Two-Phase Flow Boiling in Mini Channels

Cited by 4 publications

References 2 publications

Heat Transfer Coefficient Identification in Mini-Channel Flow Boiling with the Hybrid Picard–Trefftz Method

Heat Transfer Coefficient Identification in Mini-Channel Flow Boiling with the Hybrid Picard–Trefftz Method

Photographic Technique Application to the Determination of Void Fraction in Two-Phase Flow Boiling in Mini Channels

Application of the 2-D Trefftz Method for Identification of Flow Boiling Heat Transfer Coefficient in a Rectangular MiniChannel

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