Two-phase flow boiling in a microfluidic channel at high mass flux

2020 ◽  
Vol 32 (9) ◽  
pp. 093309 ◽  
Author(s):  
Chanyoot Keepaiboon ◽  
Ahmet Selim Dalkilic ◽  
Omid Mahian ◽  
Ho Seon Ahn ◽  
Somchai Wongwises ◽  
...  
Keyword(s):  
Mass Flux ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Microfluidic Channel ◽  
High Mass ◽  
Phase Flow ◽  
Two Phase

Pressure Drop in a Capillary Tube in Boiling Two-Phase Flow

2003 ◽  
Author(s):  
Fumito Kaminaga ◽  
Baduge Sumith ◽  
Kunihito Matsumura
Keyword(s):  
Pressure Drop ◽  
Vapor Phase ◽  
Mass Flux ◽  
Two Phase Flow ◽  
Capillary Tube ◽  
Flow Boiling ◽  
Phase Flow ◽  
Two Phase ◽  
System Pressure ◽  
Phase Pressure

Two-phase pressure drop is experimentally examined in a flow boiling condition in a tube of diameter 1.45 mm using water in ranges of pressure from 10 to 100 kPa, mass flux from 18 to 152 kg/m2s, heat flux from 13 to 646 kW/m2, and exit quality from 0.02 to 0.77. Also, pressure drop in an adiabatic air-water two-phase flow is measured at atmospheric pressure using the same test section and mass flux ranges of liquid and gas as those in the flow boiling. Decreasing system pressure the pressure drop significantly increases at a given mass flux. Influence of vapor phase on the pressure drop is found to be large both in the adiabatic and the diabatic conditions. The frictional pressure drop correlation for the adiabatic two-phase flow is developed and applied to predict pressure drop in the flow boiling. But it cannot give satisfactory predictions. The Chisholm correlation calculating a two-phase pressure drop multiplier is modified to account the influence of vapor phase in a capillary tube and the modified correlation can predict the pressure drop in the flow boiling within an error of 20%.

Two-Phase Flow Patterns During Microchannel Vaporization of CO2 at Near-Critical Pressures

2003 ◽  
Author(s):  
Jostein Pettersen
Keyword(s):  
Heat Transfer ◽  
Flow Pattern ◽  
Mass Flux ◽  
Two Phase Flow ◽  
Bubble Formation ◽  
Glass Tube ◽  
Flow Patterns ◽  
High Mass ◽  
Phase Flow ◽  
Two Phase

Carbon dioxide (CO2 / R-744) is receiving renewed interest as a refrigerant, in many cases based on systems with microchannel heat exchangers that have high pressure capability, efficient heat transfer, and compact design. A good understanding of two-phase flow of evaporating CO2 in microchannels is needed to analyze and predict heat transfer. A special test rig was built in order to observe two-phase flow patterns, using a horizontal quartz glass tube with ID 0.98 mm, externally coated by a transparent resistive film. Heat flux was obtained by applying DC power to the film, and flow patterns were recorded at 4000 or 8000 frames per second by a digital video camera. Flow patterns were recorded for temperatures 20°C and 0°C, and for mass flux ranging from 100 to 580 kgm−2s−1. The observations showed a dominance of intermittent (slug) flow at low x, and wavy annular flow with entrainment of droplets at higher x. At high mass flux, the annular/entrained flow pattern could be described as dispersed. The aggravated dryout problem reported from heat transfer experiments at high mass flux could be explained by increased entrainment. Stratified flow was not observed in the tests with heat load. Bubble formation and growth could be observed in the liquid film, and the presence of bubbles gave differences in flow pattern compared to adiabatic flow. The flow pattern observations did not fit generalized maps or transition lines showed in the literature.

scholarly journals Identifying synchronization between flow boiling inside two parallel minichannels using joint recurrence plots

2018 ◽  
Vol 240 ◽  
pp. 03006
Author(s):  
Hubert Grzybowski ◽  
Iwona Gruszczyńska ◽  
Romuald Mosdorf
Keyword(s):  
Mass Flux ◽  
High Speed ◽  
Phase Synchronization ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Measurement Data ◽  
Heat Rate ◽  
Phase Flow ◽  
Two Phase ◽  
Oscillation Analysis

In this study the flow boiling inside two parallel tubes with a diameter of 1 mm was analysed in order to determine synchronization level between the channels. An experimental setup was built to investigate the pressure and temperature oscillation in parallel minichannels. During the experiments, the two-phase flow patterns were recorded by high speed camera and also the presence of vapour in channel outlet was measured by laser-phototransistor sensor. Various types of two-phase flow instabilities were observed in investigated the system. Experiment was carried out for various heat rate and mass flux. The method of identifying synchronization between flow boiling between parallel channel will be presented on measurement data recorded for heat rate q equal to 50.15 W and the average mass flux ṁ equal to 38.8 kg/m2s. The signal was subjected to a nonlinear analysis based on the joint recurrence plot (JRP) method. The JRP method was carried out in order to determine synchronization level between signals from parallel channels. Results of pressure and laser-phototransistor oscillation analysis shows that during flow boiling phase synchronization and phase shift between the channels can be detected using appropriate RQA indicators.

Pressure Drop of Two-Phase Flow Boiling with R-22 and R-290 in 7.6 mm Diameter Tube

2016 ◽  
Vol 818 ◽  
pp. 23-27
Author(s):  
Agus Sunjarianto Pamitran ◽  
Nasruddin ◽  
Helmi Dadang Ardiansyah ◽  
Muhammad Idrus Alhamid
Keyword(s):  
Heat Flux ◽  
Pressure Drop ◽  
Mass Flux ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Saturation Temperature ◽  
Phase Flow ◽  
Lower Mass ◽  
Two Phase ◽  
Experimental Pressure

The characteristics of two-phase flow boiling of R-290 are required for replacing R-22 that has been phased-out. The present study focuses on experimental pressure drop for R-22 and R-290. The experiment was run with heat flux of 5.09 kW/m2 to 19.03 kW/m2, mass flux of 114.91 kg/m2s to 751.74 kg/m2s and saturation temperature of 4.77°C to 18.12°C. The present result showed that pressure drop was affected by heat flux, mass flux and saturation temperature. Lower mass flux, heat flux and saturation temperature results in lower pressure drop. The pressure drop of R-290 is lower than that of R-22. Among the existing pressure drop prediction methods, Lokhart-Martinelli (1949) gives the best prediction for the present pressure drop data.

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