scholarly journals Two-phase pressure drop of refrigerants during flow boiling in small channels: an experimental investigation and correlation development

2000 ◽  
Vol 26 (11) ◽  
pp. 1739-1754 ◽  
Author(s):  
T.N Tran ◽  
M.-C Chyu ◽  
M.W Wambsganss ◽  
D.M France
Keyword(s):  
Experimental Investigation ◽  
Pressure Drop ◽  
Flow Boiling ◽  
Two Phase ◽  
Small Channels ◽  
Phase Pressure

Experimental Adiabatic Two-Phase Pressure Drops of R134a, R236fa and R245fa in Small Horizontal Circular Channels

2011 ◽  
Author(s):  
Chin L. Ong ◽  
John R. Thome
Keyword(s):  
Pressure Drop ◽  
Flow Boiling ◽  
Homogeneous Model ◽  
Prediction Methods ◽  
Two Phase ◽  
Pressure Drops ◽  
Wide Range ◽  
Small Channels ◽  
Experimental Pressure ◽  
Phase Pressure

Experimental adiabatic two-phase pressure drops data for refrigerants R134a, R236fa and R245fa during flow boiling in small channels with internal diameters of 1.03, 2.20 and 3.04 mm are presented. The main purpose was to investigate the effects of channel confinement on adiabatic two-phase pressure drops. Thus, the two-phase pressure drop trends were systematically investigated over a wide range of test conditions for all three refrigerants and channel sizes. Statistical comparisons have also been made by comparing the experimental pressure drop data database with various macroscale and microscale prediction methods from the literature. The comparison showed relatively moderate accuracy for three prediction methods developed for macroscale flows, i.e. Baroczy and Chisholm, Friedel and the homogeneous model with the Cicchitti et al. viscosity relation. As for microscale prediction methods, the Cioncolini et al. annular flow model worked best with 68.5% of the data within ± 30%, followed by the Sun and Mishima and the Zhang et al. methods. Combining this database with the LTCM lab’s earlier database for 0.509 and 0.790 mm channels, there appears to be no evidence of a macro-to-microscale transition, at least with respect to two-phase pressure drops.

High Heat Flux Subcooled Flow Boiling of Methanol in Microtubes

2015 ◽  
Author(s):  
Farzad Houshmand ◽  
Hyoungsoon Lee ◽  
Mehdi Asheghi ◽  
Kenneth E. Goodson
Keyword(s):  
Heat Flux ◽  
Pressure Drop ◽  
Flow Boiling ◽  
High Heat ◽  
Heat Fluxes ◽  
Two Phase ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow ◽  
Inner Diameter ◽  
Phase Pressure

As the proper cooling of the electronic devices leads to significant increase in the performance, two-phase heat transfer to dielectric liquids can be of an interest especially for thermal management solutions for high power density devices with extremely high heat fluxes. In this paper, the pressure drop and critical heat flux (CHF) for subcooled flow boiling of methanol at high heat fluxes exceeding 1 kW/cm2 is investigated. Methanol was propelled into microtubes (ID = 265 and 150 μm) at flow rates up to 40 ml/min (mass fluxes approaching 10000 kg/m2-s), boiled in a portion of the microtube by passing DC current through the walls, and the two-phase pressure drop and CHF were measured for a range of operating parameters. The two-phase pressure drop for subcooled flow boiling was found to be significantly lower than the saturated flow boiling case, which can lead to lower pumping powers and more stability in the cooling systems. CHF was found to be increasing almost linearly with Re and inverse of inner diameter (1/ID), while for a given inner diameter, it decreases with increasing heated length.

Two-Phase Pressure Drop and Boiling Heat Transfer in a Single Horizontal Microchannel

2006 ◽  
Author(s):  
Cheol Huh ◽  
Moo Hwan Kim
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Mass Flux ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Local Flow ◽  
Heat Transfer Coefficients ◽  
Phase Pressure

With a single microchannel and a series of microheaters made with MEMS technique, two-phase pressure drop and local flow boiling heat transfer were investigated using deionized water in a single horizontal rectangular microchannel. The test microchannel has a hydraulic diameter of 100 μm and length of 40 mm. A real time observation of the flow patterns with simultaneous measurement are made possible. Tests are performed for mass fluxes of 90, 169, and 267 kg/m2s and heat fluxes of from 100 to 600 kW/m2. The experimental local flow boiling heat transfer coefficients and two-phase frictional pressure gradient are evaluated and the effects of heat flux, mass flux, and vapor qualities on flow boiling are studied. Both the evaluated experimental data are compared with existing correlations. The experimental heat transfer coefficients are nearly independent on mass flux and the vapor quality. Most of all correlations do not provide reliable heat transfer coefficients predictions with vapor quality and prediction accuracy. As for two-phase pressure drop, the measured pressure drop increases with the mass flux and heat flux. Most of all existing correlations of two-phase frictional pressure gradient do not predict the experimental data except some limited conditions.

scholarly journals Flow boiling of water in a minichannel: The effects of surface wettability on two-phase pressure drop

2011 ◽  
Vol 31 (11-12) ◽  
pp. 1894-1905 ◽  
Author(s):  
Hai Trieu Phan ◽  
Nadia Caney ◽  
Philippe Marty ◽  
Stéphane Colasson ◽  
Jérôme Gavillet
Keyword(s):  
Pressure Drop ◽  
Flow Boiling ◽  
Surface Wettability ◽  
Two Phase ◽  
Phase Pressure

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%.

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