Visualization of Two-Phase Flows in Nanofluid Oscillating Heat Pipes

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
Qi-Ming Li ◽  
Jiang Zou ◽  
Zhen Yang ◽  
Yuan-Yuan Duan ◽  
Bu-Xuan Wang
Keyword(s):  
Heat Transfer ◽  
Flow Regime ◽  
Ccd Camera ◽  
Glass Tube ◽  
Outer Diameter ◽  
Two Phase Flows ◽  
Two Phase ◽  
Oscillating Heat Pipe ◽  
A Charge ◽  
Heat Loads

Two-phase flows in an oscillating heat pipe (OHP) charged with deionized (DI) water and a nanofluid (0.268% v/v) were experimentally investigated. The OHP was made of quartz glass tube (with an inner diameter of 3.53 mm and an outer diameter of 5.38 mm) and coated with a transparent heating film in its evaporating section. The internal two-phase flows at different heat loads were recorded by a charge-coupled device (CCD) camera. Only column flow was observed in the DI water OHP while in the nanofluid OHP the flow first was column, then slug and annular flows as the heat load was steadily increased. Heat transfer in the OHP was strongly related to the two-phase regime. The flow regime transitions effectively increased the operating allowable heat loads in the nanofluid OHP two- to threefold relative to the DI water OHP. The nanofluid OHP had a much lower thermal resistance than the DI water OHP with the most effective heat transfer in the nanofluid OHP occurring in the slug flow regime.

Experimental Investigation on Nanofluids Effectiveness on Heat Transfer in Oscillating Heat Pipe

2013 ◽  
Vol 856 ◽  
pp. 98-102 ◽  
Author(s):  
Hamid R. Goshayeshi ◽  
Ali Khosravi ◽  
Mehdi Abedpour Karizaki
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Pipe ◽  
High Speed ◽  
Oscillatory Flow ◽  
Glass Tube ◽  
Heat Pipes ◽  
Oscillating Heat Pipe ◽  
Flow And Heat Transfer ◽  
Heat Loads

An experimental investigation of the oscillatory flow and heat transfer in a vertical oscillating heat pipe (OHP) was conducted. The oscillating heat pipe was made of a copper-glass tube. Flow inside the oscillating heat pipe at different heat loads was recorded by a high speed camera. Through this research, the authors investigated the effect of utilizing nanofluids on heat transfer amount in heat pipes. The employed nanofluids in this study were water-Fe2O3, water-SiO2and water-TiO2with various volumetric concentrations. The results show that after adding nanoparticles in the base fluid (here water) heat transfer rate increases significantly. It's also noteworthy, of the all applied nanofluids, water-TiO2mixture presents the best enhancement in heat transfer amount.

scholarly journals Study of Pressure Drops and Heat Transfer of Nonequilibrial Two-Phase Flows

Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2275
Author(s):  
Aleksandr V. Belyaev ◽  
Alexey V. Dedov ◽  
Ilya I. Krapivin ◽  
Aleksander N. Varava ◽  
Peixue Jiang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Flow Regime ◽  
Flow Boiling ◽  
Experimental Studies ◽  
High Mass ◽  
Calculation Methods ◽  
Two Phase Flows ◽  
Two Phase ◽  
Pressure Drops ◽  
Wide Range

Currently, there are no universal methods for calculating the heat transfer and pressure drop for a wide range of two-phase flow parameters in mini-channels due to changes in the void fraction and flow regime. Many experimental studies have been carried out, and narrow-range calculation methods have been developed. With increasing pressure, it becomes possible to expand the range of parameters for applying reliable calculation methods as a result of changes in the flow regime. This paper provides an overview of methods for calculating the pressure drops and heat transfer of two-phase flows in small-diameter channels and presents a comparison of calculation methods. For conditions of high reduced pressures pr = p/pcr ≈ 0.4 ÷ 0.6, the results of own experimental studies of pressure drops and flow boiling heat transfer of freons in the region of low and high mass flow rates (G = 200–2000 kg/m2 s) are presented. A description of the experimental stand is given, and a comparison of own experimental data with those obtained using the most reliable calculated relations is carried out.

Comparison of Pressure Drop and Endwall Heat Transfer Measurements to Flow Visualization Testing of Solid and Porous Pin Fin Arrays

2009 ◽  
Author(s):  
Jared M. Pent ◽  
Jay S. Kapat ◽  
Mark Ricklick
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Visualization ◽  
Local Heat Transfer ◽  
Ccd Camera ◽  
Local Heat ◽  
Transfer Coefficients ◽  
Porous Aluminum ◽  
Pin Fins ◽  
A Charge

This paper examines the local and averaged endwall heat transfer effects of a staggered array of porous aluminum pin fins with a channel blockage ratio (blocked channel area divided by open channel area) of 50%. Two sets of pins were used with pore densities of 0 (solid) and 10 pores per inch (PPI). The pressure drop through the channel was also determined for several flow rates using each set of pins. Local heat transfer coefficients on the endwall were measured using Thermochromatic Liquid Crystal (TLC) sheets recorded with a charge-coupled device (CCD) camera. Static and total pressure measurements were taken at the entrance and exit of the test section to determine the overall pressure drop through the channel and explain the heat transfer trends through the channel. The heat transfer and pressure data was then compared to flow visualization tests that were run using a fog generator. Results are presented for the two sets of pins with Reynolds numbers between 25000 and 130000. Local HTC (heat transfer coefficient) profiles as well as spanwise and streamwise averaged HTC plots are displayed for both pin arrays. The thermal performance was calculated for each pin set and Reynolds number. All experiments were carried out in a channel with an X/D of 1.72, a Y/D of 2.0, and a Z/D of 1.72.

Comparison of 30 Boiling and Condensation Correlations for Two-Phase Flows in Compact Plate-Fin Heat Exchangers

2017 ◽  
Author(s):  
Wenhai Li ◽  
Ken Alabi ◽  
Foluso Ladeinde
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Flow Boiling ◽  
Transfer Coefficients ◽  
Two Phase Flows ◽  
Two Phase ◽  
Heat Transfer Coefficients ◽  
Heat Exchanger Design ◽  
Micro Channels ◽  
Vertical Tubes

Over the years, empirical correlations have been developed for predicting saturated flow boiling [1–15] and condensation [16–30] heat transfer coefficients inside horizontal/vertical tubes or micro-channels. In the present work, we have examined 30 of these models, and modified many of them for use in compact plate-fin heat exchangers. However, the various correlations, which have been developed for pipes and ducts, have been modified in our work to make them applicable to extended fin surfaces. The various correlations have been used in a low-order, one-dimensional, finite-volume type numerical integration of the flow and heat transfer equations in heat exchangers. The NIST’s REFPROP database [31] is used to account for the large variations in the fluid thermo-physical properties during phase change. The numerical results are compared with Yara’s experimental data [32]. The validity of the various boiling and condensation models for a real plate-fin heat exchanger design is discussed. The results show that some of the modified boiling and condensation correlations can provide acceptable prediction of heat transfer coefficient for two-phase flows in compact plate-fin heat exchangers.

On the Application of Macro-Pipe Two-Phase Heat Transfer Correlations and Flow Regime Maps to Mini-Channels

2006 ◽  
Author(s):  
Avram Bar-Cohen ◽  
Ilai Sher ◽  
Emil Rahim
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flow Regime ◽  
Annular Flow ◽  
Negative Slope ◽  
Two Phase ◽  
Heat Transfer Correlations ◽  
Two Phase Heat Transfer ◽  
Flow Regime Maps

The present study is aimed at evaluating the ability of conventional “macro-pipe” correlations and regime transitions to predict the two-phase thermofluid characteristics of mini-channel cold plates. Use is made of the Taitel-Dukler flow regime maps, seven classical heat transfer coefficient correlations and two dryout predictions. The vast majority of the mini-channel two-phase heat-transfer data, taken from the literature, is predicted to fall in the annular regime, in agreement with the reported observations. A characteristic heat transfer coefficient locus has been identified, with a positive slope following the transition from Intermittent to Annular flow and a negative slope following the onset of partial dryout at higher qualities. While the classical two-phase heat transfer correlations are generally capable of providing good agreement with the low-quality annular flow data the quality at which partial dryout occurs and the ensuing heat transfer rates are not predictable by the available macro-pipe correlations.

Experimental Visualization and Numerical Simulation of Liquid-Gas Two-Phase Flows in a Horizontal Pipe

2017 ◽  
Author(s):  
Milad Darzi ◽  
Chanwoo Park
Keyword(s):  
Numerical Simulation ◽  
Gas Flow ◽  
Cfd Simulation ◽  
Glass Tube ◽  
Flow Patterns ◽  
Two Phase Flows ◽  
Two Phase ◽  
Mixture Flow ◽  
Horizontal Pipe ◽  
Flow Rates

This paper presents the results of both visualization experiment and numerical simulation for two-phase (water-air mixture) flows in a horizontal tube. A visualization experimental setup was used to observe various two-phase flow patterns for different flow rates of water/air mixture flow in a glass tube of 12 mm in diameter. Total of 303 experimental data points were compared with Mandhane’s flow map. Most of the data for stratified, plug and slug flows were found to be in good agreement. However, annular flow was observed for relatively lower gas flow rates and also wavy flow occurred at relatively higher liquid flow rates in this experiment. A three-dimensional Computational Fluid Dynamics (CFD) simulation was performed using OpenFOAM employing “interFoam” as the solver to simulate the two-phase flows in horizontal pipe based on Volume-Of-Fluid (VOF) method. The simulated and experimentally observed flow patterns for the same set of superficial velocities shows acceptable similarities for stratified, wavy, plug, slug and annular flows. Also, the computed values of the void fraction and pressure drop for the numerical simulations shows reasonable agreement with well-known correlations in literature.

Recent Progress in the Studies of Gas-Liquid Two-Phase Flows at Microgravity Conditions

2003 ◽  
Author(s):  
Tomoji Takamasa ◽  
Takashi Hibiki
Keyword(s):  
Recent Progress ◽  
Interfacial Area ◽  
Phase System ◽  
Two Phase Flows ◽  
Two Phase ◽  
Interfacial Area Transport ◽  
Drift Flux ◽  
Wide Range ◽  
Microgravity Conditions ◽  
Heat Loads

In a thermal system of spacecraft, two-phase flow system now is an excellent alternative to the conventional single-phase system in transporting large amount of thermal energy at a uniform temperature regardless of variations in the heat loads. In addition, two-phase flows exist in a wide range of applications and enabling technologies in space. This report outlines recent progress in the studies of gas-liquid two-phase flows at microgravity conditions, especially for which regarding to interfacial area transport and drift flux.

scholarly journals Experimental Analysis of Gas–Liquid–Solid Three-Phase Flows in Horizontal Pipelines

2020 ◽  
Vol 105 (4) ◽  
pp. 1035-1054
Author(s):  
Paolo Sassi ◽  
Youssef Stiriba ◽  
Julia Lobera ◽  
Virginia Palero ◽  
Jordi Pallarès
Keyword(s):  
Flow Visualization ◽  
Flow Regime ◽  
Solid Particles ◽  
High Complexity ◽  
Flow Conditions ◽  
Two Phase Flows ◽  
Two Phase ◽  
Three Phase ◽  
Inner Diameter ◽  
The Individual

AbstractThe dynamics of three-phase flows involves phenomena of high complexity whose characterization is of great interest for different sectors of the worldwide industry. In order to move forward in the fundamental knowledge of the behavior of three-phase flows, new experimental data has been obtained in a facility specially designed for flow visualization and for measuring key parameters. These are (1) the flow regime, (2) the superficial velocities or rates of the individual phases; and (3) the frictional pressure loss. Flow visualization and pressure measurements are performed for two and three-phase flows in horizontal 30 mm inner diameter and 4.5 m long transparent acrylic pipes. A total of 134 flow conditions are analyzed and presented, including plug and slug flows in air–water two-phase flows and air–water-polypropylene (pellets) three-phase flows. For two-phase flows the transition from plug to slug flow agrees with the flow regime maps available in the literature. However, for three phase flows, a progressive displacement towards higher gas superficial velocities is found as the solid concentration is increased. The performance of a modified Lockhart–Martinelli correlation is tested for predicting frictional pressure gradient of three-phase flows with solid particles less dense than the liquid.

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