scholarly journals Effect of Surface Cavity Shape on PM Deposition and Pressure Drop in DPF Porous Material

2018 ◽  
Vol 67 (5) ◽  
pp. 562-567 ◽  
Author(s):  
Maki NAKAMURA ◽  
Masakuni OZAWA
Keyword(s):  
Pressure Drop ◽  
Porous Material ◽  
Cavity Shape ◽  
Surface Cavity ◽  
Effect Of Surface

Numerical Investigation of Two-Phase Flow Over Unglazed Plate Collector Covered With Porous Material of Wire Screen for Solar Water Heater Application

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
T. Salameh ◽  
Y. Zurigat ◽  
A. Badran ◽  
C. Ghenai ◽  
M. El Haj Assad ◽  
...  
Keyword(s):  
Surface Tension ◽  
Porous Material ◽  
Water Flow ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Phase Flow ◽  
Two Phase ◽  
Solar Water ◽  
Wire Screen ◽  
Effect Of Surface

This paper presents three-dimensional numerical simulation results of the effect of surface tension on two-phase flow over unglazed collector covered with a wire screen. The homogenous model is used to simulate the flow with and without the effect of porous material of wire screen and surface tension. The Eulerian-Eulerian multiphase flow approach was used in this study. The phases are completely stratified, the interphase is well defined (free surface flow), and interphase transfer rate is very large. The liquid–solid interface, gas–liquid interface, and the volume fraction for both phases were considered as boundaries for this model. The results show that the use of porous material of wire screen will reduce the velocity of water flow and help the water flow to distribute evenly over unglazed plate collector. The possibility of forming any hot spot region on the surface was reduced. The water velocity with the effect of surface tension was found higher than the one without this effect, due to the extra momentum source added by surface tension in longitudinal direction. The use of porous material of wires assures an evenly distribution flow velocity over the inclined plate, therefore helps a net enhancement of heat transfer mechanism for unglazed solar water collector application.

Theoretically-Based Leidenfrost Point Model

2000 ◽  
Author(s):  
John D. Bernardin ◽  
Issam Mudawar
Keyword(s):  
Bubble Nucleation ◽  
Liquid Gallium ◽  
Interface Temperature ◽  
Sessile Droplet ◽  
Solid Interface ◽  
Leidenfrost Temperature ◽  
Size Characterization ◽  
Surface Cavity ◽  
Effect Of Surface ◽  
Good Agreement

Abstract This study presents a theoretically-based model of the Leidenfrost point (LFP); the minimum liquid/solid interface temperature required to support film boiling on a smooth surface. The model is structured around bubble nucleation, growth, and merging criteria, as well as surface cavity size characterization. It is postulated that for liquid/solid interface temperatures at and above the LFP, a sufficient number of cavities (about 20%) are activated and the bubble growth rates are sufficiently fast that a continuous vapor layer is established nearly instantaneously between the liquid and the solid. The model is applicable to both pools of liquid and sessile droplets. The effect of surface cavity distribution on the LFP predicted by the model is verified for boiling on aluminum, nickel and silver surfaces, as well as on a liquid gallium surface. The model exhibits good agreement with experimental sessile droplet data for water, FC-72, and acetone. While the model was developed for smooth surfaces on which the roughness asperities are of the same magnitude as the cavity radii (0.1–1.0 μm), it is capable of predicting the boundary or limiting Leidenfrost temperature for rougher surfaces with good accuracy.

Thermal performance evaluation of a microchannel with different porous media insert configurations

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Rouhollah Moosavi ◽  
Mehdi Banihashemi ◽  
Cheng-Xian Lin
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Performance Evaluation ◽  
Pressure Drop ◽  
Porous Material ◽  
Thermal Performance ◽  
Longitudinal Direction ◽  
Performance Ratio ◽  
Content Type ◽  
Porous Blocks

Purpose This paper aims to numerically investigate the thermal performance evaluation of a microchannel with different porous media insert configurations. Design/methodology/approach Heat transfer and pressure drop of fluid flow through a three-dimensional (3D) microchannel with different partially and filled porous media insert configurations are investigated numerically. The number of divisions and positions of porous material inside the microchannel for 12 different arrangements are considered. A control volume method is used for single-phase laminar flow with the Darcy–Forchheimer model used for the porous media. The geometry of the problem consists of a microchannel with a rectangular cross-section of 0.4 mm × 0.2 mm and length 20 mm, with a stainless steel porous material insert with a porosity coefficient of ε = 0.32 and a Darcy number of Da = 2.7 × 10−4. Findings Numerical results show that when the transverse arrangement is used, as the number of partitions increases, the thermal performance is improved and the heat transfer increases up to 300% compared to that of the plain microchannel. Comparing the obtained results from the microchannels with transverse and longitudinal configurations, at low Reynolds numbers, the transverse arrangement of porous blocks and at high Reynold numbers, the longitudinal arrangement present the best thermal performance which is virtually four times higher compared to the obtained Nu numbers from the plain microchannel. The results show that as the volume of porous material is constant in the cases with various transverse porous blocks, the pressure drop is not changed in these cases. Also, the highest thermal performance ratio is when the porous material is placed along the walls in a longitudinal direction. Originality/value To the best knowledge of the authors, in the previous research, the effect of the arrangement and location of the porous medium in the transverse and longitudinal direction in the microchannel and their effect in different states on the behavior of flow and heat transfer has not been numerically investigated. In this study, the porous media configuration and its placement in a 3D microchannel were numerically studied. The effect of porous material layout and configurations in different longitudinal and transverse directions on the pressure drop, heat transfer and thermal performance in the 3D microchannel is investigated numerically.

Experimental Investigation of the Effect of Surface Tension and the Correlation on Void Fraction and Frictional Pressure Drop of an Air-Liquid Two-Phase Flow in a Horizontal Flat Capillary Rectangular Channel

2003 ◽  
Author(s):  
Hideo Ide ◽  
Tohru Fukano
Keyword(s):  
Surface Tension ◽  
Pressure Drop ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Rectangular Channel ◽  
Surfactant Solution ◽  
Phase Flow ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Effect Of Surface

Air-liquid two-phase flow in a horizontal flat capillary rectangular channel has been studied to clarify the effects of concentration of surfactant solution on the flow phenomena, such as flow patterns, pressure drop, void fraction and so on. The concentrations of surfactant solution were 0, 10, 50 and 100 ppm and the surface tension of each solution was reduced to about 34mN/m from that of pure water of about 72mN/m. The dimension of the channel used was 10.0 mm × 1.0 mm. The drag reduction by mixing the surfactant was examined in both the single phase flow and the two-phase flow. The experimental data of two-phase frictional pressure drop and holdup were compared with the respective correlations which were previously proposed by the other researchers and the present authors. Finally, we proposed new correlations of two-phase frictional pressure drop and holdup in which the effect of surface tension and the aspect ratio of cross section of channel were taken into account.

Experimental Study on the Effect of Surface Tension on Void Fraction and Frictional Pressure Drop of an Air-Liquid Two-Phase Flow in a Horizontal Flat Narrow Rectangular Channel

2003 ◽  
Author(s):  
Hideo Ide ◽  
Tohru Fukano
Keyword(s):  
Surface Tension ◽  
Pressure Drop ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Pure Water ◽  
Rectangular Channel ◽  
Phase Flow ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Effect Of Surface

Air-liquid two-phase flow in a horizontal flat capillary rectangular channel has been studied to clarify the effects of surface tension on the flow phenomena, such as flow patterns, holdup and frictional pressure drop and so on. The concentrations of surfactant solution were 0, 10, 50 and 100 ppm and the surface tension of each solution was reduced to about 34mN/m from that of pure water of about 72mN/m. The dimension of the channel used was 10.0 mm×1.0 mm. The drag reduction by mixing the surfactant was examined in both the single phase flow and the two-phase flow. The experimental data of void fraction and two-phase frictional pressure drop were compared with the respective correlations which were previously proposed by the other researchers. Finally, we proposed new correlations of two-phase frictional pressure drop in which the effect of surface tension and the aspect ratio of cross section of channel were taken into account.

Effect of surface wettability on pressure drop in single and two-phase flow

2003 ◽  
Vol 2003 (0) ◽  
pp. 349-350
Author(s):  
Yuta UCHINO ◽  
Yasuyuki TAKATA ◽  
Sumitomo HIDAKA ◽  
Tadamichi NAKAMURA
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Surface Wettability ◽  
Phase Flow ◽  
Two Phase ◽  
Effect Of Surface
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