Numerical Flow Visualization and Thermal Transport Phenomena Over a Slot-Perforated Flat Surface in Pulsating Channel Flow

2002 ◽  
Author(s):  
Shuichi Torii ◽  
Wen-Jei Yang
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Channel Flow ◽  
Heat Transfer Performance ◽  
Theoretical Study ◽  
Flat Surface ◽  
Plate Thickness ◽  
Transfer Performance ◽  
Thermal Fields ◽  
Thermal Fluid Flow

A theoretical study is performed to investigate unsteady, two-dimensional, incompressible thermal-fluid flow over both sides of a slot-perforated flat surface, which is placed in a pulsating channel flow. The roles of both the pulsating Strouhal number and the ratio of the channel width to the plate thickness, W/δ, on the velocity and thermal fields are disclosed. It is found from the study that: (i) when the channel stream is pulsated, the alternating change in the fluid flow disturbs the thermal boundary layer formed along the plate and induces mixing of the upper and lower streams of the plate downstream from the slot, resulting in an amplification of heat transfer performance, and (ii) heat transfer performance at the plate is attenuated with a decrease in W/δ.

Effect of Blockage Factor on Thermal-Fluid Flow Transport Phenomenon Over Slot-Perforated Flat Surface in Channel

2003 ◽  
Author(s):  
Shuichi Torii ◽  
Shinzaburo Umeda ◽  
Wen-Jei Yang
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Transfer Performance ◽  
Flat Surface ◽  
Plate Thickness ◽  
Transfer Performance ◽  
Thermal Fields ◽  
Blockage Factor ◽  
Exchange Resins ◽  
Thermal Fluid Flow

A numerical and experimental study is performed to investigate unsteady, two-dimensional, incompressible laminar flow over both sides of a slot-perforated flat surface, which is placed in a channel. Enhances is placed on the effect of the blockage factor, i.e., the ratio of plate thickness, δ, to channel width, W, on the heat transfer performance and the velocity and thermal fields. It is found from the study that: (i) when the slot width is increased, the alternating change in the fluid flow disturbs the thermal boundary layer formed along the plate and induces mixing of the upper and lower streams of the plate downstream from the slot, resulting in an amplification of heat transfer performance; (ii) heat transfer performance at the rear plate is induced with an increase in d/δ and Re; and (iii) by contrast, heat transfer performance is attenuated with an increase in the blockage factor, whose effect becomes larger in the lower region of the Reynolds number. These results are confirmed by the flow visualization using ion-exchange resins.

Thermal Fluid Flow Transport Phenomenon Over Vertical Slot-Perforated Flat Fins With Heat Sink in Natural Convection Environment

2005 ◽  
Author(s):  
Shuichi Torii ◽  
Wen-Jei Yang ◽  
Naoko Iino
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Heat Sink ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Vertical Slot ◽  
Flow Transport ◽  
Thermal Fluid Flow

A theoretical study is performed to investigate unsteady thermal and fluid flow transport phenomena over vertical slot-perforated flat fins with heat sink, which are placed in a natural convection environment. Emphasis is placed on the effects of Rayleigh number and fin pitch on heat transfer performance and velocity and thermal fields. It is found from the study that (i) in the high Rayleigh number region, the alternating changes in the fluid flow take place for larger fin pitch, (ii) the alternating flow in the space area between two fins is mutually interacted by the corresponding one from the adjacent in-line plate fines, resulting in an amplification of heat transfer performance, and (iii) heat-transfer performance is intensified with an increase in the fin pitch, whose trend becomes larger in the higher Rayleigh number region considered here.

Thermal Fluid Flow Transport Phenomena in a Channel Containing Slot-Perforated Flat Plates

2007 ◽  
Author(s):  
Shuichi Torii ◽  
Wen Jei Yang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Heat Transfer Performance ◽  
Numerical Study ◽  
Plate Thickness ◽  
Transfer Performance ◽  
Flat Plates ◽  
Lower Region ◽  
Blockage Factor

A numerical study is performed to investigate unsteady, two-dimensional, incompressible laminar flow over both sides of a slot-perforated flat surface in a pulsating channel flow. Enhances is placed on the effects of the pulsating Strouhal number, the Reynolds number Re, the blockage factor, i.e., the ratio of plate thickness, d, to channel width, W, on the heat transfer performance and the velocity and thermal fields. It is found from the study that: (i) when the fluid stream is pulsated, the alternating change in the fluid flow disturbs the thermal boundary layer formed along the plate and induces mixing of the upper and lower streams of the plate downstream from the slot, resulting in an amplification of heat-transfer performance; (ii) heat transfer performance at the rear plate is induced with Re; (iii) by contrast, heat transfer performance is attenuated with an increase in the blockage factor, whose effect becomes larger in the lower region of the Reynolds number; and (iv) heat transfer performance is intensified with an increase in fSr, whose effect becomes minor in the lower region of the Reynolds number.

Thermal Transport Phenomena Over Slot-Perforated Flat Fins With Heat Sink in Forced Convection Environment

2004 ◽  
Author(s):  
Shuichi Torii ◽  
Wen-Jei Yang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Forced Convection ◽  
Heat Sink ◽  
Heat Transfer Performance ◽  
Transport Phenomena ◽  
Transfer Performance ◽  
Thermal Fields ◽  
High Reynolds

A theoretical study is performed to investigate unsteady thermal and fluid flow transport phenomena over flat fins with heat sink, which are placed in a forced convection environment. Emphasis is placed on the effects of Reynolds number and fin pitch on heat transfer performance and velocity and thermal fields. It is found from the study that (i) in the high Reynolds number region, the alternating changes in the fluid flow take place for larger fin pitch, (ii) the alternating flow in the space area between two fins is mutually interacted by the corresponding one from the adjacent in-line plate fines, resulting in an amplification of heat transfer performance, and (iii) heat-transfer performance is intensified with a decrease in the fin pitch, whose trend becomes larger in the higher Reynolds number region considered here.

Flow Visualization and Thermal-Fluid Flow Phenomenon in Single Plate Heat Exchanger with Various Plate Shapes Formed by Shock Processing Method

2011 ◽  
Vol 673 ◽  
pp. 35-39 ◽  
Author(s):  
Shuichi Torii
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Transfer Performance ◽  
Plate Heat Exchanger ◽  
Transfer Performance ◽  
Plate Heat ◽  
Single Plate ◽  
Thermal Fluid Flow

The aim of the present study is to improve heat transfer performance and to attenuate pressure drop in plate heat exchanger with the different plate shapes. In this study, the single plate model of the plate heat exchanger is made and the thermal fluid flow characteristics in the narrows channel are examined for two different shaped plates, i.e., separate herringbone and plover patterns and the results are compared with that of flat or herringbone plate. In addition, the flow of the fluid with the surface of the rugged plate in the plate heat exchanger was visualized by tuft method. It is found that if the separate herringbone plate whose pith is 2 is employed, heat transfer performance is substantially enhanced for the high Reynolds number region, while pressure drop is suppressed.

A Study on Flow Boiling in Microchannel With Piranha Pin Fin

2015 ◽  
Author(s):  
X. Yu ◽  
C. Woodcock ◽  
Y. Wang ◽  
J. Plawsky ◽  
Y. Peles
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Fluid Flow ◽  
Pressure Drop ◽  
Heat Transfer Performance ◽  
Flow Boiling ◽  
Transfer Performance ◽  
Flow Conditions ◽  
Pin Fin ◽  
Flow And Heat Transfer

In this paper we reported an advanced structure, the Piranha Pin Fin (PPF), for microchannel flow boiling. Fluid flow and heat transfer performance were evaluated in detail with HFE7000 as working fluid. Surface temperature, pressure drop, heat transfer coefficient and critical heat flux (CHF) were experimentally obtained and discussed. Furthermore, microchannels with different PPF geometrical configurations were investigated. At the same time, tests for different flow conditions were conducted and analyzed. It turned out that microchannel with PPF can realize high-heat flux dissipation with reasonable pressure drop. Both flow conditions and PPF configuration played important roles for both fluid flow and heat transfer performance. This study provided useful reference for further PPF design in microchannel for flow boiling.

Experimental and Numerical Studies of Fluid Flow Confined in Microchannel

2016 ◽  
Author(s):  
Yan Wang ◽  
Xiang Ling
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Friction Factor ◽  
Heat Transfer Performance ◽  
Pure Water ◽  
High Heat Flux ◽  
Transfer Performance ◽  
Parallel Microchannels

The heat transfer performance of fluid flowing in a microchannel was experimentally studied, to meet the requirement of extremely high heat flux removal of microelectronic devices. There were 10 parallel microchannels with rectangular cross-section in the stainless steel plate, which was covered by a glass plate to observe the fluid flowing behavior, and another heating plate made of aluminum alloy was positioned behind the microchannel. Single phase heat transfer and fluid flow downstream the microchannel experiments were conducted with both deionized water and ethanol. Besides experiments, numerical models were also set up to make a comparison with experimental results. It is found that the pressure drop increases rapidly with enlarging Reynolds number (200), especially for ethanol. With comparison, the flow resistance of pure water is smaller than ethanol. Results also show that the friction factor decreases with Reynolds number smaller than the critical value, while increases the velocity, the friction factor would like to keep little changed. We also find that the water friction factors obtained by CFD simulations in parallel microchannels are much larger than experiment results. With heat flux added to the fluid, the heat transfer performance can be enhanced with larger Re number and the temperature rise could be weaken. Compared against ethanol, water performed much better for heat removal. However, with intensive heat flux, both water and ethanol couldn’t meet the requirement and the temperature at outlet would increase remarkably, extremely for ethanol. These findings would be helpful for thermal management design and optimization.

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