scholarly journals High-Performance Microchannels Development Using Magnetic Stabilization

2017 ◽  
Author(s):  
Seth Newport ◽  
Geoffrey Ormston ◽  
Michael Benedict ◽  
Ayyoub Mehdizadeh Momen
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Surface Area ◽  
High Performance ◽  
Packed Bed ◽  
Large Surface Area ◽  
Hydrodynamic Performance ◽  
Excessive Pressure ◽  
High Heat Transfer ◽  
Magnetic Stabilization

Creating a large surface area from a packed bed of particles is a necessary step for many packing, chemical, and heat transfer applications. However, the excessive pressure drop across the packed bed is not desirable in many of these applications. This problem can be addressed by using microchannels instead of the packed bed of particles, providing a high heat transfer rate at the acceptable pressure drop range. Microchannels offer a reduced amount of pressure drop due to their ability to introduce a low resistance flow passage while still providing the large surface area for heat and mass transfer. In this study, a magnetic stabilization process was developed to fabricate microchannels from the fine ferrite particles. The experimental hydrodynamic performance evaluation of such structures is described in this paper. This unique microchannel fabrication method can significantly improve thermal and hydrodynamic performance, while providing additional flexibility to control the porosity of the packed bed of particles.

An Analytical Study of the Optimized Performance of an Impingement Heat Sink

2004 ◽  
Vol 126 (4) ◽  
pp. 528-534 ◽  
Author(s):  
S. B. Sathe ◽  
B. G. Sammakia
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Sink ◽  
High Performance ◽  
Cross Flow ◽  
High Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
High Heat Transfer ◽  
Flow Through

The results of a study of a new and unique high-performance air-cooled impingement heat sink are presented. An extensive numerical investigation of the heat sink performance is conducted and is verified by experimental data. The study is relevant to cooling of high-power chips and modules in air-cooled environments and applies to workstations or mainframes. In the study, a rectangular jet impinges on a set of parallel fins and then turns into cross flow. The effects of the fin thickness, gap nozzle width and fin shape on the heat transfer and pressure drop are investigated. It is found that pressure drop is reduced by cutting the fins in the central impingement zone without sacrificing the heat transfer due to a reduction in the extent of the stagnant zone. A combination of fin thicknesses of the order of 0.5 mm and channel gaps of 0.8 mm with appropriate central cutout yielded heat transfer coefficients over 1500 W/m2 K at a pressure drop of less than 100 N/m2, as is typically available in high-end workstations. A detailed study of flow-through heat sinks subject to the same constraints as the impingement heat sink showed that the flow-through heat sink could not achieve the high heat transfer coefficients at a low pressure drop.

An Analytical Study of the Optimized Performance of an Impingement Heat Sink

2003 ◽  
Author(s):  
S. B. Sathe ◽  
B. G. Sammakia
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Sink ◽  
High Performance ◽  
Cross Flow ◽  
High Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
High Heat Transfer ◽  
Flow Through

The results of a study of a new and unique high performance air-cooled impingement heat sink are presented. An extensive numerical investigation of the heat sink performance is conducted and is verified by experimental data. The study is relevant to cooling of high power chips and modules in air-cooled environments and applies to workstations or mainframes. In the study, a rectangular jet impinges on a set of parallel fins and then turns into cross-flow. The effects of the fin thickness and gap nozzle width and fin shape on the heat transfer and pressure drop are investigated. It is found that pressure drop is reduced by cutting the fins in the central impingement zone without sacrificing the heat transfer due to a reduction in the extent of the stagnant zone. A combination of fin thicknesses of the order of 0.5 mm and channel-gaps of 0.8 mm with appropriate central cut-out yielded heat transfer coefficients over 1500 W/m2K at a pressure drop of less than 100 N/m2, as is typically available in high-end workstations. A detailed study of flow-through heat sinks, subject to the same constraints as the impingement heat sink showed that the flow-through heat sink could not achieve the high heat transfer coefficients at a low pressure drop.

Accelerating ion diffusion with unique three-dimensionally interconnected nanopores for self-membrane high-performance pseudocapacitors

Nanoscale ◽  
2017 ◽  
Vol 9 (46) ◽  
pp. 18311-18317 ◽  
Author(s):  
Yuan Gao ◽  
Yuanjing Lin ◽  
Zehua Peng ◽  
Qingfeng Zhou ◽  
Zhiyong Fan
Keyword(s):  
Aspect Ratio ◽  
Surface Area ◽  
Structural Stability ◽  
High Aspect Ratio ◽  
High Performance ◽  
Three Dimensional ◽  
Rate Capability ◽  
Large Surface Area ◽  
Nanoporous Structure ◽  
Ion Diffusion

Three-dimensional interconnected nanoporous structure (3-D INPOS) possesses high aspect ratio, large surface area, as well as good structural stability. Profiting from its unique interconnected architecture, the 3-D INPOS pseudocapacitor achieves a largely enhanced capacitance and rate capability.

Heat Transfer Performance of Aluminum Foams

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Simone Mancin ◽  
Claudio Zilio ◽  
Luisa Rossetto ◽  
Alberto Cavallini
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Pressure Drop ◽  
Fluid Dynamic ◽  
Foam Core ◽  
Aluminum Foams ◽  
Experimental Heat ◽  
High Heat Transfer ◽  
Experimental Heat Transfer ◽  
Core Height

Because of their interesting heat transfer and mechanical properties, metal foams have been proposed for several different applications, thermal and structural. This paper aims at pointing out the effective thermal fluid dynamic behavior of these new enhanced surfaces, which present high heat transfer area per unit of volume at the expense of high pressure drop. The paper presents the experimental heat transfer and pressure drop measurements relative to air flowing in forced convection through four different aluminum foams, when electrically heated. The tested aluminum foams present 5, 10, 20 and 40 PPI (pores per inch), porosity around 0.92–0.93, and 0.02 m of foam core height. The experimental heat transfer coefficients and pressure drops have been obtained by varying the air mass flow rate and the electrical power, which has been set at 25.0 kW m−2, 32.5 kW m−2, and 40.0 kW m−2. The results have been compared against those measured for 40 mm high samples, in order to study the effects of the foam core height on the heat transfer. Moreover, predictions from two recent models are compared with heat transfer coefficient and pressure drop experimental data. The predictions are in good agreement with experimental data.

A Multiobjective Parameter Study of Two-Phase Flow Channel Design

2020 ◽  
Author(s):  
Nicholas A. Evich ◽  
Nicholas R. Larimer ◽  
Mary I. Frecker ◽  
Matthew J. Rau
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Two Phase Flow ◽  
Circular Cross Section ◽  
Parameter Study ◽  
Phase Flow ◽  
Two Phase ◽  
Flow And Heat Transfer ◽  
High Heat Transfer ◽  
Manufacturing Techniques

Abstract Advanced manufacturing techniques have improved dramatically in recent years and design freedom for engineered components and systems has never been greater. Despite these advancements, the majority of our design tools for thermal-fluids systems are still rooted within traditional architectures and manufacturing techniques. In particular, the complex nature of two-phase flow and heat transfer has made the development of design methods that can accommodate these complex geometries enabled by new manufacturing techniques challenging. Here, we investigate a new design method for two-phase flow systems. We conduct a multiobjective parameter study considering two-phase flow and heat transfer through a single channel with a circular cross section. To increase our design degrees of freedom, we allow the channel to increase or decrease in cross-sectional area along its flow length, but constrain the channel inlet and outlet to a constant hydraulic diameter. Maximizing heat transfer and minimizing pressure drop are the two design objectives, which we evaluate using two-phase heat transfer correlations and the Homogeneous Equilibrium Model. We find that using small expansion angles can greatly reduce two-phase flow pressure drop and also provide high heat transfer coefficients when compared to straight channel designs. We present a set of feasible designs for varying input heat fluxes, liquid mass flow rates, and channel orientation angles and show how the ideal expansion channel angle varies with these operational conditions.

Experimental and numerical study on pressure drop and heat transfer performance of grille-sphere composite structured packed bed

2018 ◽  
Vol 227 ◽  
pp. 719-730 ◽  
Author(s):  
Jingyu Wang ◽  
Jian Yang ◽  
Zhilong Cheng ◽  
Yan Liu ◽  
Yitung Chen ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Transfer Performance ◽  
Numerical Study ◽  
Packed Bed ◽  
Transfer Performance
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