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Chen K.,Louisiana State University | Meng W.J.,Louisiana State University | Mei F.,Enervana Technologies LLC | Hiller J.,Argonne National Laboratory | Miller D.J.,Argonne National Laboratory
Acta Materialia | Year: 2011

A single crystal Al specimen was molded at room temperature with long, rectangular, strip diamond punches. Quantitative molding response curves were obtained at a series of punch widths, ranging from 5 μm to 550 nm. A significant size effect was observed, manifesting itself in terms of significantly increasing characteristic molding pressure as the punch width decreases to 1.5 μm and below. A detailed comparison of the present strip punch molding results was made with Berkovich pyramidal indentation on the same single crystal Al specimen. The comparison reveals distinctly different dependence of the characteristic pressure on corresponding characteristic length. The present results show the feasibility of micro-/nano-scale compression molding as a micro-/nano-fabrication technique, and offer an experimental test case for size-dependent plasticity theories. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Source


Lu B.,Louisiana State University | Meng W.J.,Louisiana State University | Mei F.,Enervana Technologies LLC
Journal of Micromechanics and Microengineering | Year: 2013

Cu-based, single- and double-layered, microchannel heat exchangers (MHEs) were fabricated and assembled. Comparative measurements on liquid flow characteristics and heat transfer performance were conducted on these devices. Results were compared at the individual microchannel level as well as at the device level. The present results demonstrate that double-layered MHEs exhibit similar heat transfer performance while suffering a much lower pressure drop penalty compared to single-layered MHEs. Another Cu-based, double-layered, liquid-liquid counter-flow MHE was fabricated, assembled and tested. Results show that a low-volume, multilayered, high-performance, liquid-to-liquid MHE is achievable following the manufacturing protocols of the present double-layered, liquid-liquid counter-flow MHE. © 2013 IOP Publishing Ltd. Source


Lu B.,Louisiana State University | Mei F.,Enervana Technologies LLC | Meng W.J.,Louisiana State University | Guo S.,Louisiana State University
Heat Transfer Engineering | Year: 2013

Microchannel heat exchangers (MHEs) have become a leading candidate for applications demanding removal of highly concentrated heat, including cooling of future generation high-performance microelectronic and power-electronic modules. Metal-based MHEs offer potential advantages over silicon-based counterparts in terms of overall heat transfer performance and mechanical robustness. Low-cost fabrication of metal-based MHEs and quantitative evaluation of their liquid flow and heat transfer characteristics are essential for establishing the technical feasibility and economic viability of such devices. Adoption of metal-based MHEs in many applications demands quantification of liquid flow and heat transfer performance with application-relevant coolants, for example, ethylene glycol (EG)/water mixtures rather than pure water. As a first step in this direction, we report here fabrication and assembly of all-Cu MHE prototypes, as well as results of flow and heat transfer testing using pure water and pure EG as the liquid medium. Results of heat transfer testing indicate sensitivity of overall heat transfer performance to entrance length effects. In the case of pure EG, the thermal entrance length is significantly influenced by its Prandtl number value under different testing conditions. Varying testing conditions led to differences in the Prandtl number, and consequently the heat transfer performance. © 2013 Taylor and Francis Group, LLC. Source


Lu B.,Louisiana State University | Meng W.J.,Louisiana State University | Mei F.,Enervana Technologies LLC
Microsystem Technologies | Year: 2012

Results of heat transfer testing of heat absorption modules (HAM), heat rejection modules (HRM), and arecirculating-liquid cooling system are reported. Lowprofile, Cu-based, microchannel heat exchangers (MHEs) were fabricated and used as the HAM as well as components for assembly of a microchannel HRM. Detailed experimental assessment of two different liquid-passing HRMs and a microchannel-based recirculating-liquid cooling system was carried out, and benchmarked against all-solid devices of the same geometric dimensions. Incorporating microchannel liquid flow through each fin, the device-level heat transfer performance of the microchannel HRM was improved by up to ∼50%. Detailed testing of a microchannel-based recirculating-liquid ooling system indicate that low-profile Cu MHEs are highly effective in heat flux removal while having a small area/ volume footprint, and that enhancing the HRM performance is critical to boosting the overall performance of such recirculating-liquid cooling systems. © 2011 Springer-Verlag. Source


Lu B.,Louisiana State University | Chen K.,Louisiana State University | Meng W.J.,Louisiana State University | Mei F.,Enervana Technologies LLC
Journal of Micromechanics and Microengineering | Year: 2010

Low-profile, Cu-based microchannel heat exchangers (MHEs) with different geometric dimensions were fabricated, bonded and assembled. A transient liquid phase (TLP) process was used for bonding of Cu-based MHEs with total thicknesses ranging from 600 μm to 1700 μm. The structural integrity of TLP-bonded Cu MHEs was examined. Device-level heat transfer testing was performed on a series of Cu-based MHEs to study the influence of microchannel dimensions on overall heat transfer performance, corroborated by computational results from a simple 2D finite element analysis. The present results demonstrate the promise of low-profile metallic MHEs for high heat flux cooling applications. © 2010 IOP Publishing Ltd. Source

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