Concepts and realization of microstructure heat exchangers for enhanced heat transfer

Brandner, Juergen J.; Anurjew, Eugen; Bohn, Lothar; Hansjosten, E.; Henning, Torsten; Schygulla, U.; Wenka, A.; Schubert, K. R.

doi:10.1016/j.expthermflusci.2006.03.009

Cited by 112 publications

(56 citation statements)

References 10 publications

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“…Recent fields of application are in the automotive, chemical and food industries, environmental technology, and the aviation and space industries [5]. Examples include: Brandner et al's [6] proposal for an electrically powered micro-heat exchanger (around 1 cm 3 active volume with the number of rectangular channels and the hydraulic diameter ranging from 650 to 2279 and from 144 to 70 μm, respectively) for use in the production of biodiesel fuel; the Printed Circuit Heat Exchanger (PCHE), whose channels can have hydraulic diameters less than 2 mm, is widely used in petrochemical plants and fuel cells [7]; Martin et al's [8] design for a heat exchanger for a micro heat pump, for heat loads of 100 W/cm 2 . The latter was made of over 150 square microchannels whose side was 100 μm.…”

Section: Fabricated As An Integral Part Of Silicon Based Devices Commentioning

confidence: 99%

Single-phase heat transfer in microchannels: The importance of scaling effects

Rosa

Karayiannis

Collins

2009

Applied Thermal Engineering

241

117

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Microscale single-phase heat transfer is widely used in industrial and scientific applications and for this reason, many related papers have been published in the last two decades. Nevertheless, inconsistencies between published results still exist and there is no generally accepted model for the prediction of singlephase heat transfer in microchannels. This paper presents a review of the experimental and numerical results available in the open literature. Heat transfer in microchannels can be suitably described by standard theory and correlations, but scaling effects (entrance effects, conjugate heat transfer, viscous heating, electric double layer (EDL) effects, temperature dependent properties, surface roughness, rarefaction and compressibility effects), often negligible in macro-channels, may now have a significant influence and have to be accounted for. Furthermore, measurement uncertainties may be more important, due to the reduced characteristic dimensions, so have to be accurately checked and, where possible, reduced. Experiments with single channels are more accurate and in good agreement with predictions from published correlations, in contrast to multi-(parallel) channel experiments. The latter are subject to maldistribution, 3D conjugate heat transfer effects and larger measurement uncertainties. Sub-continuum mathematical models for fluid dynamics are briefly reviewed and explained. These models are expected to gain a growing interest in the near future due to the rapid descent of microchannel dimensions down to the nano-scale. The paper concludes with a concise set of recommendations for purposes of performance and design. For single channels, available correlations for macro-channels can also give reliable predictions at the micro-scale, but only if all the scaling effects can be considered negligible. Otherwise, when scaling effects cannot be neglected or for the case of heat exchangers with parallel channels, suitable numerical simulations may be the sole alternative to carefully designed experiments to evaluate the heat transfer rates. KeywordsMicrochannels, scaling effects, measurement uncertainties, sub-continuum effects.

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Section: Fabricated As An Integral Part Of Silicon Based Devices Commentioning

confidence: 99%

Single-phase heat transfer in microchannels: The importance of scaling effects

Rosa

Karayiannis

Collins

2009

Applied Thermal Engineering

241

117

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“…For heat transfer enhancement of micro heat exchangers, the micro channels normally used can be replaced with modified geometries, e.g. pin fins, different channel flow paths or channel sectional areas (Brandner et al, 2006;Mohammed et al, 2011;Wu and Cheng, 2003). A disadvantage of such structures is additional pressure loss.…”

Section: Introductionmentioning

confidence: 99%

Heat transfer enhancement with gas-to-gas micro heat exchangers

Gerken

Brandner

Dittmeyer

2016

Applied Thermal Engineering

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A characterization of gas-to-gas micro heat exchangers has been performed in terms of pressure drop behavior and heat transfer performance. The gas-to-gas micro heat exchangers differ by partition wall material, partition wall thickness and flow arrangement. The pressure drop behavior has been analyzed due to the pressure losses in different sections of the gas-to-gas micro heat exchangers. Increased pressure losses in front of and behind the micro channels have been detected due to modified geometries in the inlet and outlet distribution chambers. The heat transfer performance has been determined in terms of thermal effectiveness. The comparison among different partition wall materials and partition wall thicknesses showed no significant criteria of the influence of thermal conductivity on the thermal effectiveness. An assessment due to an overall heat exchanger effectiveness has been performed to compare the gas-to-gas micro heat exchangers. For this purpose, the overall exergy loss has been calculated by combination of thermal effectiveness and pressure losses. A strong impact of the exergy loss due to pressure drop has been detected which influences the overall exergy loss of the gas-to-gas micro heat exchangers.

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“…Heat and Mass transfer analysis in microfluidic flows is significant for operation of all the microfluidic devices and separation systems. 13,14 The velocity field integrated with heat transfer for Newtonian systems has been studied by various researchers in micro-chip cooling, 15,16 microscale heat exchanger, 17 micro-electronic-mechanical-systems (MEMS), 18 microreactors, 19 etc. The corresponding mass transfer problems have applications in transdermal drug delivery, 20,21 electrolyte transport in fuel cells, 22 transport in hydrogel, 23 electrokinetic separation, 24 etc.…”

Section: Introductionmentioning

confidence: 99%

Effects of non-Newtonian power law rheology on mass transport of a neutral solute for electro-osmotic flow in a porous microtube

Mondal

2013

Biomicrofluidics

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Mass transport of a neutral solute for a power law fluid in a porous microtube under electro-osmotic flow regime is characterized in this study. Combined electroosmotic and pressure driven flow is conducted herein. An analytical solution of concentration profile within mass transfer boundary layer is derived from the first principle. The solute transport through the porous wall is also coupled with the electro-osmotic flow to predict the solute concentration in the permeate stream. The effects of non-Newtonian rheology and the operating conditions on the permeation rate and permeate solute concentration are analyzed in detail. Both cases of assisting (electro-osmotic and poiseulle flow are in same direction) and opposing flow (the individual flows are in opposite direction) cases are taken care of. Enhancement of Sherwood due to electro-osmotic flow for a non-porous conduit is also quantified. Effects if non-Newtonian rheology on Sherwood number enhancement are observed. V C 2013 AIP Publishing LLC. [http://dx

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Concepts and realization of microstructure heat exchangers for enhanced heat transfer

Cited by 112 publications

References 10 publications

Single-phase heat transfer in microchannels: The importance of scaling effects

Single-phase heat transfer in microchannels: The importance of scaling effects

Heat transfer enhancement with gas-to-gas micro heat exchangers

Effects of non-Newtonian power law rheology on mass transport of a neutral solute for electro-osmotic flow in a porous microtube

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