CFD-based optimal design of manifold in plate-fin microdevices

Tonomura, Osamu; Tanaka, Shotaro; Noda, Minoru; Kano, Manabu; Hasebe, Shinji; Hashimoto, Iori

doi:10.1016/j.cej.2003.10.022

Cited by 160 publications

(70 citation statements)

References 25 publications

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“…Even when the above-introduced scaling effects are accurately considered and can be neglected, there is flow maldistribution between the channels [65] and 3D conjugate heat transfer patterns in the solid and the fluid [41], whose effects may be significant but cannot be accounted for by standard correlations, developed for 1D flows with simplified boundary conditions. For these reasons, the design of heat exchangers with microchannels cannot be reliably made without performing accurate numerical simulations, also to address the 3D effects in the inlet and outlet manifolds and in the solid and fluid heat flow patterns.…”

Section: Measurement Uncertaintiesmentioning

confidence: 99%

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

Rosa

Karayiannis

Collins

2009

Applied Thermal Engineering

249

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: Measurement Uncertaintiesmentioning

confidence: 99%

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

Rosa

Karayiannis

Collins

2009

Applied Thermal Engineering

249

117

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“…According to Ref. [50], this microreactor can be described as a plate-fin microdevice since it has multi-microchannels, which are parallel to each other and have the same shape and size.…”

Section: Tolerances Of Channel Geometrymentioning

confidence: 99%

Computational Fluid Dynamics in Microreactors Analysis and Design: Application to Catalytic Oxidation of Volatile Organic Compounds

Odiba¹,

Olea²,

Hodgson³

et al. 2016

J Chem Eng Process Technol

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This paper deals with the design of a suitable microreactor for the catalytic oxidation of volatile organic compounds (VOCs). There are a number of ways to release VOCs into the atmosphere, typically during processing of natural gas and handling petroleum products. As VOCs are harmful to our health, there is increased scientific interest in developing technologies for their destruction. Catalytic oxidation is one of them. Microreactors have showed higher efficiency than the conventional ones, mainly due to their large surface area to volume ratio and excellent heat and mass transfer properties. The design of a microreactor can be explored based on simulation results obtained by using computational fluid dynamics (CFD) package of COMSOL Multiphysics. The first design step, based on cold flow simulation, was the selection of the most suitable microreactor geometry and configuration. Four different geometries had been proposed and simulated to evaluate the fluid behaviour in the microchannels. One of them, Type A2, allowed the most uniform flow distribution in all channels, as assessed through relative standard deviation calculations. The second design step involved the investigation of the VOCs catalytic oxidation, using propane as model molecule, occurring in the microreactor with the geometry/configuration previously found. The proposed microreactor consists of eleven parallel channels of square cross-section, with 0.5 × 10 -3 m width, 0.5 × 10 -3 m height and 0.1 m length. The catalytic microreactor was simulated for temperatures between 563 K and 663 K and inlet flow velocities from 0.01 to 1.00 m·s -1 . The exit propane conversion increased rapidly with increasing temperature for a fixed inlet flow velocity. For a fixed temperature, the propane conversion increased as the inlet flow velocity decreased.

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“…It is anticipated that the thermal boundary condition will fall between H1 and H2. Another difficulty can arise from many parallel micro-channels resulting in flow mal-distribution between the channels [27].…”

Section: Introductionmentioning

confidence: 99%

Characterising micro-channel absorber plates for building integrated solar thermal collectors

Oyinlola

Shire

2018

Building Services Engineering Research and Technology

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Abstract.This paper discusses the characterisation of micro-channel absorber plates for Compact Flat Plate solar thermal collectors. Experimental and computational studies were carried out at typical operating conditions for flat plate solar collectors; overall heat loss coefficient in the range 2 -8 W/m 2 .°C, flow rate in the range 0.01 -0.1 kg/s/m 2 and heat transfer coefficients in the range 100 -1000 W/m 2 .°C. Three Dimensional numerical analysis using commercial CFD package, Ansys CFX, showed that heat transfer occurred on only three surfaces of the channel and there was a peripheral variation of the heat flux density. It was also observed that axial thermal conduction could modify the surface boundary at the inlet and outlet, however, the middle section of the channel could be approximated as a rectangular channel with three walls transferring heat under a H1 boundary condition. Experimental studies were used to estimate the standard parameters (channel efficiency, F, collector efficiency factor, F', heat removal factor, FR, and flow factor F") for predicting performance of the flat plate collectors. An alternate parameter, channel efficiency, F, was proposed to replace Fin efficiency, F, used in standard collector analysis. The results showed that values of F and F', very close to unity could be achieved with this design when the overall heat loss coefficient is below 2 W/m 2 .°C. The analysis further revealed that increasing the fluid-plate heat transfer coefficient beyond 300 W/m 2 .°C has marginal effect on the collector efficiency factor at a given UL value. The collector flow factor F" and the heat removal factor could be improved by increasing the collector capacitance rate; this can be achieved by increasing the mass flow rate per collector area ̇/ , as well as reducing the overall heat loss, UL . This analysis is important for optimizing design and operating parameters, especially to minimize temperature gradient in the transverse and longitudinal directions.

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CFD-based optimal design of manifold in plate-fin microdevices

Cited by 160 publications

References 25 publications

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

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

Computational Fluid Dynamics in Microreactors Analysis and Design: Application to Catalytic Oxidation of Volatile Organic Compounds

Characterising micro-channel absorber plates for building integrated solar thermal collectors

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