Rectangular Microchannel Research Articles

Flow Boiling Heat Transfer of Refrigerants HFO-1234yf and HFC-134a in an Extruded Aluminum Tube with Multi-Port microchannels

Extruded flat aluminium tubes with multi-parallel ports microchannel heat exchangers are popularly used in automotive air-condition systems. The automotive air-condition is one of the earliest systems that is being banned for using a working fluid with a GWP value higher than 150. HFO-1234yf is one of the most possible candidates to replace the current refrigerant HFC-134a used in it but very few studies have been conducted for flow boiling of HFO-1234yf in rectangular microchannels. This study provides an experimental investigation and comparison on the flow boiling heat transfer of refrigerants HFO-1234yf and HFC-134a in a microchannel heat exchanger with a channel size of 0.5 mm. The test results show that the heat transfer coefficients of HFC-134a are from 0 to 22% higher than those of HFO-1234yf depending on mass velocity and vapor quality. Kandlikar and Balasubramanian (2004) correlation provides the best predictions for the present test results. The major controlling properties for flow boiling heat transfer coefficients in rectangular microchannels is similar to those for flow in larger circular tubes. They are strongly depending on the two-phase flow pattern at various flow conditions.

Performance improvement of rectangular microchannel heat sinks using nanofluids and wavy channels

In this article, the effect of two different methods of cooling enhancement, including the use of nanofluid as the coolant and sinusoidal wavy walls, on the performance of rectangular microchannel heat sinks (MCHSs) has been numerically investigated. Three-dimensional simulations based on the finite-volume approach are carried out using three different wave amplitudes (50, 100, and 200 µm) and wavelengths (1.3, 2, and 4 mm). Water-based nanofluid containing Al2O3 nanoparticles with volume fraction of 1% is employed as the coolant, and its influence on the hydraulic and thermal performance of the MCHS is compared with the water. The simulation of nanofluid flow is performed by both the single-phase method and the two-phase mixture method. Comparison between predicted results and experimental data from literature is carried out, which indicates the two-phase method is more precise than the single-phase method. Results showed that the enhanced microchannels with higher wave amplitudes and lower wavelengths performed better in terms of heat transfer, and among the investigated geometries, the wavelength of 1.3 mm and the amplitude of the 200 µm show the highest cooling performance. Using these optimal geometrical values in the wavy-walled microchannel heat sink (WMCHS), the amount of heat absorbed by the water-Al2O3 with volume fraction of 1% increases by 43% compared with the water flow in the straight-walled microchannel heat sink (SMCHS) at Reynolds number of 500. In addition, in a given geometry with fixed length and cross section area, employing wavy walls has a greater effect on heat transfer enhancement than using nanofluid instead of water. Employing optimal wavy walls in the MCHS, the amount of absorbed heat increases by 30% when the coolant is pure water and by 21% when the coolant is nanofluid. Whereas if nanofluid is used instead of water, the heat absorbed increases by 18% in SMCHS and 10% in WMCHS. Although both methods of cooling enhancement increase the pressure drop as well, the negative effect of the increase in pressure drop is less than the positive effect of increasing heat transfer in both methods.

Fabrication of Irregularity-Free, Highly Circular Cross-Sectional Microchannel

Microchannels typically have rectangular cross-sections, whereas biological channels, such as blood vessels and airways, have circular cross-sections. The difference in cross-sections causes different fluidic behaviors, resulting in differences between fluidic behavior in microchannels and biological channels. To simulate fluidic behavior in vitro, circular cross-sectional microchannels are required. We developed a circular cross-sectional microchannel with a smooth channel wall, free from cracks and irregularities. In the fabrication process of the circular cross-sectional microchannel, uncured polydimethylsiloxane (PDMS) was inserted into a rectangular cross-sectional microchannel. Then, the PDMS was pushed out by the introduction of compressed air before the curing process. During the introduction of compressed air, we observed the behavior of the uncured PDMS and found the formation and movement of protrusions along the microchannel. After pushing out the uncured PDMS, the residual PDMS was cured, resulting in a circular cross-sectional microchannel. The fabrication method was examined by varying the channel orientation and airflow direction. In the case of the horizontal orientation and airflow in an opposite direction, the circularity of the microchannel was greater than 0.99 at the centimeter scale in all cross-sections along the microchannel.

Condensation heat transfer of R134a and R410A in multiport rectangular microchannels with different aspect ratio

Experiments were performed to investigate the heat transfer coefficient (HTC) of R134a and R410A condensing in rectangular, parallel microchannels with hydraulic diameter [Dh] between 0.66 and 1 mm. Three microchannels MC-1, MC-2, and MC-3 with aspect ratios of 0.5, 0.7, and 1 respectively, were selected while keeping the constant channel length (30 cm), base area (63 cm2), and channel depth (1 mm). Tests were conducted for mass flux 200 <G < 600 kg/m2s, vapour quality 0.05 <x < 0.83, and saturation temperatures of 30 and 40 °C. It was observed that as the refrigerant mass flux and vapour quality increased, the condensation HTC of R134a and R410A increased, but the same decreased as the saturation temperature increased. Data demonstrates that R134a has a higher condensation HTC than R410A, with the maximum value of condensation HTC attained in MC-1 with an aspect ratio of 0.5, followed by MC-2 and MC-3 with an aspect ratio of 0.7 and 1, respectively. Data received from the current experimental research was compared to existing condensation HTC correlations developed for conventional channels and mini/micro channels. A novel correlation has also been proposed for condensation HTC in microchannels, and the resulting correlation agreed to the experimental data with an MAE of 5.40% and predicts the data almost within the 20% error band.

Experimental Study on Gas Flow in a Rough Microchannel

The shape and relative roughness of a rough surface have an important influence on microscale flow and heat transfer. In this study, a rectangular silicon microchannel (0.8 mm width and 11.9 μm height) with a large width-depth ratio is fabricated by the MEMS micromachining process. The silicon surface of the microchannel and the two-dimensional rough contours of the glass surface are measured, and the fractal dimensions taken as the only quantitative parameter of the surface morphology are calculated. The three-dimensional morphology of the silicon surface is measured by a confocal laser microscope and atomic force microscope. On this basis, a microscale gas flow performance test system is designed and built, and the flow characteristics of nitrogen and helium in rough silicon microchannel are experimentally studied. The experimental results show that the rough profiles of the silicon surface and the glass surface have possessed self-affine characteristics. Both nitrogen and helium show a certain degree of boundary slip when they flow in a microchannel. The degree of slip of helium flow is larger than that of nitrogen flow, which verifies the rarefied effect of microscale gas flow.

Performance analysis of microchannel heat sink with flow disrupting pins

Study of thermo-hydraulic characteristics of a novel microchannel heat sink having flow disrupting pins is numerically and experimentally carried out in this paper. Cylindrical pins are inserted from top cover into the rectangular microchannel instead of the conventional technique of pin-fins originating from the base of microchannel. Initially, the effect of pin diameter on the thermo-hydraulic performance is studied and the optimum pin diameter is established, later on thermo-hydraulic performance of pin enhanced microchannel heat sink (PE-MCHS) is compared with conventional microchannel heat sink (MCHS). Of the five pin diameters studied, pin having 0.2mm diameter (relative pin diameter γ=0.4) gives the best performance. Both conventional MCHS and PE-MCHS are subjected to heat flux ranging from 65W/cm2 to 200 W/cm2 and cooled by water flowing at Reynolds number ranging from 745 to 1500. The presence of pins disturbs the velocity distribution completely and increases the heat transfer capacity of the MCHS accompanied by higher pressure drop penalty. The average enhancement factor obtained by this technique is 1.24. Correlations showing the effect of channel width to pin diameter ratio (Wc/ Dp) on Nusselt number (Nu)and friction factor (f) are proposed.

Particularities of R134a Refrigerant Temperature Variations in a Transient Convective Regime during Vaporization in Rectangular Microchannels.

An analysis of the R134a (tetrafluoroetane) coolant’s non-stationary behavior in rectangular microchannels was conducted with the help of a newly proposed miniature refrigerating machine of our own design and construction. The experimental device incorporated, on the same plate, a condenser, a lamination tube and a vaporizer, all of which integrated rectangular microchannels. The size of the rectangular microchannels was determined by laser profilometry. R-134a coolant vapors were pressurized using a small ASPEN rotary compressor. Using the variable soft spheres (VSS) model, the mean free path, Knudsen and Reynolds numbers, as well as the dimensionless velocity profile can be assessed analytically. In order to determine the average dimensionless temperature drop in the vaporizer’s rectangular microchannels, in non-stationary regime, an analytical solution for incompressible flow with slip at the walls, fully developed flow and laminar regime was used, by aid of an integral transform approach. In the experimental study, the transitional distribution of temperature was tracked while modifying the R134a flow through the rectangular microchannels. Coolant flow was then maintained at a constant, while the amount of heat absorbed by the vaporizer was varied using multiple electric resistors. A comparative analysis of the analytical and experimental values was conducted.

Thermal and hydraulic performances of the wavy microchannel heat sink with fan-shaped ribs on the sidewall

The innovative wavy microchannel heat sinks with a variety of geometric fan-shaped ribs are proposed. The thermal and hydraulic performances of such a microchannel are given considering the thermo-physical properties. The calculation results validate its advantage in improving the thermal performance. New insights into the flow and heat transfer mechanism are obtained based on the detailed flow field evolution. The geometry parameter of fan-shaped ribs on the friction factor, Nusselt number, and thermal performance is further investigated. Results show that the heat transfer enhancement is dependent on the geometric parameters of ribs and Re. Compared with rectangular wavy microchannel, the heat transfer is enhanced in the larger Re besides Hr/Wr = 0.05. The best thermal performance of this proposed microchannel is mainly observed at the Sr/Wr = 2, and a worse thermal performance is found for the microchannel as the Sr/Wr = 1 and 4 in the lower Re. With the increase of the flow rate, a noticeable increase in PEC is found for the heat sinks with lower Sr/Wr. The maximum value of PEC occurs more early for the channel with Sr/Wr = 0.0375, and the increase rate of PEC for such microchannel with Re is lower. The PEC is larger for Hr/Wr = 0.1125 and 0.075 in the higher Re.

Electrical discharge micro-texturing using compound tool electrodes for tribological and wettability applications

ABSTRACT The present work consists of large-area surface texturing through die-sinking electrical discharge machining (EDM) using compound tool electrodes. The compound tools were machined through the wire electrical discharge machining (WEDM). The micro-textured surfaces incorporating array of nearly square/circular-shaped micro-dimples, rectangular micro-channels and square micro-pillars were analysed for their wetting properties. An increase in water contact angle (CA) indicated higher water repellence for textured surfaces with respect to the untextured ones. Further, improved frictional behaviour was elicited through tribological analysis via the ball-on-disc test, revealing a lower average coefficient of friction (CoF) compared to the untextured surface. The wear volume of textured surfaces (micro-channels and micro-pillars) exhibited a slightly higher value with respect to the untextured surface, which can be ascribed to the stress concentration from microfeatures. However, the micro-dimpled textured surface showed a relatively lower wear volume, presenting a suitable micro-texture for improved tribological characteristics.

Effects of coupling of mass transport and blood viscosity models for microchannel flows

In this study, various aspects of a continuum transport model for blood, which is treated as a suspension of red blood cells, are thoroughly investigated. Earlier, treating blood as a suspension of rigid spherical particles in plasma was reasonably successful in mimicking flow dynamics in microchannels of size 40 μ m , comparable to 4 μ m , the dimension of a red blood cell (RBC). However, it is still not entirely clear whether such success owes to the coupling of mass and momentum transport, or to a sophisticated viscosity model for blood. To understand this in detail, we obtain semi-analytical solutions to the continuum model, in the presence and absence of the coupling of mass transport of RBCs, that connects the hematocrit concentration to the local viscosity, for fully developed blood flow in circular and rectangular microchannels. In this study, the transport of RBCs in flowing fluid is modeled by the diffusive flux model (DFM). Thus, overall, we have a hierarchy of continuum models using various viscosity models for blood, with progressive inclusion of physical complexities. Our results clearly highlight the importance of such a coupled approach, without which the results are quantitatively, and sometimes even qualitatively, different. In addition, our study serves as a thorough comparison of different viscosity models for blood, especially the steady state and transient models, recently proposed by Apostolidis and Beris (2014) and Apostolidis et al. (2015), respectively. We observe that, though the transient model reduces exactly to the description by the steady model over a range of low to moderate shear rates, the transient model shows some differences, especially for the RBC concentration in the low shear rate region. In the semi-analytical framework, the Darcy friction factor and cell free layer thickness have also been computed for circular cross-sections and a range of aspect ratios of a rectangular microchannel. Our results also indicate that the cell free layer attains a constant thickness when the aspect ratio of a rectangular microchannel reaches a critical maximum value for a specified average hematocrit. • Rectangular microchannel flow is investigated by coupling with the transport of RBC. • Even a finely tuned viscosity model without RBC transport is shown to be inadequate. • Frictional characteristics are derived in the form of a semi-analytical solution. • The model is found to predict the cell free layer thickness quite well. • The steady viscosity model overpredicts WSS when compared to the transient model.

A geometrical criterion for the dynamic snap-off event of a non-wetting droplet in a rectangular pore–throat microchannel

In porous media, non-wetting phase droplets snapping off in a constricted microchannel are one of the most common phenomena in two-phase flow processes. In this paper, the application range of the classic quasi-static criterion in rectangular cross section microchannels is obtained. For three different droplet breakup phenomena—total breakup, partial breakup, and non-breakup—observed in experiments when a non-wetting phase droplet passes through a microchannel constriction, the breakup is caused by the droplet neck snapping off in a channel constriction. A critical criterion for the dynamic snap-off event in a two-phase flow is proposed considering the effect of viscous dissipation by mechanical analysis, energy dissipation analysis, and many microfluidic experiments. When the droplet front flows out of the constriction, snap-off will occur if the surface energy release exceeds the required energy for viscous dissipation and kinetic energy conversion. The unique partial breakup phenomenon is affected by droplet surfactant distribution and the acceleration effect in the constriction center. This partial breakup phenomenon in experiments is an essential evidence for the non-uniform distribution of surfactants in the droplet surface. The results of this study contribute to understanding pore-scale mass transfer and flow pattern changes within porous media.

Numerical investigation of the performance of rectangular micro-channel equipped with micro-pin-fin

To investigate the thermal and flow characteristics in a microchannel with pin fins, numerical simulation is carried out. The influence of variation in fin height is adjudged on thermo-hydraulic performance where the fin height is varied from 0.2 mm to 1 mm and Reynolds numbers from 200 to 1000 with constant heat flux imposed at the bottom of the channel. In general, heat transfer is observed to be significantly increasing with an increase in fin height and Reynolds number. However, heat transfer increases at a similar rate for each cases up to a Reynolds number of 600 but later heat transfer growth for a height of 0.8 mm is found pronounced over that for fin height of 1 mm as the Reynold number continues to increase. This may be attributed to the fact that fin height of 0.8 mm seems to have greater wetted as well as convective surface area as compared to the fin of 1 mm height. Further, available the flow passage around 0.8 mm fin is prone to form vortices much easily as compared to 1 mm fin. The profiles of temperature distribution, pressure drop, and velocity all seem to corroborate this observation.

Mathematical modeling investigation on flow boiling and high efficiency heat dissipation of two rectangular radial microchannel heat exchangers

To solve the heat dissipation problem of high heat flux devices, flow boiling heat transfer in microchannels is widely used and investigated. Two types of rectangular radial microchannel heat exchangers, without and with grooves, were experimentally studied and reported by us. To further improve their heat transfer performances by optimizing their structural parameters, two mathematical models are developed, with heat transfer coefficient (HTC) used as validation parameter. As analyzed, for two rectangular radial microchannel heat exchangers, without and with grooves, the average deviations are 3.62% and 7.03%, respectively. The modeling results show that, compared with the heat exchanger without grooves, the one with grooves always has better heat transfer performance. For two microchannel heat exchangers, without and with grooves, the influence of adjusting structure parameters on the HTC is obvious, and the maximum changes of HTC reaches 32.56 kW/m2K and 70.33 kW/m2K, respectively. Under a heating load of 400 W and a volume flow rate of 8 L/h, the heat transfer performance of heat exchanger without grooves could not be improved. While under the same conditions, the predicted HTC of the heat exchanger with grooves is improved to 102.56 kW/m2K, which is 58.69% higher than the experimental data. The results of this study are expected to provide references for the structural design optimization of microchannel heat exchangers.

Capillary flow of evaporating liquid solutions in open rectangular microchannels

Capillary flow of liquids plays a key role in many applications including lab-on-a-chip devices, heat pipes and printed electronics manufacturing. Open rectangular microchannels often appear in these applications, with the lack of a top resulting in a complex free-surface morphology and evaporation. In this work we develop a theoretical model based on lubrication theory and kinetically limited evaporation to examine capillary flow of evaporating liquid solutions in open rectangular microchannels connected to circular reservoirs. The model accounts for the complex free-surface morphology, solvent evaporation, Marangoni flows due to gradients in solute concentration and temperature and finite-size reservoir effects. Significant differences are predicted in flow behaviour between pure liquids and liquid solutions due to solvent evaporation and solute transport. Marangoni flows are found to promote more uniform solute deposition patterns after solvent evaporation. Model predictions of meniscus position evolution are in good agreement with prior capillary-flow experiments of aqueous poly(vinyl alcohol) solutions in the presence of evaporation. The model reveals that the principal mechanism through which evaporation influences the meniscus position in the experiments is the increase in viscosity with solute concentration.

Two-phase frictional pressure drop of R134a and R410A condensing inside multiport rectangular microchannels with different aspect ratio

ABSTRACT This paper presents the experimental result of R134a and R410A (without lubricating oil) pressure drop condensing along three parallel, rectangular microchannels with the aspect ratio varying from 0.5 to 1 and Dh from 0.66 to 1 mm, while maintaining the constant channel depth (1 mm), base area (63 cm2), and channel length (30 cm). All the factors accountable for change in pressure through microchannels were determined for all the configurations separately, i.e. contraction, expansion, frictional, and deceleration. Two distinct saturation temperatures were used in the present experimental study, with vapor quality 0.05 < x < 0.83 and mass flux 200 < G < 600 kg/m2s. Frictional pressure drop estimations were found to be greater than 90% of overall pressure drop. Condensation pressure drop for both the refrigerants increases directly with increasing mass flux and vapor quality, whereas it decreases with the channel aspect ratio and saturation temperature increase. At constant mass flux, R134a has a higher condensation pressure drop than R410A, and the highest value of condensation pressure drop was obtained in MC-1 having an aspect ratio of 0.5, followed by MC-2 and MC-3 having aspect ratios of 0.7 and 1, respectively.

The hydraulic and thermal performances of rectangular and square microchannel with different hydraulic diameters cooled by graphene–platinum hybrid nanofluid

The objective of this paper is to analyze the effect of hydraulic diameter and channel shape on the thermal and hydrodynamic characteristics of a microchannel cooled by Graphene–Platinum/water hybrid nanofluid for electronic cooling applications. The study was performed numerically using mathematical software called Maple 19.0. Microchannels having square and rectangular cross-sections, and hydraulic diameters ranging from 200 µm to 1,000 µm were taken into consideration. Thermal resistance, heat transfer coefficient, pressure drop, and friction factor were evaluated for different conditions and their corresponding graphs are presented and discussed. It was evident from the results that low thermal resistance and high heat transfer coefficient was achieved upon decreasing the hydraulic diameter, which is favorable for the cooling of electronic chips and devices. Based on the Reynolds number, the heat transfer coefficient increased by 2–4 times for both rectangular and square microchannels, on decreasing the hydraulic diameter from highest value (1,000 µm) to lowest value (200 µm). However, friction factor and pressure drop increased for channels with lower hydraulic diameters. In addition, rectangular microchannels exhibited better heat transfer performance, while square microchannels had lower friction factor and pressure drop. Rectangular microchannels presented a maximum enhancement of 30% in heat transfer coefficient and a reduction of 18% in thermal resistance, when compared to square microchannels. The results also suggested that the performance of microchannels with 500 µm hydraulic diameter is balanced, considering both heat transfer performance and pressure drop constraints.

Investigation on the heat transfer and energy-saving performance of microchannel with cavities and extended surface

Microchannel heat sinks (MCHSs) are widely used in microelectronic systems and are one of the most effective heat sinks in the 21st century. In this work, the fluid flow and heat transfer performance of different extended surfaces (cylindrical fins, rectangular fins, water droplets) of triangular combined cavity, 90° fan-shaped and triangular combined cavity were investigated. The comprehensive performance in microchannels were analyzed and evaluated in detail by different aspects, including flow characteristics, heat transfer characteristics, pressure drop characteristics, comprehensive thermal strengthening performance and thermal strengthening performance aimed at energy saving. The result indicated that the microchannel with the triangular combined cavity exhibited the best heat transfer performance at a low Reynolds number. However, as the Reynolds number gradually increasing, the microchannel with 90° fan-shaped and triangular combined cavity presented more obvious advantages. Furthermore, the microchannel is evaluated by the comprehensive thermal enhancement performance and the enhanced performance evaluation aiming at energy-saving. When Re<144.6, the comprehensive heat transfer performance of the microchannel with triangular combined cavity cylinder fins was the best, and the energy-saving effect was excellent. The microchannel of the 90° fan-shaped and triangular combined cavity cylindrical fins at Re>144.6 had better comprehensive heat transfer performance and energy-saving effects. Because of the combined effect of the boundary layer redevelopment and the cold and heat exchange of the fluid in the channel, the microchannel with cavity and the extended surface has better heat transfer and energy-saving performance than that of the traditional rectangular microchannel.

Experimental study of Taylor bubble flow in non-Newtonian liquid in a rectangular microchannel

The flow characteristics of gas and non-Newtonian fluid in a rectangular T-microchannel with cross section of 150 μm × 50 μm are experimentally studied. Four flow patterns are observed, including bubble flow, Taylor flow, transitional flow and annular flow. The effects of two-phase flowrate, the CMC/SDS concentration, and microchannel size on the flow pattern maps and Taylor bubble/liquid slug length are compared. The bubble length increases with gas/liquid flowrates ratio, whilst the change of slug length is opposite. The bubble length decreases with liquid viscosity or surface tension. The slug length increases with the liquid viscosity, but decreases with surface tension. Experimental data is analyzed in relationship to JG/JL, Re and Ca using dimensional analysis. Two empirical equations are given respectively to predict the Taylor bubble/slug lengths. Predictions are largely consistent with the experimental results with maximum 25% variance. This provides an important reference for the controllable operation of two-phase flow in rectangular microchannels.

Effect of Cross-Sectional Geometry on Hydrothermal Behavior of Microchannel Heat Sink

Abstract The aim of this paper is to numerically analyze the hydrothermal behavior of different cross-sectional geometries of microchannel heat sinks (MCHSs) and conduct a comparative analysis of traditional and non-traditional designs using ANSYS Fluent. It is expected that the proposed design discussed in this paper will improve the performance of MCHSs by maximizing the cooling capability and minimizing the thermal resistance and entropy generation rate, thus leading to better energy efficiency. The channel designs include a rectangular microchannel (RMC), a circular microchannel (CMC), an elliptical microchannel (EMC), a trapezoidal microchannel (TMC), a hexagonal microchannel (HMC), and a new microchannel (NMC) which has a plus-like shape. The discussed geometry of the NMC is designed in such a way that it maximizes the cross-sectional area and the wetted perimeter of the channel, keeping the hydraulic diameter constant ( D h = 412 {D_{h}}=412 µm). The performance of various channels is compared on the basis of pressure drop, wall temperature, thermal enhancement factor, thermal resistance, thermal transport efficiency, and entropy generation rates. It has been observed that the NMC is capable of cooling effectively and it can achieve a minimum wall temperature of 305 K, thus offering the lowest thermal resistance ( R th {R_{\mathrm{th}}} ), irreversible heat loss, and entropy generation rate. Moreover, the NMC has achieved the highest value of the thermal enhancement factor, i. e., 1.13, at Re = 1 , 000 \mathrm{Re}=1,000 . Similarly, it has the highest thermal transport efficiency of almost 97 % at Re = 1 , 000 \mathrm{Re}=1,000 , followed by the TMC and the RMC. Overall, the NMC has achieved the best performance in all aspects, followed by the RMC and TMC. The performance of the EMC, the CMC, and the HMC was found to be the worst in this study.

Thermal and hydraulic performance of rectangular microchannel heat sinks with trapezoidal porous configuration

In this article, the thermal and hydraulic capacity of a rectangular microchannel heat sink with different trapezoidal porous configuration’s inlet heights and outlet heights are examined. A three-dimensional model is used for microchannels with miscellaneous trapezoidal porous configuration’s inlet and outlet heights, and the laminar fluid flow and conjugate heat transfer equations are numerically solved. Darcy-Brinkmen-Forchheimer equation is utilized for transport through the porous region. For microchannels with miscellaneous porous distribution’s inlet and outlet heights, the Nusselt number, pressure drop and figure of merit (FOM), a criterion for the assessment of heat transfer and hydraulic performance simultaneously, are calculated and compared to one another and a microchannel without porous medium. It is identified that with the increase of and both the Nusselt number and pressure drop increase. However, at low microchannels with low possess higher FOMs, the parameter that evaluates the hydraulic and thermal performance at the same time. In contrast, at high microchannels with higher have higher FOMs. Furthermore, the effect of the inlet velocity and porosity are studied on the thermal and hydraulic behaviors. Reducing both the inlet velocity and porosity result in a better hydraulic and thermal performance combined, higher FOMs.