Model Of Microchannel Heat Sink Research Articles

Numerical Study of Thermal Enhancement in a Single- and Double-Layer Microchannel Heat Sink with Different Ribs.

In this paper, a microchannel heat sink model was proposed to realize single- and double- layer flow through built-in ribs. The finite element volume method was used to analyze the influence of the length, thickness and angle of the inner rib on the flow and heat transfer characteristics of the microchannel heat sink. The pressure drop, temperature field, flow field, and thermal characteristics are given. The numerical simulation results show that the rectangular rib plate makes the fluid in the microchannel heat sink flow alternately in the upper and lower layers, which can effectively enhance heat transfer. However, with the increase in rib length, the comprehensive evaluation factor decreases. The change of the angle of the rectangular rib plate has little influence on the Nusselt number. The change rate of the comprehensive evaluation factor of the thickness of the rectangular rib plate is the largest. When the Reynolds number is 1724, the comprehensive evaluation factor of Case 9 is 4.7% higher than that of Case 2. According to the parameter study of the built-in rib plate, the optimal parameter combination is given, in which the angle is 0°, the length is 7.5 mm, and the thickness is 0.2-0.3 mm.

Моделирование сопряженного теплообмена в микроканалах в среде OpenFOAM

In this paper, a numerical simulation of forced convective heat transfer in a silicon microchannel heat sink has been performed using the OpenFOAM tools. A single-phase fluid - water - was used as a heat transfer medium. The model of microchannel heat sink is represented as silicon substrate with length 10 mm, with rectangular microchannels 57 microns wide and 180 microns deep located along the full length of the heat sink. A comparative analysis in the form of cross-platform verification of the numerical results obtained with data from third-party authors was performed. The analysis of the obtained data has shown a good convergence of the study results and the possibility of using the OpenFOAM package as a computational environment for the numerical simulation of the physical processes occurring in channel radiators.

A novel transient thermohydraulic model of micro-channel heat sink

The purpose of this work is to develop an analytical model for prediction of the thermal fluid performance of a micro-channel heat sink by applying liquid thin-film theory. For this purpose, a one-dimensional transient model has been developed for a single channel of micro-channel heat sink and a series of numerical simulation was performed for various operating conditions. Mass, momentum and energy equations were applied separately for the vapor and liquid phases to predict more effective physical performance of the transient behavior. As a result, the axial distributions of mass flow, pressure, and temperature for the working fluid were obtained for vapor and liquid in the micro-channel. In particular, the phase change interface profile with the liquid thin-film was obtained using an augmented Young Laplace equation. Consequently, the interface areas of heat and mass transfer occupied by the liquid and vapor were predicted and incorporated into the governing equations of each phase. The analytical model was validated by comparison of its numerical solutions with experimental results. The discrepancy between the experimental and numerical results for the axial wall temperature was less than 4 °C, and that for the transient time to reach a steady-state wall temperature was within 1 sec. Through a series of performance simulations for a micro-channel model with pure water as the working fluid, transient response of the wall temperature, liquid film thickness, mass flow rate, liquid pressure, and vapor and liquid temperatures were investigated. The model developed in this study might be utilized for more refined performance prediction of a micro-channel heat sink.

Inverse geometric optimization for geometry of nanofluid-cooled microchannel heat sink

An inverse geometric optimization for nanofluid-cooled microchannel heat sink (MCHS) considering effects of temperature-dependent thermophyiscal properties for the water-based Al2O3 nanofluid with 1% particle volume fraction was performed under a constant pumping power constraint. A three-dimensional fluid-solid conjugated MCHS model combining the simplified-conjugate-gradient-method was used as the optimization tool. The channel number, N, the channel aspect ratio, α, and the width ratio of channel to pitch, β, affect the cooling performance of MCHS, and were all incorporated in the present, three-parameter optimization study. Increase in viscosity of the nanofluid did not always lead to enhanced MCHS performance under fixed pumping power constraint, contradicting to the results for pure water. The optimal MCHS design is closely related to the assigned pumping power: increase in the pumping power enhances cooling performance; however, in high pumping power regime the performance enhancement is not as effective as in low pumping power regime. At pumping power of 0.05 W and a uniform heat flux of qw = 100 W cm−2, the optimal design for the nanofluid-cooled MCHS presented N = 51, α = 5.69 and β = 0.62, yielding the optimal thermal resistance of RT = 0.1059 K W−1.

Optimal geometric structure for nanofluid-cooled microchannel heat sink under various constraint conditions

A numerical model is developed to analyze the flow and heat transfer in nanofluid-cooled microchannel heat sink (MCHS). In the MCHS model, temperature-dependent thermophysical properties are taken into account due to large temperature differences in the MCHS and strong temperature-dependent characteristics of nanofluids, the model is validated by experimental data with good agreement. The simplified conjugate-gradient method is coupled with MCHS model as optimization tool. Three geometric parameters, including channel number, channel aspect ratio, and width ratio of channel to pitch, are simultaneously optimized at fixed inlet volume flow rate, fixed pumping power, and fixed pressure drop as constraint condition, respectively. The optimal designs of MCHS are obtained for various constraint conditions and the effects of inlet volume flow rate, pumping power, and pressure drop on the optimal geometric parameters are discussed.

Effects of tapered-channel design on thermal performance of microchannel heat sink

A channel with a height- or width-tapered variation is designed to improve the thermal performance of a microchannel heat sink (MCHS). To this end, a three-dimensional MCHS model is constructed to analyze the effects of the height- and width-tapered ratios on the thermal performance of the MCHS. The thermal resistance and temperature distribution are taken as the thermal performance indicators. Numerical predictions show that the relationship between the thermal resistance and the width-tapered ratio is not monotonic at the fixed pumping power. The thermal resistance first decreases and then increases. A similar behavior is also exhibited by the height-tapered ratio. However, the height-tapered ratio effects can be negligible. It is also found that the width-tapered-channel design has a lower and a relatively uniform temperature distribution compared to parallel or height-tapered channel design. Moreover, the MCHS with width-tapered channel design showed a maximum enhancement in thermal performance of around 16.7% over that of the parallel-channel design when the pumping power is larger than 0.4W.