Experimental Study and CFD Modeling of Fluid Flow and Heat Transfer Characteristics in a Mini-Channel Heat Sink Using Simcenter STAR-CCM+ Software

The present work describes an experimental study and CFD modeling of fluid flow and heat transfer characteristics in a heat sink with several asymmetrical heated mini-channels. The data from the experimental research were the basis for numerical calculations. During experiments, the temperature measurement of the outer heater surface was performed by infrared thermography to verify the results of numerical calculations performed in Simcenter STAR-CCM+ software. The main objective was to determine the values of the parameters tested to evaluate the intensity of the heat transfer processes. In the numerical simulations, important variables, mainly the working fluid, heater material, the spatial orientation of the test section, and the number of mini-channels, were assumed. The results of the numerical computations were discussed. Due to simulations, it was possible to indicate which parameters tested in terms of heat transfer turned out to be the most effective. Furthermore, a mesh dependency analysis based on the grid convergence index (GCI) was performed. The residuals, as good indicators of convergence, achieved low values. Generally, the data presented showed satisfactory convergence of the results achieved as a result of the computational procedure.

Numerical simulation of thermal diamond filter for working station 1-5 of synchrotron “SKIF“

Numerical 3D-simulations of thermal loads of thermal diamond filter for the working station 1-5 of synchrotron “SKIF” has been performed. An efficient version of a water-cooling system of a CVD diamond by means of mini-channels in copper flanges with a total heat release power of 1290 W is presented. The influence of various configurations of the cooling system, different boundary conditions (thermal insulation, radiation heat exchange), water supply pressure on the maximum temperature in diamond wafer has been investigated. The influence of the temperature dependence of the properties of diamond glass has been studied. The maximum temperature on the diamond wafer is found to be 317.6 °C absorbing 1290 W of power correspond to the safe mode for some specific cooling system configuration. The corresponding flow rate of 7 °C cooling water was 13.1 l/min.

Experimental Achievements in Mini- and Micro- Channel Cooling

There are a significant number of cooling techniques for micro- and mini-sized devices. One of them is mini-channel cooling. In this review, a large amount of experimental work on mini-channel cooling by various liquids is conceptually considered, in which the threshold in the removal of specific heat flux of >1 MW/m2 has been reached. A comparison of mini-channel cooling with other cooling techniques is performed. It was established that 1) micro-channel cooling has practically no thermophysical advantages over macro- or mini-channel one; 2) single-phase cooling in mini-channels gives comparable results compared to two-phase cooling; 3) only a small set of conceptual techniques allows the mini-channel heat exchanger to overcome the limit of 10 MW/m2 or to reach the heat transfer coefficient larger than 0.2 MW/(m2*K).

Brownian Motion and Thermophoretic Effects in Mini Channels with Various Heights

Flow-through mini channels have received tremendous interest from researchers over a long period. However, the study of flow between the channel and on top of the channel has received little to no attention. In the present paper, different parameters have been used to investigate this heat enhancement. The height of 10 mini channels has been varied, allowing the corresponding aspect ratio to vary from 3 to 6, 9, and 12. When the aspect ratio is 12, flow circulates through the mini channel only, and when the aspect ratio is less than 12, flow is distributed between the one circulating inside the channel and moving on top of the channel. Different flow rates are studied corresponding to a Reynolds number varying from 250 to 1250 if water is the working fluid. Brownian and thermophoresis effects are taken into consideration to investigate the nanoparticle sedimentation. Results revealed that the optimum configuration, if one needs to take into consideration the friction factor, is 12. If one ignores the pressure drops, then the optimum configuration is when the aspect ratio is equal to 6. This means that the flow interaction between the one circulating in the channel and above the channel plays a major effect in heat removal.