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.

Modeling of Twin Screw Extrusion of Polymeric Materials

An issue of modeling of twin-screw extrusion of polymeric materials is reviewed. The paper is written in honor of Prof. James L. White who was a pioneer in studying this issue. A global approach to process modeling is presented which includes solid polymer transport, polymer plasticating, and the flow of molten polymer. The methodology of CFD modeling of twin-screw extrusion is presented as well as the examples of this modeling which show the details of the process. Optimization and scaling of twin-screw extrusion are also covered. And finally, the future prospects of developments and research of twin screw extrusion is discussed.

CFD modeling of slurry flow erosion wear rate through mitre pipe bend

Erosive wear caused by particulates slurry is one of the major concerns in the pipe bend which may results in the failure of the pipe flow system. In the present work, erosion wear rate through mitre pipe bend caused by silica sand particulates slurry has been investigated using ANSYS Fluent code. The solid spherical particulates of size 125 µm and 250 µm having density of 2650 Kg/m3, were tracked to compute the erosion wear rate using Discrete Phase Method (DPM) model. The particulates were tracked using Eulerian-Lagrange approach along with k-ɛ turbulent model for continuous fluid phase. The silica particulates were injected at solid concentration of 5% and 10% (by weight) from the pipe inlet surface for wide range of velocities viz. 1–8 ms−1. The erosion wear rate was computed through four computational erosion models viz. Generic, Oka, Finnie and Mclaury. Furthermore, the outcomes obtained through Generic models are verified through existing experimental data in the literture. Moreover, the results of DPM concentration, turbulence intensity and particle tracking were predicted to analyze the secondary flow behaviour through the bend cross section. Finally, the effect of particulate size, solid concentration and flow velocity were discussed on erosion wear rate through bend cross section. The findings show that the locality of maximum erosive wear is positioned at the extrados of the bend outlet cross section. Additionally, it is found that Mclaury model offers higher erosion rate as compared to the other models and provides benchmark for designing the slurry pipeline system.

CFD MODELING OF MICROCHANNELS COOLING FOR ELECTRONIC MICRODEVICES

A simulation of the cooling of electronic devices was carried out by means of microchannels, using water as a coolant to dissipate the heat generated from a computer processor, and thus stabilize its optimum operating temperature. For the development of this study, computational fluid mechanics modeling was established in order to determine the temperature profiles, pressure profiles, and velocity behavior of the working fluid in the microchannel. In the results of the study, the operating temperatures of the computer processor were obtained, in the ranges of 303 K to 307 K, with fluid velocities in the microchannels of 5 m/s, a pressure drop of 633.7 kPa, and a factor of safety of the design of the microchannel of 15. From the results, the improvement of the heat transfer in a cooling system of electronic devices was evidenced when using a coolant as a working fluid compared to the cooling by forced air flow traditional. ABSTRAK: Simulasi penyejukan alatan elektronik telah dibina menggunakan saluran mikro, di samping air sebagai agen penyejuk bagi menghilangkan haba yang terhasil dari pemproses komputer, dan penstabil pada suhu operasi optimum. Kajian ini mengenai model komputasi mekanik bendalir bagi menentukan profil suhu, profil tekanan, dan halaju perubahan bendalir dalam saluran mikro. Dapatan kajian menunjukkan suhu operasi pemproses komputer adalah pada julat suhu 303 K sehingga 307 K, dengan halaju bendalir dalam saluran mikro adalah pada kelajuan 5 m/s, penurunan tekanan sebanyak 633.7 kPa, dan faktor keselamatan 15 bagi reka bentuk saluran mikro. Ini menunjukkan terdapat kenaikan pemindahan haba bagi sistem penyejukan alatan elektronik ini, terutama apabila cecair digunakan sebagai penyejuk haba berbanding kaedah tradisi iaitu dengan mengguna pakai aliran udara sebagai agen penyejuk.

Design Optimization of a Helical Coil Gas Cooler Based on the Results of CFD Modeling of Erosion Wear

Simulation of erosion wear and design optimization have been performed for a convective gas cooler with a helical coil. Based on the results of simulation of the standard gas cooler design with a flat baffle used in Shell gasification-based combined cycle unit, it is concluded that the particle impact angle is the main factor determining the erosion maximum. To reduce erosion, it is necessary to install a structural element instead of the flat baffle to align the flow path of ash particles at the inlet to the gas cooler. The results of simulation for various baffle shapes show that a hemispherical baffle is optimal. The use of a hemispherical baffle plate made it possible to align the ash particle flow path at the inlet to the gas cooler channels and reduce the maximum level of erosion by a factor of almost 4 compared to the standard geometry of the baffle plate.