Numerical Simulation Study Of Flow And Heat Transfer On Microencapsulated Phase Change Material Suspension In Micro Rectangular Channels

With the rapid development of modern science and technologies especially the development of microelectronics technology and the miniaturization of the system, the number of transistors per unit area is increasing correspondingly and the speed of operation is improving.The heat generated of per unit area is increasing as well, which caused the rising of heat flux. The above factors lead to the devices malfunction and even broke down. Therefore the need for efficient heat dissipation is necessary. The purpose of this paper is getting on numerical simulation of heat transfer characteristics in the micro rectangular channels by putting the use of microencapsulated phase change material suspension as a cooling refrigerant according to its benefits of large specific heat capacity, good liquidity and so on.Firstly, by proposing a model for shape of stairs of equivalent specific heat model, setting up a 3D model of micro rectangular channels, and comparing heat absorption in different shape of stairs with the result of experiment and the relationship with the wall temperature difference of numerical simulation and experiment. We found the shape of equivalent specific heat model has a optimal value.For the mass concentration of 5% of the microencapsulated phase change material suspension, its specific heat capacity model of 3-stairs is closest to the experimental values. This model is the optimal ratio of stairs shape of equivalent specific heat model. For the mass concentration of 10% of the microencapsulated phase change material suspension, its specific heat capacity model of 3-stairs is closest to the experimental values in the case of small mass flow. However, with the increas e of the mass flow rate by the increase of the mass flow rate,part of the microencapsulated phase change is not occurred, which leads to a deviation of experimental data.Secondly, in order to comparing the advantages and disadvantages of different shapes of the equivalent thermal model, we compared in the shape of stairs, rectangular, isosceles triangle, and isosceles trapezoidmodel. We found that for the mass concentration of 5% of the microencapsulated phase change material suspension, isosceles trapezoid always showed the best cooling performance. The second is isosceles triangle, rectangle or shape of stairs. One of them is the shape of stairs of equivalent specific heat model, whose result of model is closet to the experimental result.Finally, by considering the microencapsulated phase change particles in motion and us ing the particle trajectory model for laminar flow simulation of two-dimensional micro rectangular, and comparing in five kinds of conditions different heating wall heat flux and inlet velocity which is based on the compute of equivalent specific heat model, we can find the result: The cooling effect of containing microencapsulated phase change particles suspension is better than water. The cooling effect of mass concentration of 10% of the microencapsulated phase change material suspension is better than which of 5%. With the increase of concentration of the microcapsules change phase, analog phase change melting zone length is increasing too, which shows better cooling effect. In the equivalent specific heat model, by considering the particle wall of microencapsulated phase change material, we found that heat intensity is slightly slower than the phase-change microcapsule particles themselves.