Thermohydrodynamic Modeling of Highly Elongated Water Heatsink with Continuous Rectangular Microchannels

The results of a numerical modeling of the laminar water flow and mixed conductive–convective heat transfer in highly elongated heatsink with continuous rectangular microchannels, and a width-to-length ratio of 625 (i.e., 0.2 mm to 125 mm), are presented, along with two methods of fluid entry (along and perpendicular to the base of the heatsink) for a wide range of surface heat flux density q from 30 to 2000 kW/m2 and water volume flow rate from 10 to 50 L/h (ReD=26−128). It has been demonstrated that: (1) The elongated microchannel maintains its effectiveness in heat removal by water, even under conditions of high q-value; however, in the terminal sections the temperature can approach the maximum permissible operating level for high-loaded silicon electronic components (~95–100 °C). (2) For microchannel heatsinks, the direction of the incoming flow is not of significant influence, since the microchannel structure, even with a height of 2.5 mm, exhibits substantial diffusivity and the flow in the inlet area rapidly turns along the heat distribution base; this flow further possesses the same characteristics as in the case of the input flow parallel to the axis of the microchannels. The developed model allows for the optimization of geometric, kinematic and thermal parameters of highly efficient microchannel devices, depending on the expected operating conditions.