Heat Transfer in Spiral Channel Heat Sinks

Heat transfer in a spiral heat sink is examined experimentally and analytically. The spiral channel was fabricated on a base plate of copper. The cross section of the channel is square with 1 mm sides. A copper cap plate was bolted tight to seal the channel. Water and four low viscosity silicone oils (0.65 cSt, 1 cSt, 3 cSt and 10 cSt) were used as a medium; thus a Prandtl number from 5 to 100 was examined. Tests considered fluid entering from the side of the heat sink and exiting from the middle of heat sink and entering from the side and exiting from the middle. Heat transfer behavior over a wide range of flow rates from laminar to turbulent has been examined. Enhancement due to the spiral geometry was observed, and no significant difference was reported between the side and middle inlet condition. The dimensionless mean wall flux and the dimensionless thermal flow length were used to analyse the experimental data instead of Nusselt number and channel length. The spiral channel has been discretized, so that a single Dean number can be assumed in each cell, and two current models were applied to obtain the average Nusselt number. These are used to obtain the dimensionless mean wall flux and comparisons made with the experimental points.