Micro process engineering of freestanding silicon fluidic channels with integrated platinum thermistors for obtaining heat transfer correlations

The heat transfer in silicon microchannels with integrated inline and staggered pin fin arrays is evaluated at clearance-to-diameter ratios of 0.5-0.77 in the laminar flow regime. The channels have a small width, leading to a significant influence of the channel walls on fluid flow and heat transfer. Their influence is considered when measuring the temperature distribution along the channel length and the average heat transfer. For this purpose platinum thermistors are integrated directly into the channel structures, which are released from the silicon substrate and made freestanding via deep reactive ion etching (DRIE) and selective dicing. The measurements show that a significant portion of the fluid flows below the pin fins in the clearance bypass region. Heat transfer correlations are developed with a new functional form that considers the strong influence of the clearance-to-diameter ratio on overall heat transfer.