A comparative study of enhanced thermal performance in Tesla-type microchannels

Enhancing convective heat transfer in microchannels is significant for cooling of micro-electro-mechanical systems (MEMS). The dominant laminar flow in confined domain at microscale normally results in thick thermal boundary layers, seriously deteriorate the heat transfer process because of limited disturbance of flow. In this study, a novel Tesla-type microchannel configuration with significant flow diodicity was proposed to significantly interrupt boundary layers and promote fluid mixing. Hydrodynamic and thermal performances of this as-designed configuration were comprehensively investigated through experimental and numerical studies. Thermal characteristics such as Nusselt number (Nu), thermal resistance (Rth), and performance evaluation criterion (PEC) were computed. Diodic performance was also evaluated by measuring pressure drop diodicity and thermal diodicity in different flow directions. The results demonstrate that convection heat transfer is significantly enhanced because of strong mixing and periodic interruption of liquid flow and thermal boundary layers. Compared to conventional plain-wall microchannel, the average wall temperature is dramatically reduced by about 10 K at Re = 250 because of enhanced mixing effect. Accordingly, Rth is significantly decreased by ∼ 45 %. A PEC of 1.3 is achieved as well. Overall, the Nu is ranging from 10 to 25.2 for Re ranging 100 to 450, about 1.3 ∼ 2.1 times higher than that of plain-wall microchannel. Diodic performances in terms of Dip and Dit are about 1.9 and 1.3 for Dh = 0.4 mm. The new understandings of this study might provide insights for the design of new heat sinks for potential applications in electronics cooling.