Download or read book Characterization of Heat Transfer Coefficient at Micro/nano Scale and the Effect of Heated Zone Size written by Raghu Pulavarthy and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Heat transfer mechanism from hot solids to surrounding air is crucial in thermal systems. Thermal management of devices at micro/nano length scales is very important for their reliability as they continue to shrink in size. It is agreed widely that the heat transfer coefficient increases at smaller length scales. This work presents an experimental technique to characterize the heat transfer from micro and nano scale structures using infrared microscopy. The heat transfer coefficient is found to be two orders of magnitude higher than the value at bulk length scales. It also shows an inverse relationship with temperature of the solid which suggests that the solid to air conduction is the dominating mechanism of heat dissipation at small length scales. An empirical relationship is also presented that depends on ratio of surface area to cross-sectional area, temperature differential in the heated solid and its surroundings. The heat transfer coefficient in conjunction with the temperature map from the infrared microscope can be used to measure the thermal conductivity of specimen using a heat transfer model based on micro fin geometry. It is assumed that this size effect on the heat transfer coefficient is due to the size of specimen. An experiment is presented to show the effect of the predominance of the heater size on the heat transfer coefficient. For micro-heaters, the heat transfer coefficient is measured to about 3200 W/m2 K. This value drops to about 110 W/m2 K for a millimeter scale heater and to 10 W/m2 K for a macroscopic heater; all for a nanoscale thin film specimen.