Study of the transient behavior of microfluidic heat sinks

Abstract

In this work the transient behavior of a microfluidic heat sink is studied. Transient response of a heat sink is important for situations where heat inputs are dynamic, especially for applications such as microprocessors that have surfaces which generate heat non-uniformly. Heat generation profile on their surface changes with time and sometimes this change is very rapid. It is the transient characteristics and behavior of the heat sink that determines the surface temperature profile in response to the dynamic heat input. Transient simulation of microfluidic heat sinks confirms that their characteristic approximately follows a simple first order RC equivalent circuit model. Simulations show that the steady state surface temperature of the copper heat sink in transient condition is lower than the surface temperature of the silicon and nickel heat sinks. Therefore, the copper heat sink is superior for long duration transient conditions. Also shown is that a larger heat sink thermal capacitance provides a delayed temperature rise on the surface of the heat sink during the transient. This indicates that using a material with higher heat conductance is not necessarily good if it possess a small heat capacitance. This is illustrated by the silicon heat sink performing poorer than the nickel heat sink, in terms of temperature rise during transient situation, even though it has a higher heat conductance.