Transient temperature performance of an integrated micro-thermal system

A novel integrated thermal microsystem was designed and fabricated with a heater, microchannels and distributed temperature sensors. This device allows, for the first time, an experimental study of the transient behavior of a thermal microsystem. The transient temperature behavior of the device was studied for a variety of heater power levels and forced convection flow rates, where DI water was used as the working fluid. Both heating-up rise time and cooling-down fall time due to a step current input were determined for natural and forced convection heat transfer. The transient temperature response to a sinusoidal power input was also investigated. The resulting temperature distribution was measured as a function of the input signal and the flow rate. The step response under natural convection is exponential for both heating and cooling processes. However, under forced convection, the heating-up time response exhibits a clear overshoot. The response time for both heating and cooling process is about four times faster than that for the natural convection case. Furthermore, under certain conditions, the periodic temperature response can exhibit a large peak-peak temperature without the occurrence of dry-out phenomenon.