Startup categories of manifold microchannel heat sink heated by thermal test chip

This study presents an experimental analysis of the startup behavior of a manifold microchannel heat sink within a mechanically pumped flow loop. A simulated thermal test chip, embedded with temperature sensor, acted as the heat source, facilitating rapid and precise temperature measurements in the heating zone. Using ammonia as the coolant, heat flux of 634 W/cm² over the chip area of 6 × 6 mm² was effectively dissipated. The junction temperature surged to 86 °C during the startup and finally stabilized at 75.1 °C, highlighting the importance of assessing the transient thermal performance. Within the scope of this study, the transient maximum chip temperature during startup was observed to be capable of exceeding the ultimate steady-state temperature by nearly 40 °C. Based on the dynamic response characteristics of the chip temperature, the startup processes were categorized into three types: gradual, transitional, and overshoot. And the variations in chip temperature across these startup categories were investigated in conjunction with crucial parameters such as flow rate and pressure. Furthermore, the effects of flow rate and inlet condition on the startup processes were also examined.