Investigation of flow boiling phenomenon in micro-pin-fin heat sinks adapted to actively direction-changing moving systems

Thermal management via boiling phenomenon in micro domain is one of the promising techniques for different types of aircrafts being continuously subjected to direction-changed movement. Therefore, in this paper, different from the literature, flow boiling phenomenon in expanding micro-pin-fin heat sinks with micro cavities (EH) continuously making angular motion is experimentally examined. To reveal effects of decreasing fin number (or increasing cross sectional area) along the heat sink and existence of micro cavities, the results, also, are compared to those obtained for conventional heat sink (CH). Angular range of motion (ARM = 0 degrees <-> 15 degrees, 0 degrees <-> 30 degrees and 0 degrees <-> 45 degrees), period of angular movement (PAM = 10 s, 30 s, and 60 s) and heating power (220 W and 300 W) are the variable parameters. Mass flux (G) and inlet temperature (Ti) are constants as 120 kgm(-2) s(-1) and 74 degrees C, respectively. It is concluded that the EH can successfully damp possible effect of variation in angular orientation on thermal characteristics, and thus, the EH leads to more stable thermal performance compared to CH. The key mechanism determining deviation characteristics is interaction between gravitational force and fluid inertia force. By enhancing wicking phenomenon and suppressing evaporation momentum force, the influence of angular variation can be minimized.