Abstract
A simple design micro-heat pipe was proposed. It was composed of 20.0 × 20.0 mm square flow circuit which had two adjacent narrow-sides (1.0 × 1.0 mm2 or 0.5 × 1.0 mm2) and two adjacent wide-sides (5.0 × 1.0 mm2 or 2.5 × 1.0 mm2). A heating spot was at the narrow side and a cooling spot was at the wide side. Working fluid was ethanol. The flow circuit was placed horizontally. Bubbles generated at the heating spot migrated toward the wide side, the bubbles coalesced there to form a large bubble, and then the large bubble moved to the cooling spot. Finally, the large bubble was condensed at the cooling spot. This cycle repeated continuously. As a result of it, heat transport from the heating spot to the cooling spot was produced in the micro heat pipe. An analysis of a flow mechanism was performed by solving a simple flow equation based on the flow resistance. It was proved that one-way circulation flow could be formed in the flow circuit. Predicted flow velocities were close to measured velocities. The growth rate of generated bubble in the present micro heat pipe was in agreement with the conventional prediction for heat-transfer-controlled period. The heat transport efficiency per unit mass of the proposed micro heat pipe was much better than the heat conduction of any metallic plate.
