<![CDATA[The growing demand of energy-efficient thermal management systems has increased the need in compact heat-transfer devices such as the Closed-Loop Pulsating Heat Pipe (CLPHP). This study experimentally investigates the effects of inclination angle, heat input, and working fluid on CLPHP thermal performance. A copper CLPHP with a 2 mm inner diameter, five turns, and a 65% filling ratio was tested at inclination angles of 0°, 30°, 45°, 60°, and 90°, using distilled water and ethanol as working fluids. Heat input was ranged from 10 to 50 W. The primary parameters analyzed were thermal resistance (Rth) and heat transfer rate (Qout). The results showed that thermal resistance generally decreased as heat input increased, although a slight increase occurred for ethanol at a horizontal orientation under certain conditions. The minimum thermal resistance was 0.24 °C/W for distilled water and 0.60 °C/W for ethanol, both at 50 W and 60°. The maximum heat transfer rate was 47 W for distilled water at a 90° inclination. These findings indicate that CLPHP performance depends on the combined effects of heat input, inclination angle, and working-fluid properties. Distilled water provided lower thermal resistance under the tested conditions, while the inclination associated with the best performance depended on the selected performance indicator.]]>
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