Experimental Evaluation of Performance Characteristics of a Horizontal Copper Mesh Wick-Based Miniature Loop Heat Pipe

The ever-increasing computational power of the electronic devices accompanies a greater power dissipation. Understanding and optimization of the heat rejection systems are thus vital to ensure effective thermal management of electronic devices in an often highly confined space. This paper reports the design, development, and results of an experimental investigation of a fast responding and passive heat-rejecting copper–water-based miniature loop heat pipe (mLHP) system. The designed mLHP has a square flat-faced evaporator of 20 mm length with opposite replenishment, four extended surfaces with vapor space, a liquid reservoir or compensation chamber, fin- and tube-type condenser, and different diameter transport lines. Capillary pumping action was ensured by a composite of 100PPI copper mesh with 37% porosity and absorbent wool of 20 µm average pore size. Wick hydration was safeguarded by a 67% filling ratio of mLHP at a cold state. A decrease in thermal resistance and an increase in heat transfer coefficient for evaporation were observed. The thermal resistance of the evaporator and mLHP was 0.109–0.396 °C/W and 0.132–0.644 °C/W with an uncertainty of 3.749% and 3.744%, respectively. The heat transfer coefficient for evaporation achieved during experimentation was 6.313–23.00 kW/m²K with 0.345% uncertainty. No reverse flow of vapors and evaporator dry-out was detected. The maximum temperature sustained was 108 °C against the 205 W heat load with a 4.5-min start-up duration. These results reveal the suitability of the designed miniature loop heat pipe for the heat dissipation of electronics.