Enhancement of the Thermal Performance of a Single Turn Pulsating Heat Pipe by Adding Micro-Coppers into the Base Fluid

In this research, a series of experimental and numerical studies on the thermal performance of a single-turn Pulsating Heat Pipe (PHP) using distilled water as base fluid and distilled water including micro-coppers were performed. Thermal resistance, average temperatures of the hot region (evaporator), average temperatures of the cold part (condenser), and two-phase flow regime of the system were investigated at the different filling ratios, at input powers (20, 30, 40, 50 and 60W), at a concentration of micro-coppers (0.0625 g/mL). The oscillating heat pipe was fabricated with a copper capillary tube by choosing the internal and external diameters of 4 mm and 6 mm, respectively. Experiments showed adding micro-coppers into base fluid improves the main mechanism of the PHP based on the oscillating motion of vapor plugs and liquid slugs. The lowest thermal resistance of the system at a filling ratio of 40%, at a concentration of micro-coppers (0.0625 g/ml), at heat input (60 W) was 0.95 deg C/W. Meanwhile, CFD results illustrated adding micro-coppers into base fluid increases the turbulence intensity of the system especially in the evaporator up to 45% which enhances the heat transfer through the PHP in comparison to base fluid.