Pool boiling heat transfer enhancement of distilled water with passive rotating blades installed above the heating surface

This study examined the pool boiling heat transfer of distilled water on a copper heating surface with passive rotating blades installed above the heating surface. The rotating blades were made from copper material, with a diameter of 30 mm, a core of 5 mm, a length of 50 mm, and a blade angle of 90°. The number of blades in this experiment varied between 2, 3, and 4. The study examined the effects of a varying number of blades and the distance between the heating surface and rotating blades (LSB) on the pool boiling heat transfer coefficient. The experimental results show that, when compared under the same conditions, the rotor with four blades yielded a higher heat transfer coefficient than those with two and three blades. This is because the added blades increased the area that received strike force from the bubbles. As a result, the rotating blades created more disturbance of the working fluid over the heating surface. Furthermore, when compared with the same number of blades, the LSB of 5 mm yielded a higher heat transfer coefficient than the LSB of 15 or 25 mm. This is because the increased LSB provided less chance for the bubbles to strike the rotating blades. Hence, the rotating blades did not create a disturbance of the working fluid over the heating surface.