Effect of wettability on bubble motion in slotted channels

Presented are the results of the experimental investigation on the effect of wettability on air bubble motion and size in the vertical slotted channels filled with water. Obtained are the data testifying that the change of the wettability equilibrium angle considerably affects the form and the regime of bubble motion. Given are the experimental values of bubble velocity with the volume ranging from 10 to 100 mm3 obtained at wettability angles approximately 15 deg and 90 deg. It has been found that the growth of the contact wettability angle decreases the bubble velocity. Each channel has its own limit volumes of gas bubbles. If the gas bubbles meet the requirements they secure the stable form in the motion. The wall area screened by the stationary and slowly moving bubbles reaches considerable dimentions. This should be taken into consideration while making thermal calculations of strained heat exchangers