Abstract
The impact behavior is a fundamental phenomenon because it can be seen several research fields. Then, the impact behavior of a small refrigerant drop on water surface was visualized by using high-speed video camera. The refrigerant liquid was attached inside of the concavity in after impacting. Afterward the refrigerant liquid collected in the bottom of the concavity. The shape of the concavity was consisted of the two frustums. One was for air and another was for refrigerant liquid. A refrigerant drop with a small bubble, which was trapped inside of the refrigerant drop, fell in water. When the dropping height was changed from 70mm to 150mm, the both of sizes of falling refrigerant drop in water and a trapped bubble were independent from the initial height.
