Patent ID: 10072898

Abstract:
A fin satisfies 0°<θ2<tan−1[(L±α)/{(S1−D1)/2−L/tanθ1}], where S1 is a distance between an upstream end and a downstream end of a first inclined portion, D1 is a distance between an upstream end and a downstream end of a flat portion, θ1 is an angle between a reference plane and the first inclined portion in the flow direction, θ2 is an angle between the reference plane and the second inclined portion in the flow direction, α is a distance between the reference plane and the flat portion, and L is a distance between the reference planes of the fins adjacent to each other. θ2 gradually decreases as a measurement direction of the angle is shifted from the row direction to the air flow direction and is minimum when the measurement direction is orientated in the air flow direction.