Patent ID: 7762318

Claim:
A condensing heat-exchange copper tube for a flooded type electrical refrigeration unit, comprising a smooth surface portion, a finned portion provided with a plurality of fins and a transitional portion connecting the smooth surface portion to the finned portion, each fin of said plurality of fins including a fin base close to the outer surface of the heat-exchange tube and a fin top away from the outer surface, characterized in that: each fin of said plurality of fins is further provided with a secondary fin, wherein a certain distance is provided between two axially adjacent secondary fins, and the distance between the secondary fin and the top surface of the fin is between ⅓ and ⅔ of the overall height of the fin, and wherein the secondary fin has been developed by stamping each fin radially downward from a position below each fin top; and each fin of the plurality of fins is further provided with a third fin developed by stamping each fin of the plurality of fins radially downwardly from the top surfaces of the fins, wherein a certain distance is provided between two axially adjacent third fins; and wherein a cross-section of the secondary fins define a right triangle perpendicular to each fin of the plurality of fins, a distance between an upper surface of the secondary fins and the top surface of each fin of the plurality of fins is between 0.3 and 0.7 mm, and the width of the secondary fins is between 0.15 and 0.35 mm.