| 摘要 |
PURPOSE:To reduce pressure loss and improve heat conduction index by specifying the numerical values of the advance angle, depth and pitch of spiral grooves provided in the internal wall of the heat conduction pipe for vapor-liquid two-phase flow in an air conditioner and the like. CONSTITUTION:The spiral grooves 2 are provided in the internal wall of the heat conduction pipe 1. The grooves are formed in the shape of triangle, rectangle, trapezoid or the like. When the advance angle theta of the groove is set to be less than 30 deg. and the ratio of the depth h of the groove to the inside diameter di of the heat conduction pipe h/di to be 0.03 or less, the ratio of the pitch P of the groove to the depth h thereof P/h is determined to be 10 or less. By this constitution, the pressure loss can be reduced and the heat conduction index can be improved. |
