HEATING TUBE FOR ABSORBER

PROBLEM TO BE SOLVED: To enhance absorbing performance by forming a large number of protrusions on the outer surface of a heating tube such that an absorbing liquids are exchanged in the fluid process thereby increasing the quantity of absorbing liquid being stored and spreading the absorbing liquid in the horizontal direction while furthermore mixing the absorbing liquids sufficiently utilizing the difference of surface tension due to uneven concentration. SOLUTION: N protrusions 12 having cross-sectional width (a) and height (b) are formed on the outer circumferential surface of a heating tube 10 at an interval (c) in the axial direction of tube. The interval (c) of the protrusions 12 on a circumference is set at 2-4 mm, the width (a) is set at 1-2 mm and the height (b) is set at 0.5-2 mm. Heat is exchanged when absorbing liquid flowing down from a direction perpendicular to the heating tube 10 absorbs refrigerant vapor on the surface of the heating tube 10. The liquid on the outer surface side where the absorbing liquid absorbs refrigerant and the liquid on the heating tube 10 side for cooling the absorbing liquid are mixed sufficiently because upper and lower liquids are exchanged through the difference of surface tension due to uneven concentration when the absorbing liquid flows over the protrusions 12.