BOILING HEAT TRANSFER AND PRESSURE DROP IN INTERNAL SPIRAL-GROOVED TUBES.

Abstract

Tubes with fine internal spiral grooves to achieve a higher heat transfer coefficient without an increase in the friction loss are considered measuring the boiling heat transfer coefficient and the pressure drop at various flow rates of refrigerant, vapor mass qualities and heat fluxes, while the influences of the inclination of the spiral-groove, depth of the groove and the pitch of the spiral-groove are examined. Refrigerant R-22 serves for fluid. An inside spiral-grooved tube of approx. 11. 2 mm inside diameter is tested.