Experimental Determination of Evaporation Heat Transfer Coefficients and Pressure Drops of Refrigerants in Inner Grooved Tubes

Recently, many types of tubes with improved heat transfer characteristics due to different inner spiral grooves have been widely adopted for evaporators and condensers of refrigerating machines and for air conditioning heat exchange equipment. The new possibilities in the achievements of more compact components in heat transfer processes have contributed to stir up the interest of Italian manufacturers too. In this paper several new types of inner grooved copper tubes are tested in order to verify their performance as compared with conventional smooth copper tubes in evaporation testing of R22. An original test facility, designed for this specific purpose, has been used to investigate systematically the heat transfer coefficients and pressure drops in the evaporation process, as functions of the refrigerant mass flux.