POOL BOILING HEAT-TRANSFER ON FINNED TUBES - AN EXPERIMENTAL AND THEORETICAL-STUDY

Pool boiling heat transfer of R11 is investigated experimentally and theoretically on single tubes and twin tube arrangements. Finned tubes with 19 and 26 fins per inch (fpi) are used. The refrigerant evaporates at a saturation state of 1 bar on the outside of the electrically heated tubes. For the twin tube arrangements the tube pitch is varied between s/d(F) = 3.0 and 1.05. The heat transfer on the upper tube of the twin tubes is enhanced compared with the single tube, while the heat transfer on the lower tube is not affected by the upper tube. The maximum heat transfer of the upper tube increases with increasing tube pitch.