In-tube evaporation and condensation of R-22 and R-410A with plain and internally enhanced tubes

Two-phase in-tube heat transfer and pressure drop comparisons for both evaporation and condensation were performed with R-22 and R-410A with a commercially available 9.53 mm internally enhanced tube - 60 internal ridges with 0.2 mm (0.008 ") ridge height and a helix angle of 18 degrees, The experiments were performed over appropriate mass flux ranges to ensure that the data were applicable for many uses: 100 - 400 kg/s-m(2) for the evaporation test and 200 - 800 kg/s-m(2) for the condensing tests. The R-22 evaporation data from Thors and Bogart (1994) is reprinted here for the comparison purposes and the balance of the data presented are new. The data indicate that R-410A has a substantially higher evaporation coefficient than R-22 over the bulk of the respective flow range and has a slightly higher condensation coefficient than R-22 over part of the respective flow range for a plain tube and a slightly lower condensation coefficient over the entire flow range for the enhanced tube. The results also show that R-410A has a substantially lower pressure drop than R-22 in both evaporation and condensation over the entire flow ranges.