Shell-side condensation heat transfer of R-134a - part II: enhanced tube performance

Shell-side heat transfer coefficient data are presented for the condensation of refrigerant R-134a on tube bundles constructed from two different enhanced tube geometries. The tube bundles tested are five rows wide by five rows deep and have a staggered tube arrangement with a horizontal pitch of 22.2 mm (0.875 in.) and a vertical pitch of 19.1 mm (0.75 in.). The data were obtained at a refrigerant saturation temperature of 35C (95F) over a bundle heat flux range of 18,000 to 40,000 W/m2 (5,700 to 12,700 Btu/[h ft2]). Average condensing heat transfer coefficients for the bundle as well as average condensing heat transfer coefficients for the middle tube of each row were calculated. The data show that the Tu-Cii tube performs significantly better than the G-SC tube. The row-to-row heat transfer coefficient behavior also differs between the two tube bundles. In general, the average bundle and average row heat transfer coefficients decrease with increasing heat flux. The Tu-Cii also performs better than the previously tested 40-fins-per-inch (fpi) and 26-fpi tubes, while the G-SC only performs better than the 26-fpi tube.

Shell-side condensation heat transfer of R-134a - part II: enhanced tube performance Conference Paper