IN-TUBE CONDENSATION OF R-134a, R22, R-407C AND R-410A WITH HIGHLY INTERNALLY ENHANCED TUBES

摘要

To improve heat exchanger efficiency, a highly enhanced inside tube surface has been developed. The effect of surface enhancement was evaluated by comparing two-phase in-tube heat transfer and pressure drop for condensation using R-410A, R-22, R-134a, and R-407C in 9.53mm (3/8") tubes with two internal enhancements. The experiments were mainly performed on a highly internally enhanced tube, herringbone grooves with an intermediate sets of fins positioned in the areas between the primary fins. Data for a conventional helical micro-fin tube were also taken as a baseline comparison of performance. The tests were conducted over applicable mass flux ranges for use in commercial and residential equipment: 200-1000 kg/s-m{sup}2 (147,500-737,300 lb/hr-ft{sup}2) at a typical operating temperature of 40.6°C (105°F). The data obtained indicates that the highly internally enhanced tube yielded 30% to 80% higher heat transfer coefficient than the helical micro-fin tube for all tests. However, increased surfaced enhancement did not result in significant pressure drop penalty for the flow rates less than 136 kg/hr (i.e., 300 lb/hr) in comparison to the micro-fin tube tested.