Effect of longitudinal micro fin tube enhancement in evaporation of R410A

heat transfer coefficient;micro fin tube enhancement

Vivanco Obeso, Sergio Daniel ; Hrnjak ; Predrag S.

关键词: heat transfer coefficient;    micro fin tube enhancement;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/89069/VIVANCOOBESO-THESIS-2015.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

An experimental investigation of evaporating heat transfer was conducted for smooth andcoaxial micro-finned aluminum tubes with an internal diameter of 6.3 mm. The study usedR410A at a saturation temperature of 10 °C running at mass fluxes from 100 to 250 kg/m2-s, heatfluxes from 4 to 14 kW/m2, and qualities from 0.1 to 0.8.The testing facility had a 15 cm long test section heated by a secondary heated water loop, atransparent visualization section which used a high-speed camera to capture flow regimes, andvertical and horizontal pressure drop test sections. The micro-finned enhancement factors were1.14-1.85, 0.91-1.72, and 1.05-1.66 for heat fluxes of 4, 9 and 14 kW/m2 correspondingly.Calculations for the finned tube used the molten diameter surface. Flow regimes were similar forboth tubes, except for qualities tested, and the regimes were correctly predicted by Cheng et al.(2008). Images of the flow regimes were captured for each testing quality and for mass fluxes.Pressure drop in the micro-finned tube was higher than the smooth tube for both horizontal andvertical tube orientations. The difference in pressure drop increased with higher vapor quality.