Evaporation Flow Heat Transfer Characteristics of Stainless Steel and Copper Enhanced Tubes

An experimental study was undertaken to the tube-side evaporation heat transfer characteristics of enhanced tubes and compare their performance with that smooth tubes. These experiments were conducted in order determine how R410a evaporates inside tubes; for a saturation temperature 279.15 K; mass flux values ranged from 50 250 kg/(m2·s); an inlet quality 0.2 outlet 0.8. Enhanced evaluated include herringbone (HB) helix (HX) designs microgrooves, composite dimple (HB/D), hydrophobic (HB/HY), EHT (multiple enhancement character) Experimental results show heat-transfer coefficient Cu-EHTb tube highest; its closely related increased number nucleation points are found tube; however, SS-EHT-HB/D not significantly higher than tube. The best overall capacity evaporative is shown SS-EHT-HB/HY SS-EHT-HX SS-EHT-HB/D, Cu-EHTa, had worst among all tested Additionally, it determined previously reported models can accurately predict However, when trying utilize tubes, deviation between experimentally (HTC) those predicted using ±30%; therefore, applicable use Smooth modified, after correction, modified model ±10%. Finally, effect thermal resistance wall on stainless steel-enhanced significant cannot be overlooked.