Thermal Analysis of Vapor-Phase R1234yf Flow Inside Horizontal Helical Discrete Double Inclined Ribs Tubes

In the power and refrigeration cycle, R1234yf is a refrigerant suited for replacing R134a due to its minimal ozone depletion potential and global warming potential, as well as greater efficiency and safety compared to R290. However, the use of R1234yf is still limited because the characteristics of this refrigerant have not been widely applied to heat exchangers. To determine its thermal characteristics, this research tested the vapor phase R1234yf on the tube and straight and helical DDIR tubes. Enhanced tubes and Discrete Double-Inclined Ribs (DDIR) are used to improve heat exchanger effectiveness. The refrigerant was tested at a Reynolds number of 12000 to 20000 with varying helix angles of 10, 30, and 50^o. The selected rib pitches are 10 and 20 mm. Smooth and Straight DDIR tubes are used as a reference to evaluate the improvement in helical DDIR Tube performance. Flow structures show that Helical DDIR can significantly move the trajectory of the vortex core. Based on Performance Evaluation Criteria (PEC), Helical DDIR tubes perform much better than straight tubes, with a range between 1.1 and 1.6. Meanwhile, straight DDIR tubes have lower PEC performance than straight tubes in entire Reynolds numbers.