Influence of the microfin tube structure on the thermal-hydraulic performance of mixed supercritical CO2/R32

This research establishes 5 mm three-dimensional (3-d) flow and heat transfer microfin tube theoretical models with three different geometric structures. Using these models, the thermal-hydraulic performances of supercritical CO2/R32 in tubes structures at various working conditions were investigated. The influences each factors (pressure, mass flow, structures) on performance evaluated respectively. Furthermore, orthogonal tests undertaken to obtain optimized combination overall performance. Results indicate that: more temperature media approximates critical temperature, bigger local convective coefficient. Compared non-critical temperatures, coefficient shows an eight-fold increase. closer pressure mixed is pressure, greater maximum (CHTC) lower corresponding peak point, among which, CHTC under 7.5 MPa times as large that 8.5 MPa; increases increasing velocity, generally showing a linear relationship; through calculating most optimal evaluation using tests, determined be 96 kW/(m2?K).