PDF-based modeling on the turbulent convection heat transfer of supercritical CO2 in the printed circuit heat exchangers for the supercritical CO2 Brayton cycle

Computational Characterization of Fluid Flow and Heat Transfer in the Pressure Tube of CANDU 6 Nuclear Reactor with Supercritical CO2

“…In effect the capacity of the Nuclear Reactor can be increased for more power generation. From the fig 18 we can observe that density at outlet of the pressure tube is reducing greatly in case of Carbon-dioxide. Because of this, the mass flow rate is reduced which in turn reduces the size of pump.…”

Performance Analysis and Modeling of a Printed Circuit Heat Exchanger with Air and Carbon Dioxide as Working Fluids

“…, Li et al[33] and Meshram et al[34], the mesh density at the inlet and outlets of the channel was very high as seen in Figures 4.9, 4.10 and 4.11. The reason they increased the density at the surface of the channels is to investigate the temperature profiles and gradients occurring at the inlet and outlet surfaces and hence making the mesh extremely fine at these surfaces while also increasing the mesh quality of the boundary elements.…”

Computational investigations on heat transfer of turbulent supercritical CO2 in large tubes using RANS modelling

“…very flat in the center dropping off sharply at the wall [202]. In order to reduce the thermal entrance effect, the extraction of heat transfer datasets starts from the location along the cooling wall that is certain-distance ( , ≈ 10 , as recommended in heat transfer books [183,185,201] have also demonstrated good consistency for cooling sCO2 flows in recent work [22,67,94,110,118,200,203], which is verified by the validation work in Section 5.3.1 as well. It might be due to the fact that local turbulent heat transfer of sCO2 side is less sensitive to the implementation of different types of thermal boundaries.…”

“…Most previous studies of buoyancy-affected turbulent sCO2 heat transfer focus on vertical flows, where the heat transfer performance could either be improved or impaired; some of these studies at early stages employed large vertical pipes ( ≈ 20 mm) [133,[167][168][169]. However, for horizontal orientations [44,108,110], the datasets are only available for small tubes, where the free convection [24,35,110,199,200] and pipe diameter [22,33,43,194], they usually did not offer the underlying physical explanations. In addition, the buoyancy effect within this diameter range tubes is also discussed.…”

“…RNG − model with the two-layer approach [132,139,176], LS (Launder and Sharma [86]) [27,134], YS (Yang and Shih [177]) [80,103,134] and AKN (Abe, Kondoh and Nagano [87]) [21,90,101] models well reproduced turbulent sCO2 flow and heat transfer behaviour, especially the buoyancy effects, under specified conditions. Besides, changes in operating conditions/geometries and the limitations of experimental measurements, call for generalized approaches, Hence, researchers attempt to establish correlations to predict the Nusselt number for supercritical fluids with the help of computational techniques [67], including the validated RANS models [199,200,209,210]. Induced by the density variation, buoyancy effects were observed and discussed in a range of experimental and computational studies for vertical sCO2 flows [21, 28-31, 76, 80, 90, 103, 108, 109, 119, 134, 195, 196, 211].…”