Convective heat transfer in the entrance region of a vertical tube for water near the thermodynamic critical point

Turbulent convective heat transfer is modeled for developing flow of water near the thermodynamic critical point in a constant wall temperature vertical tube with and without buoyancy force. Wall temperature effects on momentum and heat transfer, velocity profiles, property variation. heat transfer coefficient, and friction factor distribution close to the inlet (z/D < 10) are discussed. Flow acceleration near the wall increases near the critical pressure. Local axial fluid temperature decreases are observed. apparently due to local radial velocity carrying cool core fluid towards the tube wail. Comparison among models for turbulent Prandtl number shows less influence on momentum than heat transfer. (C) 1998 Elsevier Science Ltd. All rights reserved.