Analysis of Mixed Convection Strength under Laminar and Turbulent Flow

The heat transfer rate is experimentally investigated in horizontal tubes with constant heat flux boundary condition (UHF). The current study uses a modern-aged technique for contactless temperature measurement by Infra-red camera. Obtained thermal images give the two-dimensional wall temperature distribution. The data interpretation is then used for the visualization of the buoyancy-driven natural convection in laminar and turbulent pipe flow through 2D temperature contours along the length and across the test section diameter. A large variation in tube wall temperature in longitudinal as well as in the circumferential direction of the flow due to the secondary flow is observed for laminar flow under UHF. The heat transfer coefficient (HTC) ratio distribution helps in identifying the convection impact during different regimes. More strength is indicated by the HTC ratio for larger tube diameters.