Reporting the Progression of Laminar Single-Phase Flow in a Double-Pipe Heat Exchanger via a Horizontal Tube

Overcoming challenges in the context of smooth surfaces when employing forced convection with horizontally oriented circular tubes is complex, and this is because very low heat fluxes are required to counteract buoyancy effects and prevent an increase in. Past research mainly focused on the heat transfer coefficient in laminar regions of convection and paid minimal attention to forced convection in these systems. This research aimed to investigate the attributes of heat transfer coefficients in certain forced convection circumstances. Smooth, circular test sections with a diameter of 0.01 m and a length of two meters, featuring both inlet and outlet flows, were employed for this purpose. R-113 was used as the working fluid, with an inlet temperature of 22 °C. The investigation yielded various findings, including Nusselt numbers ranging from 5.50 to 7.11, Reynolds numbers ranging from 948.42 to 2263.38, and heat inputs ranging from 25 to 150 W. The extent of the laminar flow zone, determined by analyzing the development of the laminar region, was assessed for all heat experiments.