Numerical investigation of conjugate heat transfer in a flattened cross-sectional thick channel

In this study, heat transfer characteristics in steady-state laminar flow of a Newtonian fluid through straight, thick wall flattened channels is numerically investigated. The focus is on understanding the experienced conjugate heat transfer process in a channel under constant outside wall temperature conditions. By varying the thermal conductivity and thickness of the walls and Reynolds number within the range of 50–1250, a comprehensive parametric investigation is conducted. Numerical results reveal a complex interaction between the thermal characteristics of the wall material and the fluid flow regime, influencing the conjugate heat transfer characteristics. The use of a flattened cross-section channel leads to improved heat transfer performance, with a significant enhancement in the Nusselt number by approximately 37% when transitioning from a circular to a flattened cross-section configuration. For channels with relatively low wall material conductivity and a high solid-to-fluid thickness ratio, the solid-fluid interface experiences a more uniform wall heat flux condition. As a result, the streamwise temperature profile on the interface demonstrates an increased prominence in non-uniformity. Conversely, increasing the value of wall material conductivity, regardless of thickness ratio, tends to bring the solid-fluid interface closer to the constant temperature condition.