Meaning
Thermal proportionality constants govern the rate of heat transport between a solid surface and a moving fluid. The convective heat transfer coefficient defines this rate per unit area and per Kelvin of temperature difference. It establishes the boundary condition where conductive transport inside the solid meets the moving boundary layer of the fluid flow.
Its units are Watts per square meter Kelvin.
Flow Characteristic
Fluid velocity governs the thickness of the thermal boundary layer. At low velocities, laminar flow dominates and yields a lower convective heat transfer coefficient due to the thick insulating fluid layer. Turbulent flow mixes the fluid rapidly.
This mixing increases the convective heat transfer coefficient by compressing the thermal resistance into a thin layer near the wall.
Surface Geometry
Surface roughness alters the local flow structure. Rough surfaces induce local eddies that enhance convective heat transfer coefficient values. The shape of the surface determines how the fluid boundary layer develops along the flow path.
Fluid Property
Physical properties of the coolant dictate the energy transport capability. High thermal conductivity and high specific heat capacity of the fluid increase the convective heat transfer coefficient. Viscosity resists flow, which reduces the coefficient value.
Density determines the momentum of the fluid.
