Numerical Analysis of the Conjugate Cooling of a 2D Protruding Heater in Laminar Channel Flow

Abstract

The conjugate forced convection-conduction heat transfer from a 2D protruding block mounted on the lower conductive wall of a parallel plates channel was numerically investigated, using the control volumes method together with the SIMPLE algorithm. A uniform heat generation in the protruding block was transferred either directly by convection to an airflow in the channel or by conduction to the lower wall. The analysis was performed under steady state conditions, for laminar airflow with constant properties in the dynamic and thermal entrance region of the channel. This problem is related to the cooling of electronic components assembled on printed circuit boards (PCB). The board acts as a substrate providing a path for conductive heat spreading through its wall. This heat transfer eventually returns to the airflow by convection at the substrate surface. A fraction of this convective heat transfer occurs upstream of the 2D heated block and preheats the airflow before it reaches the heater surfaces. Due to this effect, it is convenient to describe the direct convection from the heater surfaces to the airflow by the adiabatic heat transfer coefficient. The considered conjugate problem was solved numerically in a domain comprising both the fluid and the solid regions. The heater was considered with a relatively high thermal conductivity and the obtained numerical results showed the effects of parameters such as the channel flow Reynolds number; the heater height in the channel; the substrate thickness; and the substrate to fluid thermal conductivities ratio. The results indicated that within the investigated range of parameters, there is a heat transfer enhancement from the heater at the expense of an increase of its average adiabatic surface temperature.