Effect of wall airflow restriction on heat-sink performance with thermoelectric coolers

Thermoelectric cold plate coolers with fan-cooled heat sinks are sometimes used on bench tops in which the cold plate is facing upwards and is parallel with the bench top. The best performance from the cooler is usually achieved when the tubeaxial fan forces air over the heat sink perpendicular to the fin base. The airflow then splits into two streams to exhaust out both ends of the heat sink. However, additional consideration must be given to the airflow restriction to the heat sink that is caused by the relative proximity of the fan to the bench top itself. The amount of airflow restriction depends on the distance between the fan inlet and the bench top which in turn affects the cooler's performance. Various heat sink and fan combinations in the perpendicular-airflow arrangement were examined for heat transfer performance in relation to the distance between the fan inlet and wall. An empirical equation was developed to correlate the impact on thermoelectric cooling performance with the distance between the fan inlet and the wall.