Various aspects of forced convection cooling of a hard disk drive in a consumer electronics application

This paper describes various aspects of forced convection cooling of hard disk drives (HDD). Most HDD suppliers do not allow the case temperature of the HDD to exceed 50 degC in order to guarantee the specified lifetime. To achieve this, the supplier often prescribes the air speed along the HDD encasing. The question then arises how these figures can be translated into optimum design-in of a HDD into an application? In an actual application one has to deal with temperature, acoustics and data streaming performance. CFD simulations are used to attain an optimum design for the air duct around the HDD. A trade off was made between pressure drop in the air duct and air velocity around the HDD. A Perspex air duct was made around the HDD according to the optimum design resulting from the CFD simulations. Temperature and sound power measurements were performed as a function of airflow through the air duct for a number of fans ranging from 40 to 60 mm. Sound power measurements were done both on a standardized fan test plenum as well as in the actual application. From these measurements the relation between cooling performance and sound power level for different fan alternatives could be established. In the Perspex air duct heat loss by conduction is minimized. However, in the actual application the HDD may be mounted on a steel bracket by means of grommets. The effect of the use of grommets on the thermal performance of the HDD as a function of airflow was also investigated