Forced convection cooling benchmark study of a HDD in various consumer electronics applications

This paper is a follow-up of a hard disk drive study presented at ITherm 2006 on thermal-acoustic optimization of a HDD placed inside an air duct with an axial fan. Today we present a benchmark study performed on a number of consumer products containing a HDD. We will show that it is possible to predict if a certain application design is close to its optimal, set-level design. This is important for early design analysis. Optimal Thermal performance of the HDD - air duct combination will be influenced by: (1) power dissipation in the set, (2) inlet vent size and location and (3) the fan finger guard pattern. The effect of these parameters is evaluated by means of numerical simulations in combination with measurements of air flow, hydraulic resistance and fan curves with and without fan guard. Flow measurements were performed on a flow bench. Acoustics were measured using an ISO-10203 fan test plenum in which the fan noise can be evaluated under relevant loads. In all cases the ISO-3741 reverberant room at Philips High Tech Campus Eindhoven was used to determine sound power. From a thermal point of view an optimum in the channel height between air duct and HDD can be determined. A small height means a high static pressure operating point of the fan resulting in more fan noise. A broad channel means more flow is needed to get the desired cooling, hence a higher airflow and thus more noise. The optimization between air duct spacing and thermal-acoustic performance of the benchmark model was investigated. The results were put into a model and compared with measurements on real application sets. The comparison shows if a certain design has room for improvement and at which cost.