1. Experimental and Theoretical Investigation of Thermal Performance of Heat Sinks
Experimental and theoretical investigations of the thermal performance of a variety of heat sinks have been made. The heat sinks investigated were: extruded (or straight finned), folded (or corrugated), elliptical finned, maxiFLOW (or fan tailed), small pin finned, cross-cut pin and small disk (or cylindrical). The experiments were done in a wind tunnel where the free stream velocity ranged from natural convection to 5 m/s. The dissipated power ranged from 0.4 W/cm2 to 2.3 W/cm2. Temperature was measured at the base of heat sinks to represent the Application Specific Integrated Circuits (ASIC) chip temperature. The experimental results of several of the simple geometry heat sinks have been compared to those predicted by a commercially available code. The code is based on solution of mass, momentum and energy equations. The experimental results are in good agreement to the theoretical prediction.
2. A Novel Heat Sink Design for Low Speed Flows – A BGA Example - ITHERM 2000
The ongoing trend in designing electronic systems is to incorporate increased functionality into ever smaller form factors. In addition, the power dissipation from most IC devices continues to increase. Additional design constraints, such as reducing system acoustic noise and weight, are also becoming more prevalent. The combined effect of all these trends is to create increasingly challenging thermal management situations that demand more efficient heat sinks and optimized designs. In this paper a new class of heat sinks are presented and their performance is compared to conventional heat sinks. maxiFLOW heat sinks feature very thin, high ratio fins that radiate at various angles from the base. The result is a very low resistance to airflow and very high efficiency of heat dissipation, especially at low airspeeds. They are also very light in weight, allowing for simple attachment methods and weight savings. To aid in designing thermal solutions that utilize these heat sinks, an analytical model has been developed to predict the thermal resistance as a function of airflow velocity for unducted flow for a conventional design. The improvements of the new design compared to the conventional design will be discussed.
3. Computer Controlled Scanner for Continuous Flow Measurement Using Single Sensor in Harsh Environments
A new technology that uses a single sensor for temperature and velocity measurements in non-isothermal fluids is presented in this paper. The system is a multi-channel scanner designed for measuring velocity and temperature in applications where single – or multi- point measurements are required. This unit uses 12-bit data acquisition system along with digital circuitry for measuring both velocity and temperature (0 to 10000 ft/min, -20 to 140 oC) with the same sensor. These unique sensors are designed to be low profile to minimize flow disturbance. Of the salient points of the new system is elimination of measurement error as seen in sensor system in dual sensor systems used in the same application. Dual sensor induced errors can be in excess of 20% that are caused when these sensors are used in non-isothermal flows. This technology provides an accurate and easy to use vehicle for mapping the temperature and velocity of flows in multitude of environments.