Younes Shabany

Radiation Heat Transfer from Plate-Fin Heat Sinks

The exact analytical correlations to calculate radiation heat transfer rate from a diffuse and gray plate-fin heat sink are presented. These correlations involve a view factor that can be exactly calculated using a rather complex set of equations. A very simple approximate correlation for this view factor is proposed that results in radiation heat transfer rates that are accurate with a maximum error of about 11%.

A Novel Scheme in Thermal Modeling of Printed Circuit Boards

This paper presents a simple yet novel analytical approach to model the heat conduction in a Printed Circuit Board (PCB) by taking advantage of the large thermal conductivity contrast between the copper and glass-epoxy layers. The model provides a compact expression for the effective thermal resistance of a PCB and captures an approximate 2-dimensional temperature distribution within the PCB copper layer using simple one-dimensional fin equations in successive copper-glass epoxy layers. The results for effective thermal resistance and temperature distributions in copper layers agree within ±10% of those predicted using finite element (FEM) simulations. The present approach can significantly improve the system level thermal modeling and design of single and multi-component PCBs.Copyright

High-Level Packaging Options for Outdoor Remote Units

Thermal performance of three high-level packaging options for natural convection and radiation cooled outdoor remote units was investigated in this work. Analytical correlations were used to determine required number and size of the fins. Then, a computational fluid dynamic simulation tool was used to investigate detailed thermal performance of three packaging options with the limitation that they use same fin and base areas. It was shown that all three designs perform almost the same if solar load is applied on the unit. However, the cube design performs worse than the narrow-deep and wide-slim designs if no solar load is applied.

A Novel Airflow Management System With Redundant Fan Field Replaceable Units

A novel airflow architecture for a networking chassis will be described in this work. This chassis is a pull system with two sets of four fans located in series at its exhaust. Each set of four fans is a field replaceable unit (FRU). The unique feature of this chassis is that one set of fans, called the rear fan FRU, is replaceable from the rear side of the chassis and the other set of fans, called the front fan FRU, is replaceable from the front side of the chassis. Computational fluid dynamics simulations and measurement data show this chassis is capable of providing up to 78% – 79% of its maximum cooling capacity when one fan FRU is removed from the chassis, and up to 62% – 67% of its maximum cooling capacity when one fan FRU has failed.Copyright

A PCM-Filled Heat Sink for an LED-Based Dental Device

A new heat sink has been designed that increases the run time of a cavity-filling resin-curing or teeth-bleaching dental device with light emitting diode. The heat sink is a hollowed copper object that is filled with a phase change material. Computational simulations and experimental measurements are presented that show the heat sink with phase change material increases the run time of the device beyond the minimum requirement of six minutes.Copyright

A New Approach to Model Axial Fans in Commercial CFD Tools

Most commercial CFD tools use fan curves to represent a fan. However, the presence of a blockage near inlet or exhaust of a fan and a restricted airflow direction will alter the fan performance, and the use of the original fan curve may result in erroneous results in these cases. A new approach to model fans will be presented in this paper. Using conservation of mass, momentum and energy, and the velocity triangles, this model relates velocity and pressure at fan exhaust to the corresponding values at fan inlet as well as fan geometry, rotational speed and fan blade lift and drag coefficients.Copyright