Thermal fact: the temperature dependence of the specific heat can be very large. Thermal fairy tale: neglecting this dependence can be a serious problem. In my Tech Data column of May 2003 the thermal capacitance was discussed. I will repeat here the most relevant issues before discussing its temperature dependence. The thermal capacity (or heat capacity) Cth is defined … [Read more...]
System Level Benefits of Augmenting Fan Cooled Servers with Localized Synthetic Jets
Raghav Mahalingam Nuventix Inc. The cooling needs of data centers and server farms have increased rapidly over the last few years due to the advent of cloud computing. The use of large banks of fans is quite common in such systems and cooling system power is a significant fraction of the operational costs. Additionally, NEBS acoustic requirements limits the use of higher speed … [Read more...]
Detailed System Level Modeling of LEDs
Introduction Developments in solid state lighting (SSL) in recent years have led to an extensive increase in the driving current of light emitting diodes (LEDs). Although corresponding increases in light output and efficiency has also been noted, current lighting design applications require the implementation of multiple diodes to allow its utilization in universal lighting … [Read more...]
Thermal Load Board Design Considerations
INTRODUCTION A Thermal Load Board (TLB) is a hardware tool used to simulate an actual application board, for example - computer motherboard, blade server board, handheld device main logic board, etc. Mounted on the TLB are a variety of heat source simulators that allow heat flux generation in a manner that closely approximates real semiconductor devices and other components … [Read more...]
Characteristic Length and the Cooling Circle
Introduction One of the most baffling things in cooling for the novice mechanical engineer is the fact that with the exact same geometries and dimensions, thermal solutions just do not perform the same. Past results do not guarantee future performance, and doubling the surface area of a tried and tested design to double the cooling capacity, as per Newton’s cooling law, does … [Read more...]
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