In this issue, we address the Seebeck coefficient, a property that determines the performance of thermocouples and Peltier elements. Basically, the Seebeck coefficient is related to the fact that electrons are both carriers of electricity and heat. If a temperature gradient exists over a piece of electrically conductive wire, there is a net diffusion of electrons from the hot … [Read more...]
Thermal Challenges In LED Cooling
Introduction During the last ten years, developments in LED semiconductors have led to an important change in LED applications from that of luminous indicator to that of illuminator. With LEDs now advancing into several lighting fields, LEDs have become one of the standard methods of producing light, joining more traditional sources such as incandescent, fluorescent and … [Read more...]
Toward A Thermal Figure Of Merit For Multi-Chip Packages
Toward A Thermal Figure Of Merit For Multi-Chip Packages Bruce M. Guenin, Ph.D., Associate Editor Introduction Last issue's Calculation Corner dealt with methods for predicting the temperature of each chip in a Multi-Chip Package (MCP) at an arbitrary combination of chip power levels using the principle of superposition [1]. One of the main points of that article was that both … [Read more...]
Comparing Liquid Coolants From Both A Thermal And Hydraulic Perspective
In the May 2006 issue the Calculation Corner focused on the comparison of liquid coolants using the Mouromtseff number [1]. For single phase forced convection, Mouromtseff found this figure of merit, Mo, to follow the form where ρ, k, cp, and � represent the density, thermal conductivity, specific heat (at constant pressure) and dynamic viscosity of the fluid. The … [Read more...]
Exploring the Limits of Air Cooling
Introduction Heat from electronic devices is an integral part of information processing, not a nuisance that can someday be eliminated. This is a physical principle that is independent of the device of information processing. However, when viewed in the historical perspective, the severity of heat problems has not monotonically increased. It came to the fore some time ago, … [Read more...]
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