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Monday, March 22, 2010

Optimization of Heat Sink Design


Economic Optimization of Heat Sink Design
INTRODUCTION
This paper describes the analysis and derivation of an optimum heat
sink design for maximizing the thermoelectric cooling performance
of a laboratory liquid chiller. The methods employed consisted of
certain key changes in the design of the heat sink in order to improve
its thermal performance. Parametric studies were performed in order
to determine the optimized cooling system design per dollar."
"The objective of this project was to analyze the thermal performance
of an initial simple heat sink design and improve cooling
performance while reducing the cost and overall size of the cooling
system. Several changes were examined in an effort to improve the
thermal performance and/or to reduce overall cost. The result
obtained has provided some guidelines for the selection/design of the
most effective and economical heat sink configuration. These results
were somewhat surprising since they are contrary to what one might
instinctively expect without the benefit of the detailed analysis
presented in this paper.


Optimization of Heat Sink Design and Fan Selection in Portable Electronics Environment
Abstract
Modern portable electronics have seen component heat loads
increasing, while the space available for heat dissipation has
decreased, both factors working against the thermal designer.
This requires that the thermal management system be optimized
to attain the highest performance in the given space. While
adding fins to the heat sink increases surface area, it also
increases the pressure drop. This reduces the volumetric airflow,
which also reduces the heat transfer coefficient. There exists a
point at which the number of fins in a given area can be optimized
to obtain the highest performance for a given fan. The primary
goal of this paper is to find the optimization points for several
different fan-heat sink designs. The secondary goal is to find a
theoretical methodology that will accurately predict the
optimization point and the expected performance.


Saturday, March 20, 2010

HOW TO CALCULATE AND SELECT A Electronic Circuit HEAT SINK


HOW TO CALCULATE AND SELECT A HEAT SINK FOR A GIVEN SOLID STATE RELAY APPLICATION

The basic structure of a Solid State Relay includes an internal power semiconductor mounted to an electrical insulator which in turn is mounted to the Solid State Relay’s base plate. To form an assembly, the SSR with an accompanying thermal interface material placed on its base plate is then torque mounted to the Heat Sink.
The thermal model representing the above configuration includes the following elements:
A.
The selected SSR with specified thermal impedance (RΘ ssr), forward voltage drop (Vf), and maximum allowed internal operating temperature (Tj).
B.
The thermal interface material placed between the SSR and the Heat Sink and its specified thermal impedance (RΘ tp).
C.
The calculated minimum Heat Sink thermal impedance rating (RΘ hs) required for proper SSR operation.
D.
The operating environment’s max ambient air temperature in °C (TA ).


How to verify the proper Heat Sink
In certain instances, once the heat sink requirements for a SSR in a particular application have been determined and installed, it may be desirable to verify that the system does indeed provide adequate cooling to ensure reliable SSR operation.
The following is a relatively simple method to check this suitability, and essentially uses some of the calculations from SELECTING A SUITABLE HEAT SINK (above) in a reverse manner. This technique may also be used on existing systems in the field that might have been more or less “empirically” designed, to gain information on their performance and potential reliabilty. This method involves determining the temperature of the internal power devices