Browsing by Author "Charles, Roody"

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A novel heat dissipation fin design applicable for natural convection augmentation
(2014-12-01)
Charles, Roody
;
Wang, Chi-Chuan
;
機械工程學系
;
Department of Mechanical Engineering
In this study, a comparative study of heat sink having various fin assembly under natural convection is investigated. The fin pattern includes a rectangular, a trapezoidal and an inverted trapezoidal configuration. Tests were performed in a well controlled environmental chamber having a heat load ranging from 3 to 20 W. From the test results, the heat transfer coefficient of the conventional rectangular fins is higher than that of the trapezoidal fins while the heat transfer coefficient of the inverted trapezoidal fins is higher than the trapezoidal one by approximately 25%, and it exceeds that of convectional rectangular fin by about 10%. The heat transfer improvements of the inverted trapezoidal fin are mainly associated with a larger temperature difference and inducing more air flow into the heat sink. (C) 2014 Elsevier Ltd. All rights reserved.
An optimized heat dissipation fin design applicable for natural convection augmentation (IMPACT 2014)
(2014)
Charles, Roody
;
Wang, Chi-Chuan
;
機械工程學系
;
Department of Mechanical Engineering
This paper performs a comparative study of heat sink having various profiles. Namely Rectangular, Trapezoidal and inverted Trapezoidal (so-called dovetail fin) which are the commonly used devices for enhancing heat transfer in electronic components. The main purpose of this research is to present a best possible Heat Sink for efficient cooling of electronic devices. Natural convection is observed when density gradients are present in a fluid acted upon by a gravitational field. Heat produced by electronic devices and circuitry must be self-indulgent to improve reliability and prevent premature failure. Integrated circuit such as CPUs, chips, graphic cards, and hard disc drives are susceptible to temporary malfunction or permanent failure if overheated. The idea is quite simple and at no additional cost. Moreover, the design is passive and no additional maintenance is needed. Simulation was done at different heat load of 3W, 5W, 10W, 15W and 20W. Experimental investigations were also performed in order to validate the proposed model; test results indicate that the dovetail fin shows better heat transfer coefficient. This is associated with its higher mean temperature difference. From the experiments Nu was determined as a function of Ra at Pr= 0.7 for an orientation with Ra ranging between (59700 and 344960). From the results; Heat transfer coefficient from of the rectangular fins is higher by (89%) than the heat transfer coefficient of the trapezoidal fins while the heat transfer of the inverted trapezoidal fins is higher than the trapezoidal one by (121%), which implies that the heat transfer of the inverted trapezoidal fins is higher by (108%) than the rectangular fins. Orientation affected the temperature distribution along the fins, therefore the temperature along the inverted trapezoidal fins has the best performance with uniform distribution, while the temperature in the trapezoidal fins increased in the positions near the base plate surface because of the complication in moving the heated air. It is also important to note that the heights, number of fins and the distance between the gaps play a major role in the cooling system due to the passage of the air flow into the fins; those parameters should be taking in consideration carefully when choosing or designing a heat sink. But the number of the fins should be optimized because it should be noted that adding more fins also decrease the distance between the adjacent fins. This may cause resistance to air flow and boundary layer interference which in return decrease the heat transfer coefficient.