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Journal ArticleDOI

On the Cooling of Natural-air-cooled Electronic Equipment Casings : Proposal of a Practical Formula for Thermal Design

01 Jan 1986-Jsme International Journal Series B-fluids and Thermal Engineering (The Japan Society of Mechanical Engineers)-Vol. 29, Iss: 247, pp 119-123
TL;DR: In this article, a simple formula for thermal designing of natural-air-cooled electronic equipment casings with standard arrangement of circuit boards and power supplies was presented, since it represents an air cooling system in its simplified form with due regard to such factors as the stack effect, air flow resistance, natural convective transfer and so on.
Abstract: This paper presents a simple formula for thermal designing of natural-air-cooled electronic equipment casings with standard arrangement of circuit boards and power supplies The formula meets the requirements as a practical formula, since it represents an air-cooling system in its simplified form with due regard to such factors as the stack effect, air flow resistance, natural convective transfer and so on The formula was applied to predict the temperature rise in two practically used electronic equipment cabinets with standard arrangements and a modeling case The predicted temperature rise values, obtained through the formula, slightly differed - within 10 percent - from the actual values based upon experiment results
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Book ChapterDOI
TL;DR: The chapter summarizes analytical, numerical, and experimental work in literature, in order to facilitate the improvement of existing schemes and provide a basis for the development of new ones on the thermal control of semiconductor devices, modules, and total systems.
Abstract: Publisher Summary Thermal control of electronic components has one principal objective, to maintain relatively constant component temperature equal to or below the manufacturer's maximum specified service temperature, typically between 85 and 100°C. It is noted that even a single component operating 10°C beyond this temperature can reduce the reliability of certain systems by as much as 50%. Therefore, it is important for the new thermal control schemes to be capable of eliminating hot spots within the electronic devices, removing heat from these devices and dissipating this heat to the surrounding environment. Several strategies have developed over the years for controlling and removing the heat generated in multichip modules, which include advanced air-cooling schemes, direct cooling, and miniature thermosyphons or free-falling liquid films. The chapter summarizes analytical, numerical, and experimental work in literature, in order to facilitate the improvement of existing schemes and provide a basis for the development of new ones. The chapter focuses on investigations performed over the past decade and includes information on the thermal control of semiconductor devices, modules, and total systems.

285 citations

Journal ArticleDOI
TL;DR: In this article, the effect of increased inclination and porosity coefficient of outlet openings on the cooling capability of a thin laptop PC was investigated, and the experimental data were reduced to a Nusselt number-Rayleigh number correlation, by using a modified reference length.
Abstract: Natural air-cooling technologies for electronic equipment have the important advantages of no fan and high reliability. However, natural air cooling has lower cooling capability than fan air cooling, so enhancement of its cooling capability is required. This paper presents the results for experimental casings designed to employ the chimney effect in natural air-cooled electronic equipment. The system casing is inclined to enhance the effectiveness of natural air cooling. Experiments were carried out using a thin laptop PC. We investigated the effect on cooling capability produced by inclining the casing and by varying the outlet positions and numbers and the porosity coefficient of the outlet openings. The results show that the temperatures inside the casing and heater surfaces are slightly diminished by the effect of increased inclination and porosity coefficient of outlet openings. Moreover, the increase in natural circulation flux in the casing was quantitatively proven by experiments. In addition, the experimental data were reduced to a Nusselt number–Rayleigh number correlation, , by using a modified reference length. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(2): 122–136, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20103

8 citations

Journal ArticleDOI
01 Aug 1998
TL;DR: In this paper, a set of simplified equations for the thermal design of natural air-cooled electronic equipment casings has been proposed, which satisfied the demand of practical air cooling systems, since it took account of factors such as the stack effect, the air flow resistance and the heat transfer due to natural convection.
Abstract: This paper describes a practical thermal design approach to natural air-cooled electronic equipment casings. A set of simplified equations for the thermal design of natural air-cooled electronic equipment casings has been proposed. The proposed set of equations satisfied the demand of practical air-cooling systems, since it takes account of factors such as the stack effect, the air flow resistance and the heat transfer due to natural convection. The effects of the outlet area and the location of the main power supply unit on the natural cooling capability of electronic equipment casings were studied using a set of equations. The results have shown that a uniform temperature distribution could be achieved when the main power supply unit was placed at the bottom of the casing. It has also been suggested that the value of the heat removed from the casing surface could be more significant than that from the outlet vent in the thermal design of natural air-cooled electronic equipment casings.

7 citations

Proceedings ArticleDOI
01 Jun 2004
TL;DR: In this paper, the authors used three models of notebook PC that have two kinds of heat sources and investigated the influence of the box inclination, the box dimensions, and the heating element size on the increase in natural circulation flux in the box.
Abstract: Natural air-cooling needs neither a fan nor a blower. However, cooling capability of natural air-cooling is low, so the improvement of its capability is indispensable. In this study, the system box is inclined for the purpose to raise the capability of natural air-cooling, and the increase in natural circulation flux in the box is quantitatively proven by experiments. The case studies used three models of notebook PC that have two kinds of heat sources. The box was inclined 0 to 90 degrees up from the horizontal plane. The influence by the box inclination, the box dimensions, and the heating element size was investigated. Moreover, the experimental data were reduced to a Nusselt number-Rayleigh number correlation that does not include explicitly the box dimensions, the heat source size, and the inclination angle.

5 citations

Book ChapterDOI
22 Dec 2011
TL;DR: In this article, the authors studied the effect of the distance between the outlet vent location and the heat source on the cooling capability of natural-air-cooled electronic equipment casings.
Abstract: As the power dissipation density of electronic equipment has continued to increase, it has become necessary to consider the cooling design of electronic equipment in order to develop suitable cooling techniques. Almost all electronic equipment is cooled by air convection. Of the various cooling systems available, natural air cooling is often used for applications for which high reliability is essential, such as telecommunications. The main advantage of natural convection is that no fan or blower is required, because air movement is generated by density differences in the presence of gravity. The optimum thermal design of electronic devices cooled by natural convection depends on an accurate choice of geometrical configuration and the best distribution of heat sources to promote the flow rate that minimizes temperature rises inside the casings. Although the literature covers natural convection heat transfer in simple geometries, few experiments relate to enclosures such as those used in electronic equipment, in which heat transfer and fluid flow are generally complicated and three dimensional, making experimental modeling necessary. Guglielmini et al. (1988) reported on the natural air cooling of electronic boards in ventilated enclosures. Misale (1993) reported the influence of vent geometry on the natural air cooling of vertical circuit boards packed within a ventilated enclosure. Lin and Armfield (2001) studied natural convection cooling of rectangular and cylindrical containers. Ishizuka et al. (1986) and Ishizuka (1998) presented a simplified set of equations derived from data on natural air cooling of electronic equipment casings and showed its validity. However, there is insufficient information regading thermal design of practical electronic equipment. For example, the simplified set of equations was based on a ventilation model like a chimney with a heater at the base and an outlet vent on the top, yet in practical electronic equipment, the outlet vent is located at the upper part of the side walls, and the duct is not circular. Therefore, here, we studied the effect of the distance between the outlet vent location and the heat source on the cooling capability of natural-air-cooled electronic equipment casings.

3 citations


Cites background or methods from "On the Cooling of Natural-air-coole..."

  • ...Re was multiplied by the term 2 /(1-)2 to give X for correlation with K, as for wire nets and perforated plates reported by Ishizuka et al. (1986): 2( /(1- ) )X = Re (16) www.intechopen.com Design of Electronic Equipment Casings for Natural Air Cooling: Effects of Height and Size of Outlet Vent…...

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  • ...Ishizuka et al. (1986) proposed the following set of equations for engineering applications in the thermal design of electronic equipment: www.intechopen.com Heat Transfer – Engineering Applications 368 = 1.78 + 3001.25 0.5 1.5eq. m o oQ S T A (h / K) T (1) = 2.5(1 - ) / 2K (2) = 1.3o m T T (3)…...

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  • ...Using the natural convective heat transfer equations for individual surfaces presented by Ishizuka et al. (1986), we expressed the amount of heat removed from the casing surfaces, Qs, as: 1.25 =s 1 mQ D T (6) www.intechopen.com Design of Electronic Equipment Casings for Natural Air Cooling: Effects…...

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  • ...K was approximated as a function of : Ishizuka et al. (1986, 1987) obtained the following relation for wire nets at low values of the Reynolds number (Re): 2 -0.95 =40( 1- / )K Re (5) where Re is defined on the basis of the wire diameter used in the wire nets....

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  • ...Ishizuka et al. (1986) and Ishizuka (1998) presented a simplified set of equations derived from data on natural air cooling of electronic equipment casings and showed its validity....

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