Journal articles: 'Natural Convection Cooling'

1

Jani, Jaronie Mohd, Sunan Huang, Martin Leary, and Aleksandar Subic. "Analysis of Convective Heat Transfer Coefficient on Shape Memory Alloy Actuatorunder Various Ambient Temperatures with Finite Difference Method." Applied Mechanics and Materials 736 (March 2015): 127–33. http://dx.doi.org/10.4028/www.scientific.net/amm.736.127.

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The demand for shape memory alloy (SMA) actuators for technical applications is steadily increasing; however SMA may have poor deactivation time due to relatively slow convective cooling. Convection heat transfer mechanism plays a critical role in the cooling process, where an increase of air circulation around the SMA actuator (i.e. forced convection) provides a significant improvement in deactivation time compared to the natural convection condition. The rate of convective heat transfer, either natural or forced, is measured by the convection heat transfer coefficient, which may be difficult to predict theoretically due to the numerous dependent variables. In this work, a study of free convective cooling of linear SMAactuators was conducted under various ambient temperatures to experimentally determine the convective heat transfer coefficient. A finite difference equation (FDE) was developed to simulate SMA response, and calibrated with the experimental data to obtain the unknown convectiveheat transfer coefficient, h. These coefficients are then compared with the available theoretical equations, and it was found that Eisakhaniet. almodel provides good agreement with the Experiment-FDE calibrated results. Therefore, FDE is reasonably useful to estimate the convective heat transfer coefficient of SMA actuator experiments under various conditions, with a few identified limitations (e.g. exclusion of other associative heat transfer factors).

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Koyama, Taihei, and Akira Ito. "Motor frame structure using natural convection cooling." Proceedings of the Thermal Engineering Conference 2016 (2016): B112. http://dx.doi.org/10.1299/jsmeted.2016.b112.

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Erbacher, Franz-Josef, and Hans-Joachim Neitzel. "Passive Containment Cooling by Natural Air Convection." Nuclear Technology 111, no. 3 (September 1995): 386–94. http://dx.doi.org/10.13182/nt95-a15868.

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Incropera, F. P. "Convection Heat Transfer in Electronic Equipment Cooling." Journal of Heat Transfer 110, no. 4b (November 1, 1988): 1097–111. http://dx.doi.org/10.1115/1.3250613.

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To maintain the best possible thermal environment in electronic packages, the engineer must establish the most efficient path for heat transfer from the electronic devices to an external cooling agent. The path is typically subdivided into internal and external components, representing, respectively, heat transfer by conduction through different materials and interfaces separating the devices from the package surface and heat transfer by convection from the surface to the coolant. Depending on the scale and speed of the electronic circuits, as well as on constraints imposed by nonthermal considerations, the coolant may be a gas or a liquid and heat transfer may be by natural, forced, or mixed convection or, in the case of a liquid, by pool or forced convection boiling. In this paper a comprehensive review of convection cooling options is provided.

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Yang, Li Jun, Bin Xiang Sun, Wei Wang, and Qi Liu. "Effect of Crushed Rock Layer Width on Natural Convection Cooling of Highway Embankment in Permafrost Regions." Applied Mechanics and Materials 204-208 (October 2012): 1638–43. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.1638.

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For the construction of the proposed Qinghai-Tibet Express Highway in permafrost regions, it will be necessary to use the new technique of cooling the ground temperature by the coarsely crushed rock layer with a low fines content. The heat convection governing equations based on airflow function in variable permeability porous crushed rock layer are derived. Comparison of the cooling capability of winter-time natural convection in the crushed rock highway embankments with various widths of crushed rock layer and an air-permeable side slope surface were studied using a finite element method. The result indicates that the cooling capability of natural convection within the crushed rock highway embankment with a crushed rock layer width of 12 m is stronger than that with a crushed rock layer width of 10 m. Under the same temperature and pressure boundaries, the storage of cold energy in the foundation soils below the wider crushed rock highway embankment due to natural convective heat transfer is larger than that below the narrower one.

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Kuang, Zhiming, and Christopher S. Bretherton. "Convective Influence on the Heat Balance of the Tropical Tropopause Layer: A Cloud-Resolving Model Study." Journal of the Atmospheric Sciences 61, no. 23 (December 1, 2004): 2919–27. http://dx.doi.org/10.1175/jas-3306.1.

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Abstract The tropical tropopause layer (TTL), and in particular the cold point tropopause, has been previously suggested as a feature decoupled from convection. Using a cloud-resolving model, the authors demonstrate that convection, in fact, has a cooling effect in the TTL that significantly affects its thermal structure. In particular, the cold point is found to be strongly tied to the convective cooling maximum. The authors interpret these as natural features of an entrainment layer such as the TTL. The recognition that the cold point tropopause is strongly tied to, rather than decoupled from, convection suggests that dehydration processes at the cold point cannot be assumed as gradual and the effect of convection may not be ignored.

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Dyko, M. P., and K. Vafai. "Fundamental Issues and Recent Advancements in Analysis of Aircraft Brake Natural Convective Cooling." Journal of Heat Transfer 120, no. 4 (November 1, 1998): 840–57. http://dx.doi.org/10.1115/1.2825903.

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A heightened awareness of the importance of natural convective cooling as a driving factor in design and thermal management of aircraft braking systems has emerged in recent years. As a result, increased attention is being devoted to understanding the buoyancy-driven flow and heat transfer occurring within the complex air passageways formed by the wheel and brake components, including the interaction of the internal and external flow fields. Through application of contemporary computational methods in conjunction with thorough experimentation, robust numerical simulations of these three-dimensional processes have been developed and validated. This has provided insight into the fundamental physical mechanisms underlying the flow and yielded the tools necessary for efficient optimization of the cooling process to improve overall thermal performance. In the present work, a brief overview of aircraft brake thermal considerations and formulation of the convection cooling problem are provided. This is followed by a review of studies of natural convection within closed and open-ended annuli and the closely related investigation of inboard and outboard subdomains of the braking system. Relevant studies of natural convection in open rectangular cavities are also discussed. Both experimental and numerical results obtained to date are addressed, with emphasis given to the characteristics of the flow field and the effects of changes in geometric parameters on flow and heat transfer. Findings of a concurrent numerical and experimental investigation of natural convection within the wheel and brake assembly are presented. These results provide, for the first time, a description of the three-dimensional aircraft braking system cooling flow field.

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Maciejewski, P. K. "Evidence of a Convective Instability Allowing Warm Water to Freeze in Less Time Than Cold Water." Journal of Heat Transfer 118, no. 1 (February 1, 1996): 65–72. http://dx.doi.org/10.1115/1.2824069.

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This experimental study explores the possibility that warm water may freeze in less time than cold water due to natural convection alone, i.e., in the absence of significant cooling by evaporation. This possibility is rooted in the following two hypotheses: (1) The Rayleigh number associated with a sample of warm water may exceed a critical value above which the convective motions within the water sample may become turbulent and enhance the rate of convective cooling, and (2) the inversion of the flow field that is expected to occur in the vicinity of maximum density, i.e., at 4°C, will occur at different points in the cooling process for identical samples of water at different levels of initial temperature and result in an enhanced rate of convective cooling after the flow field inversion for those cases at higher levels of initial temperature that enter the flow field inversion with higher kinetic energy. The results of this study establish that, under certain circumstances, a sample of water that is initially warm will freeze in less time than an identical sample of water that is initially cold due to natural convection alone.

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O, Mairura Edward, Johana Sigey K, Jeconiah Okello A, and James Okwoyo M. "Natural Convection with Localized Heating and Cooling on Opposite Vertical Walls in an Enclosure." SIJ Transactions on Computer Networks & Communication Engineering 01, no. 04 (October 17, 2013): 01–07. http://dx.doi.org/10.9756/sijcnce/v1i4/0104510101.

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MAO, YADAN, CHENGWANG LEI, and JOHN C. PATTERSON. "Unsteady near-shore natural convection induced by surface cooling." Journal of Fluid Mechanics 642 (December 4, 2009): 213–33. http://dx.doi.org/10.1017/s0022112009991765.

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Natural convection in calm near-shore waters induced by daytime heating or nighttime cooling plays a significant role in cross-shore exchanges with significant biological and environmental implications. Having previously reported an improved scaling analysis on the daytime radiation-induced natural convection, the authors present in this paper a detailed scaling analysis quantifying the flow properties at varying offshore distances induced by nighttime surface cooling. Two critical functions of offshore distance have been derived to identify the distinctness and the stability of the thermal boundary layer. Two flow scenarios are possible depending on the bottom slope. For the relatively large slope scenario, three flow regimes are possible, which are discussed in detail. For each flow regime, all the possible distinctive subregions are identified. Two different sets of scaling incorporating the offshore-distance dependency have been derived for the conduction-dominated region and stable-convection-dominated region respectively. It is found that the scaling for flow in the stable-convection-dominated region also applies to the time-averaged mean flow in the unstable region. The present scaling results are verified by numerical simulations.

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Jiracheewanun, Sujin, Steve Armfield, and Masud Behnia. "Combined natural convection cooling of a drink can." ANZIAM Journal 51 (May 3, 2011): 59. http://dx.doi.org/10.21914/anziamj.v52i0.2890.

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Salem, Mohamed, Mohamed ElSayed, Mohamed Salah, and Mohamed Ashraf. "Proposed Modeling of Natural Convection Cooling Heat Pipe." Journal of Nuclear Technology in Applied Science 10, no. 1 (January 1, 2022): 1–10. http://dx.doi.org/10.21608/jntas.2022.112703.1046.

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Lin, Wenxian, and S. W. Armfield. "Natural convection cooling of rectangular and cylindrical containers." International Journal of Heat and Fluid Flow 22, no. 1 (February 2001): 72–81. http://dx.doi.org/10.1016/s0142-727x(00)00065-5.

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Abou Elmaaty, Talal Mohamed Mahmoud. "Natural convection cooling for LEU irradiated fuel plates." Annals of Nuclear Energy 40, no. 1 (February 2012): 116–21. http://dx.doi.org/10.1016/j.anucene.2011.09.021.

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15

Moutsoglou, A., J. H. Rhee, and J. K. Won. "Natural convection-radiation cooling of a vented channel." International Journal of Heat and Mass Transfer 35, no. 11 (November 1992): 2855–63. http://dx.doi.org/10.1016/0017-9310(92)90306-d.

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JIRACHEEWANUN, S., S. W. ARMFIELD, and M. BEHNIA. "COMBINED NATURAL CONVECTION COOLING OF A DRINK CAN." ANZIAM Journal 52, no. 1 (July 2010): 59–68. http://dx.doi.org/10.1017/s1446181111000538.

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AbstractWe investigate natural convection cooling of the fluid in a drink can placed in a refrigerator by simulating the full combined boundary layer system on the can wall. The cylindrical can is filled with water at initial nondimensional temperature 0, and located within a larger cylindrical container filled with air at initial temperature −1. The outer container walls are maintained at constant temperature −1. Initially both fluids are at rest. Two configurations are examined: the first has the inner can placed vertically in the middle of the outer container with no contact with the outer container walls, and the second has the inner can placed vertically at the bottom of the outer container. The results are compared to those obtained by assuming that the inner can walls are maintained at a constant temperature, showing similar basic flow features and scaling relations, but with very different proportionality constants.

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Durgam, Shankar. "Computational cooling performance of electronic chips on printed circuit boards." Journal of Physics: Conference Series 2312, no. 1 (August 1, 2022): 012071. http://dx.doi.org/10.1088/1742-6596/2312/1/012071.

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Abstract Effect of cooling performance of heated modules resembling integrated circuit (IC) chips on printed circuit boards (PCBs) under natural and forced convection is investigated. Commercially available four different types of substrate materials viz. silica glass, glass epoxy FR4, bakelite, and copper-clad board (CCB) is used for the simulation study. Natural and forced convection cooling scenarios are used for thermal performance with a power input of 7.5 W and 15 W for heaters equipped on a substrate. The main motive of this work is to present and compare thermal performance of heated modules on different substrate materials. Results of FR4 and bakelite with a power input of 7.5 under natural convection are compared with forced convection results at Re = 500 for the same power input. The results show that copper clad boards give a better cooling performance in natural convection scenarios for both the power inputs of 7.5 W and 15 W.

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Isfandior, Turakhasanov, Nizomov Ziyovuddin, and Nematov Dilshod. "Effect of the Size of A5N Cylindrical Aluminum Specimens on the Cooling Kinetics." Trends in Sciences 19, no. 24 (November 19, 2022): 3536. http://dx.doi.org/10.48048/tis.2022.3536.

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The results of the study of “The influence of the size of cylindrical samples of A5N aluminum on the time and the rate of their cooling” are reported. According to experimental data, the temperature dependence of the heat transfer coefficient for pure metals is calculated. It has revealed that the process of cooling of the aluminum and its alloys has a relaxation behavior. It was found that the main mechanisms of natural air cooling are convection heat transfer and radiation. The characteristic cooling time due to radiation is less due to convection. The contribution of thermal radiation is noticeable at high temperatures. It was found that the characteristic times of cooling due to radiation and convection increase with increase in volume to area ratio of the sample. HIGHLIGHTS Cylindrical Al samples were made with dimensions of 2, 2.5, 3, 3.5 and 4 cm, after cleaning aluminum to grade A5N (99.999 %) The influence of the dimensions of cylindrical aluminum samples on the time and rate of their spontaneous cooling in air has been studied It has been established that the samples are cooled mainly due to convective heat transfer and thermal radiation It became known that the cooling time due to convection is longer than the time due to radiation It has been found that as the V/S value increases, the cooling time increases GRAPHICAL ABSTRACT

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FAJARDO, T. A., R. C. ANANTHESWARAN, V. M. PURI, and S. J. KNABEL. "Penetration of Salmonella enteritidis into Eggs Subjected to Rapid Cooling." Journal of Food Protection 58, no. 5 (May 1, 1995): 473–77. http://dx.doi.org/10.4315/0362-028x-58.5.473.

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Eggs were cooled to 0°C using two different cooling rates, natural convection, and forced convection at an air speed of 30.5 m/min. Upon rapid cooling using forced convection and when brought back to room temperature, eggs were more prone to penetration by Salmonella enteritidis (strain PS8NSR). Eggs cooled using forced convection had 100% penetration by PS8NSR; eggs cooled using natural convection had 91.3% penetration; and uncooled eggs had 48% penetration. Scanning electron microscopy revealed that shells of both cooled and uncooled eggs had microscopic cracks; however, cracks were more numerous and larger in shells of cooled eggs.

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Zakinyan, Arthur, Stanislav Kunikin, Andrey Chernyshov, and Vitali Aitov. "Magnetic Field Inhibition of Convective Heat Transfer in Magnetic Nanofluid." Magnetochemistry 7, no. 2 (February 1, 2021): 21. http://dx.doi.org/10.3390/magnetochemistry7020021.

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Natural convection is the main mechanism of heat transfer in many natural and technological processes, which makes it urgent to study the possibilities of controlling it. In this work, the processes of development and damping of thermal convection in a flat vertical quasi-two-dimensional layer of magnetic nanofluid are considered experimentally. The presence of the magnetic properties of the nanofluid makes it possible to effectively apply the external magnetic fields to regulate convective heat transfer. The magnetic nanofluid layer was heated from below. It was shown in this work that the imposition of an external uniform stationary magnetic field perpendicular to the temperature gradient leads to the suppression of convection. The processes of heating and cooling the metal plates in a magnetic nanofluid are studied. It is demonstrated that the suppression of convection by a magnetic field leads to a slowdown in the heating of cold and cooling of hot metal plates in a magnetic nanofluid. The obtained results can be considered as a model for understanding similar exchange processes in liquids under the action of magnetic field.

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Qian, Jin, Qihao Yu, Lei Guo, and Jun Hu. "Experimental study on convection characteristics of crushed-rock layer." Canadian Geotechnical Journal 50, no. 8 (August 2013): 834–40. http://dx.doi.org/10.1139/cgj-2011-0201.

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Research on the measurement of micro wind-velocity and the airflow characteristics in the crushed-rock layer, which is caused by temperature difference, has long been problematic. For the first time, this study obtains the airflow characteristics in a crushed-rock layer by using high-precision micro wind-velocity detectors. Based on the experimental results, this study verifies the theory that the crushed-rock layer is available for convection heat exchange of porous media in a limited space. In boundary temperature fluctuations conditions, the cooling process is closely related to the natural convection process in the crushed-rock layer, and cooling occurs rapidly during the convection heat transfer process. The warming process, which occurs by heat conduction, happens gradually over a relatively long period of time, resulting in asymmetrical temperature change. The convection process exists only in the increasing and decreasing cooling stages of the entire cooling stage. The temperature difference between the top and the bottom in the crushed-rock layer is a key factor for the occurrence of convection and its intensity, although the air temperature changes also have an effect on the natural convection process in the increasing and decreasing cooling stages. Pore-air natural convection velocity increase is related to the increase in the temperature difference. Due to the different temperature and the penetration resistance of the crushed-rock layer, the velocity rapidly decreases in the depth direction, and there exits a delay phenomenon, so better cooling effect is in accordance with an optimal thickness of the crushed-rock layer.

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Bejan, Adrian. "Optimal Internal Structure of Volumes Cooled by Single-Phase Forced and Natural Convection." Journal of Electronic Packaging 125, no. 2 (June 1, 2003): 200–207. http://dx.doi.org/10.1115/1.1566970.

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This article is a principle-based review of a growing body of fundamental research that documents the opportunity for optimizing geometrically the cooling of spaces (e.g., electronics packages) that generate heat volumetrically. The chief result of geometric optimization is the identification of an optimal internal structure—optimal spacings between components (e.g., plates and fins), optimal sizes and aspect ratios for cooling channels, and optimal frequencies for pulsating flows. The origin of these optimal geometric features—the construction of the system—lies in the global effort to use every infinitesimal volume to the maximum, i.e., to pack the volume not only with the most heat generating components, but also with the ‘most’ coolant, in such a way that every fluid packet is engaged effectively in cooling. The optimal aspect ratio for ducts with forced and natural convection corresponds to the special geometry and flow conditions where boundary layers meet just as the coolant exits the channel. This “constructal” design principle is illustrated by several classes of examples: laminar forced and natural convection, and various internal arrangements (parallel plates, staggered plates, cylinders in cross flow, square pins with impinging flow). General trends (scaling laws) of optimal geometric form are revealed by the optimal-structure results, this, in spite of the diversity of the optimized configurations.

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McEligot, D. M., C. M. Stoots, W. A. Christenson, D. C. Mecham, and W. G. Lussie. "Turbulent Natural Convection From a Vertical Cylinder to an Array of Cooled Tubes." Journal of Heat Transfer 115, no. 4 (November 1, 1993): 928–37. http://dx.doi.org/10.1115/1.2911389.

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In order to determine whether available correlations are adequate to treat a complicated, turbulent natural convection problem encountered in industrial practice, experiments were conducted by resistively heating a slender, vertical cylinder centered inside a concentric perforated tube, which was, in turn, surrounded by an array of three larger-diameter cooled tubes. The ratio of the test section temperature to the cooling tube temperature was varied up to 2.6; and the Rayleigh number, based on tube diameter and properties evaluated at the cooling tube temperature, ranged from 2.9×104 to 9.2×105. Results indicate that the convective heat transfer parameters for the perforated tube are about 15 percent higher than for the smooth bare tube centered in the same position relative to the array. The Nusselt number for convective heat transfer across the annulus between the heated test section and the perforated tube corresponded approximately to parallel laminar flow (i.e., Nus≈1).

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Ong, K. S., K. Gobi, C. H. Lim, J. C. Tan, S. Naghavi, S. Baljit, and S. Y. Wong. "Experimental Investigation on Effect of Inclination Angle of a Flat Plate Solar Air Collector." IOP Conference Series: Earth and Environmental Science 945, no. 1 (December 1, 2021): 012003. http://dx.doi.org/10.1088/1755-1315/945/1/012003.

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Abstract This study investigates the effect of inclination angle of a flat plate solar air collector in Kampar, Malaysia. Flat plate solar air collectors have been investigated since the early 1950s for air heating and crop drying. Their performances under natural convection air cooling are very similar to a photovoltaic (PV) panels for power production. A PV panel becomes hot when operating under hot weather which will affect the efficiency and lifespan. The panel could be cooled down by providing an air duct underneath which allowing natural convection air circulating inside the duct. The degree of cooling would depend upon the angle of inclination of the panel. This paper presents some experimental results on the effect of inclination angle on the performance of a flat plate solar air collector under natural convection air cooling.

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Adhikari, R. C., D. H. Wood, and M. Pahlevani. "Optimizing rectangular fins for natural convection cooling using CFD." Thermal Science and Engineering Progress 17 (June 2020): 100484. http://dx.doi.org/10.1016/j.tsep.2020.100484.

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He, S., F. Sabri, and Kamel Hooman. "Transient natural convection: scale analysis of dry cooling towers." Journal of Thermal Analysis and Calorimetry 139, no. 4 (November 30, 2019): 2891–97. http://dx.doi.org/10.1007/s10973-019-09104-9.

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Florio, L. A., and A. Harnoy. "Combination technique for improving natural convection cooling in electronics." International Journal of Thermal Sciences 46, no. 1 (January 2007): 76–92. http://dx.doi.org/10.1016/j.ijthermalsci.2006.03.007.

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Ben-Mansour, Rached, and Mohammed A. Habib. "Use of Nanofluids for Enhanced Natural Cooling of Discretely Heated Enclosures." Applied Mechanics and Materials 302 (February 2013): 422–28. http://dx.doi.org/10.4028/www.scientific.net/amm.302.422.

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Natural convection heat transfer from discrete heat sources to nanofluids is of great importance because of its application in the cooling of electronic components. The presence of the nanoparticles in the fluids increases appreciably the effective thermal conductivity of the fluid and consequently enhances the heat transfer characteristics. The present study is aimed to investigate numerically the natural convection heat transfer from discrete heat sources to nanofluids. The behavior of nanofluids was investigated numerically inside a heated cavity to gain insight into convective recirculation and flow processes induced by a nanofluid. A computational model was developed to analyze heat transfer performance of nanofluids inside a cavity taking into account the solid particle dispersion. The model was validated through the comparison with available experimental data. The results showed good agreement. The influence of the solid volume fraction on the flow pattern and heat transfer inside the cavity was investigated. The results show that the intensity of the streamlines increases with the volume fraction. It is also indicated that higher velocities along the centerline of the enclosure are achieved as the volume of nanoparticles increases. The influence of the loading factor is more distinguished at the upper heaters and in particular at the highest heater. The heat transfer increases as the volume fraction of the nanoparticles increases from 2 to 10%.

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Pakdee, W., and P. Rattanadecho. "Numerical Analysis of Natural Convection in Porous Cavities with Partial Convective Cooling Conditions." Journal of Porous Media 12, no. 11 (2009): 1083–100. http://dx.doi.org/10.1615/jpormedia.v12.i11.50.

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Behi, Hamidreza, Theodoros Kalogiannis, Mahesh Suresh Patil, Joeri Van Mierlo, and Maitane Berecibar. "A New Concept of Air Cooling and Heat Pipe for Electric Vehicles in Fast Discharging." Energies 14, no. 20 (October 10, 2021): 6477. http://dx.doi.org/10.3390/en14206477.

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This paper presents the concept of a hybrid thermal management system (TMS) including natural convection, heat pipe, and air cooling assisted heat pipe (ACAH) for electric vehicles. Experimental and numerical tests are described to predict the thermal behavior of a lithium titanate oxide (LTO) battery cell in a fast discharging process (8C rate). Specifications of different cooling techniques are deliberated and compared. The mathematical models are solved by COMSOL Multiphysics® (Stockholm, Sweden), the commercial computational fluid dynamics (CFD) software. The simulation results are validated against experimental data with an acceptable error range. The results specify that the maximum cell temperatures for the cooling systems of natural convection, heat pipe, and ACAH reach 56, 46.3, and 38.3 °C, respectively. We found that the maximum cell temperature experiences a 17.3% and 31% reduction with the heat pipe and ACAH, respectively, compared with natural convection.

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Belarche, Lahoucine, Btissam Abourida, Hicham Doghmi, Mohamed Sannad, and Meryem Ouzaouit. "Three-dimensional simulation of controlled cooling of electronic component by natural and mixed convection." Thermal Science, no. 00 (2020): 181. http://dx.doi.org/10.2298/tsci190508181b.

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The present study is the three-dimensional simulation of cooling control of electronic component, by natural convection and mixed convection in a cubical enclosure, filled with air. The heating square portion similar to the integrated electronic device and releasing a constant flux is placed on the right vertical wall of the enclosure. The same wall has, in its upper part, an extractor, while the rest of the considered wall is adiabatic. Its opposite wall has an opening maintained at a cold temperature. For low temperatures, the cooling of the component is provided by natural convection, however, in the case of strong temperature gradients, the extractor, operating at variable velocity, allows the evacuation of the dissipated heat. The cooling control of the component, the temperature distribution as well as the flow of fluid in the cavity is studied according to the governing parameters, namely the Rayleigh number, Ra and Reynolds number Re. The obtained results show that the control cooling of the electronic components has a great industrial interest compared to the continuous cooling (ventilation), by an optimal choice of the governing parameters and the material constituting the components.

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Nemec, Patrik, Katarína Kaduchová, and Milan Malcho. "Dustproof cooling of the electrical box." EPJ Web of Conferences 180 (2018): 02072. http://dx.doi.org/10.1051/epjconf/201818002072.

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In present are electrical boxes cooled by air through the intake hole on the bottom electrical box to the box space with electrotechnical elements and exhaust through the hole at the top to the surrounding by natural convection. This cooling method is effective but operate with the risk of contamination electrotechnical elements by dust sucking from surrounding air. The goal of this work is solution of the dustproof cooling of the electrical box by natural convection. The work deal with design of the device with the heat transfer by the phase change of the working fluid and experimental measuring its thermal performance at the cooling electrotechnical elements loaded by heat 1 200 W in the dustproof electrical box.

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Guo, Yun, Zhi Qiang Huang, and Shun Xin Yang. "Numerical Study on the Flow and Heat Transfer for the inside of the Cylinder Type Natural Gas Heater." Advanced Materials Research 860-863 (December 2013): 1441–44. http://dx.doi.org/10.4028/www.scientific.net/amr.860-863.1441.

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The cylinder type natural gas heater is an indispensable piece of equipment in gas production, transmission, and application systems. According to the distinctive structure of the cylinder natural gas heater, the natural convection heat transfer model of both heating surface and cooling surface in the cylinder was built, the temperature and velocity field of the natural convection of the heat-transfer medium--ethylene glycol were numerically simulated. The simulation results show that the symmetrical arrangement of heating and cooling surfaces is not conducive to the formation of an effective heat flow field. Therefore, effective optimizing the layout of the heating and cooling surfaces is obviously a problem that must be solved, to help the heat-transfer medium form a well-organized flow and enhance the heat transfer.

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Yuki, M. S., J. R. Parsons, and R. J. Krane. "An Investigation of the Passive Cooling of Table Model Television Receivers." Journal of Electronic Packaging 112, no. 4 (December 1, 1990): 279–87. http://dx.doi.org/10.1115/1.2904380.

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Economic and reliability considerations lead to the adoption of passive techniques for cooling by a combination of natural convection and radiation heat transfer. In order to facilitate the cooling by natural convection, thermal design engineers commonly incorporate vent openings in the walls of a receiver cabinet. Unfortunately, natural convection flows in complex, vented enclosures are presently not well understood and designers must employ “cut and try” methodologies to determine the sizes and locations of vent openings. Since vent openings are expensive to incorporate in consumer electronic products, it was decided to develop the techniques that would enable thermal designers to minimize the number of vent openings in a TV cabinet and maximize the effectiveness of those vents that are employed. Thus, the present study represents the first step in a rational program to develop the tools that will enable engineers to optimize the thermal design of a table model television receiver. In this initial work, experiments were performed to determine the effects of vent size and location on component cooling in a representative table model receiver. Vents were systematically blocked until the set was operated in a completely sealed condition. Measurements of component, air, and cabinet wall temperatures and the results of flow visualization experiments were used to assess the effects of various combinations of vent openings on the natural convection cooling of the receiver. Results indicate that: (1) the present design of the vent system of a representative, commercially available table model television receiver is adequate, but has not been optimized, and (2) significant improvements in the design of the vent could be achieved; that is, improved component cooling could be obtained with fewer vent openings. The results of this work, which should be directly applicable by thermal designers, will also serve to experimentally verify numerical models of the natural convection flows through television receivers that are currently under development.

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Hadavand, Mahshid, and Antonio C. M. Sousa. "Simulation of Thermomagnetic Convection in a Cavity Using the Lattice Boltzmann Model." Journal of Applied Mathematics 2011 (2011): 1–14. http://dx.doi.org/10.1155/2011/538637.

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Thermomagnetic convection in a differentially heated square cavity with an infinitely long third dimension is numerically simulated using the single relaxation time lattice Boltzmann method (LBM). This problem is of considerable interest when dealing with cooling of microelectronic devices, in situations where natural convection does not meet the cooling requirements, and forced convection is not viable due to the difficulties associated with pumping a ferrofluid. Therefore, circulation is achieved by imposing a magnetic field, which is created and controlled by placing a dipole at the bottom of the enclosure. The magnitude of the magnetic force is controlled by changing the electrical current through the dipole. In this study, the effects of combined natural convection and magnetic convection, which is commonly known as “thermomagnetic convection,” are analysed in terms of the flow modes and heat transfer characteristics of a magnetic fluid.

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Papanicolaou, Elias, and Sridhar Gopalakrishna. "Natural Convection in Shallow, Horizontal Air Layers Encountered in Electronic Cooling." Journal of Electronic Packaging 117, no. 4 (December 1, 1995): 307–16. http://dx.doi.org/10.1115/1.2792110.

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A numerical study of natural convection induced in a horizontal, enclosed air layer due to a discrete, constant heat flux source at the bottom surface is carried out in this paper. The nature of the transition from conduction to a cellular convection regime for this discrete-heating case is characterized. Multiple sources are also considered and the results are compared to those for a single source. The governing equations of continuity, momentum, and energy conservation are formulated for a two-dimensional layer. The important parameters are the overall aspect ratio (length/height of the layer), the ratio of source length to total length, and the Rayleigh number. The effect of varying these parameters is investigated, and heat transfer correlations are derived, for both single and multiple sources, in the form Nus ∝ C (Ra)c>, where Nus is the Nusselt number averaged over each source. The value of C is found to depend strongly on the aspect ratio and the source size. Based on the heat transfer results, the tendency of each geometric configuration to fully attain transition to the convection regime is evaluated. This can provide guidelines for maintaining certain critical dimensions that best exploit natural convection effects, in systems where fan-driven cooling is not available.

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Chen, Mingyi, Siyu Zhang, Guoyang Wang, Jingwen Weng, Dongxu Ouyang, Xiangyang Wu, Luyao Zhao, and Jian Wang. "Experimental Analysis on the Thermal Management of Lithium-Ion Batteries Based on Phase Change Materials." Applied Sciences 10, no. 20 (October 21, 2020): 7354. http://dx.doi.org/10.3390/app10207354.

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Temperature is an important factor affecting the working efficiency and service life of lithium-ion battery (LIB). This study carried out the experiments on the thermal performances of Sanyo ternary and Sony LiFePO4 batteries under different working conditions including extreme conditions, natural convection cooling and phase change material (PCM) cooling. The results showed that PCM could absorb some heat during the charging and discharging process, effectively reduce the temperature and keep the capacity stable. The average highest temperature of Sanyo LIB under PCM cooling was about 54.4 °C and decreased about 12.3 °C compared with natural convection in the 2 C charging and discharging cycles. It was found that the addition of heat dissipation fins could reduce the surface temperature, but the effect was not obvious. In addition, the charge and discharge cycles of the two kinds of LIBs were compared at the discharge rates of 1 C and 2 C. Compared with natural convection cooling, the highest temperature of Sanyo LIB with PCM cooling decreased about 4.7 °C and 12.8 °C for 1 C and 2 C discharging respectively, and the temperature of Sony LIB highest decreased about 1.1 °C and 2 °C.

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Kitamura, Yoji, and Masaru Ishizuka. "Chimney Effect on Natural Air Cooling of Electronic Equipment Under Inclination." Journal of Electronic Packaging 126, no. 4 (December 1, 2004): 423–28. http://dx.doi.org/10.1115/1.1827256.

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With the rapid increase of the power dissipation density in modern electronic equipment, the cooling design of electronic equipment becomes increasingly important. For widely used forced-convection air-cooled systems, the reliability of and the acoustic noise of the fan present serious concerns as the air velocity is increased to enhance the cooling capacity. Thus, the interest in natural-convection air cooling is growing to take advantage of low noise and energy savings inherent in that cooling mode. One method of promoting the capacity of natural air cooling is to incline the electronics casing, thereby, induce draft air by what is called the chimney effect. However, the effect of inclination on thermal behavior and cooling capacity has not yet been fully understood due to the involvement of many parameters in driving the draft air. This paper presents the results of experimental and numerical studies on the effect of casing inclination on the temperature rise across the casing. The numerical simulation was implemented to find out the thermal behavior inside a thin electronic casing. The simulation results are in good agreement with the experiment data. A thermal design guide is obtained regarding how the cooling effect is improved by increasing the inclination angle.

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Prakash, M. "Numerical Studies on Natural Convection Heat Losses from Open Cubical Cavities." Journal of Engineering 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/320647.

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The natural convection heat losses occurring from cubical open cavities are analysed in this paper. Open cubical cavities of sides 0.1 m, 0.2 m, 0.25 m, 0.5 m, and 1 m with constant temperature back wall boundary conditions and opening ratio of 1 are studied. The Fluent CFD software is used to analyse the three-dimensional (3D) cavity models. The studies are carried out for cavities with back wall temperatures between 35°C and 100°C. The effect of cavity inclination on the convective loss is analysed for angles of 0° (cavity facing sideways), 30°, 45°, 60°, and 90° (cavity facing vertically downwards). The Rayleigh numbers involved in this study range between 4.5 × 105and 1.5 × 109. The natural convection loss is found to increase with an increase in back wall temperature. The natural convection loss is observed to decrease with an increase in cavity inclination; the highest convective loss being at 0° and the lowest at 90° inclination. This is observed for all cavities analysed here. Nusselt number correlations involving the effect of Rayleigh number and the cavity inclination angle have been developed from the current studies. These correlations can be used for engineering applications such as electronic cooling, low- and medium-temperature solar thermal systems, passive architecture, and also refrigeration systems.

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Zambra, Carlos Enrique, Luciano Gonzalez-Olivares, Johan González, and Benjamin Clausen. "Temporal Evolution of Cooling by Natural Convection in an Enclosed Magma Chamber." Processes 10, no. 1 (January 5, 2022): 108. http://dx.doi.org/10.3390/pr10010108.

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This research numerically studies the transient cooling of partially liquid magma by natural convection in an enclosed magma chamber. The mathematical model is based on the conservation laws for momentum, energy and mass for a non-Newtonian and incompressible fluid that may be modeled by the power law and the Oberbeck–Boussinesq equations (for basaltic magma) and solved with the finite volume method (FVM). The results of the programmed algorithm are compared with those in the literature for a non-Newtonian fluid with high apparent viscosity (10–200 Pa s) and Prandtl (Pr = 4 × 104) and Rayleigh (Ra = 1 × 106) numbers yielding a low relative error of 0.11. The times for cooling the center of the chamber from 1498 to 1448 K are 40 ky (kilo years), 37 and 28 ky for rectangular, hybrid and quasi-elliptical shapes, respectively. Results show that for the cases studied, natural convection moved the magma but had no influence on the isotherms; therefore the main mechanism of cooling is conduction. When a basaltic magma intrudes a chamber with rhyolitic magma in our model, natural convection is not sufficient to effectively mix the two magmas to produce an intermediate SiO2 composition.

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Ding, Bin, Wen-Chuang Feng, Jian Fang, Shu-Zhe Li, and Liang Gong. "How natural convection affect cooling performance of PCM heat sink." International Journal of Heat and Mass Transfer 184 (March 2022): 122272. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2021.122272.

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JOHNSON, CHARLES E. "Evaluation of Correlations for Natural Convection Cooling of Electronic Equipment." Heat Transfer Engineering 7, no. 1-2 (January 1986): 36–45. http://dx.doi.org/10.1080/01457638608939643.

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Abdillah, Habibi, Geby Saputra, Novitrian, and Sidik Permana. "Study of Natural Convection Passive Cooling System for Nuclear Reactors." Journal of Physics: Conference Series 877 (July 2017): 012047. http://dx.doi.org/10.1088/1742-6596/877/1/012047.

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Mezrhab, A., H. Bouali, H. Amaoui, and C. Abid. "Natural convection‐radiation cooling of a vertical divided vented channel." Engineering Computations 23, no. 7 (October 2006): 818–39. http://dx.doi.org/10.1108/02644400610689910.

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Christen, Daniel, Milos Stojadinovic, and Juergen Biela. "Energy Efficient Heat Sink Design: Natural Versus Forced Convection Cooling." IEEE Transactions on Power Electronics 32, no. 11 (November 2017): 8693–704. http://dx.doi.org/10.1109/tpel.2016.2640454.

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Oliveski, Rejane De Césaro, Arno Krenzinger, and Horácio A. Vielmo. "Cooling of cylindrical vertical tanks submitted to natural internal convection." International Journal of Heat and Mass Transfer 46, no. 11 (May 2003): 2015–26. http://dx.doi.org/10.1016/s0017-9310(02)00508-2.

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Stevens, A. W. "Natural convection in a liquid metal enclosure with floor cooling." International Journal of Heat and Mass Transfer 39, no. 17 (November 1996): 3749–59. http://dx.doi.org/10.1016/0017-9310(96)00017-8.

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Slobodchuk, V., E. Stratmanns, S. Gordeev, V. Heinzel, D. Leichtle, A. Möslang, and S. P. Simakov. "Natural convection cooling of the IFMIF target and test cell." Fusion Engineering and Design 82, no. 15-24 (October 2007): 2677–82. http://dx.doi.org/10.1016/j.fusengdes.2007.03.057.

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Chan, K. F., C. W. Leung, and S. D. Probert. "Natural-convection cooling of a housed, simulated printed-circuit board." Applied Energy 38, no. 4 (January 1991): 245–52. http://dx.doi.org/10.1016/0306-2619(91)90078-c.

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Iatridis, A. J., C. D. Dritselis, I. E. Sarris, and N. S. Vlachos. "Transient Laminar MHD Natural Convection Cooling in a Vertical Cylinder." Numerical Heat Transfer, Part A: Applications 62, no. 7 (October 2012): 531–46. http://dx.doi.org/10.1080/10407782.2012.703082.

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Journal articles on the topic 'Natural Convection Cooling'

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