CFD-Assisted Optimization of Chimneylike Flows to Cool an Electronic Device

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Varghese Panthalookaran
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Energy Efficient ◽  
Electronic Device ◽  
Cooling System ◽  
Electronic Devices ◽  
Cost Effective ◽  
Transfer Rates ◽  
Slot Opening ◽  
Convection Cooling

Natural convection cooling provides a reliable, cost-effective, energy-efficient and noise-free method to cool electronic equipment. However, the heat transfer coefficient associated with natural convection mode is usually insufficient for electronic cooling and it requires enhancement. Chimneylike flows developed within the cabinets of electronic devices can provide better mass flow and heat transfer rates and can lead to greater cooling efficiency. Constraints in the design of natural convection cooling systems include efficiency of packing, aesthetics, and concerns of material reduction. In this paper, methods based on computational fluid dynamics are used to study the effects of parameters such as (1) vertical alignment of the slots, (2) horizontal alignment of slots, (3) area of slots, (4) differential slot opening, and (5) zonal variation in heat generation on natural convection cooling within such design constraints. Insights thus derived are found useful for designing an energy-efficient and ecofriendly cooling system for electronic devices.

An Experimental Study of Natural Convection Cooling of an Array of Heated Protrusions in a Vertical Channel in Water

1989 ◽  
Vol 111 (1) ◽  
pp. 33-40 ◽  
Author(s):  
Y. Joshi ◽  
T. Willson ◽  
S. J. Hazard
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Power Dissipation ◽  
Three Dimensional ◽  
Vertical Channel ◽  
Steady Flows ◽  
Transfer Rates ◽  
Fluid Velocities ◽  
Convection Cooling ◽  
Flow Visualizations

An experimental investigation of steady state and transient natural convection from a column of eight in-line rectangular heated protrusions in a vertical channel in water is presented. Flow visualizations and element surface temperature measurements were carried out for several power dissipation levels in the range of 0.2–1.5 W per component and channel spacings from 6.4 to 23 mm. The three-dimensional steady flows were visualized in two mutually perpendicular planes. Average component temperatures determined from the measurements on the five fluid exposed faces were used to obtain nondimensional heat transfer rates. Heat transfer data for all channel spacings except the smallest did not differ from the measurements for an isolated surface by more than 14 percent. For the smallest spacing, the component surface temperatures increased significantly due to a reduction in the fluid velocities. Measurements and flow visualizations during the transient indicated an initial diffusive transport period, followed by the evolution of convective effects. No overshoots in component temperatures were found. Steady transport responses with selectively powered components are also examined.

Fundamental Issues and Recent Advancements in Analysis of Aircraft Brake Natural Convective Cooling

1998 ◽  
Vol 120 (4) ◽  
pp. 840-857 ◽  
Author(s):  
M. P. Dyko ◽  
K. Vafai
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Flow Field ◽  
Three Dimensional ◽  
Convective Cooling ◽  
Cooling Flow ◽  
Physical Mechanisms ◽  
Braking System ◽  
Flow And Heat Transfer ◽  
Convection Cooling

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.

Probabilistic finite element analysis in heat transfer to a nuclear fuel rod bumper support

2004 ◽  
Vol 218 (12) ◽  
pp. 1499-1505
Author(s):  
Rama Subba Reddy Gorla
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Nuclear Fuel ◽  
Cost Effective ◽  
Distribution Functions ◽  
Cumulative Distribution ◽  
Element Analysis ◽  
Transfer Rates ◽  
Fuel Rod ◽  
Design Variables

Heat transfer from a nuclear fuel rod bumper support was computationally simulated by a finite element method and probabilistically evaluated in view of the several uncertainties in the performance parameters. Cumulative distribution functions and sensitivity factors were computed for overall heat transfer rates due to the thermodynamic random variables. These results can be used to identify quickly the most critical design variables in order to optimize the design and to make it cost effective. The analysis leads to the selection of the appropriate measurements to be used in heat transfer and to the identification of both the most critical measurements and the parameters.

Improvement of Temperature Evaluation Model of Biological Shielding Concrete for HTTR Test Simulating LOFC With VCS Inactive

2013 ◽  
Author(s):  
Shoji Takada ◽  
Shunki Yanagi ◽  
Kazuhiko Iigaki ◽  
Masanori Shinohara ◽  
Daisuke Tochio ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Thermal Radiation ◽  
Cooling System ◽  
Evaluation Model ◽  
Reactor Core ◽  
Reactor Power ◽  
Coolant Temperature ◽  
Water Cooling ◽  
Reactor Outlet

HTTR is a helium gas cooled graphite-moderated HTGR with the rated power 30 MWt and the maximum reactor outlet coolant temperature 950°C. The vessel cooling system (VCS), which is composed of thermal reflector plates, cooling panel composed of fins connected between adjacent water cooling tubes, removes decay heat from reactor core by heat transfer of thermal radiation, conduction and natural convection in case of loss of forced cooling (LOFC). The metallic supports are embedded in the biological shielding concrete to support the fins of VCS. To verify the inherent safety features of HTGR, the LOFC test is planned by using HTTR with the VCS inactive from an initial reactor power of 9 MWt under the condition of LOFC while the reactor shut-down system disabled. In this test, the temperature distribution in the biological shielding concrete is prospected locally higher around the support because of thermal conduction in the support. A 2-dimensional symmetrical model was improved to simulate the heat transfer to the concrete through the VCS support in addition to the heat transfer thermal radiation and natural convection. The model simulated the water cooling tubes setting horizontally at the same pitch with actual configuration. The numerical results were verified in comparison with the measured data acquired from the test, in which the RPV was heated up to around 110 °C without nuclear heating with the VCS inactive, to show that the temperature is locally high but kept sufficiently low around the support in the concrete due to sufficient thermal conductivity to the cold temperature region.

Three-Dimensional Natural Convection From Vertical Heated Plates With Adjoining Cool Surfaces

1992 ◽  
Vol 114 (1) ◽  
pp. 115-120 ◽  
Author(s):  
B. W. Webb ◽  
T. L. Bergman
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Control Volume ◽  
Three Dimensional ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Uniform Heat Flux ◽  
Infrared Thermal Imaging ◽  
Transfer Rates ◽  
Thermal Boundary Conditions

Natural convection in an enclosure with a uniform heat flux on two vertical surfaces and constant temperature at the adjoining walls has been investigated both experimentally and theoretically. The thermal boundary conditions and enclosure geometry render the buoyancy-induced flow and heat transfer inherently three dimensional. The experimental measurements include temperature distributions of the isoflux walls obtained using an infrared thermal imaging technique, while the three-dimensional equations governing conservation of mass, momentum, and energy were solved using a control volume-based finite difference scheme. Measurements and predictions are in good agreement and the model predictions reveal strongly three-dimensional flow in the enclosure, as well as high local heat transfer rates at the edges of the isoflux wall. Predicted average heat transfer rates were correlated over a range of the relevant dimensionless parameters.

Design of a Plane-Type Bidirectional Thermal Diode

1988 ◽  
Vol 110 (4) ◽  
pp. 299-305 ◽  
Author(s):  
K. Chen
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Transfer Rate ◽  
Reverse Bias ◽  
Energy Utilization ◽  
Heat Transfer Analysis ◽  
Transfer Rates ◽  
One Dimensional ◽  
Plane Type ◽  
Solar Energy Utilization

The design of a plane-type, bidirectional thermal diode is presented. This diode is composed of two vertical plates and several fluid-filled loops with their horizontal segments soldered to the vertical plates. This invention is simple in construction and low in cost. The direction of heat transfer in the invented thermal diode can be easily reversed. These features of the present invention make it very attractive to solar energy utilization. Natural convection analysis for thermosyphon operations was adopted for heat transfer calculations of the fluid-filled loops. A one-dimensional heat transfer analysis was employed to estimate the heat transfer rate and ratio of heat transfer rates of the diode under forward and reverse bias.

Flow Channelization Method to Enhance Transformer Radiator Cooling Capacity

2018 ◽  
Vol 10 (6) ◽  
Author(s):  
Subhashish Dasgupta ◽  
Anurag Nandwana ◽  
K. Ravikumar
Keyword(s):  
Natural Convection ◽  
Heat Exchangers ◽  
Fluid Dynamic ◽  
Cost Effective ◽  
Cooling Capacity ◽  
Structural Features ◽  
Cfd Analysis ◽  
Cooling Process ◽  
Effective Technology ◽  
Convection Cooling

Abstract Most oil-cooled equipment like transformers are provided with radiators or heat exchangers, for the heated oil to exchange heat with the surrounding air by natural convection cooling, assisting the overall cooling process. While such radiators are effective accessories in controlling equipment temperature rise, it is ever desirable to further enhance the cooling capacity by design modifications or incorporating simplistic and cost-effective cooling technologies. In this study, computational fluid dynamic (CFD) analysis has been performed to evaluate the possibility of improving radiator performance by flow channelizing structures. Significant benefits (up to 17% increase in heat transfer coefficient) of imposing such structures, like a top chimney and an enclosure surrounding the radiator, were obtained. Although several past studies have confirmed that natural convection cooling effect can be intensified by flow channelization, the phenomenon is unique to a particular application. Given the wide variety in applications, in terms of shape, size, and structural features, it is necessary to study the effect in a given application of interest. This study points to a new direction in enhancing the cooling capacity of transformer radiators, inducing flow channelization, an easy-to-implement and cost-effective technology. Further, the study offers interesting learnings regarding flow channelization effects, which are invaluable guidelines for designers of future radiators.

On Efficient Passive Cooling of Control Rod Drivers

2013 ◽  
Author(s):  
A. N. Gershuni ◽  
A. P. Nishchik ◽  
V. G. Razumovskiy ◽  
I. L. Pioro
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
High Performance ◽  
Cooling System ◽  
Vertical Channel ◽  
Passive Cooling ◽  
Primary Circuit ◽  
Two Phase ◽  
Primary Coolant ◽  
Control Rod

Experimental research of natural convection and the ways of its suppression in an annular vertical channel to simulate the conditions of cooling the control rod drivers of the reactor protection system (RPS) in its so-called wet design, where the drivers are cooled by primary circuit water supplied due to the system that includes branched pipelines, valves, pump, heat exchanger, etc., is reported. Reliability of the drivers depends upon their temperature ensured by operation of an active multi-element cooling system. Its replacement by an available passive cooling system is possible only under significant suppression of natural convection in control rod channel filled with primary coolant. The methods of suppression of natural convection proposed in the work have demonstrated the possibility both of minimization of axial heat transfer and of almost complete elimination of temperature non-uniformity and oscillation inside the channel under the conditions of free travel of moving element (control rod) in it. The obtained results widen the possibilities of substitution of the active systems of cooling the RPS drivers by reliable passive systems, such as high-performance heat-transfer systems of evaporation-condensation type with heat pipes or two-phase thermosyphons as heat-transferring elements.

scholarly journals A Numerical and Experimental Study of a Novel Heat Sink Design for Natural Convection Cooling of LED Grow Lights

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4046
Author(s):  
Ram Adhikari ◽  
Dawood Beyragh ◽  
Majid Pahlevani ◽  
David Wood
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Sink ◽  
Large Scale ◽  
High Efficiency ◽  
Experimental Testing ◽  
Growth Stages ◽  
Air Cooling ◽  
Convection Cooling ◽  
Heat Sink Design

Light-emitting diode (LED) grow lights are increasingly used in large-scale indoor farming to provide controlled light intensity and spectrum to maximize photosynthesis at various growth stages of plants. As well as converting electricity into light, the LED chips generate heat, so the boards must be properly cooled to maintain the high efficiency and reliability of the LED chips. Currently, LED grow lights are cooled by forced convection air cooling, the fans of which are often the points of failure and also consumers of a significant amount of power. Natural convection cooling is promising as it does not require any moving parts, but one major design challenge is to improve its relatively low heat transfer rate. This paper presents a novel heat sink design for natural convection cooling of LED grow lights. The new design consists of a large rectangular fin array with openings in the base transverse to the fins to increase air flow, and hence the heat transfer. Numerical simulations and experimental testing of a prototype LED grow light with the new heat sink showed that openings achieved their intended purpose. It was found that the new heat sink can transfer the necessary heat flux within the safe operating temperature range of LED chips, which is adequate for cooling LED grow lights.

Sign in / Sign up

Export Citation Format

Share Document