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.

Numerical Analysis of Laminar Natural Convection in Rectangular Enclosures of Different Aspect Ratios With and Without Aerosol Nanofluid

2013 ◽  
Author(s):  
Mosfequr Rahman ◽  
Andrew Hudson ◽  
Gustavo Molina ◽  
Valentin Soloiu
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Enhancement ◽  
Computer Model ◽  
Large Scale ◽  
Solid Particles ◽  
Process Equipment ◽  
Air Cooling ◽  
Transfer Enhancement ◽  
Aspect Ratios

Natural convection heat transfer in rectangular enclosures is important in many real-world engineering applications. Included in these applications are the energy efficient design of buildings, operation and safety of nuclear reactors, solar collector design, passive energy storage, heat transfer across multi-pane windows, thermo-electric refrigeration and heating devices, and the design-for-mitigation of optical distortion in large-scale laser systems, environmental engineering and electronic packaging. A common industrial application of natural convection is free air cooling without the aid of fans and can happen on small scales such as computer chips to large scale process equipment. In addition to temperature gradient convection strength within the enclosure can vary due to the existence of nanoparticles with the base fluid. The field of nanofluid research has been expanding in recent years. Most of the research performed for the purpose of heat transfer using nanofluids has been conducted on liquid based nanofluids, leaving the aerosol-based nanofluid research lagging. There is also a deficit in the research previously performed to develop a computer model of heat transfer enhancement using nanofluid. The transport of solid particles and liquid droplets in a fluid has long been a subject of great interest. Understanding, measuring, and quantifying the deposition of aerosol on walls is important in various sectors of science and technology. Some examples are the deposition of drugs and harmful substances in the nasal and respiratory tracts in medical science and engineering; deposition of particles and droplets in gas and steam turbines in power plant engineering; the atmospheric dispersal of pollutants and the determination of indoor air quality in environmental science; the transport and sedimentation of various substances in rivers in civil engineering; fouling of process and heat transfer equipments in process industries; and the transport of chemical aerosols in chemical process engineering. In this research work the case of pure air was first solved for 6 different aspect ratios, then the nanofluid was introduced and the resulting heat transfer was observed. The aerosol nanofluid used was composed of air with copper nanoparticles suspended in an enclosure. This procedure was repeated for multiple aspect ratios. This research also develops a functional computer model for heat transfer enhancement using nanofluid.

Natural and forced convection heat transfer coefficients of various finned heat sinks for miniature electronic systems

2018 ◽  
Vol 233 (2) ◽  
pp. 249-261 ◽  
Author(s):  
SW Pua ◽  
KS Ong ◽  
KC Lai ◽  
MS Naghavi
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Sink ◽  
Convection Heat Transfer ◽  
Heat Sinks ◽  
Air Cooling ◽  
Transfer Coefficients ◽  
Cooling Mode ◽  
Heat Transfer Coefficients ◽  
Experimental Heat

Downward lighting light-emitting diodes require cooling with cylindrical fin heat sinks to be mounted on top and cooled under natural convection air cooling mode. Performance simulation would involve specification of the heat transfer coefficient. Numerous methods are available to simulate the performance of conventional plate fin heat sinks including computational fluid dynamics packages. It would be feasible to perform simulation based on conventional flat plate fin heat sinks. A cylindrical fin heat sinks could be simply treated as a plate fin heat sink, if we imagine it cut open and laid out horizontally. A theoretical model is proposed in this paper. An experimental investigation is conducted here to validate its accuracy. Convective heat transfer coefficients were experimentally determined for a horizontally and vertically inclined bare plate operating under natural and forced air cooling modes. In addition, a vertical plate fin heat sink and a vertical cylindrical fin heat sink under natural convection were investigated. Power inputs were kept from 5 to 40 W in order to keep operating temperatures below 100 ℃. Comparison of the experimental heat transfer coefficients and those obtained from well-known existing Nusselt number correlations show that agreement was poor for the bare plate but satisfactory for the plate and cylindrical fin heat sinks. Although they are within the generally accepted range, it would be advisable for actual measurements to be carried out in order to provide more accurate sizing for thermal measurements.

Novel Heat Sink Design Utilizing Ionic Wind for Efficient Passive Thermal Management of Grid-Scale Power Routers

2015 ◽  
Vol 7 (3) ◽  
Author(s):  
Noris Gallandat ◽  
J. Rhett Mayor
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Numerical Model ◽  
Heat Transfer Enhancement ◽  
Thermal Management ◽  
Heat Sink ◽  
Ionic Wind ◽  
Transfer Enhancement ◽  
Enhancement Method ◽  
Heat Sink Design

This paper presents a numerical model assessing the potential of ionic wind as a heat transfer enhancement method for the cooling of grid distribution assets. Distribution scale power routers (13–37 kV, 1–10 MW) have stringent requirements regarding lifetime and reliability, so that any cooling technique involving moving parts such as fans or pumps are not viable. A new heat sink design combining corona electrodes with bonded fin arrays is presented. The model of the suggested design is solved numerically. It is predicted that applying a voltage of 5 kV on the corona electrodes could increase the heat removed by a factor of five as compared to natural convection.

An Investigation of the Effect of interrupted fin arrangements on the Thermal Performance of a Heat Sink under a Free Convection Condition

2019 ◽  
Vol 7 (1) ◽  
pp. 43-53
Author(s):  
Abbas Jassem Jubear ◽  
Ali Hameed Abd
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Natural Convection ◽  
Thermal Performance ◽  
Heat Sink ◽  
Numerical Study ◽  
Ansys Fluent ◽  
Fluent Software ◽  
Steady State Heat ◽  
Steady State Heat Transfer

The heat sink with vertically rectangular interrupted fins was investigated numerically in a natural convection field, with steady-state heat transfer. A numerical study has been conducted using ANSYS Fluent software (R16.1) in order to develop a 3-D numerical model.  The dimensions of the fins are (305 mm length, 100 mm width, 17 mm height, and 9.5 mm space between fins. The number of fins used on the surface is eight. In this study, the heat input was used as follows: 20, 40, 60, 80, 100, and 120 watts. This study focused on interrupted rectangular fins with a different arrangement and angle of the fins. Results show that the addition of interruption in fins in various arrangements will improve the thermal performance of the heat sink, and through the results, a better interruption rate as an equation can be obtained.

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.

Thermal Performance Evaluation of Friction Stir Welded Flat Plate Heat Sink Using CFD Analysis

2015 ◽  
Vol 787 ◽  
pp. 505-509
Author(s):  
A.K. Lakshminarayanan ◽  
M. Suresh
Keyword(s):  
Flat Plate ◽  
Heat Sink ◽  
High Efficiency ◽  
Base Plate ◽  
Software Tool ◽  
Cover Plate ◽  
Air Cooling ◽  
Cooling Systems ◽  
Plate Heat ◽  
Friction Stir

In an era of compact cooling requirements, where air cooling systems seem to be ineffective and consistently, being replaced by liquid cooled systems, with greater watt density heat energy dissipation. Such cooling systems must work with good quality enabling high efficiency. Hence, an attempt is made to fabricate an aluminum alloy based flat plate heat sink with cover and base plate using friction stir welding. The base plate is machined to obtain channels for fluid flow and the cover plate is fitted in the base plate and welded. Two such configurations of these heat sinks were fabricated with varying channel lengths and number of channels. The flow characteristics of the model for these configurations were analyzed numerically using computational fluid dynamics (CFD) software tool, ANSYS fluent 14.

Micro Fluidic Jets for Thermal Management of Electronics

Volume 4 ◽  
2004 ◽  
Author(s):  
Jivtesh Garg ◽  
Mehmet Arik ◽  
Stanton Weaver ◽  
Seyed Saddoughi
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heated Surface ◽  
Turbulent Jets ◽  
Harmonic Signal ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Small Scale ◽  
Air Cooling ◽  
Infrared Thermal Imaging

Micro fluidics devices are conventionally used for boundary layer control in many aerospace applications. Synthetic Jets are intense small scale turbulent jets formed from entrainment and expulsion of the fluid in which they are embedded. The idea of using synthetic jets in confined electronic cooling applications started in late 1990s. These micro fluidic devices offer very efficient, high magnitude direct air-cooling on the heated surface. A proprietary synthetic jet designed in General Electric Company was able to provide a maximum air velocity of 90 m/s from a 1.2 mm hydraulic diameter rectangular orifice. An experimental study for determining the thermal performance of a meso scale synthetic jet was carried out. The synthetic jets are driven by a time harmonic signal. During the experiments, the operating frequency for jets was set between 3 and 4.5 kHz. The resonance frequency for a particular jet was determined through the effect on the exit velocity magnitude. An infrared thermal imaging technique was used to acquire fine scale temperature measurements. A square heater with a surface area of 156 mm2 was used to mimic the hot component and extensive temperature maps were obtained. The parameters varied during the experiments were jet location, driving jet voltage, driving jet frequency and heater power. The output parameters were point wise temperatures (pixel size = 30 μm), and heat transfer enhancement over natural convection. A maximum of approximately 8 times enhancement over natural convection heat transfer was measured. The maximum coefficient of cooling performance obtained was approximately 6.6 due to the low power consumption of the synthetic jets.

Topology Optimization, Additive Layer Manufacturing, and Experimental Testing of an Air-Cooled Heat Sink

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Ercan M. Dede ◽  
Shailesh N. Joshi ◽  
Feng Zhou
Keyword(s):  
Topology Optimization ◽  
Heat Sink ◽  
Computer Aided Design ◽  
Experimental Testing ◽  
Jet Impingement ◽  
Coefficient Of Performance ◽  
Air Cooling ◽  
Additive Layer Manufacturing ◽  
Cloud Data ◽  
Layer Manufacturing

Topology optimization of an air-cooled heat sink considering heat conduction plus side-surface convection is presented. The optimization formulation is explained along with multiple design examples. A postprocessing procedure is described to synthesize manifold or “water-tight” solid model computer-aided design (CAD) geometry from three-dimensional (3D) point-cloud data extracted from the optimization result. Using this process, a heat sink is optimized for confined jet impingement air cooling. A prototype structure is fabricated out of AlSi12 using additive layer manufacturing (ALM). The heat transfer and fluid flow performance of the optimized heat sink are experimentally evaluated, and the results are compared with benchmark plate and pin-fin heat sink geometries that are conventionally machined out of aluminum and copper. In two separate test cases, the experimental results indicate that the optimized ALM heat sink design has a higher coefficient of performance (COP) relative to the benchmark heat sink designs.

Characterization of Light Weight Heat Sink Materials for Thermal Management of Electronics

2007 ◽  
Author(s):  
Tunc Icoz ◽  
Mehmet Arik ◽  
John T. Dardis
Keyword(s):  
Thermal Management ◽  
Heat Sink ◽  
High Efficiency ◽  
Computational Study ◽  
Heat Sinks ◽  
Advanced Materials ◽  
Air Cooling ◽  
Thermal Management Of Electronics ◽  
Thermal Solution

Thermal management of electronics is a critical part of maintaining high efficiency and reliability. Adequate cooling must be balanced with weight and volumetric requirements, especially for passive air-cooling solutions in electronics applications where space and weight are at a premium. It should be noted that there are systems where thermal solution takes more than 95% of the total weight of the system. Therefore, it is necessary to investigate and utilize advanced materials to design low weight and compact systems. Many of the advanced materials have anisotropic thermal properties and their performances depend strongly on taking advantage of superior properties in the desired directions. Therefore, control of thermal conductivity plays an important role in utilization of such materials for cooling applications. Because of the complexity introduced by anisotropic properties, thermal performances of advanced materials are yet to be fully understood. Present study is an experimental and computational study on characterization of thermal performances of advanced materials for heat sink applications. Numerical simulations and experiments are performed to characterize thermal performances of four different materials. An estimated weight savings in excess of 75% with lightweight materials are observed compared to the traditionally used heat sinks.

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