scholarly journals Mathematical modeling and numerical simulation of heat dissipation in led bulbs

2020 ◽  
Vol 24 (3 Part A) ◽  
pp. 1877-1884 ◽  
Author(s):  
Diego Alarcón ◽  
Eduardo. Balvís ◽  
Ricardo Bendaña ◽  
Alberto Conejero ◽  
de Fernández ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Numerical Simulation ◽  
Numerical Simulations ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Thermal Contact ◽  
Heat Sinks ◽  
Experimental Measurements ◽  
Heating And Cooling ◽  
The Common

We present a detailed study of heating and cooling processes in LED luminaires with passive heat sinks. Our analysis is supported by numerical simulations as well as experimental measurements, carried on commercial systems used for outdoor lighting. We have focused our analysis on the common case of a single LED source in thermal contact with an aluminum passive heat sink, obtaining an excellent agreement with experimental measurements and the numerical simulations performed. Our results can be easily expanded, without loss of generality, to similar systems.

Thermal Behaviors of Passively-Cooled Hybrid Fin Heat Sinks for Lightweight and High Performance Thermal Management

2015 ◽  
Author(s):  
Nico Setiawan Effendi ◽  
Kyoung Joon Kim
Keyword(s):  
Thermal Resistance ◽  
Heat Sink ◽  
High Performance ◽  
Heat Dissipation ◽  
Computational Study ◽  
Heat Sinks ◽  
Channel Diameter ◽  
Internal Channel ◽  
Study Results ◽  
Parametric Effects

A computational study is conducted to explore thermal performances of natural convection hybrid fin heat sinks (HF HSs). The proposed HF HSs are a hollow hybrid fin heat sink (HHF HS) and a solid hybrid fin heat sink (SHF HS). Parametric effects such as a fin spacing, an internal channel diameter, a heat dissipation on the performance of HF HSs are investigated by CFD analysis. Study results show that the thermal resistance of the HS increases while the mass-multiplied thermal resistance of the HS decreases associated with the increase of the channel diameter. The results also shows the thermal resistance of the SHF HS is 13% smaller, and the mass-multiplied thermal resistance of the HHF HS is 32% smaller compared with the pin fin heat sink (PF HS). These interesting results are mainly due to integrated effects of the mass-reduction, the surface area enhancement, and the heat pumping via the internal channel. Such better performances of HF HSs show the feasibility of alternatives to the conventional PF HS especially for passive cooling of LED lighting modules.

Design of Optimum Plate-Fin Natural Convective Heat Sinks

2003 ◽  
Vol 125 (2) ◽  
pp. 208-216 ◽  
Author(s):  
Avram Bar-Cohen ◽  
Madhusudan Iyengar ◽  
Allan D. Kraus
Keyword(s):  
Nusselt Number ◽  
Specific Heat ◽  
Rectangular Plate ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Thermal Design ◽  
Heat Sinks ◽  
And Performance ◽  
Nusselt Number Correlation ◽  
The Impact

The effort described herein extends the use of least-material single rectangular plate-fin analysis to multiple fin arrays, using a composite Nusselt number correlation. The optimally spaced least-material array was also found to be the globally best thermal design. Comparisons of the thermal capability of these optimum arrays, on the basis of total heat dissipation, heat dissipation per unit mass, and space claim specific heat dissipation, are provided for several potential heat sink materials. The impact of manufacturability constraints on the design and performance of these heat sinks is briefly discussed.

Experimental Investigation of a PCM-Based Topology Optimized Heat Sink for Passive Cooling of Electronics

2020 ◽  
Author(s):  
Jin Yao Ho ◽  
Kai Choong Leong
Keyword(s):  
Thermal Performance ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Base Temperature ◽  
Storage Unit ◽  
Cooling Of Electronics

Abstract A thermal energy storage unit filled with phase change material (PCM) can serve as a heat sink for the cooling of electronics with intermittent or periodic heat dissipation rates. The use of thermal conductive structures (TCS) is an effective method of improving the thermal performance of a PCM-based heat sink. In this paper, topology optimization is explored to develop a new class of TCS with a tree-like structure to enhance the thermal performance of a trapezoidal heat sink. The topology-optimized heat sink was then fabricated by Selective Laser Melting (SLM) using an aluminum alloy, AlSi10Mg, as the base powder. Experiments were performed to evaluate the thermal performance of the topology-optimized heat sink with the tree-like structure. In addition, a conventional longitudinal-fin heat sink of the same solid volume fraction (φ = 16.2%) and a heat sink without enhanced structure were also fabricated and experimentally investigated for comparison. Rubitherm RT-35HC paraffin wax was used as the PCM. Three different heat fluxes of 4.00 kW/m2, 5.08 kW/m2 and 7.24 kW/m2 were applied at the base of each specimen by a silicone rubber heater. The structure wall and the PCM temperatures were measured over time. Our results show that, for all heat rates tested, the topology-optimized heat sink was able to maintain a lower base temperature as compared to the fin-structure and the plain heat sinks. A thermal enhancement ratio (ε) is defined to evaluate the performance of the heat sinks with and without the use of PCM. From the experimental results, the highest ε value of 8.6 was achieved by the topology-optimized heat sink. These results indicate the better performance of the topology-optimized heat sink in dissipating heat as compared to the other specimens.

scholarly journals Application of Limit Equilibrium Analysis and Numerical Modeling in a Case of Slope Instability

2020 ◽  
Vol 12 (21) ◽  
pp. 8870
Author(s):  
Fhatuwani Sengani ◽  
François Mulenga
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Limit Equilibrium ◽  
Slope Angle ◽  
Road Construction ◽  
Soil Mass ◽  
Slope Instability ◽  
Equilibrium Analysis ◽  
Limit Equilibrium Analysis ◽  
The Common

The application of limit equilibrium analysis and numerical simulation in case of slope instability is described. The purpose of the study was to use both limit equilibrium methods (LEMs) and numerical simulations (finite element method (FEM)) to understanding the common factor imposing the selected slope into slope instabilities. Field observations, toppling analysis, rotational analysis, and numerical simulations were performed. The results of the study showed that the selected unstable slopes were associated with the sliding types of toppling; it was observed that the slopes were governed by tension cracks and layered soil mass and dominated with approximately two joints sets throughout. The simulated factor of safety (FoS) of the slopes composed of clay soil was denoted to be prone to slope instability while others were categorized as moderately stable. The simulated FoS of the slopes correlated very well with the visual observations; however, it is anticipated that properties of soil mass and other characteristics of the slopes contributed largely to the simulated FoS. The sensitivity of the model was further tested by looking into the effect of the slope angle on the stability of the slope. The results of the simulations showed that the steeper the slope, the more they become prone to instability. Lastly, Phase 2 numerical simulation (FEM) showed that volumetric strain, shear stress, shear strain, total displacement, and σ1 and σ3 components of the slope increase with the stages of the road construction. It was concluded improper road construction, steepness of the slope, slope properties (soil types), and multiple geological features cutting across are the common mechanisms behind the slope instability.

Thermal Analysis for Three-Dimensional Heat Spreader Integrated With Heat Sink

2003 ◽  
Author(s):  
Y. C. Wu ◽  
H. T. Chen ◽  
C. C. Lin ◽  
Y. H. Hung
Keyword(s):  
Heat Sink ◽  
Heat Dissipation ◽  
Three Dimensional ◽  
Heat Sinks ◽  
Heat Sources ◽  
Heat Spreader ◽  
Discrete Heat Sources ◽  
Thermal Analyzer ◽  
Parametric Studies ◽  
Overall Resistance

An effective thermal analyzer for exploring the thermal performance of 3-D heat spreader having discrete heat sources integrated with heat sink has been successfully developed in the study. The thermal performances such as local temperature distributions and isotherms on heat spreader surfaces; and overall resistance of heat spreader/sink assembly are investigated. Besides, a series of parametric studies have been performed. The parameters and conditions explored include the size and heat dissipation rate of heat sources, size and material of heat spreaders and heat sinks, type of convection in heat sink, and contact conditions between heat spreader and heat sink. The superiority of the developed thermal analyzer through two sample cases having multi-discrete heat sources has finally been demonstrated.

Determination of Interlaminar Fracture Toughness of CFRP Composite in Mode I Using Numerical Simulation with Cohesive Elements

2020 ◽  
Vol 847 ◽  
pp. 15-21
Author(s):  
Frantisek Sedlacek ◽  
Tomas Kalina ◽  
Karel Raz
Keyword(s):  
Numerical Simulation ◽  
Fracture Toughness ◽  
Numerical Simulations ◽  
Analytical Calculation ◽  
Mode I ◽  
Experimental Measurements ◽  
Cohesive Elements ◽  
Cohesive Failure ◽  
Cfrp Composite

This paper deals with the determination of parameters of the interlaminar failure of the CFRP composite laminate in mode I using numerical simulation with cohesive elements. Knowledge of these parameters is crucial to enable prediction of interlaminar strength of laminates using numerical simulations based on the finite element method with cohesive elements. There are several standardized experimental measurements for determining mode I parameters but not all that are needed for numerical simulations. However, the determination of these parameters and their evolution during cohesive failure is very problematic even if the experimental data is available. This paper deals with the design of a methodology for how to determine these parameters using the fitting process of experimental measurement and numerical simulation. The experimental measurements were done on double cantilever beam specimens according to ASTM standards. The numerical simulations were performed in the Siemens Simcenter software with NX Nastran solver. The numerical model with the obtained parameters shows very good agreement with the experimental measurements. compared to the average experimental values and the analytical calculation, the difference of fracture toughness is up to 1.6 %

Simulation of Airflow in the Burning Cave of an Auxiliary Heating System in a Greenhouse

2018 ◽  
Vol 61 (4) ◽  
pp. 1405-1416
Author(s):  
Zhanyang Xu ◽  
Wenhe Liu ◽  
Tieliang Wang ◽  
Wei Yu ◽  
Yuqing Zhang
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Numerical Simulations ◽  
Heating System ◽  
Experimental Measurements ◽  
Wall Function ◽  
Auxiliary Heating ◽  
Airflow Velocity ◽  
Cave Entrance ◽  
Turbulent Airflow

Abstract. In this study, numerical simulations of airflow were carried out in the burning cave of an auxiliary heating system. Experimental measurements were also conducted to verify the performance of the numerical model, and turbulent airflow in the burning cave was considered. The numerical simulation in the burning cave was performed for three cases:(1) with a baffle at the bottom of the burning cave entrance, (2) without a baffle at the burning cave entrance, and (3) with a baffle at the top of the burning cave entrance. The turbulent airflow was modeled using the realizable k-e turbulence model as well as the non-equilibrium wall function. The airflow velocity was assessed in the burning cave, and some suggestions were given to improve the performance of the burning cave. The results showed that the airflow entering the burning cave differed due to different positions of the baffle. The smoldering combustion was more even and the burning rate could be controlled more easily when the baffle was placed at the top of the burning cave entrance, making the airflow enter the burning cave through the bottom of the baffle. The results also showed that the maximum airflow velocity in the burning cave increased with increased distance between the baffle and the bottom of the burning cave. Keywords: Airflow, Burning cave, Greenhouse, Simulation.

Application of Thermal Contact Resistance in Simulation of Heat Dissipation by CPU Heat Sinks Based on ANSYS

2014 ◽  
Vol 941-944 ◽  
pp. 2465-2468 ◽  
Author(s):  
Yong Zhen Liu ◽  
Zhi Shi Huang ◽  
Bin Feng ◽  
Jin He Wei ◽  
Jian Min Zeng
Keyword(s):  
Contact Resistance ◽  
Heat Dissipation ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Heat Sinks ◽  
Ansys Software ◽  
Electronic Elements ◽  
Good Heat ◽  
Main Factor

With development in electronic technology, more and more electronic elements have been integrated into one chip, which has resulted in the cooling problem of the chips. In this case, heat dissipation has become the main factor that affecting the design reliability and package cost. Therefore, good heat dissipation designs are urgently need to solve the problem. An important issue resulted from simulation of heat dissipation is the determination of boundary condition between the heat sink and the CPU. The concept of thermal contact resistance was introduced to simulation of heat dissipation of CPU heat sinks in this paper. The temperature distribution of CPU heat sinks was calculated Based on ANSYS software. The result of calculation can help to understand the heat transfer characteristics of CPU heat sinks, and also offer a reference for the design and improvement of the electronic equipment.

The Application of Heat Pipe Heat Sink for High Power LED Lamps

2014 ◽  
Vol 602-605 ◽  
pp. 2713-2716 ◽  
Author(s):  
Xin Rui Ding ◽  
Yu Ji Li ◽  
Zong Tao Li ◽  
Yong Tang ◽  
Bin Hai Yu ◽  
...  
Keyword(s):  
Heat Pipe ◽  
Thermal Performance ◽  
High Power ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Heat Sinks ◽  
Practical Significance ◽  
Heat Accumulation ◽  
Element Analysis ◽  
High Power Led

LED has been regarded as the next generation lighting source. As for high power LED lamps, heat accumulation will cause a series of problems. Therefore, thermal management is very important for designing a high power LED lamp. Three types of heat sinks are designed by using the finite element analysis (FEA) method for an 180W high power LED lamp. Then the optimized heat sinks are developed and experiments are performed to demonstrate the simulated results. At the same time, the thermal performances with different working angles are investigated experimentally. The heat sink with heat pipe has a better heat dissipation performance than the conventional heat sink under the same input power. The working angles of the lamps greatly influence the thermal performance of each heat sink. For the same heat sink, the temperature varies with different install directions and working angles. Finally, the heat sink with the best thermal performance is recommended. The results have practical significance in designing high power LED lamps.

Effect of Synthetic Jets Over Natural Convection Heat Sinks

2008 ◽  
Author(s):  
Mehmet Arik ◽  
Yogen Utturkar ◽  
Murat Ozmusul
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Operating Conditions ◽  
Heat Sinks ◽  
Junction Temperature ◽  
Allowable Limit

In moderate power electronics applications, the most preferred way of thermal management is natural convection to air with or without heat sinks. Though the use of heat sinks is fairly adequate for modest heat dissipation needs, it suffers from some serious performance limitations. Firstly, a large volume of the heat sink is required to keep the junction temperature at an allowable limit. This need arises because of the low convective film coefficients due to close spacing. In the present computational and experimental study, we propose a synthetic jet embedded heat sink to enhance the performance levels beyond two times within the same volume of a regular passive heat sink. Synthetic jets are meso-scale devices producing high velocity periodic jet streams at high velocities. As a result, by carefully positioning of these jets in the thermal real estate, the heat transfer over the surfaces can be dramatically augmented. This increase in the heat transfer rate is able to compensate for the loss of fin area happening due to the embedding of the jet within the heat sink volume, thus causing an overall increase in the heat dissipation. Heat transfer enhancements of 2.2 times over baseline natural convection cooled heat sinks are measured. Thermal resistances are compared for a range of jet operating conditions and found to be less than 0.9 K/W. Local temperatures obtained from experimental and computational agreed within ± 5%.

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