Papers by Keyword: Heat Sink

Abstract: This study proposes a development for the nanosilver adhesive, which is applicable to high efficiency LED light. The important issue of LED light is heat exhaust from LED. Generally, the middle area of LED light is increased up to 380K. Therefore, the bottleneck between LED chip and heat sink are caused by high temperature. In this work, the adhesive material between LED Chip and heat sink was newly developed for improvement of bottleneck. The nanosilver was adopted to solve heat problem of chip on board package for LED light. In order to evaluate the performance of the nanosilver adhesive, the thermal analysis was performed. Moreover both adhesive performance and heat exhaust were verified through the prototype test. From the experimental test results, it is found that the developed nanosilver adhesive has the high performance.

Abstract: In this paper, the heat distribution for single chip high power LED package attached with varied heat sink fin shapes were analyzed through simulation. The main focus of this study was to scrutinize the fluctuation of junction temperature with different shapes of heat sink fin designs. The simulation was done using Ansys version 11. The single chip LED was loaded with input power of 0.5 W and 1 W . Simulation was done at ambient temperature of 25°C under three convection coefficient of 5, 10 and 15 W/m^2.oC respectively. The obtained results showed that the LED package with pyramid pin fin heat sink has demonstrated a better thermal performance compared to the LED package with cylindrical pin fin heat sink.

Abstract: This paper contains the results of research, carried out with financial support from the Ministry of Education and Science of the Russian Federation and dedicated to improving the energy efficiency of Moscow subway facilities and creation of stations with "zero" external sources heat consumption. The paper presents a method of simulation of the thermal conditions for subway tunnels, which allows, overcoming the difficulties associated with the informative uncertainty of baseline data, as well as difficulties associated with the approximation of the external parameters. Advantage of this method is the fact that the usage of so-called "base" experimentally obtained information about the natural soil thermal conditions in this model, can partially take into account the whole range of factors, which have significant influence on the formation of the thermal regime of the tunnel but are almost impossible to be taken into account within the strict formulation of the problem today.

Abstract: Thermal analysis of electronic equipment is becoming one of the primary aspects of many researches considering the trend line of reducing the size and increasing the speed. As the power of these systems increases and the space allotted to them decreases, heat flux or density becomes a critical factor in designing electronic equipment. The paper deals with thermal behavior of a particular heat sink designed for a VHF-UHF dual-band transceiver with a maximal power of 50 W. In this case, the electrical part generating this amount of power, is a MOSFET having a junction maximal temperature of 150 °C. A 3D CAD model was developed in proEngineer and finite element analyses were run in ANSYS in order to establish the best functioning conditions of the transceiver.

Abstract: A heat sink is a kind of heat exchanger that cools a device by dissipating heat into the environment. The design of heat sink by numerical simulation depends to a large extent upon boundary condition between the heat sink and its surroundings. The boundary condition is usually defined by Heat Transfer Coefficient (HTC) which can be used to measure heat resistance between heat sink and surrounding. Determination of HTC is a difficult problem, depending on many factors such as air velocity, material properties, shape of radiators and surface treatment, etc. A new simple reverse method has been suggested in the present work. The reverse method is suggested according to Mean-Value Theorem in mathematics. By comparing the temperature curves between simulation and real measurement, the temperature differences can be minimized by selecting different HTCs.

Abstract: 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.

Abstract: This paper presents theoretical and experimental works on the effect of heat transfer for a thermoelectric (TE) cooling system. The study focuses on thermal performance of the system through the optimisation of heat dissipation system for two prototypes that have aluminium and copper heat sink design, respectively. The study revealed that heat sink base area and fin height influenced thermal performance.

Abstract: Silicon is applied widely because of its good electrical properties, thermal conductivity and optical processing. It is necessary to fabricate a heat sink on silicon substrate to improve the heat dissipation ability for modern industrial application. There are many traditional methods of processing heat sink on silicon substrate. However, it is hardly to meet the requirements of today’s technology for the disadvantages such as residual stress exist, processing shape limited and inefficiency. The investigation on fabricating heat sink silicon substrate by direct later sintering was conducted in this study. By sintering a transition layer, coppery heat sink with channel width of several hundred micrometers and circinate shape has been fabricated by direct laser sintering. Furthermore, the bonding mechanism and the influence of the powder components on the interface morphology and structure have been investigated.

Abstract: Porous copper fabricated by unidirectional solidification of metal-gas eutectic can be used to manufacture a special kind of micro-channel heat sink. A three dimensional model is developed to investigate the heat transfer in porous copper heat sink. However the experimental results of heat transfer performance are far less than the simulation results. That is mainly because some of the pores are nonpenetrative. When the simulation model is modified by taking the penetration ratio into account the experimental results are consistent with the simulation results.

Abstract: Electromagnetic interference easily appears in the propulsive wheel - a key component of the mobile robots, because internal space of propulsive wheel is very small, there are numerous electronic devices, and signal communication is complex. So electromagnetic shielding is very important for the propulsive wheel. In this paper, a wheel model and an equivalent source model of electromagnetic interference of the wheel were developed based on considerations of the internal electromagnetic properties. At the same time, a secondary source of electromagnetic interference is formed by heat sink. Hence, shielding effectiveness is taken as one of the evaluation criteria for the Electro-Magnetic Compatibility (EMC) problem, and the Genetic Algorithm (GA) in the software Ansoft HFSS platform was used to optimize the first resonance frequency of heat sink.