Papers by Keyword: Heat Sink

Abstract: Aluminium alloys is widely applied in heat sink but its application of heat absorption is still unsatisfied. While, Aluminum Nitride (AIN) was discovered as another option for heat sink application because of its great thermal conductivity and it also has high electrical conductivity at high temperature. Thus, the mechanical and chemical properties of a sintered mixed powder of Alumina and AIN are investigated experimentally. There are five different compositions of mixed powder of Alumina-AIN and sintered at three different sintering temperatures which are 1400°C, 1500°C and 1600°C. As applying a high sintering temperature on samples inducted great flexural strength and increase it modulus of rupture. High sintering temperature (1600°C) also affected the materials microstructure as the particle was arranged closely between each other and reduces the amount of porosity. The application of high temperature in the mixture of AIN with Alumina reduces the occurrence of flaws like cracking and accordingly improves the strength. These combination of Alumina-AIN brought acceptable result in thermal conductivity value analysis and as well enhancing the thermal conductivity.

Abstract: Most of the LED Stage Lighting lamps use LED arrays or LED chips, while gathered chips require faster heat dissipation. If LED temperature gets too high, it will inevitably lead to its optical, electrical and color performance change, and will seriously affect LED working performance and its life. This paper mainly discussed LED Stage Lighting lamp heat dissipation, using the finite element method to analyze the LED temperature field. Then we used ANSYS Workbench to simulate the field and optimize its dissipating performance, and finally designed a LED radiator. Results showed that after the optimization, it had solved the heat accumulation problem of LED lamp, reduced the center temperature of LED effectively, keeping LED work in a proper temperature range.

Abstract: Nanofluid is the suspension of nanoparticle in a base fluid. In this paper, the heat transfer performances of the nanofluids flow through a circular shaped copper minichannel heat sink are discussed analytically. Al₂O₃-water, CuO-water, Cu-water and Ag-water nanofluids were used in this analysis to make comparative study of their thermal performances. The hydraulic diameter of the minichannel is 500 μm and total block dimension is 50mm× 50mm× 4mm. The analysis is done at different volume fractions of the nanoparticle ranging from 0.5 vol.% to 4 vol.%. The results showed that the heat transfer performance increases significantly by the increasing of volume fraction of nanoparticle. Ag-water nanofluid shows the highest performance compared to the other nanofluids. So, this nanofluid can be recommended as a coolant flow through a circular minichannel for cooling of electronic heat sink.

Abstract: Thermal design improvements of avionic devices in confined space under supersonic conditions are presented in this paper through a numerical studies and improvements on the heat sinks and cooling vents. The components locations are also rearranged. Thus the avionic device can operate in the confined space, and heat dissipation can be easier. Simulation results show that the cooling vents added on the surfaces of the electronic cabinet can make heat exchange more smoothly, and the high temperature zones are affected by the changing of the locations of heat sinks obviously. The design rules and guidelines are proposed to improve thermal design. The design and simulation results can be used as the reference for the thermal design of other avionic devices in the similar style.

Abstract: With the increase of performance demands, the nonuniformity of on-chip power dissipation becomes greater, causing localized high heat flux hot spots that can degrade the processor performance and reliability. In this paper, a three-dimensional model of the copper microchannel heat sink, with hot spot heating and background heating on the back, was developed and used for numerical simulation to predict the hot spot cooling performance. The hot spot is cooled by localized cross channels. The pressure drop, thermal resistance and effects of hot spot heat flux and fluid flow velocity on the cooling of on-chip hot spots, are investigated in detail.

Abstract: Recently, demand of aluminum alloys for manufacturing in components with high thermal conductivity application increases. However, the most aluminum die casting alloys exhibit very lower thermal properties, about only a half of pure aluminum. In die casting alloys, alloying elements are essential to obtain sufficient fluidity and mechanical strength, therefore, in this study, the effect of alloying elements, Si, Cu, Mg, Fe and Mn, on thermal conductivity, die casting characteristics and mechanical properties were analyzed and the appropriate amount of each alloying element were investigated. The results showed that Mn had the most deleterious effect in thermal conductivity and Si and Fe contents were important to improve fluidity and strength. The alloy with 1.5~2.0wt.%Si and 0.6wt.%Fe showed very good combination of high thermal conductivity and sufficient casting characteristics.

Abstract: Laser cooling is one of the critical problems in the research of high power semiconductor lasers. This paper provides an overview of microchannel heat sink which is used to cool the high power semiconductor lasers. The method of polishing after cutting is the current processing method of the heat sink, which is because the ordinary cutting method cannot meet the requirements of high quality of surface and edge burrs. This paper proposes ultra-precision fly cutting method for heat sink machining to omit the polishing processing to improve the machining efficiency, and verifies by experiments that the feasibility of the processing method and the edge quality improved by workpiece superposition processing method.

Abstract: A temperature regulation control for LED(Light Emitting Diode) lamp using a cooling fan was studied. An efficient temperature regulation scheme using fan wind at the lowest sound noise was studied. For the study, after measurement of the minimum sound noise of the fan and related temperature of the LED lamp through tests, experiments on temperature control of the LED lamp using the fan with various size of heat sinks was performed. Also, characteristics and relationship of heat sinks and fans are studied through experiments. To reduce the fan sound noise, a method of reducing the operation time with optimal size of the heat sink was studied.

Abstract: Thermoelectric energy harvesting is emerging as a promising alternative energy source to drive wireless sensors in mechanical, civil, and aerospace engineering systems. Typically, the waste heat from spindle units of machine tools creates obvious potential for thermoelectric generation. The structure of heat sinks on a thermoelectric generator has a great effect on the output voltage of the thermoelectric generator due to the temperature difference between hot and cold sides induced by heat transfer, so several typical structures of heat sinks are studied under different rotation speed of the spindle. According to the simulation study, the thermal resistance of heat sinks was presented. In the experiment, the output voltages of a thermoelectric generator were measured under different rotation speed with different structures of heat sinks. Experiment and simulation shows that the two pipes structure of the heat sink can help the generator to produce more power.

Abstract: Based on the forward voltage measurement principle, a test device was designed for junction temperature measurement. The voltage temperature coefficient is-1.49mV/°C according to the experimental data, and a series of junction temperatures were obtained on various ambient temperature. A numerical model was built by using the CFD software Flent, which was verified with the experimental data. The influence of the different structure parameters of the heat sink on heat dissipation performance was studied numerically. The results show that the optimal structure parameters were as following: Fin number is within 8~12. Fin height is within 170mm~190mm. Fin length is within 35mm~55mm. Fin thickness is within 1mm~3mm. Bases radius is within 33mm~40mm. With the chip junction temperature and the radiator weight as optimizing object, the optimal parameters were obtained as following: Fin number is 12. Fin height is 190mm. Fin length is 55mm. Fin thickness is 1.5mm. Bases radius is 33 mm.