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1.
针对室外电子设备在自然对流条件下的散热问题,设计开发了一种新型散热器翅片结构——翅片开孔式涡流发生器,易于加工且直接与翅片连接,不存在焊接的问题。利用数值模拟的方法探究了涡流发生器的布置方式与攻角对散热器散热的影响。结果表明:翅片开设三角孔,在翅片间空气流动过程中起到了明显的作用,有效降低了三角形涡流发生器造成的流动阻力,增加了空气的扰动;当涡流发生器间距为40 mm、攻角为15°时,散热器翅片高温热源区域的散热效果最好。  相似文献   

2.
铜管乐器吹奏过程中演奏者吹出的湿热气流会使管内空气和铜管本身的温度升高,导致乐器音准偏离。本文提出了对铜管乐器发声前段采用增加散热翅片的方法,增加有效换热面积,即时散发出热量,可改善铜管乐器音准的偏离。根据散热目标要求,设计出了合理的翅片结构参数,并借助FLUENT软件进行了散热效果的数值模拟。结果表明,当环境温度为12℃时,相同条件下加装散热翅片的铜管乐器外表面与环境的温差缩小为原温差的34.2%,散热效果明显,乐器音准得到保证。  相似文献   

3.
针对一款典型的UV-LED风冷翅片热管散热系统,建立了从LED阵列到散热器末端的热阻网络,应用MATLAB模拟了翅片热管散热器在设计工况和变工况下各点温度的瞬态变化性能,并选取部分点进行了实验测试。结果显示,该风冷翅片热管散热器具有较好的瞬态传热性能,其最大温差在散热器铜板处;瞬态温度响应具有滞后性;LED散热量突然急剧变化时,对芯片部分的影响较大,而环境温度或者外部的对流散热状况在短时间内的波动则对LED几乎没有影响。  相似文献   

4.
利用数值模拟的方法,探究了烟囱效应对通信基站热沉自然对流散热的强化作用,对影响热沉散热性能的主要因素及其机理进行了分析,并以热沉热阻作为优化目标,通过优化翅片间距与隔板间隙的取值提升了热沉的散热性能。在优化设计过程中,通过模糊均值聚类对拉丁超立方抽样所得的样本点进行筛选,快速并有效的缩减了设计区间,使用Kriging模型对新设计区间内的均匀样本点进行拟合,构建了热沉热阻与设计变量间的代理模型,并结合遗传算法寻优,确定了最优设计参数取值。在最优参数布置下,相比于初始热沉,热沉的发热面温度降低了15.23 K,总热阻降低了34.29%。  相似文献   

5.
聚光光伏等的快速发展都会面临散热问题,本文对翅片散热装置的散热特性作了相关分析。基于Fluent数值模拟软件,对矩形片状翅片散热器在定温加热、自然对流条件下的温度分布和速度分布进行了模拟;在温差50℃≥ΔT≥100℃、翅片高度140 mm≥H≥60 mm、翅片间距14 mm≥S≥6 mm范围内对翅片尺寸优化,得出翅片表面平均对流换热系数的变化趋势。结果表明,50~100℃内温差越大,对流换热系数越大;H取100 mm时,散热量最大,较H=80 mm时提高了32.15%;S取12 mm时散热量最大,较S=10 mm时提高了27.44%。  相似文献   

6.
利用数值模拟的方法对履带车用锯齿型翅片散热器的翅片间距和翅片切口长度进行结构优选,引入了同功耗强化传热评价指标(performance evaluation criteria,PEC),对比了不同翅片间距和翅片切口长度的散热性能。研究结果表明:翅片间距和翅片切口长度分别为2mm和4mm时,翅片的综合性能最优。根据数值计算结果研制散热器样件,利用风洞试验台对翅片切口长度为4mm,翅片间距分别为1.5、2.0和2.5mm试验样件进行测试,试验结果与仿真结果较一致,误差在10%以内。通过试验数据拟合出适用于三种翅片间距锯齿形传热器在试验的雷诺数范围内的传热和阻力性能关联式,并分析了水侧流速对空气侧传热性能的影响。  相似文献   

7.
采用数值计算方法对一种应用于半导体制冷片热端散热的翅片式热管散热器进行模拟,探究自然对流条件下不同翅片参数对散热器换热特性的影响。结合多目标遗传算法(NSGA-Ⅱ),以影响散热器散热的两个主要参数——翅片表面传热系数和肋面效率为优化目标,对散热器整体做出综合优化,并对优化结果进行K均值聚类分析,提出了翅片端优化原则。结果表明,肋面效率对散热器性能的影响有限,提高表面传热系数可显著降低散热器总热阻;与未优化方案相比,所选优化方案可使基板热端面温度下降3.5K,散热器热阻降低18.22%。  相似文献   

8.
液冷板冷却技术是解决高功率芯片热管理问题最有前途的技术之一,带翅片结构的液冷板具有低流阻、低热阻的优势,因而受到广泛关注。目前翅片结构多以实心为主,空心交错翅片对液冷板散热能力和压降等冷却特性的影响尚未得到系统的研究。对此,设计了空心交错翅片液冷板,采用数值模拟的方法研究进口温度和流量对液冷板流动换热特性的影响。模拟结果表明,空心翅片式液冷板具有良好的散热性能,随着进口温度的升高,液冷板温度不均匀性逐渐降低,但降低趋势有所减缓,而流量的增大对降低平均热阻有显著的作用,当进口流量超过1.2 L/min时,液冷板的平均热阻可低于0.04℃/W;然而,流量的增大也提高了流动阻力,当流量增大至1.7 L/min时,流体出口区域形成涡旋,产生回流区,不利于液冷板的散热效果,且流动阻力增大。  相似文献   

9.
以硅太阳能电池为研究对象,利用ANSYS建立三维电池模型,对其温度和结构进行了耦合仿真,模拟分析了未加装铝翅片和加装铝翅片的两种硅太阳能电池的温度和热应力分布。编制Matlab程序,采用迭代法对光热参数进行迭代求解,得到了转换为热量的太阳辐射值作为初始条件。研究结果表明,加装铝翅片的硅太阳能电池取得了较好的散热效果,能降低热应力,提高太阳能电池板的使用寿命。  相似文献   

10.
为研究等截面一维直翅优化问题,从Schmidt最优翅片形状假定出发,通过理论分析得到一种优化的直翅周线表达式,并找出了优化后的翅片散热效率与其几何外形之间的关系。在优化后的直翅精确解基础上,针对实际工程设计中,在散热效率与精确解偏差不大于0.12%的情况下,进一步推导出翅片所能采用的近似周线方程,为等截面直翅的工程优化设计和应用提供了依据。  相似文献   

11.
The high energy consumption in buildings in Mediterranean countries, especially in the spring and summer months due to the extensive use of air conditioning, requires immediate actions to minimise energy costs and environmental impact given the current energy crisis. Solar cooling systems offer an attractive solution, but the main drawbacks of this type of systems are the low efficiency of the currently used single-effect absorption chillers and the large areas of thermal collectors needed to produce the thermal energy. These large solar installations make difficult their building integration. A way to overcome these difficulties is the use of high efficient integrated solar concentrator systems able to achieve temperatures around 150 °C that could be used to activate the more energy efficient double-effect absorption chillers. In the frame of this concept, in the present work a comparison between two cooling systems for a specific three-floor building, with and without solar concentration, is performed. The first is a conventional system which consists of evacuated tube collectors feeding a single-effect absorption chiller. On the other hand, a Fresnel reflective solar concentrating system, integrated on the building façade, is coupled to a double-effect absorption chiller. The results show an important reduction of the solar collectors absorber area in the concentrating system compared with the standard solar thermal installation. However, the solar concentrating system requires a large aperture area. In addition, the rejected heat in the double-effect chiller is lower, implying that the investment and operation costs of the solar concentrating cooling system can be reduced significantly.  相似文献   

12.
A solar/gas cooling plant at the Engineering School of Seville (Spain) was tested during the period 2008-2009. The system is composed of a double-effect LiBr + water absorption chiller of 174 kW nominal cooling capacity, powered by: (1) a pressurized hot water flow delivered by mean of a 352 m2 solar field of a linear concentrating Fresnel collector and (2) a direct-fired natural gas burner. The objective of the project is to indentify design improvements for future plants and to serve as a guideline. We focused our attention on the solar collector size and dirtiness, climatology, piping heat losses, operation control and coupling between solar collector and chiller. The daily average Fresnel collector efficiency was 0.35 with a maximum of 0.4. The absorption chiller operated with a daily average coefficient of performance of 1.1-1.25, where the solar energy represented the 75% of generator’s total heat input, and the solar cooling ratio (quotient between useful cooling and insolation incident on the solar field) was 0.44.  相似文献   

13.
聚光型太阳能光伏光热系统(CPV/T)在传统光伏发电系统的基础上增加了聚光系统和光热系统,在通过聚光系统提高光伏效率的同时将系统中多余的热量加以利用,以达到太阳能最大化利用的目的。本文介绍了CPV/T系统的工作原理及其能效影响因素,以直接影响系统太阳能综合利用效率的聚光器技术、光伏电池技术和光伏冷却技术作为分析对象,结合近几年国内外最新研究成果比较了不同类型聚光器、光伏电池以及冷却方式的优劣,列举了常见的光伏余热利用方式。分析认为:CPV/T系统虽然具有更高的太阳能利用率,但应加大对系统尤其是聚光器经济性的分析;考虑在系统中应用叠层光伏电池缓解聚光器带来的系统体积过大问题;新电池开发过程中应更注意光伏电池的温度系数以减少冷却系统的压力,冷却技术在强化散热的同时也应注意热量的收集方法及其与利用途径的有效结合。  相似文献   

14.
One problem in concentrating photovoltaic systems without active cooling is the formation of hot spots on the solar module cells. These hot spots are a result of uneven concentration of radiation within the solar module cells. The overall effect of concentrated heating is the reduction in the fill-factor of the solar module cell and the subsequent decrease in the overall efficiency of the system. In this paper, we investigate one alternative of improving the performance of a low concentrating photovoltaic system using semi-diffuse rolled reflective elements. Our results indicate that rolling marks on the reflector aligned parallel to the plane of the solar module cell improve the performance of the photovoltaic system.  相似文献   

15.
根据上海的气候条件,以上海地区某写字楼为对象,提出4种太阳能驱动的溴化锂吸收式与电动蒸汽压缩式热泵联合制冷与供暖系统。这4种系统分别由热管式真空管集热器或抛物面槽形聚光集热器,单效或双效溴化锂吸收式制冷机,以及风冷热泵或水源热泵构成。分析比较这4种系统的节能型和经济性的结果表明,采用抛物面槽形聚光集热器+双效溴化锂吸收式制冷机+风冷热泵组成的系统,同时具备较好的节能性与经济性,一次能源利用率可降低约50%。  相似文献   

16.
In Mexico efforts are being made to promote the use of solar energy for cooling in the Agro-Food Industries (AFI), 120 industries were contacted in order to assess the solar cooling potential application in the sector. One case study was selected among the visited potential end users according to the size of the facility, the information available and their willingness to collaborate in the present project. Data from the industry was used to select the appropriate solar cooling concept and therefore the collector’s typology, and the absorption cooling system. Moreover, the operation of the system was simulated in order to define the optimal size of the collector field required. The proposed cooling system was composed by a Fresnel concentrating collector field to activate a series of air cooled single-effect ammonia–water absorption chillers. The cooling system simulation was carried out with the Transient Systems Simulation Programme (TRNSYS) which allowed to model the collector system that fulfill the required load. The calculated saved electricity was around 19% of the total consumption, this small fraction is due to the fact that the selected facility is operating continuously with very large refrigeration capacities. The specifications of the simulated solar cooling system are presented.  相似文献   

17.
设计并搭建了CPC低倍聚光太阳能PV/T单通道空气系统实验台,对不同工作环境下聚光PV/T系统的热电性能进行了实验研究。实验研究结果显示:在聚光条件下,系统的各表面温度随光照强度的增加而升高,随下部通道入口空气流速的增加而降低。聚光PV/T系统的最大输出功率可达到60W,比对应相同电池面积平板系统最大输出功率高20W。聚光PV/T系统的各效率随光照强度增加而增大,系统的最大电效率为11%,最大热效率为70%,最大火用效率为16%,比单纯发电时最大火用效率提高约5%。实验获得了一批新的有价值的实验数据,为聚光太阳能光伏光热系统的进一步研究提供了依据。  相似文献   

18.
The numerical study of solar cell temperature for concentrating PV with concentration ratio of 10× is presented in this paper. A two dimensional thermal model has been developed to predict the temperature for PV concentrator system (solar cell and lens) with and without passive cooling arrangements. Based on a thermal model, the result shows that maximum of four numbers of uniform fins of 5 mm height and 1 mm thickness can be effectively used to reduce the solar cell temperature. In addition to that, the effects of ambient temperature and solar radiation intensity on the solar cell temperature have also been investigated for the system with and without cooling fins. Based on the influencing parameters of ambient temperature and solar radiation, two separate solar cell temperature correlations has been proposed for systems with and without cooling fins to predict the cell temperature for the range of given parameters. In our previous studies, the present 2-D model was extensively validated with a comprehensive unified model [8], [9] and [10].  相似文献   

19.
As solar heating systems become a commercial reality, greater efforts are now being employed to incorporate solar cooling components in order to obtain a complete solar heating and cooling system and thus take advantage of the cost-effectiveness of year-round use of the solar equipment. Because of the exceptional performance and high efficiency of evacuated tube solar collectors, these advanced collectors are receiving considerable attention for use in solar heating and cooling systems. While improved performance is readily obtained with these sophisticated solar collectors, there are also numerous difficulties and problems associated with their use in a solar system. This paper addresses many of the design considerations which must be included in any realistic solar system design. Most of the considerations presented here are based on the experience gained in the design and performance of the solar heating and cooling systems for CSU Solar Houses I-IV.  相似文献   

20.
On a European level there is intense research activity to broaden the applications of solar thermal systems beyond their established domains (hot water, space heating support) and to foster their participation in the energy maps of the EU-Member States. Concentrated Solar Thermal (CST) systems are expected to play a key role in this effort, especially for achieving the medium and high temperatures needed, for electricity generation, for industrial applications but also for hybridized solar heating/cooling and desalination applications.This paper presents a proposal for implementation of a CST system in the building sector, based on a research carried out in the Laboratory of Environmental and Energy Efficient Design of Buildings and Settlements at the University of Thrace. Specifically, an integrated solar cooling system using parabolic trough solar collectors and double-effect chiller is discussed, used to cover the cooling needs of typical office building in Greece.As it was shown, the use of concentrating solar collectors leads to significantly higher output temperatures that can enable the use of two stage absorption chillers with a higher COP. Alternatively, when low or medium temperature heat is required, the use of CST systems takes less space to cope with it than traditional flat plate collectors. The combination of these parameters can contribute to removing key barriers associated with the broader diffusion of solar cooling technology, enhancing the potential to become more competitive to the conventional air conditioning technologies.  相似文献   

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