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将淋水填料与盘管组合,并采用横流塔结构,构成密闭式冷却塔,成为当前闭式塔的主流塔型.塔的设计计算方法目前均基于特定填料和盘管形式的试验结果,没有通用性.本文在结合开放横流式冷却塔与蒸发冷却器的热力计算方法的基础上,针对上述塔型,提出了一种着眼于换热机理研究和性能改进的热力计算方法及相应的实验方法. 相似文献
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太阳能增强型自然通风冷却塔(SENDDCT)作为一种新型空气冷却系统,可利用太阳能提高自然通风冷却塔的效率。利用FLUENT软件建立太阳能增强型冷却塔的三维模型,研究太阳辐射强度和环境温度对其性能的影响;同时设计并搭建太阳能增强型冷却塔的实验系统,在实际天气条件下研究太阳辐射强度对其换热性能的影响。模拟结果表明太阳辐射强度一定时,通过换热器的空气流速以及换热率都会随着环境温度升高而降低。太阳辐射强度为500 W时,环境温度由10℃升到40℃,换热率由1.106 kW下降到0.281 kW。实验结果表明有辐射时冷却塔入口处的平均空气温度要比无辐射时的高5℃;实验期间无辐射时的平均换热率为0.682 kW,有辐射时的平均换热率为0.794 kW,即利用太阳能将平均换热率提高了0.112 kW。 相似文献
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为进一步提高管壳式换热器壳程换热效率,设计了一种布置于壳程肋片上的仿生鸟喙式涡流发生器。采用ANSYS FLUENT软件结合田口正交试验模拟了矩形通道中鸟喙式涡流发生器的传热特性,分析了纵向高度、斜截角度、迎流攻角、入口距离、流向间距5种结构参数对强化传热和综合热性能的贡献率及最佳结构组合。流动通道为长方体,其长、宽、高分别为1 600,240和40 mm,温度为286.86 K的空气流体从入口以1.491~3.195 m/s的速度流入,通道底部为337.048 K的恒温换热面。结果表明:纵向高度对于强化换热特性的贡献率最高,达到4744%,最强换热效果组合的换热因子较空矩形通道提高了185.71%;迎流攻角对于综合热性能的贡献率最高,达到了总占比的31.35%,利用正交试验分析得到的最强组合较空通道的综合热性能提高了47.82% 相似文献
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The present work is focused on the computational analysis of heat and mass transfer in an indirect contact cooling tower. The main objectives of the study are to contribute to the understanding of heat and mass transfer mechanisms involved in the problem and to check the possibility of making use of a commercial computational fluid dynamics (CFD) code for simulating mass and heat transfer phenomena occurring in indirect cooling towers. The CFD model uses as boundary conditions the temperatures of the tubes obtained by a correlation model developed by Mizushina. The available mass transfer correlations for indirect cooling towers are presented and compared with a correlation obtained from CFD simulations. The assumption of analogy between heat and mass transfer is also discussed. 相似文献
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Jose A. Sirena 《传热工程》2013,34(6):68-74
Abstract A simple theoretical expression has been developed to relate the number of diffusion units involved in thermal processes controlled by mass transfer with the pressure loss in associated convection or forced air flows. The expression allows the analytical evaluation of a previously defined thermo-fluid dynamic parameter as a function of the liquid/gas ratio in cooling towers. It has been found that experimental data, obtained from different commercial cooling tower fills, behave in a similar way to the calculated theoretical values. A thermo-fluid dynamic efficiency has also been derived that is useful for the quantitative qualification of cooling towers, cooling tower fills, and heat transfer processes in which the mass transfer prevails. 相似文献
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JOHN R. THOME 《传热工程》2013,34(4):36-37
Abstract A prototype cooling tower was used to explore the potential of using cooling towers compared with radiator cooling systems with 3 MW diesel engines. The working parameters were the water mass flow rate, water inlet temperature, air mass flow rate, and humidity ratio. The water mass flow rate was relatively the most effective. Three methods of calculation were used to evaluate performance—namely, heat and mass balance, psychrometric chart, and the heat and mass transfer method. The first was the best in comparison with experiments. The economic analysis of both the cooling tower and radiator systems showed that it would be more economical in the long run to use cooling towers for diesel engines. 相似文献
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Giorgia F. Cortinovis Marcelo T. Ribeiro José L. Paiva Tah W. Song José M. Pinto 《Applied Thermal Engineering》2009,29(14-15):3124-3131
Cooling towers are widely used in many industrial and utility plants as a cooling medium, whose thermal performance is of vital importance. Despite the wide interest in cooling tower design, rating and its importance in energy conservation, there are few investigations concerning the integrated analysis of cooling systems. This work presents an approach for the systemic performance analysis of a cooling water system. The approach combines experimental design with mathematical modeling. An experimental investigation was carried out to characterize the mass transfer in the packing of the cooling tower as a function of the liquid and gas flow rates, whose results were within the range of the measurement accuracy. Then, an integrated model was developed that relies on the mass and heat transfer of the cooling tower, as well as on the hydraulic and thermal interactions with a heat exchanger network. The integrated model for the cooling water system was simulated and the temperature results agree with the experimental data of the real operation of the pilot plant. A case study illustrates the interaction in the system and the need for a systemic analysis of cooling water system. The proposed mathematical and experimental analysis should be useful for performance analysis of real-world cooling water systems. 相似文献
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Hongmin Li 《International Journal of Heat and Mass Transfer》2010,53(4):797-810
This paper presents a thermal fluid analysis on the air cooling of a permanent magnet electric motor with a centrifugal impeller. A numerical model is developed for the heat transfer and fluid flow process. The flow rates of the cooling air are also experimentally measured. The agreement between the numerical model prediction and experimental data is reasonably good. Detailed structures of the cooling flow are presented. Convection heat transfer on the surface of the armature is quantified. Comments on the application of the motor architecture are given. Design modifications are proposed for performance improvements. 相似文献
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This paper presents the study of the flow structure and heat transfer, and also their correlations on the four walls of a radial cooling passage model of a gas turbine blade. The investigations focus on heat transfer and aerodynamic measurements in the channel, which is an accurate representation of the configuration used in aeroengines. Correlations for the heat transfer coefficient and the pressure drop used in the design of radial cooling passages are often developed from simplified models. It is important to note that real engine passages do not have perfect rectangular cross sections, but include corner fillet, ribs with fillet radii and special orientation. Therefore, this work provides detailed fluid flow and heat transfer data for a model of radial cooling geometry which possesses very realistic features. 相似文献
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Wind towers for passive evaporative cooling offer real opportunity for improving the ambient comfort conditions in building whilst reducing the energy consumption of air-conditioning systems.This study aims at assessing the thermal performance of a bioclimatic housing using wind towers realized in a hot dry region of Algeria. Performance monitoring and site measurement of the system provide data which assist model validation. The analysis and site measurement are encouraging, and they confirm the advantage of the application of this passive cooling strategies in hot dry climate.A mathematical model is developed using heat and mass transfer balances. For a more effective evaporative cooling, a number of improvements on wind tower configurations are proposed. 相似文献
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This paper presents the study of the influence of channel geometry on the flow structure and heat transfer,and also their correlations on all the walls of a radial cooling passage model of a gas turbine blade.The investigations focus on the heat transfer and aerodynamic measurements in the channel,which is an accurate representation of the configuration used in aeroengines.Correlations for the heat transfer coefficient and the pressure drop used in the design of internal cooling passages are often developed from simplified models.It is important to note that real engine passages do not have perfect rectangular cross sections,but include a comer fillets,ribs with fillet radii and a special orientation.Therefore,this work provides detailed fluid flow and heat transfer data for a model of radial cooling geometry which has very realistic features. 相似文献
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在济钢中板厂ACC现场采集数据并进行统计,借助MATLAB平台,对影响ACC水冷模型中的换热系数进行了回归分析,建立了水冷换热系数模型。研究表明,利用MATLAB进行二元线性回归得到的水冷换热系数模型与现场实测数据吻合程度高,此模型可为中板厂ACC现场生产提供理论参考。 相似文献