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首页> 外文期刊>Clean air >EXPERIMENTAL INVESTIGATION OF THE EFFECT OF HEAT TRANSFER AND PRESSURE DROP ON PERFORMANCE OF A FLAT TUBE BY USING WATER-BASED A1_2O_3 NANOFLUIDS
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EXPERIMENTAL INVESTIGATION OF THE EFFECT OF HEAT TRANSFER AND PRESSURE DROP ON PERFORMANCE OF A FLAT TUBE BY USING WATER-BASED A1_2O_3 NANOFLUIDS

机译：水性A1_2O_3纳米流体对传热和压降对扁管性能影响的实验研究

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摘要

The aim of the present study was to experimentally investigate the heat transfer and pressure drop characteristics in a vertical flat tube with nanofluids. Aluminum oxide nanoparticles with average size of 20 nm were used to prepare the nanofluids of different volume fractions (0.1%, 0.2%, 0.3%, and 0.4%) without the use of any surfactant. The thermophysical properties, i.e., thermal conductivity, viscosity, and density over a wide range of temperatures (30°C–65°C) were measured experimentally. The thermal conductivity, viscosity, and density increased with the concentration of nanofluids. The heat transfer coefficient and pressure drop were estimated for different inlet temperatures of nanofluids (45°C–85°C) for the Reynolds number range 10,000–30,000, while the air velocity was kept constant at 0.55 m/s. During the experimentation, it was observed that the heat transfer coefficient and pressure drop increased with the Reynolds number and particle volume fraction. It was also observed that the heat transfer coefficient increased with the fluid inlet temperature because the viscosity and density of the fluid decreased at higher temperatures, while the pressure drop decreases slightly with increase in the fluid inlet temperatures. The heat transfer coefficient increased when the particle volume fraction was increased from 0.1% to 0.4% and maximum heat transfer coefficient was enhanced by 14% with the use of 0.4% v/v concentration of nanofluids at Reynolds number 30,000 and inlet temperature 85°C. The pressure drop ratio was 1.4 for 0.4% v/v concentrations of Al _( 2 ) O _( 3 ) nanoparticles.
机译：本研究的目的是通过实验研究具有纳米流体的垂直扁平管中的传热和压降特性。使用平均粒径为20 nm的氧化铝纳米粒子来制备不同体积分数（0.1％，0.2％，0.3％和0.4％）的纳米流体，而无需使用任何表面活性剂。实验测量了在宽温度范围（30°C–65°C）下的热物理性质，即热导率，粘度和密度。导热系数，粘度和密度随纳米流体的浓度而增加。对于雷诺数范围为10,000–30,000的纳米流体的不同入口温度（45°C–85°C），估计了传热系数和压降，而风速保持恒定在0.55 m / s。在实验过程中，观察到传热系数和压降随雷诺数和颗粒体积分数的增加而增加。还观察到，传热系数随着流体入口温度的增加而增加，这是因为在较高温度下流体的粘度和密度降低，而压力降随着流体入口温度的升高而略有下降。当使用雷诺数30,000和入口温度85°C的0.4％v / v浓度的纳米流体时，当颗粒体积分数从0.1％增加到0.4％时，传热系数增加，最大传热系数增加14％。 。对于0.4％v / v的Al _（2）O_（3）纳米粒子，压降比为1.4。

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