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CFD analysis on a flat tube with semi-circular fins under laminar flow conditions was performed with graphene-based nanofluids considering the nanofluids as incompressible. Different simulations were performed at four different concentrations of nanofluids (0.01%, 0.1%, 0.2%, and 0.4%) and at different volume flow rates (4, 6, 8, and 10 LPM) and at four different forced convective heat transfer coefficients at different wind velocities at 300 K (50, 100, 150, and 200 W/m2 K). It was observed that with an increase in the concentration of nanoparticles in nanofluids, the thermal conductivity of base fluid water was increased (at 353 K the nanofluid of 0.4% volume concentration, the thermal conductivity of nanofluid increased by 200% with respect to base fluid). Graphene-based nanofluids have higher effectiveness than most nanofluids hence it is considered for the analysis, at 0.4% concentration of nanofluid the effectiveness observed was 36.84% at 4 LPM, and for water, the effectiveness was 28.22% under similar conditions. The effect of flow rate on temperature drop was significant. At 4 LPM and at 0.4% of nanofluid, an outlet coolant temperature of 333 K was observed whereas the water outlet temperature at 10 LPM is 346.13 K. The effect of forced convective air heat transfer coefficient was significantly high. At h = 50 W/m2 K the outlet temperature of 0.4% nanofluid at 4 LPM was 345.25 K and at h = 200 W/m2 K, the outlet coolant temperature was 333.47 K. A single tube of the radiator was considered for the analysis whereas the original radiator consists of 50 tubes due to problems of Ansys in meshing. 相似文献
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Experimental Investigation of Overall Heat Transfer Coefficient of Al2O3/Water–Mono Ethylene Glycol Nanofluids in an Automotive Radiator 
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下载免费PDF全文 In this research, the overall heat transfer coefficient of Al2O3/water–mono ethylene glycol (MEG) nanofluids is investigated experimentally in a car radiator under laminar flow conditions. The experimental rig developed is similar to the automotive cooling system. The stable nanofluid used is prepared by a two‐step method. Ultrasonication is done for proper dispersion of 20 nm Al2O3 nanoparticle in carrier fluid water and MEG mixture with 50:50 proportions by volume. The experimental study showed that use of a nanofluid enhances the overall heat transfer coefficient as compared to the base fluid. In this study as the nanoparticle volume fraction increases from 0% to 0.8%, the overall heat transfer coefficient also increases. It was observed that as the nanofluid inlet temperature increased from 65 °C to 85 °C, the overall heat transfer coefficient decreased. It was found that using a 0.2% volume fraction Al2O3/water–MEG nanofluid can enable a 36.69 % reduction in surface area of the radiator. 相似文献
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This research work discusses the heat transfer improvement in a tractor radiator with nanosized particles of CuO with water as base fluid. The nano materials and its suspension in fluids as particles have been the subject of intensive study worldwide recently since pioneering researchers recently discovered the anomalous thermal behavior of these fluids. The engine cooling in heavy vehicles is an important factor for their performance in the intended application. Here, the tractor engine radiator cooling is enhanced by the nanofluid mechanism of heat transfer for its improved performance in agricultural work. Through the improvement of tractor engine cooling through the radiator a greater area can be ploughed and cultivated within a short time span. Heat transfer in automobiles is achieved through radiators. In this research work an experimental and numerical investigation for the improved heat transfer characteristics of a radiator using CuO/water nanofluid for 0.025 and 0.05% volume fraction is done with an inlet temp of 50 °C to 60 °C under the turbulent flow regime (8000 ≤ Re ≤ 25000). The overall heat transfer coefficient decreases with an increase in nanofluid inlet temperature of 50 °C to 60°C. The experimental results of the heat transfer using the CuO nanofluid is compared with the numerical values. The results in this work suggest that the best heat transfer enhancement can be obtained compared with the base fluid by using a system with CuO/ water nanofluid‐cooled radiators. 相似文献
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M. Veera Krishna 《亚洲传热研究》2020,49(3):1374-1385
An attempt is made to investigate the steady magnetohydrodynamic convective flow of the viscous nanofluid due to a permeable exponentially stretching porous surface. Water is used as a traditional fluid while nanoparticles include copper and alumina. The fluid is electrically conducting, subject to an applied magnetic field with a constant strength. Convective type boundary conditions are employed in modeling the heat transfer process. The nonlinear partial differential equations governing the flow are reduced to an ordinary differential equation by similarity transformations and then solved using the Runge‐Kutta fourth‐order method. A parametric study of the physical parameters is made, and a representative set of numerical results for the velocity and temperature, as well as local shear stress and local Nusselt number, is presented graphically. Hartman number increase diminishes the velocity and has the contrary result in the subjective sense for the mass transfer parameter. An increase in the Prandtl number Pr lessens the temperature and thickness of the thermal boundary layer. The main conclusions have been indicated. 相似文献
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Usman Allauddin Rafay Mohiuddin Hafiz Mohammad Usman Khan Naseem Uddin Waqar A. Khan 《亚洲传热研究》2021,50(1):81-104
In the current numerical study, the thermal and flow field performance of an array of confined multiple jets with air, water, and water‐Al2O3 nanofluid in the maximum crossflow configuration over the target plate with and without pin fins is investigated. The numerical results are validated with the experimental data; it is found that a reasonable prediction related to heat transfer can be made. For this study, steady‐state Reynolds‐averaged Navier‐Stokes simulations with the shear‐stress transport turbulence model in ANSYS Fluent were performed. The simulations are performed with volumetric concentration to 3% and the jet's Reynolds number Re = 15 000 to 35 000. In all cases, the jet outlet‐to‐target plate distance is 3. It is found that the increase in values of the volumetric concentration of nanoparticles results in a decrease of the Nusselt number and an increase of the convective heat transfer coefficient. This is because there is an increase in thermal conductivity of the working fluid with the increase in the volumetric concentration of nanoparticles for the same Reynolds number. About 81.5% and 89.1% enhancement in the average heat transfer flux values is observed for flat and pin fin‐roughened target plates, respectively, for . 相似文献
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新型传热工质纳米流体的研究与应用 总被引：2，自引：0，他引：2
介绍了一种在强化传热领域具有广阔应用前景的新型传热（冷却）工质——纳米流体,分析了纳米流体的导热机理、导热性能以及影响其导热系数的各种因素,阐述了纳米流体对流换热性能的研究、纳米流体的制备及其稳定性和应用前景。 相似文献
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To investigate the heat transfer characteristics of a car radiator involved nanofluids, we used GAMBIT & FLUENT softwares and calculated the effective physical parameters using some famous models as a single‐phase mixture. Carbon nanotubes and boron nitride nanotubes have been used in less than 1% volume concentration in flat and twisted tubes. Our results show that nanofluids application in a twisted tube gives a great enhancement in the thermal performance in comparison of the flat tube. 相似文献
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The present study was aimed to utilize low‐cost alumina (Al2O3) nanoparticles for improving the heat transfer behavior in an intercooler of two‐stage air compressor. Experimental investigation was carried out with three different volume concentrations of 0.5%, 0.75%, and 1.0% Al2O3/water nanofluids to assess the performance of the intercooler, that is, counterflow heat exchanger at different loads. Thermal properties such as thermal conductivity and overall heat transfer coefficient of nanofluid increased substantially with increasing concentration of Al2O3 nanoparticles. Specific heat capacity of nanofluids were lower than base water. The intercooler performance parameters such as effectiveness and efficiency improved appreciably with the employment of nanofluid. The efficiency increased by about 6.1% with maximum concentration of nanofluid, that is, 1% at 3‐bar compressor load. It is concluded from the study that high concentration of Al2O3 nanoparticles dispersion in water would offer better heat transfer performance of the intercooler. 相似文献
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A possible way to enhance the rate of heat transfer in the spiral plate heat exchanger (SPHE) is by employing hybrid nanofluids as its working medium. Hence, in the present work, effects of hybrid nanofluids on the thermal performance of SPHE has been investigated numerically. First, a countercurrent SPHE is designed and modeled. Later, simulation of SPHE has been carried out by employing conventional fluid , nanofluids , and hybrid nanofluids to investigate the heat transfer rates. Finally, the performance of SPHE using hybrid nanofluid is compared with that of using water and nanofluids. The heat transfer augmentation of approximately 16%‐27% with hybrid nanofluids of overall 4% nanoparticles volume concentration and 10%‐16% with 2% nanoparticles volume concentration is observed when compared with that of pure water. Therefore, it can be inferred that the application of hybrid nanofluids in SPHE seems to be one of the promising solutions for augmentation of its thermal performance. 相似文献
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Atul Bhattad 《亚洲传热研究》2020,49(4):2344-2354
Exergy–energy analysis of the plate heat exchanger is experimentally performed with different Al2O3–MgO hybrid nanofluid (HyNf) as a hot fluid. There were six combinations of fluids, namely, deionized (DI) water, ethylene glycol–DI water brine (1:9 volume ratio), propylene glycol–DI water brine (1:9 volume ratio), base fluids and their respective Al2O3–MgO (4:1 particle volume ratio) HyNfs of 0.1% total volume concentration. The effects of different flow rates and hot inlet temperatures on the heat transfer rate, heat transfer coefficient, pump work, irreversibility, and performance index (PI) are investigated. It is witnessed that the heat transfer rate, heat transfer coefficient, pump work, and irreversibility enhances with the flow rate and nanoparticle suspension. While the PI declines with a rise in the flow rate, the heat transfer rate, heat transfer coefficient, PI, and irreversibility rise up maximum for MgO–alumina (1:4) DI water HyNf upto 11.8%, 31.7%, 11.1%, and 4.05%, respectively. The pump work enhances upto 1.6% for MgO–alumina (1:4)/EG–DI water (1:9) HyNf. 相似文献
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One of the main problems that limit the extensive use of photovoltaic (PV) systems is the increase in the temperature of PV panels. Overheating of a PV module decreases the performance of the output power by 0.4% to 0.5% per 1°C over its rated temperature that in most cases is 25°C. An effective way of improving electrical performance (power output and efficiency) and reducing the rate of thermal degradation of a PV module is to reduce the operating temperature of the PV surface by a cooling medium. To achieve this, nanofluids can be considered as a potentially effective solution for cooling. In this study, two types of nanofluids, namely Al2O3 and TiO2 water‐based mixture of different volume flow rates and concentrations (0.01%, 0.05%, and 0.1%) by weight, were used. Also, three PV panels were cooled simultaneously using nanofluids, water, and natural air, respectively. Results showed that nanofluids for cooling enhanced heat transfer rate much better than water and natural air. Best results were achieved for TiO2 nanofluids at the considered concentration (0.1 wt%). Nanofluid cooling of turbulent flows for such an application has not been investigated before. These results represent the first application of nanofluid cooling in the turbulent flow regimes and in outdoor conditions including real solar irradiation. 相似文献
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The parabolic trough collector is 1 of the most deployed solar concentrating collectors in the world. In this research, the commercially available LS‐2 collector has been modeled using the engineering equation solver. The developed model is validated using the experimental results of the Sandia National Laboratory, LS‐2 collector test. The study presents a comparison of the exergetic performance of 4 different absorber tube geometry configurations: conventional absorber tube, longitudinal finned tube, absorber tube with twisted tape insert, and converging‐diverging absorber tube. The system is analyzed to observe the nature of exergy losses and exergy destruction for the various design configurations with the use of Therminol VP‐1 and Al2O3‐Therminol VP‐1 nanofluids. The results show that the biggest cause of reduced useful work is because of the destructed exergy from the sun to the absorber. While the optical errors account for a higher percentage of exergy losses. The converging‐diverging absorber geometry produced the best exergetic enhancement of 0.65% with the use of Therminol VP‐1 and 0.73% with the use of Al2O3/Therminol VP‐1 nanofluid. 相似文献
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The buoyancy flow and heat transfer characteristics inside a solar collector having the flat‐plate cover and sinusoidal corrugated absorber are analyzed numerically. The water‐based nanofluid with alumina and copper nanoparticles is used as the working fluid inside the solar collector. The governing partial differential equations with proper boundary conditions are solved by the finite element method using Galerkin's weighted residual scheme. The behavior of both nanoparticles related to performance such as temperature and velocity distributions, radiative and convective heat transfers, mean temperature, and velocity of the nanofluid is investigated systematically. This performance includes the solid volume fraction, namely ?1 and ?2, with respect to Al 2 O 3 and Cu nanoparticles. The results show that the better performance of heat transfer inside the collector is found by using the highest ?2 than ?1. The result of this study expresses a good agreement with the theoretical result available in the literature. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res, 43(1): 61–79, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21061 相似文献
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采用计算流体力学的方法,研究了分别含Al2O3、Cu O、Si O2的3种纳米机油在纳米颗粒体积分数为1%、3%、5%时相对于传统机油的振荡传热能力和机油在油腔内流动的规律。结果表明,纳米颗粒的加入改变了流体的物性参数,纳米流体的传热效果比传统机油更好,且内冷油腔的传热系数随着纳米流体体积分数的增加而增加,但对内冷油腔内瞬态机油的瞬态分布和充油率的影响不大;纳米流体的黏度、密度、导热系数、比热容都能影响内冷油腔的传热性能,密度的增加会使流体对壁面的冲击作用更强,从而增强油腔的传热能力;在纳米颗粒体积分数为5%时CuO纳米机油的传热系数比Al2O3、SiO2纳米机油分别高8.2%和14.6%。 相似文献
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In recent years, developing an energy efficient conventional heat pipe is more important because of the development of electronics and computer industries. To enhance the thermal performance of heat pipe, different nanofluids have been widely used. In this paper, an experimental investigation of heat transfer performance of heat pipe has been conducted using three different working fluids such as DI water, CuO nanofluid and TiO2 nanofluid. The heat pipe used in this study is made up of copper layered with two layers of screen mesh wick for better capillary action. The Parameters considered in this study are heat input, angle of inclination and evaporator fill ratio. The concentration of nanoparticle used in this study is of 1.0 wt.%. From the experimental results, comparisons of thermal performance were made between the heat pipes using various working fluids. Among various fill ratio charged, the heat pipe shows good thermal performance when it is operated at 75% fill ratio for all working fluids. However, the heat pipe operated with CuO nanofluid showed higher results compared with TiO2 nanofluid and DI water. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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对使用三种水基纳米流体作为工质的铜丝平板热管的传热特性进行了实验研究.使用的纳米流体分别是平均粒径20 nm的Cu纳米颗粒、平均粒径50 nm的Cu纳米颗粒和平均粒径50 nm的CuO纳米颗粒的水基悬浮液(简称水基20 nm Cu、50 nm Cu、50 nm CuO纳米流体),着重分析了纳米流体种类,纳米颗粒质量分数、运行温度或工作压力对热管传热特性的影响.研究结果表明,使用纳米流体作为工质可以显著提高热管的传热特性;在不同运行温度条件下,不同的纳米流体均在质量分数1.0％时具有最佳传热效果;纳米流体是一种适用于铜丝平板热管的新型工质. 相似文献