Investigations for effect of Al2O3–H2O nanofluid flow rate on the efficiency of direct absorption solar collector

Gupta, Hemant; Agrawal, Ghanshyam Das; Mathur, Jyotirmay

doi:10.1016/j.csite.2015.01.002

Cited by 131 publications

(39 citation statements)

References 28 publications

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“…As a result, the temperature distribution inside the solar collector becomes relatively uniform, leading to less heat loss from the collector surface and improved thermal efficiency [6,7]. Nanofluids has been studied intensively for direct absorption solar collectors (DASCs) in low-temperature applications [8][9][10][11][12][13][14][15][16][17][18]. In addition, the optical property of various nanofluids have also been studied intensively to improve its photothermal conversion efficiency [19][20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Performance analysis of a direct-absorption parabolic-trough solar collector using plasmonic nanofluids

2019

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A parabolic trough solar collector is a dominant technology for high-temperature industrial applications, but efficient use of a conventional surface-based parabolic trough solar collector (SBPTSC) is limited by its high radiation loss due to the high surface temperature. Recently, direct-absorption parabolic trough solar collector (DAPTSC) using nanofluids has been proposed, and its thermal efficiency has been reported to be 5-10% higher than the conventional SBPTSC for inlet temperature up to 250 • C. However, the inner tubes of the receivers of the existing DAPTSCs are all transparent, so the sun rays entering the inner tube can only travel once through the nanofluids. As a result, the optical path length for the sun rays is limited by the inner tube size, which in turn requires high value of the absorption coefficient of nanofluids. Due to the approximately linear relation between the absorption coefficient and the particle concentration, higher absorption coefficient is likely to cause particle agglomeration, leading to detrimental effects on maintaining stable collector performance. In the current study, the transparent DAPTSC is improved by applying a reflective coating on the upper half of the inner tube outer surface, such that the optical path length is doubled compared to the transparent DAPTSC; thus, the absorption coefficient of the nanofluids can be reduced accordingly. The coated DAPTSC is found to have obvious advantage compared to the transparent DAPTSC at absorption coefficient below 0.5 cm −1 for a receiver with inner tube diameter of 7 cm. In addition, performance of the transparent DAPTSC, the coated DAPTSC and the SBPTSC with black chrome coating have been compared to explore their advantageous operation conditions, such as inner tube diameter, flow rate, and inlet temperature, with or without a glass envelope for vacuum evacuation. The findings in this study will facilitate the use of nanofluids in a parabolic trough solar collector with more stability and provide a guide for choosing suitable type of parabolic trough solar collectors for specific working conditions.

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Section: Introductionmentioning

confidence: 99%

Performance analysis of a direct-absorption parabolic-trough solar collector using plasmonic nanofluids

2019

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“…The application of nanofluids in low‐temperature DASCs has been the focus of various experimental and theoretical/numerical studies . A comprehensive review of the subject is found in .…”

Section: Introductionmentioning

confidence: 99%

Performance enhancement of a direct absorption solar collector using copper oxide porous foam and nanofluid

Esmaeili

Karami

Delfani³

2020

Int J Energy Res

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The current research proposes the idea of using water-saturated metal oxide foams and water-based nanofluids as solar absorber in the direct absorption solar collectors (DASCs). Specifically, the novel solar collector design utilizes copper oxide (CuO) porous foam and nanoparticle with high optical properties and is expected to have enhanced thermal performance than the conventional collectors utilizing pure water. The finite volume technique is used to solve the governing equations of flow and heat transfer in the radiative participating media. Also, to establish the reliability and accuracy of numerical solutions, the obtained results are compared with the corresponding numerical and experimental data. The computations are carried out for different nanoparticle volume fractions, foam pore sizes, working fluid mass flow rates, and both porous layer thicknesses and positions (inserted at the lower or upper wall of the collector). It is found that the efficiency of DASC partially/fully filled with metal oxide foam is maximized when the collector is completely filled with it. Compared with the water flow, the numerical results show that the collector efficiency using CuO nanofluid and metal oxide foam is improved by up to 26.8% and 23.8%, respectively. Moreover, considering the second law of thermodynamics, the use of CuO nanofluids in the DASC seems to be more effective than the use of CuO porous foam. K E Y W O R D Sdirect absorption solar collector, efficiency, metal oxide foam, nanofluid, second law of thermodynamics

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“…Though multiwalled carbon nanotubes (MWCNT) showed better heat transfer rate of about 20% for a 0.1% concentration, the research also exposed problems with nanofluids of higher concentrations . Improvements of about 8.1% and 4.2% had been observed in heat transfer by Hemanth and colleagues at 1.5 liters per minute (LPM) and 2 LPM for Al 2 O 3 nanoparticles of size 20 nm. Sandhya and colleagues used a TiO 2 nanofluid as a coolant, and noted a 35% improvement in heat transfer rate when compared with only the base fluid for a 0.5% concentration.…”

Section: Introductionmentioning

confidence: 99%

Effect of carboxyl graphene nanofluid on automobile radiator performance

Sumanth

Rao

Krishna

et al. 2018

Heat Trans. Asian Res.

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Nanofluid is a promising solution for the improvement of the radiator performance. In the current research work, the effect of the nanofluid carboxyl graphene on the performance of a radiator is studied. Carboxyl graphene nanoplatelets are added to 50:50 ethylene glycol–distilled water at three concentrations of 0.02, 0.03, and 0.04 vol%. The liquid flow rate is varied from 3 liters per minute (LPM) to 6 LPM, and the inlet liquid to the radiator has been maintained at constant temperatures of 40 °C and 50 °C. The inlet air Reynolds number is varied between 1200 and 2500. The effects of these on performance parameters such as Nusselt number, effectiveness, and friction factor are investigated. It is observed that addition of carboxyl graphene nanoplatelets increases the Nusselt number and effectiveness of radiator while friction factor is unaltered. The effectiveness of radiator increases by 27.38% and 23.41% for inlet temperatures of 40 °C and 50 °C respectively at 0.02 vol% and 5 LPM flow rate.

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Investigations for effect of Al2O3–H2O nanofluid flow rate on the efficiency of direct absorption solar collector

Cited by 131 publications

References 28 publications

Performance analysis of a direct-absorption parabolic-trough solar collector using plasmonic nanofluids

Performance analysis of a direct-absorption parabolic-trough solar collector using plasmonic nanofluids

Performance enhancement of a direct absorption solar collector using copper oxide porous foam and nanofluid

Effect of carboxyl graphene nanofluid on automobile radiator performance

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