TY - JOUR

T1 - Radiation and Energetic Analysis of Nanofluid Based Volumetric Absorbers for Concentrated Solar Power

AU - Eggers, Jan Rudolf

AU - Lange, Eckart Matthias

AU - Kabelac, Stephan

N1 - Acknowledgments: The APC for the publication of this article was funded by the Open Access fund of Leibniz Universität Hannover.

PY - 2018/10

Y1 - 2018/10

N2 - Recently, several publications gave attention to nanofluid based solar absorber systems in which the solar radiation energy is directly absorbed in the volume of the fluid. This idea could provide advantages over conventionally used surface absorbers regarding the optical and thermal efficiency. For the evaluation of this concept, a numerical approach is introduced and validated in this contribution. The results show that the optical efficiency of a volumetric absorber strongly depends on the scattering behavior of the nanofluid and can reach competitive values only if the particle size distribution is narrow and small. If this is achieved, the surface temperature and therefore the heat loss can be lowered significantly. Furthermore, the surface absorber requires very high Reynolds numbers to transfer the absorbed energy into the working fluid and avoid overheating of the absorber tube. This demand of pumping power can be reduced significantly using the concept of volumetric absorption.

AB - Recently, several publications gave attention to nanofluid based solar absorber systems in which the solar radiation energy is directly absorbed in the volume of the fluid. This idea could provide advantages over conventionally used surface absorbers regarding the optical and thermal efficiency. For the evaluation of this concept, a numerical approach is introduced and validated in this contribution. The results show that the optical efficiency of a volumetric absorber strongly depends on the scattering behavior of the nanofluid and can reach competitive values only if the particle size distribution is narrow and small. If this is achieved, the surface temperature and therefore the heat loss can be lowered significantly. Furthermore, the surface absorber requires very high Reynolds numbers to transfer the absorbed energy into the working fluid and avoid overheating of the absorber tube. This demand of pumping power can be reduced significantly using the concept of volumetric absorption.

KW - Anisotropy

KW - Energy conversion

KW - Nanofluid

KW - Scattering

KW - Solar absorption

KW - Spectral penetration depth

KW - Temperature distribution

UR - http://www.scopus.com/inward/record.url?scp=85056325469&partnerID=8YFLogxK

U2 - 10.3390/nano8100838

DO - 10.3390/nano8100838

M3 - Article

AN - SCOPUS:85056325469

VL - 8

JO - Nanomaterials

JF - Nanomaterials

SN - 2079-4991

IS - 10

M1 - 838

ER -