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• Laminar fluid flow based transport and deposition of dust on a flat plate is investigated using the one-way Euler-Lagrange coupling. • The effect of Stokes number, the particle shape and size, the particle release height and heating is described. • The analysis reveals (a) a way of mitigating the deposition and (b) the size of a solar PV panel or a solar water heater should be based on the local conditions. Hydraulically and thermally developing laminar flow induced dust deposition on a flat plate is of practical and fundamental interest with isothermal/non-isothermal and heat flux boundary conditions. The paper deals with the analysis of a steady, incompressible, two-dimensional, laminar, Newtonian fluid flow over an inclined flat plate. The reduced forms of momentum and continuity equations using boundary layer approximation are solved using the fourth order Runge-Kutta numerical scheme integrated with the shooting method. Subsequently, the energy equation with boundary layer approximations is solved for the considered flow over a flat plate using a constant heat flux or constant/variable wall temperature boundary conditions along the length. The calculated velocity and temperature profiles are used for analyzing the particle trajectory over the flat plate. Finally, the one-way coupling of Eulerian and Lagrangian approaches is presented and the effects of Stokes number, particle shape/size, and heating condition are analyzed on the transport and deposition of an inelastic isolated particle on the flat plate. The methodology will be helpful in addressing for instance, the dust deposition over a photovoltaic panel or a solar water heater, and a way of mitigating its effect on the same. [ABSTRACT FROM AUTHOR]

• Transport of an isolated, dust particle in a circular, straight, absorber pore is analyzed. • The effect of dust accumulation, in an absorber pore, on the heat transfer is analyzed. • Analysis show that dust deposition, in a straight pore, may be mitigated by applying heat-flux. • Dust accumulation is found to be detrimental, for heat transfer in an absorber pore. The deposition of dust in the absorber pores of an open volumetric air receiver (OVAR) offers a significant challenge in arid deserts. In this paper, to address this problem, two aspects are investigated, (i) the transport of an isolated dust particle in a straight, circular absorber pore, for a steady, thermally-hydraulically developing, laminar flow, and (ii) the consequences on heat transfer due to dust particles accumulation, in a straight, circular, absorber pore. The first problem is investigated with a semi-analytical approach and the second problem makes use of computational fluid dynamics simulations. The finding shows (a) a heat flux may be beneficial, for mitigating the dust deposition in a, straight, circular, clean absorber pore, (b) dust deposition in a straight, circular, absorber pore is detrimental to heat transfer, which may lead to its failure, (c) the thermal development length will be reduced for the dust deposited pore in comparison to a clean pore. The findings reveal a way of mitigating dust deposition in a clean pore, and the need for a cleaning strategy of dust deposited absorber pore, for sustainable operation of an open volumetric air receiver. [ABSTRACT FROM AUTHOR]

Several heliostats are arranged on the field for concentrating beam solar radiation onto a receiver. The flow-induced dust deposition and vibration of heliostats will lead to failure of the receiver and the entire system in eventuality. Therefore, fluid flow analysis behind a heliostat model in a narrow channel of limited length is presented depicting a field-type condition. In this paper, experiment and Large Eddy Simulation (LES) are performed. Laser Doppler Velocimetry (LDV) technique is used for horizontal velocity measurement around a heliostat with 25° angle of inclination at a Reynolds number of 60,000 basing on the length of an inclined plate. The wall-resolved coarse, intermediate and fine grids are utilized for LES with dynamic- Smagorinsky–Lilly and subgrid-scale kinetic energy transport equation based models. Comparison between local instantaneous and statistical quantities, like horizontal velocity and its root-mean-square values are presented. The flow development in the wake region of heliostat model is described using the time-dependent and the statistical horizontal velocity. Based on the adopted LES approach the coherent structures are identified with the λ ci -criterion. The analysis of power spectral density and swirling strength isosurface reveal the responsible coherent structures in the inertial subrange for transport of energy to smaller structures. Interestingly, the presence of hairpin-type vortices is observed extending from the two sides of model heliostat using the λ ci -criterion. Further, instantaneous span-wise vorticity contour reveals their alignment with flow represented by streamlines. The provided insight to these flow features and their organization is expected to frame strategies for mitigating the unsteady flow-induced vibrations and dust depositions on heliostats. [ABSTRACT FROM AUTHOR]

In India, the desert regions of Rajasthan and Gujarat are preferred for installation of solar photovoltaic (PV) and concentrated solar thermal (CST) systems because of a high level of both DNI and GHI components of solar radiation. However, such regions pose substantial challenges in terms of dust, a high ambient temperature and scarcity of water. This paper is an attempt to address issues related to the deposition of dust (a) on a mirror with stand depicting PV panel or heliostat in the wake of a similar geometry and (b) in the porous absorber of an open volumetric air receiver (OVAR). A detailed insight to the wake-region behind an inclined flat-plate or heliostat is provided based on analysis and experiment. These indicate possible measures such as modification of the geometry of collectors to mitigate the problem of dust deposition. Also, the use of a cyclone separator with defined parameters based on a decision variable has been suggested for reliable operation of an OVAR. These problems being generic in nature, similar strategies are expected to be applicable in other desert regions subject to their specific conditions. [ABSTRACT FROM AUTHOR]

In India, the desert regions of Rajasthan and Gujarat are preferred for installation of solar photovoltaic (PV) and concentrated solar thermal (CST) systems because of a high level of both DNI and GHI components of solar radiation. However, such regions pose substantial challenges in terms of dust, a high ambient temperature and scarcity of water. This paper is an attempt to address issues related to the deposition of dust (a) on a mirror with stand depicting PV panel or heliostat in the wake of a similar geometry and (b) in the porous absorber of an open volumetric air receiver (OVAR). A detailed insight to the wake-region behind an inclined flat-plate or heliostat is provided based on analysis and experiment. These indicate possible measures such as modification of the geometry of collectors to mitigate the problem of dust deposition. Also, the use of a cyclone separator with defined parameters based on a decision variable has been suggested for reliable operation of an OVAR. These problems being generic in nature, similar strategies are expected to be applicable in other desert regions subject to their specific conditions. [ABSTRACT FROM AUTHOR]