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This paper presents a numerical study of a well-established vortex flow receiver and a proposed recirculating flow Solid particle solar receiver (SPSR) capable of achieving high air temperature which is perfectly suitable for the hybrid solar thermal power plant. Solar particle receivers are modeled using discrete particle model (DPM), RNG k- e flow model and discrete ordinate (DO) radiation model. Numerical analysis is done by considering two cases (i) Recirculating flow solar receiver with non-reacting particle and without non-reacting particle as a medium of transferring heat (ii) Vortex flow solar receiver with non-reacting particle and without non-reacting particle as a medium of transferring heat. The examination is carried out to compare the parametric sensitivity of both solar particle receivers with particle and air and without particle as a medium of transferring heat by considering the solar flux that incident on the aperture of the receiver and varying the air flow rate and particle concentration, recirculation rate. The results depict that use of particle enhance the heat transfer for both cases. It is concluded from the thermal behavior of recirculating flow SPSR that about 30% higher cavity thermal efficiency and exhibit higher and uniform heat transfer than a vortex flow SPSR.

This study focuses on the enhancement of potable water productivity of an active double slope modified solar still (SS) considering the combined effect of solid rectangular fin, paraffin wax as a thermal energy storage medium, black cotton cloth as wick material, and an external condenser. The performance of three double slope SSs (modified, finned, and traditional) is evaluated considering five different cases. A comparative assessment of the performances of three double slope SSs is performed and it is perceived that the supreme productivities are 3.07, 2.70, and 2.46 L/m2 for modified, finned, and traditional SSs, respectively. The maximum efficiency of the modified SS with and without external condenser are found as 39.74% and 30%, respectively. An external condenser insertion in the modified SS boosts the productivity by approximately 10%. The average daily efficiency of the modified SS is 14.23% and 22.33% higher than the finned and traditional SS, respectively. The economic analysis is also conducted, and the cost per liter (CPL) values for traditional SS, the finned one, and the modified one are found as 0.0135, 0.0133, and 0.0117 $/L/m2, respectively. The novel modification of SS could be a propitious alternative to meet up the potable water demand in remote regions with low cost.

The use of Concentrated Solar Power technology for energy generation relies on the heating of fluids to high temperatures. One of the limitations of this technology is the low working efficiency of current solar receivers which hinders its application and utilization as a renewable clean energy source. This paper presents a novel concept to improve concentrated solar receiver efficiency through the recirculation of solid particles laden flow within the receiver. The recirculating characteristic of the fluid and solid particle mixture is expected to generate higher output fluid temperature than conventional solar receivers. This is expected to lead to significant improvements in the working performance of the concentrated solar receiver. The numerical study investigates this concept, using a commercial CFD package, employing the discrete particle model (DPM), a RNG k- e flow model and a discrete ordinate (DO) radiation model. It is found that the use of recirculating solid particles improves the energy absorption within the receiver and with it the thermal efficiency of the proposed solar receiver reaches to around 70%. Moreover, comparing this with a conventional solar receiver, this new concept exhibits a more uniform temperature distribution inside the cavity, which is mainly due to the recirculating flow characteristic and the well-controlled mixing of air and particles. The advantages of this novel concept of the solar receiver present its potential benefits in further applications in the process of energy conversion providing on enhanced heat transfer medium.