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The objective of this research article is to present a comprehensive review of the work carried out to improve the thermal as well exergetic performance of the conventional smooth absorber plate solar air heater (SAH) duct by the use of the various configurations and arrangements of extended surfaces (fins) for the forced convection. In the SAH duct, these extended surfaces are attached along the air-flow path on the top absorber, on the bottom plate, or on the both plate surfaces. It enhances the performance of the conventional SAH by increasing the surface area and makes flow turbulent by their presence. Several experimental, theoretical, and simulation works, which have been performed by the researchers by utilizing the extended surfaces to improve the thermal efficiency based on first law of thermodynamics, exergy, and entropy generation analysis on the basis of the second law of thermodynamics for SAH ducts, have been included in the present article. Subsequently, an effort has been made to calculate the Nusselt number and friction factor by using the correlations reported by the researchers for comparing the performance of different configurations of fin SAHs. This comprehensive review article will be useful for the investigators and researchers who are working in the area of extended surface SAHs.
Assuntos
Energia Solar , Luz Solar , Simulação por Computador , Convecção , Entropia , TermodinâmicaRESUMO
In the present work, an outdoor experimental investigation for solar air heater with arc-shape apex upstream flow by the use of circular cross-sectional wires as roughness elements has been carried out. The roughness elements have been expressed in non-dimensionalizing geometric parameters as relative roughness pitch (P/e), relative roughness height (e/D), and flow attack angle (α/60), and the range of these parameters varies from 8 to 15, 0.0454, and 0.75 to 1.25, respectively. For evaluation of performance of the roughened SAH, a novel parameter has been proposed and introduced in the present investigation which is thermo-hydraulic improvement parameter (THIP). With the use of present roughness geometry, considerably, Nusselt number enhancement ratio (NNER) and friction factor enhancement ratio (FFER) have been observed. The maximum NNER and FFER values obtained experimentally are about 2.83 and 1.79 times, respectively, while the maximum THIP obtained is 157.49% higher than the smooth SAH. Using the experimental results, correlations for the output parameters (Nusselt number and friction factor) as a function of input parameters (flow and roughness) have been developed.
RESUMO
Introduction: Solid lipid nanoparticles (SLNs) are solid core lipid nanocarriers, which can hold both hydrophilic and hydrophobic drugs. They can be made up of biocompatible ingredients and therefore are one of the preferred choices for drug delivery. Surface modifications of SLNs may further provide unique features to them like mucoadhesiveness or targeting capability.Areas covered: In this review, the authors have covered areas from the basic introduction of SLNs to its applications in controlled drug delivery. More specifically, the authors have covered patents disclosed related to the SLNs for the period 2014-2019; however, a summary of patents of 2008-2013 is also included.Expert opinion: SLNs have been explored for development of compositions/formulations with improved therapeutics or cosmetic applications or for nutraceutical applications. Targeted SLNs compositions have been patented as evidenced from the literature; however, not such types of enough SLNs formulations have been claimed for the same.
