Effect of charging of phase change material in vertical and horizontal rectangular enclosures in a concentrated solar receiver

Heat transfer enhancement of concentrated solar absorber using hollow cylindrical fins filled with phase change material

Combined use of volumetric expanders and Scheffler receivers to improve the efficiency of a novel direct steam solar power plant

The impact of reradiation and convection losses from the receiver is substantial on the performance of solar parabolic dish concentrator. In this paper, an experimental and theoretical study to compare the performance of the glazed and unglazed receiver of Scheffler dish for direct steam generation is presented. Tempered glass cover is provided on aperture to reduce the reradiation and convection losses from the receiver. Improvement in the efficiency of the Scheffler dish is found due to suppressed heat losses from the receiver front surface. Overall heat loss coefficient, useful energy transfer rate to water, steam flow rate, and efficiency of the system with and without glass cover on the receiver are evaluated and compared. The average solar beam intensity during experimentation was 569 W/m2 and 600 W/m2 with the glazed and unglazed receiver respectively. The average temperature at the receiver with glazing is recorded as 425oC, even at low solar beam intensity in comparison with the unglazed receiver. Overall heat loss coefficient at the front surface of the receiver is reduced to 6.04 W/m2K. It has been observed that the Scheffler dish with a glazed receiver achieves thermal performance above 50.00% within the solar beam intensity range of 600-650 W/m2. The enhancement of 8.74% in the average thermal efficiency, with glass cover on the receiver is achieved.

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Thermal performance analysis of glazed and unglazed receiver of scheffler dish

Meta-heuristic algorithms have a high position among academic researchers in various fields, such as science and engineering, in solving optimization problems. These algorithms can provide the most optimal solutions for optimization problems. This paper investigates a new meta-heuristic algorithm called Slime Mould algorithm (SMA) from different optimization aspects. The SMA algorithm was invented due to the fluctuating behavior of slime mold in nature. It has several new features with a unique mathematical model that uses adaptive weights to simulate the biological wave. It provides an optimal pathway for connecting food with high exploration and exploitation ability. As of 2020, many types of research based on SMA have been published in various scientific databases, including IEEE, Elsevier, Springer, Wiley, Tandfonline, MDPI, etc. In this paper, based on SMA, four areas of hybridization, progress, changes, and optimization are covered. The rate of using SMA in the mentioned areas is 15, 36, 7, and 42%, respectively. According to the findings, it can be claimed that SMA has been repeatedly used in solving optimization problems. As a result, it is anticipated that this paper will be beneficial for engineers, professionals, and academic scientists. 

/pdf/slime-mould-algorithm-a-comprehensive-survey-of-its-variants-1qdo9e65.pdf

Slime Mould Algorithm: A Comprehensive Survey of Its Variants and Applications

Receiver is an important element of solar concentrator system. In a Scheffler concentrator, solar rays get concentrated at focus of parabolic dish. While radiation losses are more predictable and calculable since strongly related to receiver temperature, convective looses are difficult to estimate in view of additional factors such as wind flow direction, speed, receiver geometry, prior to current work. Experimental investigation was carried out on two geometries of receiver namely cylindrical and conical with 2.7 m2 Scheffler to find optimum condition of tilt to provide best efficiency. Experimental results showed that as compared to cylindrical receiver, conical receiver gave maximum efficiency at 45° tilt angle. However effect of additional factors like wind speed, wind direction on especially convective losses could not be separately seen. The current work was undertaken to investigate further the same two geometries using computation fluid dynamics using FLUENT to compute convective losses considering all variables such at tilt angle of receiver, wind velocity and wind direction. For cylindrical receiver, directional heat transfer coefficient (HTC) is remarkably high to tilt condition meaning this geometry is critical to tilt leading to higher convective heat losses. For conical receiver, directional average HTC is remarkably less to tilt condition leading to lower convective heat loss.

Effect of Wind Flow on Convective Heat Losses from Scheffler Solar Concentrator Receivers

Parametric analysis of Scheffler solar concentrator system is performed for improvement in thermal efficiency. A Scheffler concentrator of size 2.7 m2 has been used for experimentation. Cylindrical...

Studies on Scheffler solar concentrator to optimise thermal efficiency

Scheffler concentrators are used for heating water and producing steam. Flat plate collectors are normally used for low-temperature water heating. In this research work, the performances of a flat ...

Integrated system of flat plate collector and Scheffler solar concentrator for enhancing thermal efficiency and steam generation rate

Two different Scheffler concentrators with concentration ratio 48 and 17 were installed and experimentation was carried out to improve the performance of the Scheffler solar concentrator system. Receiver is the heart of the system. Parameters used for experimentation are related to receiver only. Shape of receiver, position of receiver, inlet temperature of water of receiver, covering of receiver with glass to reduce convection losses. Concentration ratio is the ratio of aperture area to receiver area both Scheffler concentrators have receiver of same size and volume. scheffler with concentration ratio 48 generates steam up to 3 bar gauge pressure of steam and heat gain rate is 2 kw, and scheffler with concentration ratio 17 develops up to 1 bar gauge pressure of steam and heat gain rate is 0.6 kw. If temperature of water at inlet is 50 degree instead of 30 degree, performance of Schefflers improves due to reduction in thermal inertia. Conical receiver due to more surface area for heat transfer during tilt gives better performance than cylindrical receiver to generate steam. As solar radiations increases efficiency of Scheffler solar concentrators decreases. If wind speed increases from 1 to 3 m/s efficiency decreases. Keywords—scheffler concentrator, solar radiations, thermal efficiency, concentration ratio, optimization, receiver.

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Anita A. Nene

Papers

Effect of Wind Flow on Convective Heat Losses from Scheffler Solar Concentrator Receivers

Studies on Scheffler solar concentrator to optimise thermal efficiency

Integrated system of flat plate collector and Scheffler solar concentrator for enhancing thermal efficiency and steam generation rate

Comparative Analysis of Performance of Two Scheffler Solar Concentrators Having Different Concentration Ratios

Design analysis of heat exchanger for the solar water heating systems using phase change materials