Flow patterns of external solar receivers

Rodríguez-Sánchez, M.R.; Sánchez-González, Alberto; Marugán-Cruz, C.; Santana, D.

doi:10.1016/j.solener.2015.10.025

Cited by 39 publications

(21 citation statements)

References 27 publications

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“…The mass flow rate circulates in parallel in all tubes of a given panel. As it is pointed out in(Rodríguez-Sánchez et al, 2015), there are not crosses between flow paths.…”

mentioning

confidence: 86%

Thermo-mechanical modelling of solar central receivers: Effect of incident solar flux resolution

2018

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The most important constraint for central receiver design is to keep the intercepting solar flux within the tube mechanical safety limits. An error in the heliostat aiming strategy or an inaccurate estimation of the tube temperature can produce overheating of the tubes, putting at risk the power plant operation. Therefore, the development of thermo-mechanical models to predict the incident solar flux, the temperature and the thermal stresses is mandatory.The large number of tubes in the receivers makes a detailed simulation computationally expensive, and simplifications are usually done. These simplifications consist on selecting a representative tube in each panel of the receiver and reducing the spatial resolution of the incident radiation to a scale equal to one panel size. This "coarse grid model" simulation can be used with confidence to obtain the solar tower yield production with an error lower than 2.5%.However, the small resolution of this model results in errors in the wall temperature and the thermal stresses estimation, and hence in the aiming strategy selection.In this study a "fine grid model", whose cells have a size equal to the tube pitch (distance between centres of the tubes) width in the receiver, has been developed for an accurate estimation of the tube wall temperature. Using this fine grid model the temperature and the thermal stress profiles in each tube, for a given panel of the receiver, can be indirectly obtained without assuming that all the tubes of the panel have the same temperature profiles. Therefore, for modelling receiver, the fine grid model is required to determine with more accuracy the maximum tube stress and the aiming strategy, especially in the real situation of a highly nonuniform solar flux onto the receiver.

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“…The mass flow rate circulates in parallel in all tubes of a given panel. As it is pointed out in(Rodríguez-Sánchez et al, 2015), there are not crosses between flow paths.…”

mentioning

confidence: 86%

Thermo-mechanical modelling of solar central receivers: Effect of incident solar flux resolution

2018

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“…The heliostat was affected by the fenestration geometrical factors like external solar shading, despite its flexible weight, height, or shape (spherical/circular). The freer the heliostat geometry, the more the decrease in the radiation reflecting on the receiver surface, associated with the sunlight fallen on the heliostat surface, because of optical losses [12] [42].…”

Section: Heliostat Fieldmentioning

confidence: 99%

“…One of the major problems associated with the heat interchange in the external receiver was a high-temperature flux occurring at the receiver's surface (external area) and all transitory thermal processes, which lead to heat spots that can cause a failure or complete collapse of the external receiver. Additionally, the receiver heat or solar flux dissemination must be controlled for improving the performance and energy storage [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Solar Tower Power: The Impact of External Receiver on Optimal Performance and Energy Storage

Shatnawi,

Lim,

Ismail

2019

IJEAT

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An external receiver was seen as a major component of the Solar Tower Power (STP) plant. This generated stable power from concentrated sunlight. However, the flux distribution on its surface was an issue related to the external receiver that could affect the performance and energy storage in STP. The heat flux increased during long-term use, failure reduction, receiver efficiency and performance. The main advantage of the STP structure was its substantial heat storage capacity which allowed the system to generate stable and continuous electric power. In this study, the researchers reviewed existing literature to investigate the effect of the STP external receiver on the optimum energy storage and performance of the STP; especially regarding the solar flux distribution and efficiency. The researchers aim to improve the external receiver’s optimal performance without affecting the incident heat fluxes. The literature review indicates that ideal receiver conditions lead to solar energy flux distribution optimal performance. Therefore, system optimisation was necessary to satisfy all limitations; like loss occurring due to heliostat field, solar flux flow patterns, external tubular receiver designs, and Heat Transfer Fluid (HTF) selection. These limitations, along with factors affecting these limitations, are reviewed in this study.

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“…Related to the HTF, Boerema et al [5] compared the advantages of using different HTF and Rodríguez-Sánchez et al [6] optimized the flow pattern of the external receivers which enlarges the useful lifetime of the receivers. On the other hand, several authors proposed new concepts of solar receivers, among them Garbrecht [7] studied a receiver geometry based on hexagonal pyramid-shaped elements, Rodríguez-Sánchez et al [8] analysed an external receiver in which the tubes were replaced by bayonet tubes, Boerema et al [9] investigated new designs using different tube diameters in each panel, Turner and Sansom [10] studied a low-cost modular receiver that consists on a volumetric cavity receiver formed by tubular structures, and Yang et al [11] introduced a high temperature two-phase flat heat pipe receiver, with sodium as HTF, which homogenises the temperature in cavity systems.…”

Section: Introductionmentioning

confidence: 99%

Feasibility study of a new concept of solar external receiver: Variable velocity receiver

Rodríguez-Sánchez

Sánchez-González

Santana

2018

Applied Thermal Engineering

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The deployment of new solar power tower plants mainly depends on becoming costcompetitive with traditional forms of electricity generation. The solar field represents around 40% of the solar power tower investment cost, thus the cost reduction of such subsystems is mandatory to achieve that goal. This reduction could be done by increasing the solar flux intercepted by the receiver, which would increase the peak flux. Therefore, new concepts of solar receivers are required to accommodate such high peak flux.The proposed receiver, which withstands high peak flux, consists on a Traditional External Tubular Receiver (TETR) equipped with valves that allow the division of each panel of the receiver in two independent panels, increasing the velocity of the heat transfer fluid in specific zones of the receiver. This receiver configuration, named Variable Velocity Receiver (VVR), avoids tube overheating. Moreover, this novel receiver allows more concentrated aiming strategies, which increases the optical efficiency of the solar field and permits to reduce the number of heliostats in the field. Given a specific generation capacity, the size of the solar field required by a VVR is 12.5% smaller in comparison to a TETR.Such efficiency improvement has a negligible effect in tube mechanical stresses; even though pressure drop and parasitic consumption of the power plant increase. This new receiver configuration also gains hours of operation, even in winter: in hours with low solar irradiance all the panels can be split in two, increasing the number of passes and the velocity of the heat transfer fluid and accomplishing the transition from laminar to turbulent regime. Therefore, this receiver is able to reduce the levelized cost of energy.

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Flow patterns of external solar receivers

Cited by 39 publications

References 27 publications

Thermo-mechanical modelling of solar central receivers: Effect of incident solar flux resolution

Thermo-mechanical modelling of solar central receivers: Effect of incident solar flux resolution

Solar Tower Power: The Impact of External Receiver on Optimal Performance and Energy Storage

Feasibility study of a new concept of solar external receiver: Variable velocity receiver

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