The increasing global demand for sustainable energy has driven advancements in solar thermal technologies,particularly in solar parabolic dish collectors(PDCs).The performance of a PDC depends on the absorption of sol...The increasing global demand for sustainable energy has driven advancements in solar thermal technologies,particularly in solar parabolic dish collectors(PDCs).The performance of a PDC depends on the absorption of solar irradiance and heat loss through the receiver.Furthermore,to address the problems of solar intermittency and lack of irradiance after sunset requires thermal energy storage.Consequently,an appropriate design of the receiver is necessary for maximizing the performance of the PDC.This study investigated the incorporation of phase change materials(PCMs)into conical cavity receivers to enhance the thermal energy storage and efficiency of PDCs.To examine this,a comparative experimental analysis was conducted on a PCM-filled conical receiver and a conventional cylindrical receiver under identical operating conditions.The methodology involved measuring key performance metrics,such as the thermal efficiency,exergy efficiency,Nusselt number,and heat transfer coefficients,across varying flow rates of the heat transfer fluid.The results demonstrated that the PCM-integrated conical receiver achieved a 42%increase in the thermal efficiency and a 31%improvement in the exergy efficiency compared to the cylindrical design.The capacity of the conical receiver for intercepting solar radiation and PCM integration contributed to superior heat transfer performance,particularly at higher flow rates,as evidenced by the elevated Nusselt numbers and convection heat transfer coefficients.These findings highlight the potential of PCM-integrated conical receivers for mitigating the challenges of intermittent solar irradiance and enhancing the reliability and sustainability of solar thermal systems.展开更多
The optical performance of a receiver has a great influence on the efficiency and stability of a solar thermal power system.Most of the literature focuses on the optical performance of receivers with different geometr...The optical performance of a receiver has a great influence on the efficiency and stability of a solar thermal power system.Most of the literature focuses on the optical performance of receivers with different geometric shapes,but less research is conducted on the effects of critical geometric parameters.In this paper,the commercial software TracePro was used to investigate the effects of some factors on a conical cavity receiver,such as the conical angle,the number of loops of the helical tube,and the distance between the focal point of the collector and the aperture.These factors affect the optical efficiency,the maximum heat flux density,and the light distribution in the conical cavity.The optical performance of the conical receiver was studied and analyzed using the Monte Carlo ray tracing method.To make a reliable simulation,the helical tube was attached to the inner wall of the cavity in the proposed model.The results showed that the amount of light rays reaching the helical tube increases with the increasing of the conical angle,while the optical efficiency decreases and the maximum heat flux density increases.The increase in the number of loops contributed to an increase in the optical efficiency and a uniform light distribution.The conical cavity receiver had an optimal optical performance when the focal point of the collector was near the aperture.展开更多
In recent years,research on enhancing the efficiency of clean and renewable energy systems has increased.This study examines how a micro-scale solar Brayton cycle application performs about the conical cavity thermal ...In recent years,research on enhancing the efficiency of clean and renewable energy systems has increased.This study examines how a micro-scale solar Brayton cycle application performs about the conical cavity thermal receiver shape.Additionally,it establishes the ideal receiver configuration under consideration.The new work explicitly addresses the optimization of a microscale conical model,building on earlier studies by the research team that stressed the significance of reducing total heat losses.The receiver model was created using Design Modeler and treated using CFD analysis in ANSYS 2021R2 Workbench software to limit the convective mode of heat loss.Surface optimization techniques were then used,and the results were examined.To confirm the achieved results,the direct optimization method was also utilized,and it gave the same results.The internal height and the two edges on the bottom width of the receiver were found to have the greatest influence on the value of the heat transfer coefficient.Thermally,the dimensions of the optimized conical shape were found to be 384,198,114,48 and 57 mm for the internal height,total width,top width,left edge and right edge respectively.The results of this investigation showed that by reducing the heat transfer coeffi-cient by up to 90%,the tested shape’s thermal performance was significantly improved.It consequently led to an increase in overall system efficiency of around 1.3%e1.95%.展开更多
This study examines the Carolina Bays and Nebraska Rainwater Basins,using high-resolution LiDAR elevation models to analyze their unique shapes.The research reveals that well-preserved Bays exhibit precise elliptical ...This study examines the Carolina Bays and Nebraska Rainwater Basins,using high-resolution LiDAR elevation models to analyze their unique shapes.The research reveals that well-preserved Bays exhibit precise elliptical geometry,distinguishing them from various oriented lakes they are often compared to.While the timing of their formation is discussed,the primary goal of this paper is to establish a repeatable method for quantifying the elliptical nature of these dominant geomorphic landforms.By applying the least squares method to points selected along the perimeters of these extraordinary basins,the study confirms their elliptical geometry with an error margin of less than 3%.This rigorous mathematical approach sets a high standard for any hypothesis attempting to explain the origin of these depressions using natural environmental conditions.Notably,the long axes of these elliptical basins converge near the Great Lakes region,and since ellipses can be described as conic sections,this finding supports the plausibility of a cosmic impact origin.The study suggests that these basins may be secondary impact features formed during a past glacial cycle of the Laurentide Ice Sheet.This research establishes a strong mathematical foundation to support future studies on the possible impact origin of the Carolina Bays and Nebraska Rainwater Basins.展开更多
文摘The increasing global demand for sustainable energy has driven advancements in solar thermal technologies,particularly in solar parabolic dish collectors(PDCs).The performance of a PDC depends on the absorption of solar irradiance and heat loss through the receiver.Furthermore,to address the problems of solar intermittency and lack of irradiance after sunset requires thermal energy storage.Consequently,an appropriate design of the receiver is necessary for maximizing the performance of the PDC.This study investigated the incorporation of phase change materials(PCMs)into conical cavity receivers to enhance the thermal energy storage and efficiency of PDCs.To examine this,a comparative experimental analysis was conducted on a PCM-filled conical receiver and a conventional cylindrical receiver under identical operating conditions.The methodology involved measuring key performance metrics,such as the thermal efficiency,exergy efficiency,Nusselt number,and heat transfer coefficients,across varying flow rates of the heat transfer fluid.The results demonstrated that the PCM-integrated conical receiver achieved a 42%increase in the thermal efficiency and a 31%improvement in the exergy efficiency compared to the cylindrical design.The capacity of the conical receiver for intercepting solar radiation and PCM integration contributed to superior heat transfer performance,particularly at higher flow rates,as evidenced by the elevated Nusselt numbers and convection heat transfer coefficients.These findings highlight the potential of PCM-integrated conical receivers for mitigating the challenges of intermittent solar irradiance and enhancing the reliability and sustainability of solar thermal systems.
文摘The optical performance of a receiver has a great influence on the efficiency and stability of a solar thermal power system.Most of the literature focuses on the optical performance of receivers with different geometric shapes,but less research is conducted on the effects of critical geometric parameters.In this paper,the commercial software TracePro was used to investigate the effects of some factors on a conical cavity receiver,such as the conical angle,the number of loops of the helical tube,and the distance between the focal point of the collector and the aperture.These factors affect the optical efficiency,the maximum heat flux density,and the light distribution in the conical cavity.The optical performance of the conical receiver was studied and analyzed using the Monte Carlo ray tracing method.To make a reliable simulation,the helical tube was attached to the inner wall of the cavity in the proposed model.The results showed that the amount of light rays reaching the helical tube increases with the increasing of the conical angle,while the optical efficiency decreases and the maximum heat flux density increases.The increase in the number of loops contributed to an increase in the optical efficiency and a uniform light distribution.The conical cavity receiver had an optimal optical performance when the focal point of the collector was near the aperture.
文摘In recent years,research on enhancing the efficiency of clean and renewable energy systems has increased.This study examines how a micro-scale solar Brayton cycle application performs about the conical cavity thermal receiver shape.Additionally,it establishes the ideal receiver configuration under consideration.The new work explicitly addresses the optimization of a microscale conical model,building on earlier studies by the research team that stressed the significance of reducing total heat losses.The receiver model was created using Design Modeler and treated using CFD analysis in ANSYS 2021R2 Workbench software to limit the convective mode of heat loss.Surface optimization techniques were then used,and the results were examined.To confirm the achieved results,the direct optimization method was also utilized,and it gave the same results.The internal height and the two edges on the bottom width of the receiver were found to have the greatest influence on the value of the heat transfer coefficient.Thermally,the dimensions of the optimized conical shape were found to be 384,198,114,48 and 57 mm for the internal height,total width,top width,left edge and right edge respectively.The results of this investigation showed that by reducing the heat transfer coeffi-cient by up to 90%,the tested shape’s thermal performance was significantly improved.It consequently led to an increase in overall system efficiency of around 1.3%e1.95%.
文摘This study examines the Carolina Bays and Nebraska Rainwater Basins,using high-resolution LiDAR elevation models to analyze their unique shapes.The research reveals that well-preserved Bays exhibit precise elliptical geometry,distinguishing them from various oriented lakes they are often compared to.While the timing of their formation is discussed,the primary goal of this paper is to establish a repeatable method for quantifying the elliptical nature of these dominant geomorphic landforms.By applying the least squares method to points selected along the perimeters of these extraordinary basins,the study confirms their elliptical geometry with an error margin of less than 3%.This rigorous mathematical approach sets a high standard for any hypothesis attempting to explain the origin of these depressions using natural environmental conditions.Notably,the long axes of these elliptical basins converge near the Great Lakes region,and since ellipses can be described as conic sections,this finding supports the plausibility of a cosmic impact origin.The study suggests that these basins may be secondary impact features formed during a past glacial cycle of the Laurentide Ice Sheet.This research establishes a strong mathematical foundation to support future studies on the possible impact origin of the Carolina Bays and Nebraska Rainwater Basins.
