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Concentrating characteristics of the sunlight have an important effect on the optical-thermal conversion efficiency of solar concentrator and the application of the receiver. In this paper, radiation flux in the focal plane and the receiver with three focal lengths has been investigated based on Monte Carlo ray-tracing method. At the same time, based on the equal area-height and equal area-diameter methods to design four different shape receivers and numerical simulation of radiation flux distribution characteristics have also been investigated. The results show that the radiation flux in the focal plane increases with decreasing of the focal length and the diameter of the light spot increases with increasing of the focal length. The function of the position with a maximum of radiation flux has been obtained according to the numerical results. The results also show that the radiation flux distribution of cylindrical receiver has the best performance in all four receivers. The results can provide a reference for future design and application of concentrating solar power.

With the rapid development of global economy, the challenges for environment and energy are more and more important to the human. Concentrating solar power (CSP) is regarded as an effective way to solve energy problem [

A large number of advancements have taken place in recent years in an effort to make radiation flux of the receiver more uniformly and effectively. As for the CSP system, there are some researches that focus on the solar radiation, conversion efficiency, and storage tank [

In the above literatures, these researches focus on the energy conversion efficiency and the concentrating types, but the effect of the local length of parabolic dish and geometrical configuration of the receiver on the radiation flux and the system’s efficiency is limited. In this paper, the concentrating ways of sunlight firstly have been established based on Monte Carlo ray-tracing method. After that, the effect of the local length on the radiation flux in the local plane and the receiver has been investigated. Finally, the effect of the geometrical configuration of the receiver on the radiation flux distribution has been simulated. The present study can provide a reference for the future design and application of CSP plant.

The Monte Carlo ray-tracing method, referred to as MCRT, is a popular tool with high accuracy in this field [

In this study, the radiation flux distributions of the local plane and receiver within three local lengths, that is, 2500 mm, 3250 mm, and 4000 mm, have been obtained. In simulation process, the basic parameters are as follows: incident solar irradiation in the air is 1100 W/m^{2}, system error is 0 mrad, radius of the parabolic dish concentrator is 2600 mm, height of the parabolic dish concentrator is 520 mm, reflectivity of the parabolic dish concentrator is 0.9, radius of the cylindrical receiver is 100 mm, and height of the cylindrical receiver is 260 mm.

Light spot performance of the local plane in different local lengths has been simulated and shown in Figure ^{2} when the local length is 2500 mm. Meanwhile, the results show that the diameter of light spot is about 30.0 mm and radiation flux of light spot is about 21.80 MW/m^{2} when the local length is 3250 mm. The results also show that the diameter of light spot is about 37.0 mm and radiation flux of light spot is about 18.58 MW/m^{2} when the local length is 4000 mm.

Radiation flux distribution in focal plane with different focal lengths: (a) 2500 mm; (b) 3250 mm; (c) 4000 mm.

3D radiation flux distribution of the receiver in different local lengths has been simulated and shown in Figure

Radiation flux distribution in the receiver with different focal lengths: (a) 2500 mm; (b) 3250 mm; (c) 4000 mm.

Figure

Effect of the focal length on the performance of concentrating characteristics.

To investigate the effects of the geometrical configurations on the radiation flux distribution, four receivers (i.e., frustum, inverted frustum, cylindrical, and conical receivers) shown in Figure

Design parameters of the receiver based on equal area-height method.

Shapes | Height (mm) | Radius in the bottom (mm) | Radius in the top (mm) |
---|---|---|---|

Frustum | 260 | 120 | 78 |

Inverted frustum | 260 | 78 | 120 |

Cylindrical | 260 | 100 | 100 |

Conical | 260 | 168 | 0 |

Design parameters of the receiver based on equal area-radius method.

Shapes | Height (mm) | Radius in the bottom (mm) | Radius in the top (mm) |
---|---|---|---|

Frustum | 235 | 100 | 120 |

Inverted frustum | 285 | 100 | 80 |

Cylindrical | 260 | 100 | 100 |

Conical | 510 | 100 | 0 |

Four types of the receiver.

Figure

Radiation flux distribution based on equal area-height method.

Frustum

Inverted frustum

Cylindrical

Conical

Figure

Radiation flux distribution based on equal area-radius method.

Frustum

Inverted frustum

Cylindrical

Conical

In this paper, radiation flux in the focal plane and the receiver with three focal lengths has been investigated based on MCRT method. Also, four different shape receivers have been designed and simulated based on the equal area-height and equal area-diameter methods. The main conclusions can be given as follows:

The radiation flux in the focal plane increases with decreasing of the focal length and the diameter of the light spot increases with increasing of the focal length.

The positions with the maximum flux are about 60 mm, 127 mm, and 160 mm when the local lengths are 2500 mm, 3250 mm, and 4000 mm, respectively. The function of the position with a maximum of radiation flux has been obtained according to the simulation results in this paper.

The results show that the radiation flux distribution of cylindrical receiver has the best performance in all four receivers, which will result in a higher efficiency of the system.

This paper aims to know the characteristic of radiation flux distribution for the receiver in different focal lengths and geometrical configurations and make a starting point to motivate future investigation in this field.

The authors declare that there is no conflict of interests regarding the publication of this paper.

This work is supported by the National Natural Science Foundation of China (nos. 51406033 and 21306022), University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province (no. UNPYSCT-2015075), and the Natural Science Foundation of Heilongjiang Province (no. LC2012C35). Besides, a very special acknowledgement is made to the editors and referees who made important comments to improve this paper.