Study On Flexible Transmission System Of High-intensity Solar Energy

Solar energy in space has several advantages,such as high energy intensity,no shelter,and nothing to do with the atmosphere and time,so it has been widely studied in the utilization of space energy.However,there are two efficient ways of centralized collection,wireless transmission,reception,storage and conversion of space energy: microwave-based and laser-based wireless energy transmission.The overall efficiency of these two methods is not high enough because of too many times of energy conversion.Therefore,in order to further improve the efficiency,this paper proposes a flexible transmission system of high-strength solar energy with simple structure,high transmission efficiency,light weight and flexible transmission.In this paper,a single optical path in the array system is selected for research.The plane Fresnel lens is used to converge the sunlight,and then it is coupled into the optical fiber bundle for steering and transmission,which is transmitted to the energy receiving end by the transmitter.From the theoretical design and calculation,the parameters and energy transmission efficiency of each part are obtained.Then,a flexible transmission system of high-strength solar energy is designed and built,and then experimental research is carried out to explore the performance parameters of the system.Finally,the main conclusions of this paper are as follows:(1)Firstly,in the actual situation(assuming that the angle between the incident light and the incident interface of Fresnel lens is 4),the inclination angle of Fresnel lens and the deviation angle of the outgoing light increase with the increase of the radius of the lens ring.The growth rate of the tilt angle is nonlinear,and the growth law of the deviation angle of the emergent light can be regarded as linear.Considering the selection limit of the angle of light deviation(18),a lens with a focal length of 100 mm can be selected.At the same time,the transmittance of Fresnel lens with a focal length of 100 mm and the variation law of light power before and after the lens with the lens radius are obtained by calculation.The results show that the decrease of transmittance of planar Fresnel lens with the increase of lens radius can not be ignored.Secondly,the main factors of optical fiber energy transfer efficiency are end reflection loss,material absorption loss,total reflection loss at the interface between core and cladding and filling coefficient.Finally,the theoretical energy transfer efficiency of the energy transmitting end of the high-strength solar energy flexible transmission system is obtained.(2)Design and build a platform of high-intensity solar energy flexible transmission system.After experimental study,it is found that the transmission distance of energy has great influence on the efficiency of high-intensity solar energy flexible transmission system.The energy transfer efficiency of the system decreases with the increase of energy transmission distance,and the decreasing rate keeps increasing.The reason is that besides the energy loss caused by air and dust,the light outside the aspheric converging lens can’t be collected and utilized,resulting in additional energy loss.The incident angle of optical fiber decreases,and the energy transmission efficiency increases.When the incident angle of the optical fiber is constant,the shorter the length and the larger the diameter of the optical fiber bundle,the smaller the energy loss and the higher the energy transmission efficiency of the flexible transmission system of high-strength solar energy.Meanwhile,the experimental efficiency results of the optical fiber bundle C are in good agreement with the theoretical model.Under different bending conditions,the emission efficiency of the energy emitting end of the high-intensity solar energy flexible transmission system is similar,among which the non-bending form has the highest efficiency,so it can ensure flexible transmission.Different droplet densities have obvious negative effects on the energy transmission efficiency of high-intensity solar energy flexible transmission system.Under a certain energy transmission distance,the type and area of the converging lens at the energy receiving end of wireless energy transmission of high-energy sunlight will have different effects on the energy transmission efficiency of the system.At the energy receiving end of the system,a larger plane Fresnel lens(150mm in diameter)is used to receive and converge the energy,which can increase the energy transmission efficiency of the system.When the aspheric converging lens is used for convergence,the longer the energy transmission distance is,the lower the energy transmission efficiency of the system will be after a certain transmission distance is exceeded.(3)This paper also considers the influence of high temperature on optical fiber,and pays attention to the temperature change of optical fiber bundle in the process of energy transmission.The heat balance of the optical fiber is analyzed by the micro-element method,and the variation law of energy density with the diameter of the optical fiber under different plane Fresnel lens diameters is obtained.Firstly,the larger the radius of the plane Fresnel lens,the larger the geometric concentration ratio and the higher the energy flow density.Secondly,the variation law of steady-state temperature with fiber diameter was obtained when different temperature control coatings were added with different plane Fresnel lens diameters(23mm,25 mm and 30mm).The larger the Fresnel lens radius is,the higher the geometric concentration ratio and the higher the energy flow density,which leads to more energy being converted into heat,and the steady-state temperature will increase.Finally,the comparison shows that the steady-state temperature of white paint SR107 temperature control coating is the lowest.The system studied in this paper can be applied not only to the energy supply of space satellites,but also to the photovoltaic base on the ground,with high application adaptability and high research value.