Performance Study Of Linear Fresnel Lens Coupled Compound Parabolic Concentrato

In the current soaring demand for energy,the capacity of traditional energy has been endangered,and with the rapid development of science and technology,the efficient use of renewable energy becomes more and more important.In response,countries around the world have launched energy policies and committed themselves to finding efficient,low-cost and clean alternatives to renewable energy.This field has also become the focus of many scholars.At present,as one of the most potential and promising new energy sources,the collection and application of solar energy has become a popular target.In order to broaden the application field of solar energy,a linear Fresnel lens coupled with a standard compound parabolic compound（S-CPC）surface structure（LFL-CPC）is constructed based on the edge ray principle and optical principle.And,through the establishment of laser experimental device to verify the actual concentrating ability,the optical performance and the annual radiation acquisition of S-CPC were analyzed.Finally,a LFL-CPC surface shape which is more suitable for practical engineering application and has practical application prospect is obtained.The main research contents of this paper are as follows:（1）Based on linear Fresnel lens principle and optical principle,a special linear Fresnel lens structure is proposed.Based on analytic geometry and edge ray theory,the surface shape of S-CPC plane absorber was derived,and finally the surface shape of LFL-CPC was constructed.Based on Monte Carlo ray tracing method,and an experimental laser device was built to verify the feasibility of LFL-CPC surface structure.（2）By analyzing the geometric parameters of LFL-CPC,the surface structures of LFL-CPC under six different geometric focus ratios（C_g）were obtained,and the optical advantages of LFL-CPC were analyzed.Compared with S-CPC,it is found that the addition of linear Fresnel lens structure can realize the focus of light in the whole angle and the whole year,which solves the problem of limited light angle of S-CPC.This also avoids the"sudden"spotlight in January,February,October,November and December,which can improve the"adaptability"of CPC to different external environments,and ensures the stability and continuity of CPC in actual operation.（3）Comparing the optical efficiency and average optical efficiency of LFL-CPC and S-CPC with six different structures,it is found that the surface shape of LFL-CPC reaches the critical value when C_g is about 2,which is equivalent to that of S-CPC.When C_g is in the range of 1.4-1.8,its optical efficiency and average optical efficiency are higher than S-CPC.The average optical efficiency values are increased by 44.8%,20.1%and 3.4%compared with S-CPC,respectively,which indicates that suitable C_gstructure can bring higher optical efficiency to CPC.（4）Based on the principle of direct radiation and the analysis of regional meteorological data,the LFL-CPC surface shape also reaches the critical value when C_g is 2,which is similar to S-CPC.When the C_g of LFL-CPC was in the range of 1.4-1.8,the total radiant energy obtained on the absorber under unit optical port increased by 28.1%,14.8%and 3.9%,respectively,compared with that of S-CPC.As for the radiation energy obtained per unit absorber,combined with the actual heat demand（the heat demand is high in spring and winter）,it is found that when C_g is 2,the radiation energy obtained by LFL-CPC on the absorber in spring and winter is the highest,with a value of 2771.9 MJm^-2a^-1.Then,based on the comparison of energy distribution between LFL-CPC and S-CPC absorbers with C_g is 2,it is found that LFL-CPC can have smoother energy distribution,better surface uniformity and lower local energy peak distribution（the maximum difference between the two is about 125032W/m²）when the average uniformity value of LFL-CPC is the same as that of S-CPC,which is0.086.Thus indicating that LFL-CPC has actually better practical feasibility.