Abstract: As a system with the lowest cost among the mainstream concentrating solar power（CSP）methods，linear Fresnel system has a promising development prospect. In addressing the concentrating uniformity and thermal cost-effectiveness of Fresnel system，Tra- cepro（an optical software）and COMSOL（a finite element software）are coupled to simulate the focusing process of solar concentrat- ing system，and the design method for a novel trapezoidal multifocus Fresnel lens condenser is proposed. By uniformly dispersing the foci of lens and reflectors，concentrating uniformity of the collector is improved，and risks related to efficiency and safety caused by un- even heat collection is mitigated. Moreover，the use of a novel coupled strain boundary heat source improves the accuracy of simulation while simplifying simulation. The results show that at under an inlet temperature of 423.15 K and a flow velocity of 0.2 m/s，the surface temperature difference of collector tube is only 1.1 K，and the maximum circumferential thermal strain is 0.72 cm. Under the same working conditions，the surface temperature difference of a traditional Fresnel lens concentrating system is 71 K，and the maximum strain is 2.0 cm. Therefore，the trapezoidal multifocus Fresnel lens concentrating system has better safety，and will play a positive role in the promotion of CSP technology.

Key words: linear Fresnel, trapezoidal multifocus, optical software, finite element software, thermal efficiency, solar power

摘要： 线性菲涅尔系统是主流光热发电方式中成本最低的系统，有良好的发展前景。针对菲涅尔系统聚光均匀性和热经济性问题，采用光学软件Tracepro和有限元软件COMSOL耦合的方法模拟太阳能聚光系统的聚焦过程，提出了一种新型梯形多焦点菲涅尔透镜聚光器设计方法。通过均匀分散透镜和反射镜聚光焦点，提高集热器聚光均匀性，降低因集热不均而产生效率问题和安全性问题的风险，并采用新型耦合应变的边界热源，可以在简化模拟的同时提高模拟的准确性。结果表明在入口温度为423.15 K、流速为0.2 m/s下集热管表面的温差仅为1.1 K，最大周向热应变量为0.72 cm，同工况下的传统菲涅尔透镜聚光系统表面温差为71 K，最大应变为2.0 cm。因此，梯形多焦点菲涅尔透镜聚光系统有更好的安全性，对光热发电技术的推广有积极的作用。

关键词: 线性菲涅尔, 梯形多焦点, 光学软件, 有限元软件, 热效率, 太阳能