Pinpoint accurate adaptive structures for heliostats made from high performance concrete for central tower power plants

为中央塔式发电厂采用高性能混凝土制成的定日镜精确定位自适应结构

• 批准号: 389020360
• 负责人: Professor Dr.-Ing. Peter Mark
• 金额: --
• 依托单位: Lehrstuhl für Massivbau
• 依托单位国家: 德国
• 项目类别: Research Grants (Transfer Project)
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/389020360?language=en
• 关键词: Pinpoint; accurate; adaptive; structures; heliostats

In the second funding period of SPP 1542, the applicants recently work on "Light deformation-optimised shell structures made from micro-reinforced UHPC for parabolic trough power plants". The investigations revealed high-performance concrete being promising for utmost precise and stable structural members. So far, specific action effects, determined by wind tunnel testing and a holistic accuracy criterion for solar collectors were derived. Additionally modular FE-models were set-up, that respect an effective stiffness of complex structures e.g. by means of local void formers placed according to experimental results. These are complemented by multi-level optimisation with a priori variance-based sensitivity analysis. Finally a specific concrete has been composed matching all demands of persistent shape and tensile strength to realize a prototype (3,2 x 2,2 m). Now, these insights and strong interest from the solar industry encourage a transfer to similar fields of application namely heliostats, envisaged to be manufactured in serial production and industrial precision. The objectives are to further increase the accuracy, to establish adaptive collector shapes consequently and to augment the entire production chain. Conventional reinforcement shall be reduced or even avoided by pre-stressing. That way cost-efficient production for a wide range of applications can be achieved. Among these, heliostats are solar collectors able to biaxially track the sun and to focus solar irradiation on a central receiver at the solar tower. Regarding reflection properties up to tenfold precision has to be achieved compared to parabolic troughs. However, adaptive manufacturing is indispensable, since the heliostats geometry, more precisely its paraboloidal surface, widens with the distance to the focal point. Envisaged are circular shells with outer bracings composed from repeated segments of similar shape. In order to realise a fully equipped and geometrically verified full-scale prototype in cooperation with industrial partners, theoretical and production-based prerequisites must be met before. Key is a multi-scale optimisation-based structural design that is sustainable, highly accurate and robust against uncertainties arising from geometry and material. Governing geometric variations are identified by means of few control parameters and enable to design an adaptive and cost-effective precision formwork allowing for finishing inner surfaces subsequently. The prototype will be circumferentially pre-stressed and possesses reflectors as well as mature links to the substructure equipped with measuring devices. Expected is a shell surface with an effective thickness of 2-3 cm (average of shell and bracings) that is highly accurate up to the submillimetre range.

在SPP 1542的第二个资助期，申请者最近致力于“抛物线槽发电厂用微增强超高性能混凝土制成的轻变形优化壳体结构”。研究表明，高性能混凝土有望成为最精确和稳定的结构构件。到目前为止，通过风洞试验确定了具体的作用效应，并得出了太阳能集热器的整体精度标准。此外，还建立了模块化有限元模型，该模型考虑了复杂结构的有效刚度，例如通过根据实验结果放置局部空洞成形器。通过基于先验方差的敏感度分析的多水平优化来补充这些优化。最后，配制出满足所有持久形状和抗拉强度要求的混凝土，实现了原型(3，2×2，2米)。现在，太阳能行业的这些洞察力和浓厚的兴趣鼓励转移到类似的应用领域，即定日镜，设想以批量生产和工业精度制造。其目的是进一步提高精度，从而建立自适应的收集器形状，并扩大整个生产链。应通过施加预应力来减少甚至避免常规钢筋。这样就可以实现具有成本效益的广泛应用的生产。其中，定日镜是一种太阳能收集器，能够双向跟踪太阳，并将太阳辐射集中在太阳塔的中央接收器上。关于反射特性，与抛物线槽相比，必须达到十倍的精度。然而，自适应制造是必不可少的，因为定日镜的几何形状，更准确地说，它的抛物面，随着距离焦点的距离而加宽。设想的是带有外支撑的圆形壳，由形状相似的重复段组成。为了实现与工业合作伙伴合作的设备齐全和几何验证的全尺寸原型，必须满足理论和基于生产的先决条件。KEY是一种基于多尺度优化的结构设计，可持续、高精度，并对几何和材料引起的不确定因素具有健壮性。通过几个控制参数识别控制几何变化，并能够设计出自适应且经济实惠的模板，从而允许随后对内表面进行精加工。原型将采用环向预应力，并具有反射器以及与配备测量设备的子结构的成熟连接。预计壳体表面的有效厚度为2-3厘米(壳体和支撑的平均厚度)，精度高达亚毫米。