轴上和轴外的定日镜对准策略的比较A COMPARISON OF ON-AXIS AND OFF-AXIS HELIOSTAT ALIGNMENT STRATEGIES.pdfVIP

A COMPARISON OF ON-AXIS AND OFF-AXIS HELIOSTAT ALIGNMENT STRATEGIES ScottA. Jones Sun+Lab Sandia National Laboratories PO BOX5800-0703 Albuquerque, NM 87185 ABSTRACT Heliostat installation and alignment costs will be an important element in future solar power tower projects. The predicted annual performances of on- and-off axis strategies are compared for 95 m2 flat-glass heliostats and an external, molten-salt receiver. Actual approaches to heliostat alignment that have been used in the past are briefly discussed, and relative strengths and limitations are noted. The optimal approach can vary with the application. 1. INTRODUCTION All costs must be minimized in the quest to build competitive solar power plants. For power tower plants, the cost of heliostat installation and alignment are significant. This paper provides information about the performance and practical issues associated with different alignment approaches. Although not exhaustive, this work opens a topic that may ultimately be helpful in minimizing the overall system cost of new plants. Fig. 1 Lug0 heliostat at Solar Two. Original Solar One The annual performance predictions discussed in this study receiver is visible in the background. were originally undertaken to support the Solar Two project. In addition to predicting the annual performance Additionally, experiments showed the nominally flat, but expected of the Lug0 heliostats, suggested times for off-axis somewhattwisty, Lug0 mirror modules prevented the use of alignment were presented [11. One hundred and eight, 95