A heliostat is one of the most important implement in a solar power tower system. A heliostat accounts for almost 40% of all the installation cost for solar power tower generation facilities, also its demand is growing as the solar power generation market is rapidly growing. The heliostat model is designed and developed in this study considering the development of commercial heliostat element technology. Also the optical performance is compared using the flux mapping method. It is studied whether or not it is economically feasible and it can be used in the real solar power tower system.
Two types of the heliostat are made. One is the primary model (the conventional type), and the other is the weight-reduced model. The driving part is the same, only the reflection part is changed. The weight-reduced model not only is easier to install in the plant, but also reduces the installation costs. The solar power tower plants which is commercially available should have thousands of heliostats installed. In order to reduce the installation time and cost, the weight-reduced model is needed to be developed, analyzed, and tested their performance.
The optical performance is divided by two parts, one is the flux distribution and the other is tracking error. For the optical performance test, the flux mapping method is used. The modeling code that is previously owned by KIER is modified using the ray tracing method and the Gaussian interpolation with the field data from the Daegu site.
When the concentration ratio is high, the heat flux also becomes high. However, it means the temperatures at the radiometer and the target are also high. If they are not able to withstand in the high temperatures, we need to be careful when the devices are selected.
When the heliostats were built in Daegu area, the heliostats were built on the left side of the target because there was no large space. It was not installed in a very good geographical location, also the heliostats had the cosine effect. But the average tracking accuracy of the experiments are less than 3 mrad. If the other conditions are good, it could be expected less than 3 mrad in whole experiments.
The weight-reduced model could be efficient in installation and economically effective. However, the weight-reduced model is easy to be warped and has shorter life than the original model. We need study more about these problems in the future.