On October 5, 2018, the small centralized solar heating demonstration system developed by Solar Thermal Energy department of Institute of Electrical Engineering of the Chinese Academy of Sciences (IEECAS), in the absence of any auxiliary energy, has been running for more than three months to supply clean heat for Jianguo Hotel located in Zhangjiakou city of Hebei province, with a heating area of 3,000-5,000 square meters. IEECAS has successfully promoted the centralized solar heating technology developed for many years to demonstration applications.
Solar tower heating system
The heating system is mainly composed of a solar tower concentrating system (heliostat field), a cross-season water storage system, and an automatic control system, which can realize solar energy collection and storage throughout the year, and effectively solve the problem of clean heating in the winter for the buildings. The heliostat has a aperture area of 760 m2 and a cross-season water storage capacity of 3000 m3, which meets the winter heating requirements of the 3000 m2 building in the park. The cross-season heat storage mode was operated from April to the beginning of October 2018, and the heating mode was operated from the middle of October 2018 to the present. The all key components involved in the system are from the proprietary intellectual property of the Chinese Academy of Sciences.
Compared with other solar heating systems, the designer fully uses the mountain topography to deploy the heliostats as the solar concentrator, at the same time, the volumetric heat absorbers and tube-tube heat absorbers have been developed to use porous materials for high efficient heat collection. According to the calculation, when the outlet water temperature of the system reaches 90℃, the thermal efficiency in winter can reach more than 50% (converted to the solar aperture area).
Secondly, the system uses an optimized water storage system to achieve efficient and low-cost heat storage. Through the inter-season hot water storage system, coupled with inclined layer control technology and low heat loss technology, the system is able to reduce the mixed heat loss of the hot water storage body. Ensuring that the construction cost of the hot water storage body is not higher than 330 yuan/m3, the discharged (taken) heat can reach more than 80% of the stored heat. Taking this heat storage body as the experimental research object, IEECAS established the dynamic heat transfer model of natural convection and soil coupling in large space, which lays a technical foundation for the thermal design of large-capacity and inter-season hot water storage.
In addition, IEECAS also developed a full-system dynamic thermal performance simulation optimization platform from solar radiation, heat collection to building load. The platform can reflect the real-time changes of key parameters of the system when the conditions of solar irradiance changes and building load changes, system parameter configuration and simulation platform with precise control logic.
The solar thermal energy department led by Prof. Wang Zhifeng, researcher of IEECAS has long been committed to the research of solar thermal power generation technology (CSP).In this project, he learned from some CSP technology and applied the solar concentration and heat absorption technology to the building heating system, which played a leading role in the domestic industry. The stable operation of the demonstration project laid the foundation for the smooth implementation of the renewable energy supply of the Zhangjiakou Winter Olympics in 2022 and the pilot project of the Chinese Academy of Sciences.
Solar collection system