Solar absorber


The absorber is one of the important components of the […]

The absorber is one of the important components of the solar thermal power generation system. According to the different heating methods of the working fluid, it can be divided into two types: indirect heat absorption type and direct heat absorption type.
The indirect endothermic absorber can be divided into an open type and a window type according to whether the heat exchange chamber is sealed or not.
According to the structure of the absorber, it can be divided into a tubular absorber and a heat pipe absorber.
The tubular solar absorber can receive sunlight in various directions, and the arrangement and tracking requirements of the heliostat are not high, and the manufacturing and processing processes are simple, which is beneficial to the large-scale utilization of solar energy. However, since the heat absorption is exposed to the surrounding environment and the radiant heat loss is large, the heat efficiency of such an absorber is relatively low. The tubular absorber has been described and studied in detail. The successful application of tubular solar absorber power plants is the US tower thermal power generation and play. Use water as a heat carrier and play. A molten salt medium is used. Compared with the tubular absorber, the heat pipe absorber can reduce the quality of the solar heat absorber and improve its thermodynamic performance, but its application is generally limited, and the free-loading state and heat transfer capacity of some high-temperature heat pipes are prone to be limited. , the heat transfer coefficient is small, the heat transfer effect is not ideal and other defects. The direct endothermic solar absorber is also called a cavity absorber. The absorber is characterized in that the inner surface of the cavity absorber has the characteristics of a black body, which greatly improves the absorption capacity of the incident solar energy and the flow of the working medium. Heat transfer and incident light heating the heating surface occur on the same surface, reducing the dependence on the wall material. However, the light inlet of such absorbers is often limited, which increases the difficulty in arranging the heliostat field to some extent. At present, the operating temperature of the cavity absorber can reach up to 1300 ° C, and the pressure of the absorber with high pressure window can reach 30 atm.
The direct endothermic solar absorber can be divided into a non-pressure chamber type and a pressure chamber type. In order to further improve the outlet temperature of the working fluid and reduce the requirements on the wall material of the cavity, a solar particle absorber is proposed. The heat exchange mode of the absorber is to first let the working medium in the absorber cavity and the heat transfer carrier molecule. Or ion clusters, and then convert the solar radiation energy absorbed by these carriers into thermal energy of the working gas by heat conduction, convection and radiation. In such an absorber, the highest temperature occurs in the working fluid rather than the absorber wall, and due to the heat exchange of the carrier particles, the overall heat exchange efficiency of the working medium is improved, thereby improving the performance of the absorber.