Application Of All-glass Evacuated Solar Collector Tube In Solar Chimney Plant

Solar energy is an inexhaustible and environmentally-friendly renewable energy source. Solar chimney power generation is a new technology to use the greenhouse effect technology, chimney technology and turbine technology synthetically, and it can develop and make use of the solar energy efficiently. However, the large-scale commercial applications for solar chimney power generation have been postponed for the disadvantages, e.g. low conversion efficiency, less engineering safety, and high construction capital caused by the higher chimney. The airflow velocity field and temperature field distribution play an important role in the system energy conversion and the turbine power output.This thesis firstly analyzes the characteristics of all-glass evacuated solar collector tubes used to absorb solar heat radiation and to heat up the inner air quickly. Secondly, it discusses the parameter variation (e.g. temperature, velocity and pressure) under different solar radiant intensity when the airflow is heated up, and finally investigates the influence of the solar chimney system on electrical efficiency.The principle, characteristic and main configuration of the solar chimney power generation system are introduced. A solar chimney can be formed by four main components: solar collector, chimney, turbine and energy storage layer, and detailed description and performance analysis have been investigated especially.The distribution characteristic referring to the pressure field, the velocity field and the temperature field have been simulated using the FLUENT 6.3 software, and the effect factors of the flow field and temperature field have also been analyzed accordingly. The computer code for all-glass evacuated solar collector tube is built based on the Physical model and the interface of FLUENT, moreover, the boundary conditions are set on the basis of three different air stagnation states. The pressure field, the velocity field and the temperature field distribution are analyzed and observed distinctly under different solar radiant intensity of 600 w/m~2,800 w/m~2,1000w/m~2 and 1200w/m~2 which employ different location mode of the evacuated solar collector tube(e.g. center, top, middle and bottom).In conclusion, the mathematical model proposed in this paper is based on the reasonable hypotheses referring to the airflow in the solar chimney system. Numerical investigation have been performed to simulate the pressure field, the velocity field and the temperature field using the common commercial CFD software FLUENT 6.3. With the other conditions fixed, the performance characteristic are obtained considering different influence of the temperature, the pressure and the velocity of air with varied solar energy radiation intensity. It is hoped that the simulated results should provide the design instruction and operation optimization for the next experimental study.