The Parametric Optimization Of The Solar Heating System With Seasonal Water Pit Storage

The growing need of energy has caused a question on how to well apply the renewable energy. For recent years, a large number of solar thermal systems appear along with the restrictions to application. How to further decrease the investment, improve the efficiency and increase the solar fraction has come into focus.First we measured a real project which is a solar heating system with seasonal storage in Shandong, China. By analyzing the project, we found that the system didn’t fully embody the energy conservation advantages of the solar system due to the design and control strategies. Thus, improvements should be proposed correspondingly. Meanwhile, we built a model of the system in TRNSYS and verified it based on the test data obtained from the project in Shandong.Next, the impact factors of the solar heating system with seasonal water pits storage were analyzed using the validated model. To minimize the influences of uncertain factors, the optimal height-diameter ratio of tank and water pit were brought in. With regard to the impact factors, the remarkable technological economic design parameters were selected such as the collector areas, the thermal storage operation temperature, the volume of collection water pit, buffer tank volume and the thermal storage starting time. The orthogonal schedule was chosen to analyze the TRNSYS simulation. To reduce the impact of high weighting factors on the low weighting factors, the mixed level table L36(63*33) was selected in the orthogonal test and the random level orthogonal table was chosen in the orthogonal table design.Finally, the related technical and economic parameters data were established based on the initial cost estimate index of the system equipment, operating cost and so on, which are the parameters optimization of the solar heating system with seasonal water pits storage. The optimization mainly uses the equations in criterions; matches uncertain parameaters between collector area and building area then gives their ratio ranges. The matching ratio range between thermal storage water pit volume and collector area, buffer tank volume and collector area were given by coupled with the criterions. The range data between the initial cost and operating cost were provided combined with the TRNSYS simulation in the different levels by using the orthogonal table L25(56). Hence, the best optimal values were given in the solar heating system with seasonal water pits storage in different regions.