Study On The Optimal Design Of One Centralized Solar Heat Water System

At present, there is a lot of research on concentrated solar hot water system.Heating collection section of centralized solar hot water system always classified by unit, namely there is only one system corresponding to a unit, and most of the systems are direct system whose hot water storage tank generally set on the top of the building. But the design or research of changing original unitary multi-centralized solar hot water systems to be a holistic solar hot water system is little.This study is aim at the above problem.Firstly,In this paper, analyzed the background and significance of the centralized solar water heating system, and then the applicability of the it in Xi’an area.Secondly, studied the system from three aspects such as the classification, composition and layout,combined with the characteristics of Xi’an region.Finally, the research model of integrated solar hot water system is established, and then the studies on collection and heat supply were conducted to investigate the system optimization design respectively.In the heating collection section, mainly uses two methods of theory calculation and software simulation by TRNSYS to analysis the value of some parameters of solar hot water system in the area of heat calculation,such as cold water temperature calculation, occupancy rate, solar guaranteed rate, exploring how to achieve the optimal heat collection area.In the heating supply section,optimize supply and return water pipe diameter of the heating pipe network to accurate the calculation of pipeline pressure drop through the main methods of theoretical analysis and programming calculation at first.And then set the pressure drop line of hot backwater pipe as control line to adjust the pressure of branch nodes grafted from main nodes to ensure the smooth work of heat supply network.The researches indicate that:it is more reasonable to calculate the concentration of solar heat collection area after parameter optimization;holistic system was more stable than unitary system after introducing the concept of occupancy; The selection of the value of cold water calculated temperature in system according to annual average temperature was more reasonable; The introduce of occupancy and the optimization of cold water calculated temperature improve the solar fraction in system; The adoption of programming method for pipe network optimal design well terminated the repetition and complexity in calculation of heating pipe network circulation flow,the accuracy was improved a lot, and the poor flow in heating circulation line was solved.