Study On Water-saving Technology Of Water Distribution Systems For Existing Buildings

Energy-saving and ejection-decreasing have been put forward in the eleventh five-year plan, and the city structures are changing to green buildings. So it is necessary to save water and energy in order to promote the healthy and harmonious development of the whole society. It is one of the important work to save water and energy for existing buildings. The objective of traditional building design is to guarantee the safety of water supply. In addition, the existing buildings have large areas, old equipment and imperfect functions, which lead to heavily wasting water. Known from the description of this paper, there is still large water-saving and energy-saving room for water distribution systems of existing buildings. In this paper, a water-saving method has been brought forward with a view to solve the phenomenon of over-pressure outflow. The computer simulation method has been adopted to calculate the water-saving improvement process. The research would give reference for water-saving improvement of existing buildings and the design of water supply for new buildings, as well as some suggestion for the revision of the design code.The hydraulic monitoring method has been put forward in this paper. The flow data loggers and pressure data loggers have been set to collect data with one minute interval synchronously, which were installed at the beginning of horizontal branch pipes. The stochastic end-use water demand model has been established, which describes that water use process could be approximated as rectangular pulse process. The model uses water intensity, duration, and frequency to calculate water demand. Duration and frequency can be described by stochastic functions, which could be retrieved by monitoring data. Combining the stochastic end-use model with EPANET, the hydraulic model of water distribution systems for existing buildings have been built. The stochastic end-use water demand model produced node demands with one minute interval to do EPS, so as to solve the problems of short duration and strong stochastic water use.The harm of over-pressure outflow and solving methods have been introduced. The sorts, theory and installment of water supply reducing valves have been described. The water-saving rate and energy-saving rate could be calculated by the hydraulic model of water distribution systems for existing buildings. The comprehensive assessment of the effect of water-saving reform in water distribution systems of existing buildings has been established. The hydraulic model of water distribution systems for existing buildings has been applied to washrooms of a student dormitory in a university of Harbin. The stochastic washing tap water demand model was built and the hydraulic model was used to simulate over-pressure outflow of water distribution systems. The results showed it was heavily over-pressured within dormitory. The relationship of pressure and outflow was measured. According to the design code, limited pressure of nodes has been put forward to prevent over-pressure outflow, considering safety water supply and water-saving. Due to centralized water use and long idle time, water distribution systems not only need to reduce static pressure, but also need to limit dynamic pressure, in order to protect water instruments and control leakage. So reduce valves have been selected to the project, and have been installed optimally. Water-saving rate and energy-saving rate have been calculated by simulation and the result of assessment of the effect of water-saving reform is excellent.