基于感阻理论的暖通空调水管网动态特性分析-analysis of dynamic characteristics of hvac water pipe network based on resistance sensing theory.docx

AbstractThis paper studies the hydraulic characteristics of the closed water network in the HVAC system. The dynamic characteristics is mainly reflected in the transient changes of pressure and flow over the time when the water system is running at the variable conditions or when the pump start and stop. The dynamic characteristics of the pipe network is affected by pump characteristic, network topology, network impedance distribution, constant pressure level, the special characteristics of equipment in the system and so on. The characteristic parameters in the hydraulic changing process, such as pressure fluctuations, flow changes, the system maximum pressure value, variable conditions stable time, is an important basis that reflected Whether the system is operating safety, flow control is effective, fan coil unit and other equipment control strategy is feasible.Based on the theory of rigid pipe and drew on the electrical network theory, we divided the characteristics of the common elements of the pipe network into two major categories of resistive and inductive, and put forward the method of simplifying the pipe network based on the equivalent inductance -resistance model. By a combination of numerical simulation and actual experiments, we proposes to fit flow curve with S-shaped function during the pump start process, deduced the lift curve equation and put forward the method of exterminating lift fluctuations and the value of the maximum pressure. We also study the buffer mechanism of the ideal inductance element. with the aid of CFD software ,we analyze hydraulic cushioning properties of the buffer tank under variable flow conditions, puts forward the evaluation index of tank buffering capacity. Study the impact of buffering capacity affected by tank structure, flow rate, import connection position and some other factors ,in order to obtain the beneficial reference for the buffer tank structure design, type selection in the actual engineering .Another important