Analysis of chilled water hydraulic condition of external ice melting open systems for district cooling

 For the external ice melting open system, gives the judgment of negative pressure condition of the chilled water pipeline in the upstream series system of the chiller and analyses the possible position of negative pressure point in the system. For the form of the secondary pump system, deduces the relationship between the resistance of the ice pool inlet pipe regulating valve and the height difference between ice pool liquid level and the highest point of the pipe network in order to keep positive pressure under different operation conditions. Provides the calculation formulas of the minimum resistance of the valve and the pump head under positive pressure operation. Puts forward the regulation strategies of valves with different functions. Finally, calculates the values of valve resistance and pump head under different operation conditions through actual project cases and performs the valve selection calculation.