Discharge Coefficients of Hole in the Cartridge of Constant Flow Valve

摘要

It is very important factor to control the flow rate of hot water in the large apartment complex and building. The uniform distribution of hot water to each apartment is also required to control the heating load and save energy. Even though the apartment is top or bottom floors, the heating flow rate should be similar in each apartment. For this purpose, the constant flow valve is used with the temperature control unit. There is variable flow path to adjust flow rate constant even though the inlet pressure of the valve and pressure difference is changed. As the inlet pressure of the valve is larger (large pressure difference), the flow path is smaller. As the inlet pressure of the valve is smaller (small pressure difference), the flow path is larger. So the flow rate through the flow control valve becomes constant. The flow rate data in the variable flow path is required to design the constant flow valve. The flow path is composed of small holes and complex triangle shape. The flow pattern in a hole is completely different with that of the orifice flow meter because the hole is quite small and it is in the vertical cylinder wall. The flow data in those flow paths is not available in the literature. The performance of this control valve is affected by the area and discharge coefficients of holes in the cylindrical cartridge. The flow inside of the control valve is very complex and different from the differential flow elements. If the discharge coefficients of the differential flow meters are used in the design of control valves, the performance of this control valve will not be obtained as expected. The discharge coefficient data of the orifice hole in the cylindrical cartridge are required for the optimum design of the control valve. For the basic study of the variable flow path in the constant flow valve, the hole size and flow direction effects were investigated.