Research on bypass pipeline design of air conditioning chilled water primary pump constant-frequency systems

In this paper, a simplified mathematical model of the air conditioning chilled water primary pump constant-frequency system is established using the circuit simulation method. This model can be used to calculate the total flow rate, pump head, user side flow rate, bypass pipe flow rate, and the minimum resistance coefficient of the bypass pipeline of the primary pump constant-frequency system. By analysing the temperature difference between the supply and return water on the user side, the calculation formula for the design bypass flow rate of the bypass pipe when multiple chillers operate simultaneously is derived. It is found that under partial load conditions, when the temperature difference between the supply and return water on the user side is greater than the design temperature difference, the design bypass flow rate of the bypass pipe is greater than the rated flow rate of the largest single chiller.