Discussion on temperature difference range between heating supply and return water of two-pipe air conditioning water systems

For the two-pipe air conditioning water system in hot summer and cold winter zone, the transmission and distribution pipe network and the terminal are determined according to the summer working conditions. Under the determined electricity price policy, the greater the temperature difference between the supply and return water in winter is, the better the energy saving and economy is, but due to the influence of the structure of the terminal heat exchange equipment on the water flow state requirements, the temperature difference between the supply and return water cannot be increased indefinitely. Combined with the energy saving requirements, the laminar flow Reynolds number, the heat exchange coefficient of the terminal heat exchange equipment and the adjustment accuracy of the valve of the two-pipe system, taking a practical project in Shanghai as an example, the temperature difference of 10 to 25 ℃ between the winter air conditioning supply and return water of the project is obtained by using the test algorithm, which can be used as a reference for similar engineering designs.