An Experimental Study on the Flow Characteristics of Electric Control Ball Valves and the Energy Saving Effects of Variable-Frequency Water Pumps in Building Central Heating Systems

Central heating systems typically exhibit high energy consumption and carbon emissions. Within these networks, the flow characteristics of electric control ball valves are critical for precise thermal regulation. Theoretical research on this topic is already extensive. However, further investigation through field tests is needed to elucidate both the intrinsic flow behaviors of these valves and their coupling with proportional-integral-derivative (PID) control, as well as the energy efficiency comparison between variable-frequency water pumps and valve-based modulation. Therefore, a semi-physical smart heating simulation and experimental platform was proposed, and corresponding field tests were conducted. The valve was subsequently applied to both household-level room temperature regulation and building mean room temperature regulation, and the room temperature responses under various PID parameter settings were also evaluated. The research results indicate that when the opening degree of the electric control ball valve is within the range of 10% to 60%, the valve can maintain sufficient regulation sensitivity. For household-level room-temperature regulation, increasing the proportional gain from P = 10 to P = 20 under proportional-only control accelerated the thermal response and shortened the room-temperature rise process. At P = 10, introducing the integral action prolonged the rise time, while the addition of derivative action further delayed the thermal response, with a larger derivative parameter producing a more pronounced damping effect. For building-level mean room-temperature regulation, the heating response was relatively rapid, whereas the cooling process exhibited a slower and asymmetric temperature decay due to the thermal inertia of the tested building. Compared with valve opening modulation, variable-frequency operation reduces pump input power by 60.12%, whereas valve opening modulation yields only a 7.19% reduction. It indicates that regulating flow by adjusting pump frequency is more energy-efficient than relying only on valve opening modulation under the tested operating conditions. These findings provide a practical basis for the efficient operation and optimization of central heating systems.