An on-off regulation method by predicting the valve on-time ratio in district heating system

Good room temperature control is beneficial for users' thermal comfort and health. It also helps reduce energy consumption and carbon dioxide emissions inside the buildings. However, there are certain limitations with the current thermostatic valves commonly used in central heating systems, especially the ones used in China, since they cannot satisfactorily adjust room temperatures. In response to such problems, an intelligent on-off regulation method is presented in this paper. The room temperature can be maintained by controlling the valves according to the on-time ratio predicted by this method. The on-time ratio is predicted for each cycle, and the current ratio is decided by checking a 6-order fuzzy-control table with room temperature deviations in the last step, as well as room temperature set points. Two major factors that may affect the controlling effect are also discussed: the length of the controlling cycle and the design of the fuzzy-control table. A proper controlling cycle and optimal controlling table have been worked out. Besides, the robustness and application effectiveness of this strategy have also been discussed in this paper. The results show that the room temperature can be maintained in the range of set point +/- 0.5 A degrees C by using this method in different conditions. It is fair to say that this method is a stable, reliable and advanced controlling method, with robust and accurate control.