Development of a dynamic simulator for the evaluation of DHC plant operation

The energy consumption of air conditioning for the business and home use is about 9% of the total energy consumption in Japan. It is effective for the energy conservation to reduce the consumption. The reduction of air conditioning energy has been promoted mainly by the development of high efficiency equipment. For further reduction, the optimum control of the air conditioning together with the heat supply equipment will make a contribution. A dynamic simulation is expected to be one of the tools for the optimization. The paper presents development of a dynamic simulator for the purpose of the evaluation of district heat and cool (DHC) plant operation and control. A double effect absorption chiller model and a cooling tower model are developed for the simulator. The developed chiller model is based on the dynamic approach which accommodates the heat capacity of the equipment and the sensible and latent heat of the internal liquid to evaluate the energy loss derived from the time delay of the startup. The steam system model which consists of the steam header, pipes and valves has been developed for the study of the impact by the mutual steam accommodation in the neat future with the neighboring combined heat and power plant. The boundary of the simulator is the equipment and system inside the DHC plant and the flow pipes to the district demand is not accommodated. The outputs of developed models suitably describe the equipment test data. These models are applied to the developed DHC plant dynamic simulator and the results of the simulation show good accordance with the DHC plant data. The simulator is confirmed to be a useful tool for the study of optimum DHC plant operation and control. Further, it can be useful for the evaluation of the impact on the DHC plant in the plant expansion and modification or in the plant connection and cooperation with the neighboring plant.