Comparison of Modeling Approaches to Optimize a District Heating & Cooling Facility

Azbil is optimizing setpoints for a district heating-cooling facility. A commercial process simulator (CHEMCAD) is being used to model the facility operation. The model is first validated against historical performance, and then used to recommend new setpoints online.

A building in Yokohama supplies chilled and heated water to several neighboring buildings in the office district. User demand and the weather are difficult to predict. The building has the option to turn on/off several cooling towers and multiple refrigeration units. Substantial cost savings can be achieved by changing the number of active units to minimize the power used by the pump networks, cooling tower fans, and refrigeration networks.

Previously an LP (linear programming) optimization model was developed for this facility using process control concepts (gain, transfer functions, black box, etc.). Azbil is developing a model which uses a commercial process simulator to model the process. Using a commercial process simulator reduces the amount of time to develop the model, and increases the accuracy of the model used to determine optimized setpoints.