A Simplified Dynamic Model for Chilled-Water Cooling and Dehumidifying Coils—Part 1: Development (RP-1194)

Abstract Dynamic coil models are useful in the development and evaluation of feedback controllers and fault detection and diagnostics algorithms. Existing models in the literature have not been validated fully using experimental data and have not been evaluated in terms of trade-offs between model accuracy and computational requirements. This paper develops a computationally fast, distributed model for the transient behavior of cooling and dehumidifying coils. The model utilizes several steady-state performance indices that simplify dynamic modeling, including fin efficiency, air-side effectiveness, and water-side effectiveness. Predictions from the simplified model were compared with a detailed reference model and with other simplified models from the literature. Comparisons with detailed experimental measurements are given in a companion paper (Zhou and Braun 2007). The model provides very accurate predictions of coil transient performance and executes more than 1000 times faster than real-time on a 1.2 GHz personal computer. As a result, it is very practical for implementation within system simulation programs that execute over long time periods, such as a year.