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Chilled water systems in large-scale central air conditioning consume more than 30 % of the total energy. To reduce this energy consumption, a model can be used to explore the optimal operating parameters of chilled water systems. The chilled water system is a multivariable highly coupled nonlinear system. The type and number of variables change with the hydraulic characteristics of the piping network and the operating data sparsity is high. For these reasons, data-driven methods are not suitable for modeling chilled water systems. Therefore, there is an urgent need to develop a model that is not constrained by the type and number of variables and can establish a complete data structure. According to the principles of differential pressure equilibrium, flow conservation, and thermal equilibrium, this study establishes a physical model of the hydraulic–thermal coupling of chilled water systems. The hydraulic–thermal characteristics of chilled water systems under multiple operating conditions were investigated, and the reliability of the model was verified through experiments. Furthermore, the difficulty of effective modeling owing to dynamic changes in the types of variables and lack of operating data were addressed. The study showed that the model has a wide range of applications, high reliability, and high computational efficiency. • Physical models are not affected by changes in the type and number of variables. • Enable model convergence and computational efficiency by building a database. • Model applications to big data simulation; sensitivity analysis; boundary problems, etc. • High reliability of the model verified by experiments. [ABSTRACT FROM AUTHOR]