Integrated System Model of District Cooling for Energy Consumption Optimization

Abstract

The successful modeling of a multi-plant district cooling (DC) system presents several challenges in integrating system level requirements with engineering analysis for verification and optimization. Currently, the ability to predict the behavior and performance parameters such as chilled water temperature difference, annual energy consumption, and central chiller plant coefficient of performance (COP) of the dynamic system is limited. Effective modeling and efficient simulation are required when it comes to complex physical systems. This paper presents an integrated model that combines system architecture with physical modeling to represent and simulate a multi-plant district cooling system (DCS). We refer to this model as model-based systems engineering (MBSE) model of the DC system. A systems modeling language (SysML) model is created to develop a multi-domain architecture of the DC system that will satisfy stakeholder needs and requirements. This model is capable of executing behavior and parametric aspects (or “views”) of the system. A closed-loop of information flow was developed to map SysML constructs with their respective Modelica models to support the integration of simulated experiments with SysML construct. The integrated MBSE model is successfully implemented and the results show that the IPLV.SI value of the chiller model was 6.4157, which is in the acceptable range. Based on the initial conditions provided by the actual plant, the simulation results show that the chilled water temperature predictions by Modelica as 4.8℃ verify the corresponding stakeholders’ requirements captured in the SysML model.