A Decoupled Step-wise Model-based Energy-efficient Control for Industrial Space Cooling: A Case Study of a Large-scale Manufacturing Factory

The industrial sector is a predominant contributor to global energy consumption and carbon emissions. In manufacturing factories, district cooling systems account for a large portion of the building's energy consumption. However, field operators often lack understanding of the interactions between water-side systems, distribution piping networks, and demand-side systems (air-side systems and rooms) due to the complexities of HVAC control management, manufacturing schedules, and heat flow in and around the building. This results in suboptimal system coordination and business decisions. Specifically, water pumps, supply water temperatures, and equipment sequencing are frequently operated based on empirical settings, leading to inefficiencies as the static characteristics of the control parameters cannot adapt to changing operating conditions or actual demands. Therefore, this study proposes a decoupled step-wise model-based energy-efficient control method for pumps and water-side units. The method establishes and integrates a Modelica-based water-side system model, distribution system model and room thermal response model to dynamically adjust the operation of pumps, set points of supply water temperature, and equipment sequencing by predicting the status of the demand-side system under different working conditions. A case study at a large parts manufacturing factory showed that by applying the dynamic adjustment strategy, this method can reduce energy consumption by 26.35% for pumps and 29.01% for chiller units during typical cooling seasons under the premise that the indoor temperature is controlled, demonstrating the significant potential of the proposed method for improving energy efficiency.