Determining the Maximum Cooling Distance of a District Cooling System Relative to a Decentralized Benchmark: A Supply-Side Energy-Equivalent Approach

The service range of a district cooling system is strongly affected by the energy consumption of chilled-water distribution in the supply-side pipe network. With increasing cooling distance, pump operating energy consumption, pump-induced temperature-rise loss, and pipeline cooling loss all increase, which may weaken the supply-side distribution-energy advantage of centralized cooling. This study proposes a method for determining the maximum cooling distance of a district cooling system based on a supply-side energy-equivalent boundary. The boundary is defined as the distance at which the total supply-side energy consumption of the district cooling system equals that of the decentralized cooling system under the same load conditions. Unlike cost-based evaluation methods, the proposed criterion does not rely on economic parameters such as electricity price, material cost, construction cost, or maintenance cost, but determines the boundary based on supply-side energy consumption. A district cooling system in Guangzhou is used as the case study. Under the baseline condition, the maximum cooling distance is 1564 m. Increasing the supply–return water temperature difference from 7 °C to 12 °C increases the maximum cooling distance by 294.38%. Increasing the decentralized system main-pipe length from 250 m to 600 m increases it by approximately 175%. When the number of users increases from 8 to 12, the distance increases by 23.1%. A front-concentrated layout of high-load users increases the distance by 36.93% compared with a uniform layout. The proposed method provides an energy-based planning reference for cooling-source siting, user connection range determination, and district cooling pipe-network scheme evaluation.