High Temperature District Cooling: Challenges and Possibilities Based on an Existing District Cooling System and its Connected Buildings

In this paper, High Temperature District Cooling (HTDC) has been defined with temperature levels of 12 -14 degrees C supply and 20-22 degrees C return. This is based on an analysis of operational data from an existing district cooling system in Gothenburg, Sweden and 37 building chilled water systems, connected to the district cooling system by means of heat exchangers. The analysis showed that the actual building chilled water temperatures varied between 6-16 degrees C supply and 8-25 degrees C return when the outdoor temperature is 25 degrees C or more, and that the share of free cooling almost doubled with higher supply and return temperatures in the district cooling system. Moreover, challenges and possibilities for the existing district cooling system to use HTDC were identified. The challenges included lack of incentives for current customers to upgrade and optimize their building chilled water systems, while the possibilities included decoupled cooling loads in the building chilled water systems and outdoor temperature compensated supply water temperatures. High temperature district cooling supports the development of district cooling as part of a future smart energy system, which integrates large shares of renewable energy sources and provides cooling to more energy efficient buildings with lower cooling demands. (C) 2020 Elsevier Ltd. All rights reserved.