6th generation district heating and cooling networks::design, experimental results and future challenges

This paper describes the design and testing of an innovative lab-sized 6th generation district heating and cooling network (6GDHCN) using CO2 as heat transfer fluid to evaluate its simultaneous heating and cooling capabilities and highlight current design challenges and future pathways to enhance the system. The 6GDHCN distinguish from its predecessor by the use of phase change phenomena to transfer heat. The innovative use of phase change significantly enhances energy density, thus enabling smaller infrastructure requirements and simpler deployment in dense urban environments. The experimental setup, developed to emulate real-world conditions on a reduced scale, includes a central plant circulating CO2 through network connecting cooling and heating users. Experiments focused on validating the concept and the correct operation of each subsystem as well that of the overall facility. Similarities with a larger facility provided a solid basis of demonstration of the emulation capabilities. In particular, the experiments allowed to identify the major design challenges and identify pathways for enhancing system resilience, scalability, and energy efficiency in sustainable thermal networks.