Heating and cooling in residential buildings hold a 28% share in the total energy consumption of Europe, out of which 75% of the energy is still generated from fossil fuels, while only 19% comes from renewable energy sources. To increase the share of renewable energy in the near future, the French energy commission has identified 4th generation district heating networks as a plausible option. Key hardware components for next generation smart urban heating networks are heat and cold storages, which allows a shift between production and consumption as necessary.
The prototype that will be studied in this thesis couples in a same component heat and cold storage, in order to obtain significant gains in terms of compactness and cost. Cold storage is based on ice-water phase change transition around finned tubes in charging mode (-6°C), and on direct contact between water and ice in discharging mode (direct contact = water flow through the ice and directly exchange heat without any wall between water and ice). Heat storage is based on thermocline technology with water (60-70°C) as coolant.
The prototype is currently under manufacturing in the framework of a European Project and will be operational at the beginning of the thesis. The objective of the thesis is on the one hand to experimentally characterize the performances of the storage, on the other hand to work on a numerical modelling of the storage. The thermos-hydraulical modeling of the discharge in cold mode, with direct contact between ice and water, is particularly challenging. The study of the addition of Phase Change Material capsules for heat storage (50-60°C), in order to boost energy and power, will also be studied with potential implementation in prototype during the thesis.