Flexible waste heat management and recovery for an electro-intensive industrial process through energy/exergy criteria
Résumé
The French National Laboratory for High Magnetic Fields (LNCMI) provides high magnetic fields for an international community of users. On the site of Grenoble DC electricity is used to feed dedicated high power electro-magnets to produce steady magnetic fields. The magnets electrical consumption is fully dissipated as heat at variable temperatures. An ongoing project for the LNCMI electro-intensive installation analyses the opportunities for waste heat recovery into the nearby district heating network. Recent studies have pointed out energy recoveries of the order of 20% considering waste heat at 35 °C heat pumped to 85 °C and a thermal storage. One of the main reasons for this low recovery rate is the temporal mismatch between the LNCMI's activities and the district's residential heat needs. From 2020, the LNCMI has signed a new electricity contract that provides more flexibility to the high field experiment planning. Two strategies are explored to improve the waste heat recovery energy and exergy rates. Firstly, the rescheduling of the LNCMI planning of experiments in order to mitigate the temporal mismatch. Secondly, management of the cooling loops of the process to adjust waste heat at relevant temperatures. The energy analysis accounts for recovered heat quantity, while the exergy analysis accounts for the major sources of irreversibility within the LNCMI's processes. MILP optimisation problem formulation and solving proved these two strategies to be energy and exergy efficient for the LNCMI waste heat recovery. This work offers promising research and operational perspectives for flexible energy systems optimal management with both energy and exergy criteria.
Domaines
Energie électrique
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