In order to reach its overall objective, the consortium defined secondary objectives, which led to the definition of the three scientific Work Packages.
The first Work Package aims at developping environmentally sound synthetic methods for the preparation of spin crossover materials for barocalorics, and to characterise the thermal and functional properties of these materials in light of their potential application in barocaloric cooling devices. Here we have successfully synthesized a handful of promising candidate compounds on the 100mg scale, we performed a comprehensive literature review to identify promising candidate molecules, we launched investigations to determine the (pressure, temperature) phase diagrams for most of the compounds synthesized we synthesized so far, completed with barocaloric measurements (calorimetric i.e. thermodynamic characterizations under pressure, with oils as pressure transmitting media.
The second Work Package aims at obtaining densified objects with centrimetric sizes and optimized properties, by preparing molecular “ceramics” starting from the best-performing compounds identified through a thorough exploration of sintering conditions (so-called sintering maps), and characterizing the barocaloric properties of those ceramics (as compared to the properties of the starting bulk compound). Here we have mostly advanced in the sintering aspect, with various new candidate materials having been successfully sintered, with sintering density maps establishing adequate sintering conditions having been established for most of them. Concerning the measurement of barocaloric properties, a benchmark test has been performed on a compound of interest on which the barocaloric effect had been reported in the literature on bulk powder. We thus benchmarked our characterization comparing measurements on both powder and a sintered pellet respective to the data published.
The last quite ambitious Work Package, which has not started yet, aims at designing and building a proof-of-concept demonstrator of a solid-state barocaloric regenerator. We plan to do so by performing a comprehensive numerical modeling and optimization of operational, material and geometrical aspects of barocaloric regenerators, coupled with the study, optimization and selection of the heat transfer and pressure transmitting fluids. We will also work on the barocaloric material, by upscaling the synthesis of selected best performing barocaloric compounds to pre-industrial scale, and optimizing the shaping of those compounds in order to be applied in the barocaloric regenerator. We also need to work on Life Cycle Analysis, by ascertaining the behaviour upon cycling and ageing of the compounds once shaped. The final steps will deal with pressure generation and pressure work recovery systems, and then last but certainly not least we will manufacture a barocaloric regenerator, implement it into a proof-of-the-concept device and test it for the cooling performance. We are targeting a small-scale device (with up to 200 g of barocaloric material) that would be able to produce up to 100 W of cooling power (basically about the power used in a kitchen fridge) and a temperature span of 20 degrees.
