Water capture in stable composite materials for heat storage: Application to vehicle cabins heating – STOCK-CAR

The objectives of STOCK-CAR fit into the current requirements for environment-friendly and energy-saving processes. The project targets the development and experimental evaluation of innovative thermochemical heat storage (TCHS) materials for heating (during off periods) the cabin of a truck. The TCHS system will use the waste heat lost to the engine coolant or the exhaust gases for charging the material and water vapor for discharging. The optimization of the TCHS system needs progress not only on the material level (the available materials do not satisfy all needed requirements) but also on the functioning of the reactor model. STOCK-CAR will tackle both issues by starting from synthesis of original materials, going through a deep characterization of their physico-chemical properties and storage performances and then testing in a small-scale reactor. Functionalized and composite materials with added salts on mesoporous structures will be investigated. Mesoporous oxides (SiO2, Al2O3, ZrO2) and phosphates as well as hierarchical materials (with micro/meso/macropores) will be synthesized as supports of hydrated salts (Na3PO4, CaCl2, MgSO4, SrBr2). Surface modification of the porous oxides will induce modifications of the chemical and textural properties. Great improvements in the understanding of the key parameters for an efficient heat thermal storage are expected by controlling the oxide porosity and the chemical nature of the walls (organic functionalization). In the domain of phosphates, more stable mesoporous ALPO and SAPO will be synthesized with various chemical composition and pore size as well as hierarchical ALPO/SAPO containing both mesopores and macropores. Screening methodology will be developed for controlling the physical and thermodynamic factors governing the performance and durability of the storage systems, and to rationalize the materials design and elaboration. In order to assess the reliability of the composite, the thermal behaviour and physical structure of the synthesized materials in water vapor presence, will be studied. By determining the thermodynamic parameters and kinetics of the water/solid interaction by calorimetry, energy density vs sorption capacity, the best TCHS materials will be selected for reactor modeling and optimization of the process. Reactor at lab scale will be designed and processed for testing maximum of samples before the realization of a real heat storage system adapted at truck cabin dimensions. In parallel with the experimental approaches, the numerical developments will be also performed by involving both energy and exergy analysis of the process in order to highlight the critical components of the system, the critical phases of the cycle and to provide outlooks over optimization potential. The partners of STOCK-CAR believe that by significant advancements in new materials with tuned ability to store heat for a variable, controllable period of time and with controlled rate of charging/discharging reactions, it will be possible to develop a high efficient TCHS system. STOCK-CAR seeks not only the industrial application but also the fundamental understanding of the absorption/desorption process of developed compounds which is an important step for such application. This will make the developed methodology transferrable to many other complex/extended systems in sorption processes where solid-vapor interactions are prevailing. The goals proposed in STOCK-CAR are achievable taking into account the involved teams (LMCPA, LMI, IRCELYON and LOCIE) which comprises engineers/scientists specialized in materials, thermodynamics, heat science and process development.