Selection and Optimal Use of Nanoporous Materials for Adsorption Energy Technologies

Due to the large waste of heat in the power and industrial sectors, our use of energy is inefficient. Moreover, it relies on rapidly depleting and greenhouse-gas-emitting sources such as fossil fuels. While the scarcity of energy resources is a relevant societal concern, the emission of climate-altering gases poses serious threats to global ecosystems and our civilization.The development and deployment of heat-powered adsorption energy technology tackles all of these issues:Adsorption heat pumps and chillers require little electricity, which could save strain on the power gridAdsorption energy storage allows long-term management of heat, increasing energy efficiencySeparation of carbon dioxide by adsorption allows for carbon-neutral and negative-emission technologyAdsorption energy technology runs on low-grade heat, which improves the system efficiency and enables the use of solar energy.The deployment of the technology is constrained by:Relatively low energy efficiencyLow power density/ high required volumeHigh capital costsThese challenges are sensitive to a better selection and use of the nanoporous adsorbent materials employed.In this thesis, after identifying the main areas of research necessary to improve the understanding and the performance of adsorption energy transformers, materials' characterization and modelling tools are used to tackle some of them.In particular, the research focuses on:Minimizing the experimental effort necessary to screen a large number of adsorbent materialsIntegrating the selection of the adsorbent and the design of the adsorption energy processesDeveloping a novel modelling method for heat and mass transfer within the material to enable affordable simulationsTailoring a sustainable activated carbon for the heating/cooling operation in district heating networksDeveloping and pre-design an adsorption heat exchanger based on the agitated screw-conveyor conceptApplying the rapid adsorption coatings to the post-combustion capture of carbon dioxideInvestigating the effects of long-term use and storage of the adsorbentThe results show that characterization and modelling activities dedicated to the adsorbent materials are effective to develop improved adsorption technology.In particular, better methods of characterization guarantee an accurate selection of the adsorbent material from a wide range of candidates. This process triggers increases in performance, especially when the materials are integrated with the process energy flows.The proposed modelling method was capable of describing accurately the dynamics of adsorption. This enables less expensive simulations for material and technology development. In fact, the ideal process parameters for the production of activated carbon were identified. Furthermore, the model proved to be compatible with the feasibility study of an agitated heat and mass exchanger, which is a first-of-a-kind. The device provides good material usage and power density.The application of concepts and methods developed for heat transformers to gas separation delivered promising results. High rates of adsorption were demonstrated and different materials could be ranked. However, some limitations were highlighted and further research is envisaged.Finally, ageing tests were useful to determine the conditions in which material degradation happens and the effect it has on a selection of adsorbents.