Sinergies between organic-matrix combustion synthesis and Pt-promotion on the performances of Co-based FT catalysts

Ninety years after its discovery, Fischer–Tropsch Synthesis (FTS) is recently receiveing new interest as the key-process to convert synthesis gas derived from natural gas, coal and biomass, into high quality transportation fuels. While most of the original FTS processes relied on high-temperature bulky Fe-based catalysts, the attention today has shifted toward low-temperature Co-based supported catalysts, which exhibit higher activity and selectiv-ity. Due to the constant turnover frequency of cobalt crystallites bigger than 6 nm, the activity of cobalt catalyst linearly depends on the number of metallic active sites located on the support. In turn, the number of Co-metal centers is determined by the Co particle size (i.e. cobalt dispersions), the Co loading, and the Co reduction degree. Understanding the role of these parameters and controlling such parameters during the synthesis rep-resent one of the most significant challenge in view of the development of highly active catalysts to be used within intensified FTS reactors. The synthesis of highly active catalysts has been recently reported by both academic and industrial research groups. With respect to conventional supported FTS catalysts, which are prepared by incipient wetness impregnation, highly active catalysts have been obtained either by adding PGM as promoters or by adopting new synthesis routes, such as the organic matrix combustion, OM. PGM have been found able to favor cobalt reduction, thus increasing the fraction of cobalt which takes part to the reaction. OM, which consists in the addition of an organic material to the precursors-containing solution and in the combus-tion/decomposition of such compound during a fast calcination step, has been found effective in the synthesis of small and stable (with respect to sintering) Co-crystallites, at least in the case of SiO2 supported catalysts. How-ever, small crystallites are known to be much more resilient to reduction then bigger Co-aggregates. In this work, we investigated for the first time the synergies between the OM method, using urea as fuel, and the adoption of PGM, platinum in particular, as reduction promoter

Preliminary study of the mechanical and hygrothermal performance of concrete reinforced with fibrillated cellulose

Cement, being the most widely used building material, is the responsible for a large share of greenhouse gas emissions. To reduce the environmental impact of its production, natural fibres can be used as eco-friendly additives. Moreover, their potential use in traditional lime-based mortars makes them an ideal choice for green buildings as well as for the retrofit of historical buildings. An innovative cementitious composite reinforced with fibrillated cellulose (hereafter called «green concrete») was tested to assess its mechanical and physical properties. Samples were casted using Portland cement and natural hydraulic lime and varying the ratios among the constituents. Viscosity and setting time of the fresh pastes were determined with a viscosimeter and a Vicat apparatus, while their hydration was studied by thermal analysis. The influence of the fibres on the flexural strength of the final composite was determined through mechanical tests. The expected hygrothermal performance of the «green concrete» was explored through dynamic hygrothermal simulation to investigate its potential use as a retrofit material. A sensitivity analysis (SA), based on the hygrothermal properties of natural-based building materials similar to the «green concrete», was conducted to identify the parameters influencing more the simulation of annual internal temperature and moisture variations. The preliminary assessment of the mechanical properties of the «green concrete» showed that at higher percentages the cellulose fibres can negatively affect the workability/setting time of the fresh pastes and the flexural strength. The most promising samples were identified and will undergo further investigation. The SA results outlined that the «green concrete» might not be effective for thermal insulation, although it might be used as a moisture-buffering layer by adjusting the values of the free water saturation moisture content, the equilibrium moisture content at RH=80% and the dry vapour diffusion resistance factor of the final composite

Calibrating the Dynamic Energy Simulation Model for an Existing Building: Lessons Learned from a Collective Exercise †

Calibration of the existing building simulation model is key to correctly evaluating the energy savings that are achievable through retrofit. However, calibration is a non-standard phase where different approaches can possibly lead to different models. In this study, an existing residential building is simulated in parallel by four research groups with different dynamic simulation tools. Manual/automatic methodologies and basic/detailed measurement data sets are used. The calibration is followed by a validation on two evaluation periods. Monitoring data concerning the windows opening by the occupants are used to analyze the calibration outcomes. It is found that for a good calibration of a model of a well-insulated building, the absence of data regarding the users' behavior is more critical than uncertainty on the envelope properties. The automatic approach is more effective in managing the model complexity and reaching a better performing calibration, as the RMSE relative to indoor temperature reaches 0.3 degrees C compared to 0.4-0.5 degrees C. Yet, a calibrated model's performance is often poor outside the calibration period (RMSE increases up to 10.8 times), and thus, the validation is crucial to discriminate among multiple solutions and to refine them, by improving the users' behavior modeling

BIM-BEM support tools for early stages of zero-energy building design

Due to the Energy Performance of Building Directive 2010/31/UE (EPBD) recast, new and existing buildings have the aim to achieve the Zero Energy Buildings (ZEBs) requirements, in order to reduce the carbon emission and the energy building demand. Therefore, the building process cost is increasing, related to the applications of performant construction and efficiencies energy systems. In literature, several studies highlight the importance of innovative approaches in order to reduce the cost of the ZEB targets achievement, during the early stage design process. In this framework, Building Information Modeling (BIM) is a useful process that integrated building design since the first design stage, providing high-performance energy solutions and obtaining a single model reducing time and cost during the building design. In fact, in Italy, the regulatory obligations are progressively defined: with the Ministerial Decree 560 of 1 December 2017 (Baratono Decree), the time scale with which the obligation to use BIM will come into force has been established. The obligation started from 1 January 2019 for public tenders for an amount equal to or greater than 100 million euros, then there will be a gradual entry up to 2025 for public works contracts worth less than one million. The research proposes a new workflow that allows to performing energy analysis through the BIM and Building Energy Modeling (BEM) optimization interoperability, allowing to support the zero-energy building during the early stage design

Testing the BIM-ladybug tools interoperability: A daylighting simulation workflow

While a considerable number of studies on Building Information Modelling (BIM) have been conducted in recent years, this area of research has long been considered important in the building sector, with particular concerns about Energy Design. In this regard, the work proposes an automated early design workflow to evaluate the building daylighting performance during the first design stages. Thanks to the potential use of interchange files and visual coding tools, such as Grasshopper, it is possible to implement the parametric design concepts, thus automating complex tasks. Specifically, in the analysed workflow, environmental algorithms and simulations are integrated to achieve reliable results with the minimum error percentage in data loss. The main finding concerns the BIM applications to perform daylighting design by the use of Ladybug tools from the Autodesk Revit export

An HBIM Integrated Approach Using Non-Destructive Techniques (NDT) to Support Energy and Environmental Improvement of Built Heritage: The Case Study of Palazzo Maffei Borghese in Rome

Built heritage energy and environmental improvement is increasingly being recognised as a key driver in the fight against climate change. This effort necessitates a thorough understanding of the building to guide the selection of technologies and design solutions. To have a picture of the buildings' characteristics and behaviour that is as complete as possible, in situ studies are essential, although the complexities and heterogeneities of historical buildings make these analyses still challenging, especially in professional practice. To address these issues, the paper describes an integrated approach including the field application of Non-Destructive Techniques (namely, Heat Flow Meter measurements, Infrared thermographies and indoor environmental monitoring) within a Heritage Building Information Modelling process. This interdisciplinary/integrated approach fostered the use of each type of analysis's results to guide the subsequent analyses and incrementally deepen the knowledge of the building. The methodology was applied to a case study in the historical city centre of Rome in Italy. The analyses will be of service in developing dynamic building performance simulations to support the design of the interventions

Testing the Revit–EnergyPlus interoperability by the use of Ladybug tools.

Although a considerable number of studies on Building Information Modelling (BIM) have conducted in recent years, the theme is already widely recognized in the building sector, with perplexity in Energy Design. In this regard, the work proposes an automated early design workflow to evaluate the building daylighting performance during the first design stages. Thanks to the potential use of interchange files and visual coding tools, such as Grasshopper, it is possible to implement the parametric design concepts, thus automating complex tasks. In detail, in the analysed workflow, environmental algorithms and simulations are integrated to achieve reliable results with the minimum error percentage in data loss. The main finding concerns the BIM applications to perform daylighting design by the use of Ladybug tools from the Autodesk Revit expor

Thermal and electrical characterization of a semi-transparent dye-sensitized photovoltaic module under real operating conditions

Dye-sensitized solar cell technology is having an important role in renewable energy research due to its features and low-cost manufacturing processes. Devices based on this technology appear very well suited for integration into glazing systems due to their characteristics of transparency, color tuning and manufacturing directly on glass substrates. Field data of thermal and electrical characteristics of dye-sensitized solar modules (DSM) are important since they can be used as input of building simulation models for the evaluation of their energy saving potential when integrated into buildings. However, still few studies in the literature provide this information. The study presented here aims to contribute to fill this lack providing a thermal and electrical characterization of a DSM in real operating conditions using a method developed in house. This method uses experimental data coming from test boxes exposed outdoor and dynamic simulation to provide thermal transmittance (U-value) and solar heat gain coefficient (SHGC) of a DSM prototype. The device exhibits a U-value of 3.6 W/m2·K, confirmed by an additional measurement carried on in the lab using a heat flux meter, and a SHGC of 0.2, value compliant with literature results. Electrical characterization shows an increase of module power with respect to temperature resulting DSM being suitable for integration in building facades

BIM tools interoperability for designing energy-efficient buildings

The constructive complexity of the building envelope, together with the high degree of performance required in new dwellings, entails the application of computer-based modelling tools over the design processes. Furthermore, to achieve the NZEB (net zero energy building) qualification, the use of BPS (building performance simulation) tools during the early design stage becomes indispensable. In this context, the present research aims to analyse the interoperability potential offered by BIM-based (Building Information Modelling) software to optimize the modelling phase and to improve simulation results. The research shows advantages and drawbacks related to a workflow adoption based on 3D BIM implemented in Autodesk Revit, and on energy simulation in IDA-ICE environment, by means of a visual algorithmic programming tool. The Bestest ASHRAE case study has been considered as reference system to test and verify the actual process optimization. The outcomes identify what is the correct information set which is needed for the energy analysis to get suitable energy simulation result with the minimum data losses