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Optimization of Pyrolysis Parameters by Design of Experiment for the Production of Biochar from Sewage Sludge
Get PDFSewage sludge management is a key concern in today’s world. Improper disposal can lead to various environmental issues including air, water and soil pollution. Among the available technologies, thermal treatments, particularly pyrolysis, are gaining interest for their ability to reduce sewage sludge volume and to recover materials and energy from it. This study explored the influence of some relevant parameters in the thermal pyrolysis process. The design of experiment, named central composite design, was accounted to optimize temperature, heating rate and residence time in order to maximize the biochar yield and its CO2 adsorption capacity. A two-factor interaction model provided a satisfactory interpretation of the results. Within the studied ranges, maximum values of 47.8 wt% and 0.514 mol CO2/kg were obtained for the yield and CO2 adsorption capacity, respectively. Two significant experiments were repeated in a different pyrolysis system highlighting how other factors (e.g., reactor geometry, granulometry, etc.) can influence the quantity and the quality of produced biochar. The biochar obtained under the best pyrolysis conditions was characterized by a surface area of 124 m2/g and an ash content of 61 wt%. Lastly, the theoretical energy balance showed that the drying process is the main energy-intensive step in the pyrolysis of sewage sludge
MELCOR – DAKOTA coupling for uncertainty analyses in the SNAP environment/architecture
Get PDFUncertainty estimation to assess figures of merit characterizing evolution of a severe accident transient is a topic of current investigation in development of best-estimate plus uncertainty methodology. The probabilistic method to propagate input uncertainty is one of the methodologies used to develop Uncertainty Analyses (UAs). Using this methodology, UAs are performed by sampling probability distributions that describe the range of possible values that computer simulation model inputs can have. For each sample (or realization) of a set of uncertain input parameters, a computer simulation is performed. From the range of code simulation results obtained for each input realization, a distribution of code results is obtained. In this process, the distribution of input uncertainties is propagated to obtain a distribution of possible code results (i.e., the code output uncertainty). This probabilistic methodology is facilitated using Uncertainty Tools (UTs), which can be coupled with the accident analysis computer code to perform an UA. One of the UTs currently available is DAKOTA, developed by Sandia National Laboratories. DAKOTA is also provided as a SNAP plug-in. SNAP is a graphical user interface designed to support the use of USNRC codes (MELCOR, TRACE, etc). This paper is entirely derived from the NUREG/IA-532 issued by USNRC in April 2023 (Mascari et al., 2023) and has as a major target to summarize the main needs of UA in severe accident, the main element of the probabilistic method to propagate input uncertainty, and the workflow within SNAP to assist other interested analysts with their applications given they are members of the USNRC Cooperative Severe Accident Research Program (CSARP)
Monitoring climate related risk and opportunities for the wine sector: The MED-GOLD pilot service
Get PDFMED-GOLD was a 54-months research and innovation project, whose main aim was to co-develop climate services for three staples of the Mediterranean food system, namely grapes, olives and durum wheat. This paper describes the methodology adopted for the co-development of the pilot climate service for the wine sector, focusing on the Douro Wine Region in northern Portugal. In the first step, the MED-GOLD industrial partner SOGRAPE identified key decisions and users’ needs for the wine sector in the Douro region by involving managers from their own vineyards in that region. From this information, the relevant bioclimatic indicators (and associated essential climate variables) were selected. Afterwards, two compound risk indices, the Sanitary and Heat Risk indices, were introduced as a combination of some of the aforementioned bioclimatic indicators. This methodological work was validated against the empirical climate characterization for the region of interest, of several ‘bad’ and ‘good’ years chosen by users according to their recollections of grape and wine production outcomes, namely quality and yields. In this paper, the overall strategy for selection of these years is presented. The components of the service based on historical climate, seasonal predictions and longer-term climate projections are described along with the visual interface developed: the MED-GOLD Dashboard, an interactive tool that displays detailed historical climate data, seasonal predictions and climate projections. The Dashboard consists of an ICT platform with a map-based user-focused front end to aid easy access to and manipulation of the data. The Dashboard was iteratively co-designed with the users to ensure their needs were met
Basic design and construction of an experimental plant for the study of thermal oils to be used as heat transfer fluids
Get PDFIl seguente rapporto tecnico descrive un impianto sperimentale in grado di testare fluidi di scambio termico sottoposti a cicli di riscaldamento – raffreddamento. L’impianto è stato progettato e realizzato nell’ambito del progetto ARDECO, nato tra l’accordo tra ENEA e CEA, per lo studio della stabilità termica di diversi oli diatermici da usare in un sistema di mitigazione incidentale per impianti nucleari di IV generazione raffreddati a sodio liquido. L’impianto è costituito da uno scambiatore di calore tubolare a singolo tubo riscaldato elettricamente per effetto Joule e dotato di un sistema di termocoppie in grado di misurare la temperatura dell’olio sulla parete e nel centro del tubo, permettendo di determinare sperimentalmente il coefficiente di scambio termico ed eventuali variazioni causate dalla degradazione termica del fluido testato. Nel corso dei test lo stato di degradazione dell’olio termico è stato periodicamente analizzato mediante misure offline di campioni di fluido. L’impianto permette inoltre l’analisi di eventuali prodotti di degradazione termica in fase solida e gassosaThe following technical report describe a pilot scale plant able to study liquid heat transfer fluids behaviour undergoes to thermal cycles. A single pipe joule heated heat exchanger was designed and constructed in ENEA C.R. Casaccia in the framework of ARDECO Project to test the thermal stability of different thermal oils to be used in a safety system for a Sodium cooled generation IV nuclear power plant. The oil loop is equipped with a thermocouples system placed along the tube allowing to measure temperature values online and then to experimentally calculate the heat transfer coefficient and its variation. By testing heat transfer fluids in real-like conditions the thermal stability can be experimentally tested; degradation processes and related heat exchange coefficient drop can be studied. The oils degradation rate was periodically checked through offline analysis of oil sampled from the loop. Solid and gaseous degradation products can also be detected and analysed
Design and Development of an Electronic Board for Supporting the Operation of Electrochemical Gas Sensors
No full textA New Method for Selective Extraction of Torularhodin from Red Yeast Using CO2-SFE Technique
Get PDFTorularhodin is a dark pink colored carotenoid belonging to the xanthophylls group that can be biologically synthesized by red yeasts, especially by Rhodotorula and Sporobolomyces genera. The growing interest in this molecule is due to its biological activities such as antioxidant, anticholesterolemic, anti-inflammatory, antimicrobial, and anticancer. To satisfy potential commercial markets, numerous methods have been proposed to develop a cost-effective and environmentally friendly downstream process for the purification of torularhodin. However, obtaining high purity products without resorting to the use of toxic solvents, which can leave residues in the final preparations, remains a major challenge. In this context, the present study aimed to develop a new efficient method for the isolation of torularhodin from the red yeast Rhodotorula strain ELP2022 by applying the extraction technique with supercritical CO2 (CO2-SFE) in two sequential steps. In particular, in the first step, the dried lysed biomass of yeast was subjected to the action of CO2 in supercritical conditions (CO2SC) as sole solvent for extraction of apolar carotenoids. In the second step, the residual biomass was subjected to the action of CO2SC using ethanol as a polar co-solvent for the extraction of torularhodin. Both steps were carried out at different operating parameters of temperature (40 and 60 °C) and pressure (from 300 to 500 bar) with a constant CO2 flow of 6 L min−1. Regardless of the operating conditions used, this method allowed to obtain an orange-colored oily extract and a red-colored extract after the first and second step, respectively. In all trials, torularhodin represented no less than 95.2% ± 0.70 of the total carotenoids in the red extracts obtained from the second step. In particular, the best results were obtained by performing both steps at 40 °C and 300 bar, and the maximum percentage of torularhodin achieved was 97.9% ± 0.88. Since there are no data on the selective recovery of torularhodin from red yeast using the SFE technique, this study may be a good starting point to optimize and support the development of industrial production of torularhodin by microbial synthesis. This new method can significantly reduce the environmental impact of torularhodin recovery and can be considered an innovation for which an Italian patent application has been filed. In a circular bioeconomy approach, this method will be validated up to a pilot scale, culturing the strain Rhodotorula spp. ELP2022 on low-cost media derived from agri-food wastes. Graphical Abstract: (Figure presented.
Thermal conductivity assessment of cotton fibers from apparel recycling for building insulation
Get PDFThe impressive growth of the clothing market in the last decades comes along with an increase in the textile waste, nowadays mostly incinerated or landfilled. To improve the circularity of the sector, the possibility to recycle the textile waste into thermal insulation products for the building envelope has started to emerge. While the scientific literature agrees that the thermal conductivity of products based on textile waste is comparable to conventional thermal insulators, very few studies provide a comprehensive characterization of their heat transfer behavior in terms of the relevant parameters. This study focuses on post-consume cotton in the form of loose fibers with density 30, 50 and 70 kg/m3. By exploiting complementary experimental techniques, it is found that the effective thermal conductivity ranges between 0.0381 W/(m∙K) (ρ = 30 kg/m3, T = 10 °C, RH = 17 %) and 0.0546 W/(m∙K) (ρ = 50 kg/m3, T = 30 °C, RH = 80 %). The conductivity of the loose cotton fibers is predominantly sensitive to temperature and relative humidity, while the influence of density and the vertical/horizontal orientation appear less significant. These results highlight the complexity of the characterization of the thermal performance of such fibrous materials and the need to perform tests under fully controlled environmental conditions. Moreover, they are key for an accurate prediction of the performance of such insulating materials in real building operation, possibly achieved through dynamic energy simulations including heat and vapor transfer and modelling the conductivity variation with temperature and moisture
Ammonia-powered ships: Concept design and feasibility assessment of powertrain systems for a sustainable approach in maritime industry
Get PDFThe decarbonization of the shipping industry is pushing towards the introduction of low-carbon fuels such as hydrogen carriers and towards the installation of cleaner propulsion systems. Among different hydrogen carriers, ammonia (NH3) is considered a promising option due to its high volumetric energy density and to its easier storage and transportation in comparison with pure hydrogen. Therefore, this study is focused on the design, modeling, and feasibility assessment of ammonia-based propulsion systems for shipping applications. Two NH3-based fuel cell power generation systems are analyzed: i) a NH3-based Proton exchange membrane Fuel Cell (PEMFC) system and ii) a NH3-based Solid Oxide Fuel Cell (SOFC) system. These systems are designed to replace a conventional diesel powertrain installed on board a container ship. The fuel consumption, according to the ship load profile, is calculated and the analysis on the masses and volumes of the fuel storage tanks and of the ammonia powertrain systems is performed. Results highlight that on board installation of the proposed ammonia-based propulsion technologies causes greater masses and volumes with respect to the conventional diesel system. This criticality, in the face of an advantage in terms of avoided CO2 emissions per cruise, could be overcome by accepting a cargo capacity reduction. It is estimated a cargo reduction in the range 3.3% − 4.8% for the proposed fuel cell-based powertrain solutions. However, by valorizing the avoided CO2 emissions, it is possible to recover the economic penalty due the cargo reduction and break-even with the reference diesel scenario
On the impact of hollow silica powder on the performance aerogel glazing systems in buildings: Results from laboratory and simulation analyses
Get PDFAerogel-based glazing systems are an effective solution to reduce space heating energy use in buildings, even if overheating risks in temperate climates exist due to the high solar transparency of the systems. This study analyzes the potential of an innovative solution, based on a mixture of granular aerogel and hollow silica powder, in small concentrations, to increase the reflectance of the aerogel layer and reduce solar transmission. A set of glazing samples, different in aerogel layer and powder concentration, were produced and test in laboratory to determine the relevant solar and thermal properties. It was found that at 7.5 % powder concentration the solar and light transmittance were reduced up 0.48 and 0.45 in a 0–1 scale, respectively. Analogously, the solar and light reflectance increased up 0.49 and 0.46, respectively. The thermal resistance of the system increased up to 0.18 m2K/W, peaking at 1.88 m2K/W for the 34 mm aerogel layer sample. The thermo-physical properties were used as input to simulate an office building in different climatic conditions; it was found that the proposed technology ensured total energy savings for 4 % powder concentration and higher; cooling energy savings were up to 21 % and total energy savings up to 21 %
A note on differential equations of logistic type
Get PDFLogistic equations play a pivotal role in the study of any nonlinear evolution process exhibiting growth and saturation. The interest for the phenomenology they rule goes well beyond physical processes and covers many aspects of ecology, population growth, economy. According to such a broad range of applications, there are different forms of functions and distributions which are recognized as generalized logistics. Sometimes they are obtained by fitting procedures. Therefore, criteria might be needed to infer the associated nonlinear differential equations, useful to guess “hidden” evolution mechanisms. In this article we analyze different forms of logistic functions and use simple means to reconstruct the differential equation they satisfy. Our study includes also differential equations containing nonstandard forms of derivative operators, like those of the Laguerre type