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Influence of Plant Evapotranspiration Process on the Summer Cooling of a Solar Bioclimatic Greenhouse Internal Environment
No full textBuildings require a very high energy consumption for their climatization, and they are now called to provide comfortable indoor environments minimizing their environmental footprint in cities. Bioclimatic solar greenhouses are interesting infrastructures attached to buildings that can act as passive solar systems, allowing the reduction of energy needs for indoor acclimatization. The current work aims to investigate the thermal effects on summer cooling determined by the biochemical process of plant evapotranspiration performed by a natural 'green' system, placed inside a bioclimatic solar greenhouse. Four horticultural plant species (celery, lettuce, tomato, and grapevine), exhibiting a high evapotranspiration potential, were cultivated inside a bioclimatic solar greenhouse to test their effective evapotranspiration capacity and the hypothesis that the presence of a set of plants could favor summer cooling of building indoor spaces allowing a cost saving for air conditioning. Plant species, resulting very suitable to practice domestic horticulture in the bioclimatic solar greenhouse located in Mediterranean area, were selected according to their specific crop coefficient during the full vegetative development (Kc, int). Evapotranspirated water was measured for each of the four species and for the whole 'green' system. Grapevine resulted the most efficient, reaching a maximum of evapotranspirated water almost equal to 1 kg (per individual plant grown in a 12 L pot), in a hot summer day of year 2020. Moreover, in summer 2021, a LED system was implemented inside the greenhouse, to increase the internal level of shadowing, to allow natural ventilation and, at the same time, to guarantee the radiation necessary for photosynthesis and evapotranspiration processes to plants. Under these conditions, the 'green' system integrated in the bioclimatic solar greenhouse allowed a light reduction of the internal air temperature, making this environment more livable during the hot season, while being positively exploited for domestic agriculture
Continuous multiphase Bunsen reactor of iodine-sulfur thermochemical water splitting cycles for hydrogen production: Experimental, Modelling and Design Insights
No full textThermochemical water splitting cycles (TWSCs) hold promise for sustainable H2 production in future energy systems, with Iodine-Sulfur (IS) and Nickel-Iodine-Sulfur (NIS) processes standing out as efficient options. The core of both these processes lies in the Bunsen reaction, underscoring the need to identify optimal operational conditions and plant solutions for this crucial reaction section. Thus, in this study, a continuous counter-current flow Bunsen reactor fed with 5 NL h−1 of SO2 was constructed and tested. An inventive aspect was the introduction of solid I2 pellets from the top to enhance saturation at the liquid-liquid interface between sulfuric and hydriodic product phases, promoting segregation. This ingenious design achieved nearly complete SO2 conversion and optimal H2SO4 and HI concentrations in the respective product phases, while avoiding undesirable byproduct formation. The study further advanced the modelling of the experimental reactor by employing innovative kinetic and liquid-liquid equilibrium description approaches, and demonstrating exceptional validation accuracy of R2 = 0.9988. Additionally, with the aim of obtaining design charts as a potential tool for Bunsen reactor design, a microscopic model describing the gas phase trend along bubble or packed Bunsen-type reactors was developed. The model's dimensionless analysis revealed a characteristic times ratio (Bu) comprehensively describing all the phenomena occurring to the gas phase within the Bunsen reaction section, and identified an optimal Bu value of 0.4 for pure SO2 gas inlet. Overall, the study's innovative strategies and models contribute significantly to the advancement of Bunsen reactor engineering
3D-printing for the rehabilitation and health monitoring of structures with FBG: Experimental tests
No full textNowadays 3D-printing technology is part of many construction processes in different engineering fields, thanks to the possibility of precisely reproducing the shape of complex elements and the availability of different printing materials. In this context, the paper presents the results of tensile experimental tests on samples 3D-printed in PLA (PolyLactic acid), and analyse the effect of the printing process and aging test. Referring to the interest in producing smart components, some samples were printed with an embedded single-mode fiber optic with acrylate coating, commonly used for FOSs (fiber optic sensor). In particular, some samples were produced with pristine optical fiber to test the procedure, while others were produced with the FBG (Fiber Bragg Grating) sensor. The results are discussed in terms of strength and stiffness in both pre-peak stage and post-peak one (ductility and softening), and the functionality of the embedded FBG sensors in operating as strain sensors is reported
Effect of combined refrigerant leakage and HEX fouling on performances on an air-to-air EHP in different Italian Climates
No full textThe use of heat pumps for the needs related to the heating and cooling in the building sector has largely increased and it is expected to increase more with the limitations in the use of burners. Even though the use of heat pumps has, generally, a reduced environmental impact, it is important to preserve the performance of the machine during its lifetime to control the direct and indirect environmental impact. In this regard, the effect of some soft faults is relevant, such as refrigerant leakage and heat exchanger fouling, which may contribute to highly degrade system performances, since their evolution often remains unidentified for long periods of time. In particular, it is important to quantify the potential performance degradation that faults may cause on heat pump systems, as well as to identify the most influencing parameters for implementing monitoring strategies. This work analyzes the effect of these three faults on the behavior of an air-to-air reversible electric heat pump for domestic heating and cooling, both on actual performance and heating/cooling capacity, and of seasonal performance in five different Italian climate conditions of Courmayeur, Milan, Rome, Palermo, Pantelleria. Results show the effect of standalone and combined soft faults on both actual system performance and capacity in heating and cooling operating modes, analyzing counterbalance and superposition effects. Also, the results of lifetime (12 years) performance are presented assuming for each climate condition different scenarios of fault evolution and maintenance strategy
An Italian InterLaboratory comparison on personal dose equivalent for dosimetry services: promoting measurements reliability and addressing new digital challenges
Get PDFAn InterLaboratory Comparison on personal dose equivalent, Hp(10), a fundamental part of radiation protection dosimetry measurements, was organized aiming at evaluating the measurement capability of dosimetry services across Italy, in order to ensure the reliability of the measurements. For the intercomparison, each participant sent their own passive dosimeters, which were exposed to gamma radiation beams emitted from a S-Cs source and to medium-energy filtered X-ray beams of the wide spectrum series, at the ISO 4037-1 W-80 quality. Results were evaluated by applying the statistical estimator R, which compares the communicated dose equivalent values and the reference, assigned values, and then evaluated using trumpet curves. Data were acquired using web forms, collected in internal databases, and processed using statistical software, aiming at the automation of analysis and preparation of technical reporting. Results indicate a good level of maturity in the measurement capabilities in radiation protection dosimetry in the italian dosimetry services who participated. The intercomparison was an opportunity for mutual improvement between the participating dosimetric services and the organizing institute: the former were able to compare themselves and have their capabilities assessed from an external provider; while, the latter had the chance to improve their management and organization skills for a large, multi-lateral intercomparison
Infrared radiative effects of desert dust in the Mediterranean during the long dust season of summer 2021
No full textThe central Mediterranean during summer 2021 has been characterized by synoptic conditions leading to an extended period with dust transport from the Sahara desert. In particular, very stable and persistent conditions with elevated values of the aerosol optical depth occurred in the second half of June and early July. In this study we integrate ground-based observations to determine the atmospheric conditions and derive the radiative effect produced by the Saharan dust aerosol at the surface in the IR spectral region. As shown by previous studies, desert dust produces a non negligible radiative effect in the IR, which partly offsets that acting in the solar spectral range. The determination of the surface radiative effect requires that the IR irradiance without aerosol is known. The summer 2021 dataset for Lampedusa has been analyzed in order to determine the downwelling IR irradiance without Saharan dust by means of an empirical formula. The application of this formula has allowed to reliably determine the downwelling IR irradiance without dust with an estimated accuracy of about 3 Wm-2; thus, the IR radiative effect was calculated as the difference between the measured irradiance and that estimated with the empirical formula. The mean value of the IR radiative effect (ARF) is 13.4 Wm-2, producing a radiative effect efficiency (FE), i.e. the radiative effect per unit optical depth, of 26.3 Wm-2. The mean estimated uncertainty on ARF is about 30%. We also used MODTRAN6 radiative transfer model to calculate the IR radiative effect in a selected case characterized by high aerosol optical depth. The radiative effect obtained in the selected case is in good agreement with that derived with the empirical method
A new binning method to choose a standard set of Quasars
No full textAlthough the Lambda Cold Dark Matter model is the most accredited cosmological model, information at intermediate redshifts (z) between type Ia Supernovae (z = 2.26) and the Cosmic Microwave Background (z = 1100) is crucial to validate this model further. Here, we present a detailed and reliable methodology for binning the quasars (QSO) data that allows the identification of a golden sample of QSOs to be used as standard candles. This procedure has the advantage of being very general. Thus, it can be applied to any astrophysical sources at cosmological distances. This methodology allows us to avoid the circularity problem since it involves a flux–flux relation and includes the analysis of removing selection biases and the redshift evolution. With this method, we have discovered a sample of 1253 quasars up to z = 7.54 with reduced intrinsic dispersion of the relation between Ultraviolet and X-ray fluxes, with δint=0.096±0.003 (56% less than the original sample where δint=0.22). Once the luminosities are corrected for selection biases and redshift evolution, this ‘gold’ sample allows us to determine the matter density parameter to be ΩM=0.240±0.064. This value is aligned with the results of the ΛCDM model obtained with SNe Ia
Copper-Enhanced CO2 Electroreduction in SOECs
No full textThe development of a Co-free and Ni-free electrocatalyst for carbon dioxide electrolysis would be a turning point for the large-scale commercialization of solid-oxide electrolysis cells (CO2−SOECs). Indeed, the demand for cobalt and nickel is expected to become critical by 2050 due to automotive electrification. Currently, the reference materials for CO2−SOEC electrodes are perovskite oxides containing Mn or Co (anodes) and Ni-YSZ cermets (cathodes). However, issues need to be addressed, such as structural degradation and/or carbon deposition at the cathode side, especially at high overpotentials. This work designs the 20 mol % replacement of iron by copper in La0.6Sr0.4FeO3−δ as a multipurpose electrode for CO2−SOECs. La0.6Sr0.4Fe0.8Cu0.2O3−δ (LSFCu) is synthesized by the solution combustion method, and iron partial substitution with copper is evaluated by X-ray powder diffraction with Rietveld refinement, X-ray photoelectron spectroscopy, thermogravimetric analyses, and electrical conductivity assessment. LSFCu is tested as the SOEC anode by measuring the area-specific resistance versus T and pO2. LSFCu structural, electrical, and electrocatalytic properties are also assessed in pure CO2 for the cathodic application. Finally, the proof of concept of a symmetric LSFCu-based CO2−SOEC is tested at 850 °C, revealing a current density value at 1.5 V of 1.22 A/cm2, which is remarkable when compared to similar Ni- or Co-containing systems
Status of DTT ECH Transmission Lines and Antennae
No full textThe divertor tokamak test (DTT) facility is designed to study the power exhaust methods in scenarios similar to those expected in future fusion plants like DEMO. The project foresees 45 MW of external additional heating power to the plasma, provided by electron cyclotron heating (ECH), ion cyclotron heating, and neutral beam injector. This article focuses on the present status of the design of the transmission lines (TLs) and antennas for the ECH system. In the first operational phase, the system shall include 16 gyrotrons (1 MW/170 GHz/100 s), grouped into two clusters of eight sources each. In a later stage, the total installed power shall be doubled for a total of four clusters. Quasi-optical TLs connect the EC sources, located in a dedicated building, to the tokamak, via mirrors transmitting the microwave beams inside vacuum pipes to reduce losses and risks of arcing in air. Each TL consists of three main sections: two single-beam (SB) sections with small mirrors dedicated to a single beam at the beginning and the end of the line and a midsection of multibeam (MB) mirrors for the transmission of all the eight beams of the cluster. The beams at the output of the TL match the antennas installed in the equatorial and upper ports of the same vacuum vessel sector, through corrugated circular waveguides (WGs). The WGs are needed to reduce the vacuum conductance between the DTT vessel and TLs environments, being the connection with the vacuum vessel managed by all-metal gate valves without diamond windows. The two antennas consist of independent launching modules for each beam composed by two mirrors, one fixed and one steerable. All the components of the system are actively water-cooled to limit deformations of the mirrors surface to ensure the required quality of the beams and to reduce the transmission losses
Riptide: a proton-recoil track imaging detector for fast neutrons
No full textRiptide is a detector concept aiming to track fast neutrons. It is based on neutron-proton elastic collisions inside a plastic scintillator, where the neutron momentum can be measured by imaging the scintillation light. More specifically, by stereoscopically imaging the recoil proton tracks, the proposed apparatus provides neutron spectrometry capability and enable the online analysis of the specific energy loss along the track. In principle, the spatial and topological event reconstruction enables particle discrimination, which is a crucial property for neutron detectors. In this contribution, we report the advances on the Riptide detector concept. In particular, we have developed a Geant4 optical simulation to demonstrate the possibility of reconstructing with sufficient precision the tracks and the vertices of neutron interactions inside a plastic scintillator. To realistically model the optics of the scintillation detector, mono-energetic protons were generated inside a 6 × 6 × 6 cm3 cubic BC-408 scintillator, and the produced optical photons were propagated and then recorded on a scoring plane corresponding to the surfaces of the cube. The photons were then transported through an optical system to a 2 × 2 cm2 photo sensitive area with 1 Megapixel. Moreover, we have developed two different analysis procedures to reconstruct 3D tracks: one based on data fitting and one on Principal Component Analysis. The main results of this study will be presented with a particular focus on the role of the optical system and the attainable spatial and energy resolution