Recycling behaviour of italian citizens in connection with the clarity of on-pack labels. A bottom-up survey

The present work studies, through an online survey, the recycling behaviours of a representative sample of Italian end users, in connection with the effectiveness of on-pack recycling indications of different packed materials. The study has a special focus on the clarity of on-pack recycling indications to convey waste sorting information, and the impact of clear and straightforward labelling to improve the sorting result. The work took advantage of social media as the distribution platform, thus obtaining a relatively high involvement of citizens. To investigate the representativeness of the sample, some of its characteristics were subject to checks and comparisons to their corresponding values of the Italian population. According to almost three-quarters of the responders, a clear and straightforward labelling will improve the result of their waste sorting drastically. The general awareness of the answerers relative to the importance of waste recycling and willingness to improve the quality of their sorted waste is very high among the participants but the overall satisfaction of the on-pack indications is relatively low. The score of on-pack labels in conveying information on recycling and waste segregation is evaluated as improvable. A higher perception of circular economy concept leads to more re-utilisation of the packaging parts, which increases with the awareness about the importance of recycling

Numerical Investigation of the Performance of a Solar Air Heater Equipped with a Packed Bed

In this work, a numerical study based on pore-scale CFD analysis has been carried out on a solar air heater equipped with intermittent packed beds. Hydraulic and thermal characteristics of the air were determined by testing a range of mass flow rates and various collector configurations, including one (SAH-M1), two (SAH-M2), and three (SAH-M3) packed beds. After the validation of the numerical simulations with general correlations, results showed that as the number of packed zones increases, the total pressure drop grows. As a result, the maximum pressure drop was obtained as 115 kPa for the collector with three packed zones, operating at Re ~ 1.3 × 105. Detailed thermal analysis proved that the intermittent integration of packed beds has the potential to also increase the heat transfer exchange between each packed zone, improving the convection by 25% in the second zone to the first zone and 35% in the third zone to the second zone at Re ~ 1.3 × 105. This enhancement effect can be attributed to the increase in the turbulence conditions of the fluid regime from one bed to the other. Evaluating the effects of design parameters showed that the bed spacing could not change the thermo-hydraulic characteristics significantly, while particles’ randomness may only affect the pressure drop by 13%

Development of an Equivalent Porous Medium Model for a Tubular Receiver Equipped With Raschig Rings

The porous insert has become one of the promising methods for heat transfer enhancement in many industrial applications ranging from small electronic devices to nuclear reactors, and large solar fields. For the assessment of such systems, the CFD numerical studies are usually employed by scientists to investigate the heat and mass transfer inside the region in micro or macro scales. Although micro studies are accurate and provide a detailed analysis of the process, they cannot be used for every study due to complex and costly computational resource they may demand for the case under study. Therefore, sometimes macro-scale simulations become more favorable thanks to the reduction in time and cost as well as the simplification over the morphology of the porous medium they offer. For these reasons, this study aims at developing a macro model for a novel porous disc made of Raschig Rings, to be applied to the tubular solar absorber for future simulations. The methodology devised in this study was to exploit detailed micro-scale simulations, achieving the macro properties and then developing a new equivalent macro model of a porous medium, based on the obtained properties. Numerical data indicated that when the developed macro model is compared to the micro simulations, the thermo-hydraulic results are in good agreement. Applying the macro model to a solar absorber working under linear Fresnel heating showed that the proposed porous disc could reduce the temperature rise on the tube wall by 40%

identification of the postulated initiating events of accidents occurring in a toroidal field magnet of the eu demo

AbstractThe design of the European Union (EU) DEMO reactor magnet system, currently ongoing within the EUROfusion consortium, will take advantage of the know-how developed during the design and manufacturing of ITER magnets; however, DEMO will suffer some new, more severe challenges, e.g., larger tritium inventory and higher neutron fluence, both having an impact on safety functions accomplished, among the other systems, also by the magnets. For these reasons, and in view of the need to demonstrate a high availability of the reactor (aimed at electricity production), a new, more systematic assessment of the system safety is required. As a contribution in this direction, the initiating events (IEs) of the most critical accident sequences in the EU DEMO magnet system (with special reference to the toroidal field magnets) are identified here, adopting first a functional analysis and then a failure mode, effects, and criticality analysis. In particular, the following are provided: (1) the EU DEMO magnet syste..

One-side heating test and modeling of tubular receivers equipped with turbulence promoters for solar tower applications

Tubular receivers in central tower systems suffer the high mechanical stresses caused by the temperature gradient typically established along the tube and across its circumference due to the one-side heating. In the present work, the thermal behavior of three different absorber tubes is investigated both experimentally and numerically. The tubes, manufactured in Cr alloy 718 (Inconel®), were smooth or with repeated rib-roughness (annular or helical ribs), and were tested at the solar furnace SF60 of the Plataforma Solar de Almería (PSA) in 2017 within the international access program of SFERA II project, financed by the EU. The specific focus of the tests was the assessment of the role of turbulence promoters in reducing the peak wall temperature when a strong one-side heating is present, contributing to the reduction of the thermal gradients between the irradiated and the non-irradiated (back) side of the tube. The experimental results show that the use of turbulence promoters reduce the wall temperature with respect to the case of a smooth tube, as expected, although the comparison between the samples is not trivial in view of the change in the optical properties induced by the progressive oxidation of the irradiated surface. Computational Fluid Dynamic (CFD) 3D models have been developed for the three samples and they have proven the capability to very-well reproduce the experimental results. A fair comparison between the different simulated tubes in the same controlled conditions of one-side heating has been performed numerically, assessing quantitatively the temperature reduction induced by the turbulence promoters, and the best performance of the Inconel® tube equipped with helices

Analysis of the effects of primary heat transfer system isolation valves in case of in-vessel loss-of-coolant accidents in the EU DEMO

As DEMO is the first European device planned to produce electricity from fusion, the volume of its Primary Heat Transfer Systems (PHTS) will be consistently larger if compared to present or next-generation tokamaks such as ITER. The consequences of an in-vessel Loss-Of-Coolant Accident (LOCA) would then be more important, and within the EUROfusion Consortium different possible mitigation measures are being investigated. Among these, the introduction of Isolation Valves (IsoVs) on the main cooling loops of the Breeding Blanket is being considered, in view of the many benefits they would introduce, not only in case of accidents, but also e.g. during the maintenance of the in-vessel components. Fast-closing IsoVs on the PHTS would help in relaxing not only the requirements of the VV pressure suppression system (VVPSS) design, but also those related to the expansion volumes that shall accommodate the contaminated coolant discharged from the PHTS after a LOCA. In the present work, the GETTHEM code, the system-level thermal-hydraulic model developed for the EU DEMO at Politecnico di Torino, is used to assess the beneficial effects of the introduction of the IsoVs. The effects of the actuation time of the IsoVs and of their location are parametrically investigated, considering both water and helium as PHTS coolants, with particular reference to the reduction of the in-vessel space-averaged pressure and of the suppression system size

Experimental investigation on an air tubular absorber enhanced with Raschig Rings porous medium in a solar furnace

An experimental study was carried out to assess the performance of a tubular absorber enhanced with Raschig Rings (RR) porous medium for CSP applications. Two alternative designs with different porous lengths of 20 and 40 mm were fabricated and compared with two conventional tube designs with and without surface coating. Several tests were conducted at the solar furnace SF60 of the Plataforma Solar de Almeria (PSA) within the international access program of the SFERA III project, financed by the EU. The main scope of the study was to provide comprehensive detail on the hydraulic and thermal characteristics of the modified tube for further optimization and deployment in point-focusing solar systems. Therefore, evaluations were directed to determine the effects of each design on the pressure losses and the tube wall temperature, as well as on the useful heat gain. Results indicated that although the porous inserts rise the pressure losses through the fluid flow, the higher wetted area in the porous zone for heat transfer between the air and the heated plate reduces the wall tem-perature significantly. Moreover, applying the PYROMARK 2500 as the surface coating has a high influence on increasing solar absorption and reducing thermal losses. Further investigations revealed that the integration of the porous medium changes the temperature profile formed all over the tube, transforming a Gaussian shape in the plain pipes to a spline shape with two peaks in the modified tubes. Increasing the energy and exergy effi-ciencies of the solar absorber up to 30-50% and 60-70%, respectively, demonstrated the improving effects of the proposed porous material for future applications in the solar industry

Remote digital monitoring during the retention phase of orthodontic treatment: A prospective feasibility study

Objective: To evaluate if a remote digital monitoring system added at the end of orthodontic treatment could positively influence the retention phase by reducing the occurrence of misfit of removable appliances, number of emergency appointments (EA), and orthodontic relapse. Methods: Twenty-seven patients who completed active orthodontic treatment were divided into the study and control groups. In addition to the standard chairside follow-up appointments at month 1 (T1), month 3 (T2), month 6 (T3), the study group patients were monitored using Dental Monitoring® with monthly intra-oral scans. Occurrence of misfit of removable retainers, number of EAs, and intercanine width change were recorded for both groups. Differences in EAs and retainer fit were assessed using the chi-square test. Intra-group and inter-group differences in the intercanine width were assessed with Friedman test and Mann–Whitney U test, respectively (α = 0.05). Results: The study group showed a significantly lower occurrence of misfit of removable retainers (p = 0.027) compared to the control group. No significant inter-and intra-group difference was found in the EAs and intercanine width change at each time-point. Conclusions: Integrating remote monitoring systems, such as Dental Monitoring®, to the retention phase of the orthodontic treatment may lower the occurrence of misfit of removable retainers. However, a small sample size and a short observation period limit the strength of this evidence. These preliminary results tentatively suggest that remote monitoring technologies may be beneficial, especially during the COVID-19 pandemic, when the regularity of in-office visits might be disrupted

Effects of RANS-Type turbulence models on the convective heat loss computed by CFD in the solar two power tower

The effect of the choice of Reynolds-Averaged Navier-Stokes (RANS) type turbulence closure on the Computational Fluid Dynamics (CFD) prediction of convective heat losses from the Solar Two central receiver is considered in this paper for a simplified receiver geometry approximated by flat panels. Computed convective losses at steady state are ~ 2-3% (1%) of the total power absorbed by the receiver, at high (low) wind speed, depending on the turbulence model chosen. The simulation results are consistent with those of available correlations for rough cylinders, if the macroscopic roughness due to the panel edges is accounted for, as well as with the low speed experimental results, within the respective error bars

Experimental and numerical investigation of a porous receiver equipped with Raschig Rings for CSP applications

In the context of central solar tower systems, tubular receivers are among the most appealing absorber solutions: the absorbed solar radiation is transferred from the tube external surface to the heat transfer fluid (HTF) flowing within the absorber. In the case of air as HTF, very high temperatures of the coolant can be obtained in principle, thus increasing the efficiency of the downstream thermodynamic cycle. To explore the possible applicability of a porous medium made of Raschig Rings (RRs), already successfully adopted in the heat removal from the resonant cavity of a technological device, the gyrotron, where the heat flux can go up to 20–25 MW/m2 and removed by subcooled water, a mock-up of a planar receiver equipped with RRs has been tested in a solar furnace, using air as coolant. The test results are presented here and analyzed1. Furthermore, a numerical model of the mock-up, where the RRs are modeled in detail by the Discrete Element Method, is presented and its capability to reproduce the measured data demonstrated. The model shows, for the tested configuration, an enhancement of the heat transfer of a factor of ~5 with respect to a plain channel with the same envelope, and a Performance Evaluation Criteria of 2–2.5 when the device is compared to the same receiver configuration, but without RRs