Influence on energy demand of thickness, thermal conductivity, and volumetric heat capacity of ladle working lining in secondary steel-making process

The secondary steel-making process involves several steps during which steel is kept in a ladle, that is, a vessel made of an outer steel layer (carpentry), an intermediate refractory layer, and an internal refractory layer. Unlike the intermediate layer, the internal layer undergoes a progressive reduction in thickness and a periodic restoration. Traditionally, it is made of alumina or magnesite. During the process, the ladle undergoes unsteady heating and cooling; therefore, heat transfer depends on thermal conductivity and heat capacity. This study aims to identify the ladle internal layer characteristics that affect the energy demand. This analysis investigates the effect of the internal layer thickness S, volumetric heat capacity C, and thermal conductivity λ. Through the Design Of the Experiments (DOE), different scenarios have been selected and analyzed by means of numerical simulations performed on a numerical model defined in COMSOL Multiphysics. The energy demand as a function of the internal layer properties has been estimated, and it has emerged that low thermal conductivity and heat capacity values require a lower amount of energy

Larval development and post-larval growth of Branchiomma bairdi (Annelida: Sabellidae) from a Mediterranean population

Branchiomma bairdi is a Caribbean fan worm introduced in several localities worldwide, including the Mediterranean Sea, where the species' range has rapidly expanded. Reproduction in B. bairdi was previously investigated in both extra-Mediterranean and Mediterranean areas, but no information is available on larval development and post-larval growth. In the present article, we examined these features for a population from the Mar Grande of Taranto (Ionian Sea). The species is hermaphrodite, and fertilization occurs in situ. Mucus seems to play an important role in fertilization, and also in preserving eggs before fertilization. The trochophore stage develops within the mucus and after hatching, larvae swim for about 3 d before settlement. The trochophore showed a distinct prototroch and two red dorsolateral larval eyes. The pelagic stage takes only 96 h even though prototroch is maintained after settlement, disappearing at 5 d, when larvae showed three chaetigers and branchial crown consisted of four radioles. Some interesting observations concerning changes in the morphology of chaetae and in the number of uncini during growth are also reported, together with discussion of the development of stylodes, an important diagnostic feature in Branchiomma species identification

Design of a 5th Generation District Heating Substation Prototype for a Real Case Study

The evolution of district heating networks is moving toward low temperatures in heat distribution with so called 4th generation networks. However, the lowest heat transfer fluid temperatures in district heating are achieved through ultra-low temperature networks, referred to as 5th generation district heating networks (5GDHNs). Low temperatures in heat distribution results in an extremely different configuration of 5GDHN compared to traditional district heating network, especially in the grid substation due to the inability to directly couple the grid with the buildings. This paper presents a detailed design of a 5th generation substation prototype, which is carried out to verify the proper operation and monitor the performance of this type of substation in a real case study. The prototype is fed by low-temperature waste heat, currently dissipated through evaporative towers, and will be built in the city of Brescia, Italy. The layout of the substation prototype, consisting of a bidirectional pumping system, a reversible water-to-water heat pump, an inertial thermal energy storage and a heat exchanger, is presented. An analysis is performed to figure out which refrigerant offers the best performance of the heat pump. In addition, fixed the refrigerant, the performance of the grid connected heat pump is found to be increased from 29.5% to 55.5% for both heating and cooling compared with a stand-alone air-to-water heat pump solution. Finally, the process flow diagram and the piping and instrumentation diagram of the substation are presented and commented

Improving the energy performance of a 3D-printed wall using recycled material

In this paper, we present the results of a preliminary experimental campaign conducted on a 3D-printed wall 40 cm thick made of three concrete walls, connected by metal pins and concrete curbs to form three types of cavity - one rectangular and two triangular. The tests were performed in a climatic chamber at the Pietro Pisa Laboratory of the University of Brescia. The wall thermal performance has been evaluated by examining four scenarios in which the cavities have been filled with insulating material made of cellulose-based recycled flakes characterized by a declared thermal conductivity of 0.038 W/mK. The wall thermal transmittance U is measured based on the temperatures and heat fluxes measured through the structure. Based on the degree of filling, the wall thermal transmittance ranges between 1.58 W/m2K for the wall without insulation, and 0.28 W/m2K for the configuration with all cavities completely filled

Performance analysis of a large TES system connected to a district heating network in Northern Italy

The addition of storage capacity to district heating systems increases flexibility and expands the range of usable heat sources. Despite their apparently simple nature, thermal energy storage (TES) tanks display a wide range of performances due to different construction and operation choices, as proven by numerous literature studies. However, most of the investigations focus on domestic-size tanks of few cubic metres or, on the other hand, very large seasonal storages of hundreds of thousands of cubic metres. In this work, the performances of a 5000 m3 TES recently introduced in a district heating network in Brescia, Italy, are experimentally analysed using temperature and flow rate measurements acquired over two months in the heating season. First-law efficiencies, exergy, and stratification parameters are calculated and discussed. Energy and exergy efficiencies computed for all examined cycles are above 90%, in line with literature values for smaller and larger TESs. The thermocline profile is generally stable through the cycle unless anomalous events occur, and its average thickness is below 4% of the water height. The combined analysis of single-point indicators, thermocline profiles, and qualitative temperature heatmaps shows that short partial charge/discharge events followed by long stand-by periods negatively affect performances. Stratification efficiency and stratification number give further time-dependent information on the vertical distribution of temperatures in the TES. Heat losses towards the outside are also estimated and discussed in the light of integrative measurements performed on other TESs with similar characteristics, showing that particular care must be paid to the top, where dissipation could be increased by evaporation phenomena if the water surface is not protected

Numerical and experimental study on metamaterials featuring acoustical and thermal properties

Metamaterials can be defined as materials which, for their peculiar composition or structure, exhibit characteristics that are not normally found in nature. "Multifunctional" metamaterials could be used to optimise different characteristics at the same time. In this paper the authors try to apply them for thermal and acoustic optimization of external building walls. Thermal optimization consists in obtaining a low transmittance, important in winter, and a low periodic thermal transmittance, important in summer. Acoustic optimization consists in obtaining high sound transmission loss, to respect the law prescriptions, and a good sound absorption coefficient, if possible. In this way should be possible enhance the comfort conditions in buildings and reduce the energy demand for winter heating and summer cooling. The proposed solution consists of several layers with different suitable characteristics: the sequence of the layers has been chosen with particular care. The thermal analysis has been performed by means of a self-developed code based on the ISO 13786 standard. The acoustic behaviour of the single layers has been determined following the procedure given by the ASTM E2611-09 standard using a four-microphone impedance tube and the transfer matrix method has been used for the complete assembly. This preliminary combined study showed encouraging results

EMISSIONS REDUCTION FROM PELLET STOVESTHROUGH BURNER POT MODIFICATIONS

In this study, results of an extensive set of experiments onfive wood pellet stoves (8-11 kW nominal power) have been per-formed to verify whether carbon monoxide (CO), particulatematter (PM) and nitrogen monoxide (NO) emissions can be re-duced upon modification of burner pot geometry, depth and airinlet positions. A modification of “traditional” burner pot geom-etry brings CO emission close to zero. Also PM emissions arereduced but not as much as those of CO. It is verified that increas-ing the burner pot’s depth, PM emissions can be further reducedcompared to the less deep burner pot. Finally, since plots of in-stantaneous emissions versus O2content exhibit significant scat-tering and do not show a clear correlation, plots of mean valueof emissions, over narrow intervals of O2, versus O2are intro-duced. These plots show an optimal interval of O2content thatminimizes emissions

Effects of Long COVID on Psycho-Physical Conditions in the Italian Population: A Statistical and Large Language Model Combined Description

Background: Long COVID refers to the persistence or development of signs and symptoms well after the acute phase of COVID-19. Objective of the study: To investigate the long-term outcomes of the SARS-CoV-2 infection in terms of psychological, social, and relational consequences within the Italian population. Materials and methods: We conducted an observational, cross-sectional, and multicenter study using an online questionnaire distributed to a sample of the Italian population. By utilizing the Short Form 12 Health Survey (SF-12) and the Hikikomori scale, we assessed perceived quality of life and social isolation, respectively. The questionnaire also included an open-answer question: “What will you remember about the pandemic period?”. We used generative artificial intelligence to analyze and summarize the corresponding answers. Results: A total of 1097 people participated in this study. A total of 79.3% (n = 870) of participants declared that they had been hospitalized and 62.8% (n = 689) received home care. Physical symptoms included headaches (43%, n = 472) and asthma (30.4%, n = 334). Additionally, 29.2% (n = 320) developed an addiction during the pandemic and, among these, 224 claimed internet addiction while 73 declared an emotional addiction. Furthermore, 51.8% (n = 568) experienced limitations in carrying out daily life activities. According to the Hikikomori scale, participants with positive SARS-CoV-2 infection exhibited higher levels of isolation compared to the others (p < 0.001). Participants without COVID-19 showed higher levels of emotional support (p < 0.001). Our semiautomatic analysis of the open-ended responses, obtained by a procedure based on a free large language model, allowed us to deduce and summarize the main feelings expressed by the interviewees regarding the pandemic. Conclusions: The data collected emphasize the urgent need to investigate the consequences of long COVID in order to implement interventions to support psychological well-being

Perception of changes in marine benthic habitats: The relevance of taxonomic and ecological memory

Having a reliable ecological reference baseline is pivotal to understanding the current status of benthic assemblages. Ecological awareness of our perception of environmental changes could be better described based on historical data. Otherwise, we meet with the shifting baseline syndrome (SBS). Facing SBS harmful consequences on environmental and cultural heritage, as well as on conservation strategies, requires combining historical data with contemporary biomonitoring. In the present “era of biodiversity”, we advocate for (1) the crucial role of taxonomy as a study of life diversity and (2) the robust, informative value of museum collections as memories of past ecosystem conditions. This scenario requires taxonomist skills to understand community composition and diversity, as well as to determine ecosystem change trends and rates. In this paper, we focus on six Mediterranean benthic habitats to track biological and structural changes that have occurred in the last few decades. We highlight the perception of biological changes when historical records make possible effective comparisons between past reference situations and current data. We conclude that the better we know the past, the more we understand present (and will understand future) ecosystem functioning. Achieving this goal is intrinsically linked to investing in training new taxonomists who are able to assure intergeneration connectivity to transmit cultural and environmental heritage, a key aspect to understanding and managing our changing ecosystems

Two cases study of fouling colonization patterns in the Mediterranean Sea in the perspective of integrated aquaculture systems

Fouling assemblage colonizing fish-farms is considered mostly to produce negative impacts causing financial loss. By contrast, large evidences emerged on the bioremediation role by biofouling associated to aquaculture facilities, even if the fouling assemblages thriving in the water column was poorly investigated. The aim of the present work was to investigate the macrofouling assemblages over one year of immersion, in order to single out the fouling species, which play the most remarkable role for the bioremediation of the marine areas affected by aquaculture activities. With this in mind, we studied the fouling community dynamics in two Mediterranean maricultural facilities, respectively in the Mar Grande of Taranto (Ionian Sea) and in the Gulf of Gaeta (Tyrrhenian Sea), using the same experimental design and time frame. Two experiments were carried out using artificial panels anchored to two finfish cages. The one-year old fouling communities in the two sites were compared at four seasons of immersion, four submersion durations and three depths, both communities from structural and functional points of view. Notwithstanding the quite similar species composition of fouling of the two sites, the biofouling showed the highest biodiversity in the Mar Grande of Taranto. In the Gulf of Gaeta mussels, Mytilus galloprovincialis, dominated at all the times and depths, whilst in the Mar Grande of Taranto they were especially abundant at the surface with the deepest panels being largely colonized by polychaete sabellids. The co-occurrence of the filter-feeders Mytilus-sabellids recorded in the Gulf of Taranto also highlighted the highest filtration capability. Our results suggest two different fouling assemblages as candidates for bioremediation in integrated multitrophic aquaculture facilities: both a monospecific system dominated by mussels and a multi-specific system with sabellids and mussels as most abundant filter-feeders