Search Results (10)

Steam is widely used in industry as a heat carrier for thermal processes and is primarily generated by gas-fired steam boilers. The decarbonization of industrial thermal demand relies on the capability of clean and renewable technologies to provide steam through reliable and cost-effective systems. Concentrating solar thermal technologies are attracting attention as a heat source for industrial steam generation. In addition, electricity-driven high-temperature heat pumps can provide heat using either renewable or grid electricity by upgrading ambient or waste heat to the required temperature level. In this study, linear Fresnel solar collectors and high-temperature heat pumps driven by photovoltaics are considered heat sources for steam generation in industrial processes. Energetic and economic analyses are performed across the European countries to assess and compare their performances. The results demonstrate that for a given available area for the solar field, solar thermal systems provide a higher annual energy yield in southern countries and at lower costs than heat pumps. On the other hand, heat pumps driven by photovoltaics provide higher annual energy for decreasing solar radiation conditions (central and northern Europe), although it leads to higher costs than solar thermal systems. A hybrid scheme combining the two technologies is the favorable option in central Europe, allowing a trade-off between the costs and the energy yield per unit area. Full article

Complying with strict PM₁₀ and PM_2.5 limit values poses challenges in many European regions, influenced by diverse factors such as natural, regional, and local anthropogenic sources. Urban air pollution, exacerbated by road transport, local industry, and dust resuspension, contrasts with rural areas affected by solid fuel-based local heating and increasing wood burning. This study focuses on village of Sučany, located in Slovakia, analysing PM concentrations during non-heating and heating seasons. The method of analysis relies on the use of the MP101M air quality analyser that utilises beta radiation absorption method. One set of measurements was conducted at five distinct locations during the heating season (18/01/2019 to 28/02/2019) and non-heating season (14/08/2018 to 1/10/2018). Significant differences emerged during the non-heating season with corresponding PM₁₀ averages of 23.0 µg/m³ and PM_2.5 at 19.3 µg/m³. In contrast, the PM₁₀ averaged 53.9 µg/m³ and 52.8 µg/m³ during the heating season. The heating season shows PM_2.5 contributing up to 98% of total PM₁₀. The distribution of PM₁₀ and PM_2.5 pollution and the location of the potential source obtained using polar plots differed during the heating and non-heating seasons. This research underscores the impact of local heating on air quality in a typical Slovak village. The key recommendation for targeted interventions is supporting up-to-date air quality data, education, and financial incentives for citizens in order to implement cleaner and modern heating solutions. Full article

Industrial heat sources (IHSs) are key contributors to anthropogenic heat, air pollution, and carbon emissions. Accurately and automatically detecting their production areas (IHSPAs) on a large scale is vital for environmental monitoring and decision making, yet this is challenged by the lack of high-resolution thermal data. Sustainable Development Science Satellite 1 (SDGSAT-1) thermal infrared spectrometer (TIS) data with the highest resolution (30 m) in the civilian field and a three-band advantage were first introduced to detect IHSPAs. In this study, an IHSPA identification model using multi-features extracted from SDGSAT-1 TIS and Landsat OLI data and support vector machine (SVM) was proposed. First, three brightness temperatures and four thermal radiation indices using SDGSAT-1 TIS and Landsat OLI data were designed to enlarge the temperature difference between IHSPAs and the background. Then, 10 features combined with three indices from Landsat OLI images with the same spatial resolution (30 m) and stable data were extracted. Second, an IHSPA identification model based on SVM and multi-feature extraction was constructed to identify IHSPAs. Finally, the IHS objects were manually delineated and verified using the identified IHSPAs and Google Earth images. Some conclusions were obtained from different comparisons in Wuhai, China: (1) IHSPA identification based on SVM using thermal and optical features can detect IHSPAs and obtain the best results compared with different features and identification models. (2) The importance of using thermal features from the SDGSAT-1 TIS to detect IHSPAs was demonstrated by different importance analysis methods. (3) Our proposed method can detect more IHSs, with greater spatial coverage and smaller areas, compared with the methods of Ma and Liu. This new way to detect IHSPAs can obtain higher-spatial-resolution emissions of IHSs on a large scale and help decision makers target environmental monitoring, management, and decision making in industrial plant processing. Full article

The prevalent high-energy, high-pollution and high-emission economic model has led to significant air pollution challenges in recent years. The industrial sector in the Beijing–Tianjin–Hebei (BTH) region is a notable source of atmospheric pollutants, with industrial heat sources (IHSs) being primary contributors to this pollution. Effectively managing emissions from these sources is pivotal for achieving air pollution control goals in the region. A new three-stage model using multi-source long-term data was proposed to estimate atmospheric, delicate particulate matter (PM_2.5) concentrations caused by IHS. In the first stage, a region-growing algorithm was used to identify the IHS radiation areas. In the second and third stages, based on a seasonal trend decomposition procedure based on Loess (STL), multiple linear regression, and U-convLSTM models, IHS-related PM_2.5 concentrations caused by meteorological and anthropogenic conditions were removed using long-term data from 2012 to 2021. Finally, this study analyzed the spatial and temporal variations in IHS-related PM_2.5 concentrations in the BTH region. The findings reveal that PM_2.5 concentrations in IHS radiation areas were higher than in background areas, with approximately 33.16% attributable to IHS activities. A decreasing trend in IHS-related PM_2.5 concentrations was observed. Seasonal and spatial analyses indicated higher concentrations in the industrially dense southern region, particularly during autumn and winter. Moreover, a case study in Handan’s She County demonstrated dynamic fluctuations in IHS-related PM_2.5 concentrations, with notable reductions during periods of industrial inactivity. Our results aligned closely with previous studies and actual IHS operations, showing strong positive correlations with related industrial indices. This study’s outcomes are theoretically and practically significant for understanding and addressing the regional air quality caused by IHSs, contributing positively to regional environmental quality improvement and sustainable industrial development. Full article

Liquid fuel is widely used in industry and transportation. Liquid fuel leakage usually results in some spill fire accidents. In this paper, the effect of slope on the spread and burning behaviors of continuous spill fire from a point discharge source was studied by experiments. The flame spread rate, burning rate, heat convection at the bottom surface, flame feedback radiation, and flame height were analyzed. The results show that the spread area has an increasing trend with the slope, and the length of the spread area increases obviously, while the width of spread area shows an opposite trend. Moreover, the burning rate and the flame height of the steady stage decreases significantly with the slope increase, which can be attributed to the increase of heat convection between the fuel layer and bottom for the larger slopes. Subsequently, a burning rate model for the steady stage is built considering fuel layer heat loss and validated by the current experimental data. This work can provide guidance for the thermal hazard analysis of liquid fuel spill fires from a point source. Full article

As the greenhouse cultivation industry considers new ways to reduce energy demand and increase sustainable production, the global energy crisis constitutes a major issue. In this paper, two different energy sources for heating and cooling the root zone area of baby leafy vegetables grown in hydroponic tanks by resistors and chillers, respectively, were compared in order to fully cover power demand. The energy needs in the first case were met by the public electricity grid, while in the second case, the energy needs were covered by a photovoltaic system. The greenhouse was equipped with photovoltaic panels, an inverter, a charge controller and a storage system. The target-value of the root zone temperature was 22 °C. Data on solar radiation, root zone temperature, air temperature and humidity from the indoor and outdoor space of the greenhouse were recorded, and the energy production and carbon footprint for different seasons of the year were evaluated along with the crop yield. The results showed that the energy provided by solar panels was able to cover 58.0%, 83.3% and 9.6% of the energy for heating or cooling the root zone area during the spring, summer and winter periods, respectively. Regarding the carbon footprint of the energy used between the two systems, the system with the PV had a substantially lower value, which was calculated at 1.6 kg CO₂-eq kg⁻¹, compared to 49.9 kg CO₂-eq kg⁻¹ for the system with PPG for the whole year. Full article

In this paper, a 3D transient multi-physical field model is developed to capture the complex processes inside a fused magnesia furnace. The multi-physics model integrates electromagnetism, thermodynamics, decomposition reactions, and flow. The three-phase submerged magnesia furnace includes an arc, magnesite ores, a melting pool, and a solidification ingot. For a more comprehensive analysis of the optimal design of industrial operations, the influence of the key index of electrode insertion depth on temperature and reaction is also discussed. The results show that the current density in the fused magnesia furnace is almost the same as the joule heat distribution, and there is an obvious area of low energy density affected by the skin effect, which leads to the waste of electric energy. The temperature at the center of the arc reaches 12,000 K, and the plasma areas formed at the end of the three electrodes are connected to each other to form a closed current path, which provides energy for the process of melting magnesia. The arc region is an ellipsoid with a length of ~30 mm and a diameter of ~49 mm. The decomposition reaction of magnesite mainly occurs in the arc area, and the radiation heat provided by the high-temperature arc is used as the heat source. There is almost no magnesite in the molten pool, and the molten pool only provides energy for the melting process of magnesia. When the electrode insertion depth is 0.4, 0.5, 0.6, and 0.7 m, the arc length is 0.049 m, 0.066 m, 0.068 m, and 0.059 m, respectively. According to the simulation results, there is an optimal electrode insertion depth. Full article

This paper presents a low speed drive system with a simple and reliable construction, which can be used in an area where there is no power supply (isolated areas, forests, agricultural fields, etc.) and which operates on the basis of two heat sources, one from solar radiation and one provided by water. Alternatively, this system can be used to recover energy from wastewater from industry. The operation and role of the parameters that can influence the value of the rotation speed of the drive system are analyzed through a simulation, maintaining a constant speed in the case of the prototype is achieved through the control system because in real situations the temperature of heat sources can vary within certain limits. The models and tests performed highlight the parameters of the analyzed drive system and the limits of the range in which its speed can vary. Full article

Increasing the service life of die casting dies is an important goal of the foundry industry. Approaches are either material- or process-related. Despite new material concepts, hot work steels such as H11 are still predominantly used in the uncoated condition for die casting dies. In order to withstand the stresses that occur, this steel is used exclusively in the quenched and tempered condition. Required properties such as high high-temperature strength and high hardness combined with high toughness are, in principle, contradictory and can only be adjusted consistently over the entire die by furnace-based heat treatment. However, the results of various investigations have shown that improvements in the thermal shock resistance and wear resistance of hot work tool steels can be achieved by thermally influencing the microstructure near the surface. Based on these studies and related findings, an approach to surface heat treatment using the electron beam was developed. Due to the particle character of the radiation and the associated possibility of high-frequency beam deflection, the electron beam offers significantly greater flexibility in energy input into the workpiece surface compared with lasers or induction. The overall technological concept envisages replacing furnace-based heat treatment in the production of casting dies by localized and demand-oriented boundary layer heat treatment with the electron beam. The experiments include, on the one hand, the experimental determination of a suitable temperature–time interval with a focus on short-term austenitization. On the other hand, a simulation-based approach of boundary layer heat treatment with validation of a suitable heat source is investigated. Regarding short-term austenitization, the corresponding temperature and time range could be narrowed down more precisely. Some of these parameter combinations seem to be very suitable for practical use. The test specimens show a hard surface layer with a depth of at least up to 6 mm and a very tough buffer layer. Numerical simulation is used to estimate the resulting metallurgical microstructure and the achievable hardness as a function of the temperature–time interval. In addition, the results provided show the possibility of determining and optimizing the material properties by means of a simulation-based approach within the framework of a purely digital process planning and subsequently transferring them into a process planning. In the technical implementation, a temperature control was first established by means of a two-color pyrometer. In the further course of research, the pyrometer will be supplemented by an internally installed infrared camera, which will allow the reproducible setting of specified temperature profiles even for complex, large-area contours in the future. Full article

The amount of energy used in agricultural production, processing and distribution is constantly increasing. During the winter months in the greenhouse production industry, the supplemental lighting required to keep up production levels results in high expenditure. Current technology uses broadband high-pressure sodium (HPS) lamps, which is not the most efficient light source for crop production. Recent breakthroughs in the development of light source technologies have led to new opportunities for the use of sustainable and highly efficient light sources in the form of LEDs (light-emitting diodes) for greenhouse lighting. The aim of the study was to evaluate the efficiency of using photosynthetically active radiation (PAR) light for cucumber yielding, production processes and its influence on the variable costs in the cultivation of cucumbers using three different types of lighting. The research was carried out using three individual greenhouse growing area compartments, whereby the plants contained within were lit using three combinations: 1. HPS standard illumination from top HPS sodium lamps—control, 2. HPS-LED—HPS toplighting and LED interlighting, and 3. LED-LED—100% LED lighting, both toplighting and interlighting with LED. The research was conducted in two independent winter crop cycles. The results of the research conducted indicate that the efficiency of light use was the highest in the LED-LED combination and the lowest in HPS, and the use of supplemental lamp lighting in the LED-LED combination (interlighting and toplighting) gives the most favorable surplus of all the variable costs over the value of production to be obtained. Despite the highest absolute level of variable costs in this type of supplemental lighting, the production value was higher by as much as 32.55% in relation to the HPS combination, which also translated into a gross margin that was higher by about ¾. However, it is worth pointing out that, in the HPS-LED combination, the share of lighting and heating costs in the total value of production was the lowest. It is also a combination currently recommended in the literature as being the most beneficial in greenhouse production. Full article