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Peak power shaving in heating systems can be achieved using heat accumulators, traditionally implemented in the form of water storage tanks. Their heat capacity can be increased by using a phase change material (PCM) instead of water, which, however, usually requires a change in the tank design. The innovation of this paper is an interesting concept to use plastic capsules filled with a PCM that replace part of the water volume in an existing heat accumulator. The aim of this paper is to compare the cooling rate of the same volume of water as that of the water mixed with the PCM capsules to initially verify the heat storage potential of the capsules. The results of pilot experimental studies on a laboratory scale are presented and discussed, showing the potential of this idea for heat storage. The partial replacement of water with capsules (40% of the total volume) results in significantly faster heat accumulation with the same tank volume (3.85 times at the beginning of the process) and more heat stored (decrease in the temperature of water alone by 14 K and water with PCM capsules by 26 K in the same period of time), which gives promising perspectives for the use of this solution on a semitechnical scale and further in a real-size heating system. [ABSTRACT FROM AUTHOR]

Being one of the pillars supporting modern industry, the additive manufacturing (AM) field has gone through significant developments over the years, and that is certainly also the case of deposition processes based on the use of the electric arc. However, although most of the knowledge for that specific purpose comes from the more consolidated arc welding counterparts, inherent and yet critical challenges emerge from arc additive manufacturing (Arc-AM). As main advantage, Arc-AM processes offer the capacity to build metallic parts at very high deposition rates and at accessible prices (given their arc welding roots), but generally at the cost of high heat input levels and of tendency for heat accumulation occurrence. Such a negative facet leads to many complications concerning quality factors of the parts, which are related to thermal effects as in terms of geometry/aspect characteristics, distortions, macro/microstructural features, residual stresses, and mechanical properties, and even of production time, invariably in an intertwined connection. The solution, in this case, depends on a large extent on implementations of proper thermal management of the parts being built, which have been indeed the focus of attention of many research and development efforts in the field of Arc-AM over the years as this review aims to present. Thus, the general intent of this work is to contribute to further developments in Arc-AM via a comprehensive review of the related thermal management approaches that have been attempted. The idea is to facilitate the comparison and assessment for suitability of the different thermal management approaches, helping developers working on Arc-AM processes with the foundations for their application and/or improvement. As the subject of thermal management in Arc-AM tends to a more mature scenario, this review ultimately aims at the establishment of a more direct bridge on that matter between academia and industry. Thus, a scientific and hence more critical perspective of the related knowledge is balanced with a technological/engineering and hence more informational side of it. To be representative, it covers information produced over a decade (2013–2022) on scientific and technological developments that somehow have effects via thermal consequences on the metallic layers during the Arc-AM processing time. And it is organized in three main parts. First, in Section 1, after the introduction to the subject of interest and presentation of the general and specific objectives as well as of the scope and delimitations of the review, the complications related to poor thermal management are compiled and discussed in such a way that its importance is characterized and the scientific bases for understanding the functions/effects of the diverse approaches to it are stablished. Then, in Section 2, a systematic bibliometric survey of related publications is presented in detail for auditability and future consultations, and the various thermal management approaches (in fact applied to different Arc-AM processes, metallic materials, and part shapes within the period of analysis) are categorized and then briefly described and representatively discussed in dedicated subsections, which eventually include preliminary remarks and general guidelines for application. The first main section (specifically the part on complications related to poor thermal management) as well as the subsections of the second one were actually built in such a way that they can be consulted individually depending on specific interests of the audience. At the end, in Section 3, the entire subject is recapitulated with combined graphical data, being the main remarks on the thermal management approaches for Arc-AM outlined and the ways by which they are applied to the different deposition processes, materials, and parts globally quantified and characterized. For closure, within the same section, opportunity windows for further developments on thermal management for Arc-AM are finally drawn. Despite the quantity and diversity of approaches identified, as has always been the case in modern manufacturing, the thermal management technology in Arc-AM is expected to keep evolving in the face of new challenges and different scenarios with constant advancements, for which this review will hopefully serve as a relevant source of consultation. [ABSTRACT FROM AUTHOR]

A whole series of factors influence the temperature of the soil surface and surface layers. The soil surface is heated by solar radiation during the day. It radiates some of the obtained heat at night. The heat exchange between the soil and the atmosphere depends on the air and soil temperatures and the speed of air movement. Precipitation may also affect surface soil layers, but this was not considered in this study. In the mentioned interaction, a specific temperature field of the surface layers of the soil is established. To increase the building's energy efficiency, the aim is to optimize the operation of its heating and cooling systems and to reduce heat loss to the environment as much as possible. Heat loss through the floor of the building or the walls of the recessed part into the ground changes the established temperature field of the ground. The heat spreads in the soil and is given to the atmospheric air. During the research, to validate the numerical model, the heat flow density was analysed to determine how it changes while maintaining a constant temperature of the heating surface at a certain depth of the soil. It was found that the new thermodynamic equilibrium, depending on the seasonality, can be reached in a time interval of up to a week. The temperature change in the artificially limited volume of the ground under the building or next to it can be treated as the work of the ground thermo-accumulator: its charge or discharge by heat. This makes it possible to reduce the annual energy costs of the building by more than ten percent. [ABSTRACT FROM AUTHOR]

As a green and sustainable geothermal development technology, energy piles have received wide attention in the field of energy underground structure engineering. This work examines the variation rules of the pile-soil temperature, stress-strain, side friction resistance, and pile-top displacement of a full-scale parallel multi-U-type energy pile under the action of temperature loading using a combination of numerical modeling and field testing. As the number of parallel U-type heat exchanger tubes increases, the temperature of the energy pile body rises. However, after a certain number is reached, the effect of additional increases on the temperature rise of the pile body decreases. Additionally, there is a phenomenon known as thermal interference between the heat exchanger tubes, which should be kept at a suitable distance to minimize their mutual influence. The parallel 5U-type energy pile's temperature is fairly evenly distributed along the depth direction, and the strain of the pile body demonstrates that the two ends of the pile body change in size, with the middle end having the largest restraining stress. When combined with the change in pile side resistance, this location is thought to produce the displacement's zero point. The pile top displacement increases by 0.65 mm for every 5 °C increase in the water entry temperature. [ABSTRACT FROM AUTHOR]

In the process of wire-arc directed energy deposition, when the inter-layer idle time is not long enough, a heat accumulation effect occurs. That is, the residual temperature does not return to room temperature, and as the material continues to be deposited, the residual temperature of the just deposited layer significantly increases. In this paper, an analytical solution is derived for the residual temperature field during the layer-by-layer depositing process of thin-walled components. There are two main contributions. First, the Eulerian coordinate system is employed to simplify the depositing process. In comparison with the solution expressed in the Lagrangian coordinate system, this treatment avoids the updating of the solution domain, resulting from the movement of the heat source. Second, the temperature field, expressed as a continuous function of position in the Eulerian coordinate system, allows for the introduction of virtual heat sources and their mirror images to account for heat convection and radiation on the boundary. The validity and accuracy of the present analytical solution are verified through comparisons with finite element simulations and experimental results. This analytical solution of the residual temperature will be used in an inherent strain method developed by the authors, to efficiently investigate the impact of heat accumulation on residual stress and deformation, in a follow-up work. [ABSTRACT FROM AUTHOR]

The pressing need from various technological sectors, e.g. aerospace, automotive and microfiltration, for higher drilling throughput at increasingly lower cost has propelled the continuous commercial development of ultrashort lasers offering very high average powers. Although such laser sources provide a huge potential for production upscaling, it is still challenging to fully utilise their output. The problem relates to unwanted thermal effects that degrade the overall process performance, especially in laser drilling of metal foils. Therefore, effective solutions are still required to exploit these new advances in ultrashort laser technology. Herein, we study throughput upscaling by utilising a 120 W femtosecond diode-pumped solid-state laser in both single-pulse and MHz burst modes for percussion drilling of 300 µm thick stainless-steel foils. The influence of critical laser processing parameters was investigated for maximum drilling efficiency and best hole quality. Heat accumulation effects induced by MHz burst mode in high-density hole drilling were analysed and compared with those of nanosecond laser pulses of similar total temporal length. The results demonstrate new capability using MHz burst mode processing to improve drill rate and hole quality compared to single-pulse. Despite that, MHz burst mode showed similar heat-related issues with a nanosecond laser in high-density drilling operations. [ABSTRACT FROM AUTHOR]

In recent years, pistachio (Pistacia vera L.) cultivation is undergoing a great expansion in Spain, which is promising for regions where water and winter chilling are not limiting. Many areas of Castilla y León (Spain) provide suitable conditions for pistachio production, but heat requirement could be a limiting factor. The aims of this study were (i) to investigate the status of pistachios in Castilla y León and the relationships between phenology and agroclimatic conditions and (ii) to assess the performance of three pistachio cultivars ('Kerman', 'Lost Hills', and 'Golden Hills') in a plantation within this region. This work describes the phenological and productive behavior of three pistachio varieties in seven orchards over three years. The chilling requirements were exceeded, and heat accumulation was sufficient to complete the cycle in all seasons. Bloom and harvest occurred later in 'Kerman' than in 'Golden Hills' and 'Lost Hills'. In general, 'Kerman' had higher nut yield than the other two cultivars but also had more non-split and blank nuts, aspects that should be considered for future plantations. Despite the interannual variability in yield, a trend to increase the production with water received was observed, but this also affected the quality and modified the splitting percentage. [ABSTRACT FROM AUTHOR]

Deeply buried pipe energy pile (DBP-EP) offers the capability to harness geothermal energy from significantly deeper subterranean layers than those available inside buried pipe energy pile (IBP-EP). Despite its potential, there is a notable scarcity of research on the thermomechanical behavior of DBP-EP. This study meticulously observed the thermal variations in the soil surrounding the DBP-EP, the mechanical response of the pile itself, the earth pressure at the pile toe, and the displacement occurring at the pile's top during the heating phase across various operational conditions. The findings show that for every 1 °C increase in inlet temperature, the temperature difference between the inlet and outlet increases by about 0.27 °C. The method of load application at the pile top during heating markedly influences the frictional resistance along the pile's sides. Furthermore, When the pile top load rises from 0.26 kN to 0.78 kN, the observed vertical load at the pile foot decreases by 2.2–8.51%. This indicates that the increase in the pile top load reduces the downdrag effect on the sandy soil near the pile toe. This reduction subsequently diminishes the impact of vertical loads on the pile toe. Notably, after continuous operation for 8 h, the rate of increase in pile top displacement for DBP-EP shows a decline. Additionally, for every 1 °C rise in the inlet water temperature, the final displacement at the pile top diminishes by approximately 0.03‰D. This research endeavors to furnish a robust theoretical foundation for the structural design and practical engineering applications for DBP-EP. [ABSTRACT FROM AUTHOR]

Femtosecond lasers are promising tools for achieving high-precision processing of thin materials without causing any thermal surface damage and bulk distortion. However, thermal damage can occur even with ultrashort laser pulses. This is because of high electron penetration depth and heat accumulation at high fluence and high repetition rate. Nanoparticle redeposition can be dramatically altered with variation in repetition rate. The symmetry of microholes and ablation efficiency vary with laser polarization. The laser wavelength affects the ablation efficiency and surface roughness. Therefore, understanding these laser–matter interactions that depend on the laser parameters is essential for high-precision laser processing. This article reviews laser–matter interactions in the 64FeNi alloy, as well as analytical models for designing the desired hole size and taper angles. This can help establish strategies for creating various high-precision microstructures using femtosecond lasers. [ABSTRACT FROM AUTHOR]

Screens used in modernizations of buildings to diversify the facade also provide shade on the walls. The article presents a comparison of the effectiveness of shades with different degrees of shading in terms of energy savings. On summer days, especially when there is a lot of sunlight and air temperatures are above 30°C, the covers reduce the temperature on the outer surface of the wall and, as a result, improve the microclimate of the rooms. Lower temperatures result in less heat accumulated during the day. The results were compared for various masonry materials. Less heat energy accumulated in the wall reduces the energy demand to cool the internal air. Energy savings were estimated over 50 years of building use. A method was proposed to quickly compare the effectiveness of the different shading shields. [ABSTRACT FROM AUTHOR]

The rise of wire arc additive manufacturing (WAAM) is attributed to the various field applications of additive manufacturing (AM), especially in producing large metal structures. The wire arc additive manufacturing is a process that can produce near-net-shape structures with high deposition rates and relatively lower costs. Due to the nature of the WAAM process, which is based on layer-by-layer fabrication and repeated heating and cooling cycles, surface defects can occur on the deposited layer, such as pores, cracks, oxidation, and geometric deviation. In understanding the factors that can affect the stability and mechanism of the WAAM process, online monitoring systems has been studied by researchers. This paper aims to critically review the different monitoring techniques as well as distinct sensing methods that can be applied in the WAAM process to enhance the quality of the 3D object. In conducting this review paper, the systematic literature review (SLR) method is chosen to enhance a better understanding of the current research works of monitoring systems in the WAAM process. The high heat accumulation and cooling rate process are found to be the most crucial factors that could influence the geometrical accuracy, microstructure, and mechanical properties of the deposited layer. [ABSTRACT FROM AUTHOR]

ABSTRACTThe laser power bed fusion (LPBF) forming process introduces heat accumulation and variations in powder layer thickness, which can destabilize the melt track and reduce surface quality. This phenomenon is especially more serious in the early printing stage. To tackle this stability problem, we proposed a novel approach optimizing process parameters on a layer-specific basis. At first, a numerical database was constructed through a set of numerical simulations. Then, a neural network prediction model was trained based on the database. Finally, this prediction model was embedded into a genetic algorithm for layer-based prediction. To verify the prediction results on processing parameters and calibrate the prediction model, physical experiments were prepared. The developed model consistently exhibited relative errors mostly within 6%. It is noteworthy that the relative errors between the numerical simulation results and the expected values were only 0.77% in width and 1.11% in depth. Printing optimization test was applied for an LPBF machine with a Invar alloy powder. The proposed method yielded positive results in both numerical simulations and the printing test. It can be further adopted for new material printing parameter optimization due to an efficient printing stability in the early-stage for LPBF process.

In the context of directed energy deposition (DED), the production of complex components necessitates precise control of all processing parameters while mitigating undesirable factors like heat accumulation. This research seeks to explore and validate with various materials the impact of a geometry-based analytical model for minimizing heat input on the characteristics and structure of the resultant DED components. Furthermore, it aims to compare this approach with other established methods employed to avoid heat accumulation during production. The geometry of the fabricated specimens was assessed using a linear laser scanner, cross-sections were analyzed through optical microscopy, and the effect on mechanical properties was determined via microhardness measurements. The specimens manufactured using the developed analytical model exhibited superior geometric precision with lower energy consumption without compromising mechanical properties. [ABSTRACT FROM AUTHOR]

Wire arc additive manufacturing is the derivative of the metal AM process based on arc welding and a preferred technology for manufacturing large metallic components with medium to low complexity. The major problem with the WAAM process arises due to severe heat accumulation within the built structure and repeated heating-cooling cycles during layer-by-layer material deposition. Therefore, the interlayer time interval influences the microstructure and mechanical properties of the components. This paper has characterized the impact of interlayer cooling time on the microstructure and mechanical properties of SS-316L build. The local thermal cycle causes a non-uniform cooling rate, which alters the structure of the grains. The grain size decreases with increased interlayer time interval due to a faster cooling rate brought on by the low inter-pass temperature. A wider and smaller wall was deposited with less time interval. X-ray diffraction analysis confirms the formation of austenite and ferrite phases in all WAAM components with a slight difference in intensity. The wall constructed with a maximum time interval has a maximum value of average Vickers micro-hardness 244.00 HV0.5 and possesses the least coefficient of friction due to its improved property by the formation of fine grains. The maximum volume of materials was worn out from the wall deposited with lesser cooling time. The designed numerical model predicts the peak temperature and heat accumulation within the built structure which further relates to the morphological and mechanical properties of printed parts. [ABSTRACT FROM AUTHOR]

Laser hot wire directed energy deposition (LHW-DED) is a layer-by-layer additive manufacturing technique that permits the fabrication of large-scale Ti-6Al-4V (Ti64) components with a high deposition rate and has gained traction in the aerospace sector in recent years. However, one of the major challenges in LHW-DED Ti64 is heat accumulation, which affects the part quality, microstructure, and properties of as-built specimens. These issues require a comprehensive understanding of the layerwise heat-accumulation-driven process–structure–property relationship in as-deposited samples. In this study, a systematic investigation was performed by fabricating three Ti-6Al-4V single-wall specimens with distinct interlayer delays, i.e., 0, 120, and 300 s. The real-time acquisition of high-fidelity thermal data and high-resolution melt pool images were utilized to demonstrate a direct correlation between layerwise heat accumulation and melt pool dimensions. The results revealed that the maximum heat buildup temperature of the topmost layer decreased from 660 ° C to 263 ° C with an increase to a 300 s interlayer delay, allowing for better control of the melt pool dimensions, which then resulted in improved part accuracy. Furthermore, the investigation of the location-specific composition, microstructure, and mechanical properties demonstrated that heat buildup resulted in the coarsening of microstructures and, consequently, the reduction of micro-hardness with increasing height. Extending the delay by 120 s resulted in a 5% improvement in the mechanical properties, including an increase in the yield strength from 817 MPa to 859 MPa and the ultimate tensile strength from 914 MPa to 959 MPa. Cooling rates estimated at 900 ° C using a one-dimensional thermal model based on a numerical method allowed us to establish the process–structure–property relationship for the wall specimens. The study provides deeper insight into the effect of heat buildup in LHW-DED and serves as a guide for tailoring the properties of as-deposited specimens by regulating interlayer delay. [ABSTRACT FROM AUTHOR]

As a green and sustainable geothermal development technology, energy piles have received wide attention in the field of energy underground structure engineering. This work examines the variation rules of the pile-soil temperature, stress-strain, side friction resistance, and pile-top displacement of a full-scale parallel multi-U-type energy pile under the action of temperature loading using a combination of numerical modeling and field testing. As the number of parallel U-type heat exchanger tubes increases, the temperature of the energy pile body rises. However, after a certain number is reached, the effect of additional increases on the temperature rise of the pile body decreases. Additionally, there is a phenomenon known as thermal interference between the heat exchanger tubes, which should be kept at a suitable distance to minimize their mutual influence. The parallel 5U-type energy pile’s temperature is fairly evenly distributed along the depth direction, and the strain of the pile body demonstrates that the two ends of the pile body change in size, with the middle end having the largest restraining stress. When combined with the change in pile side resistance, this location is thought to produce the displacement’s zero point. The pile top displacement increases by 0.65 mm for every 5 °C increase in the water entry temperature.

In recent years, pistachio (Pistacia vera L.) cultivation is undergoing a great expansion in Spain, which is promising for regions where water and winter chilling are not limiting. Many areas of Castilla y León (Spain) provide suitable conditions for pistachio production, but heat requirement could be a limiting factor. The aims of this study were (i) to investigate the status of pistachios in Castilla y León and the relationships between phenology and agroclimatic conditions and (ii) to assess the performance of three pistachio cultivars (‘Kerman’, ‘Lost Hills’, and ‘Golden Hills’) in a plantation within this region. This work describes the phenological and productive behavior of three pistachio varieties in seven orchards over three years. The chilling requirements were exceeded, and heat accumulation was sufficient to complete the cycle in all seasons. Bloom and harvest occurred later in ‘Kerman’ than in ‘Golden Hills’ and ‘Lost Hills’. In general, ‘Kerman’ had higher nut yield than the other two cultivars but also had more non-split and blank nuts, aspects that should be considered for future plantations. Despite the interannual variability in yield, a trend to increase the production with water received was observed, but this also affected the quality and modified the splitting percentage.

Deeply buried pipe energy pile (DBP-EP) offers the capability to harness geothermal energy from significantly deeper subterranean layers than those available inside buried pipe energy pile (IBP-EP). Despite its potential, there is a notable scarcity of research on the thermomechanical behavior of DBP-EP. This study meticulously observed the thermal variations in the soil surrounding the DBP-EP, the mechanical response of the pile itself, the earth pressure at the pile toe, and the displacement occurring at the pile’s top during the heating phase across various operational conditions. The findings show that for every 1 °C increase in inlet temperature, the temperature difference between the inlet and outlet increases by about 0.27 °C. The method of load application at the pile top during heating markedly influences the frictional resistance along the pile’s sides. Furthermore, When the pile top load rises from 0.26 kN to 0.78 kN, the observed vertical load at the pile foot decreases by 2.2–8.51%. This indicates that the increase in the pile top load reduces the downdrag effect on the sandy soil near the pile toe. This reduction subsequently diminishes the impact of vertical loads on the pile toe. Notably, after continuous operation for 8 h, the rate of increase in pile top displacement for DBP-EP shows a decline. Additionally, for every 1 °C rise in the inlet water temperature, the final displacement at the pile top diminishes by approximately 0.03‰D. This research endeavors to furnish a robust theoretical foundation for the structural design and practical engineering applications for DBP-EP.

Metal additive manufacturing is associated with thermal cycles of high rates of heating, melting, cooling, and solidification. Some areas within the build experience thermal cycles that depend on the paths of the energy source. Additionally, geometrical features, such as thin walls and overhangs, can lead to heat accumulation, potentially affecting the microstructure, fatigue life, and induced residual stresses that may lead to dimensional distortion and cracking. The identification of significant heat accumulation can be used for part quality monitoring to inform the design process, enhance the quality of printed parts, and optimize the process parameters. This study aims to efficiently identify heat accumulation with affordable in-situ infrared imaging for further characterization and mitigation to enhance the quality of printed parts. A computational framework employing machine learning is developed to identify zones of local heat accumulation in real time. The effectiveness of this approach is demonstrated by experiments conducted on a build with a wide variety of geometrical features. In addition, characterization and detailed analyses of detected local heat accumulation zones are provided.

To investigate the interaction mechanism between a laser, water jet, and substrate, a model is developed to simulate the temperature field evolution and removal process during water jet-guided laser (WJGL) cutting of silicon. The model accounted for the temperature-dependent properties of the silicon absorption coefficient, as well as the physical processes of solid-liquid-gas phase change. A three-dimensional finite volume model of WJGL cutting of silicon is created, incorporating laser energy input, water jet impact-cooling, and silicon phase transition and removal. The volume of fluid (VOF) method is employed to trace the interphase interface and obtain the groove shape. The validity of the model is verified by comparing simulation results with experimental data. The simulation results show that the groove cross section is characterized by a "V" shape. The groove depth nonlinearly increases from 52 to 385 μm with an increasing number of cuts. Additionally, the residual temperature of the silicon substrate rises from 837 to 1345 K as the number of scans increases from 1 to 10. The findings offer valuable insights into WJGL cutting research, specifically shedding light on the intricate details of the laser-water jet-substrate interaction mechanism. [ABSTRACT FROM AUTHOR]

Gasoline produced by hydrotreating light and heavy naphtha and reforming hydrotreated heavy naphtha, hydrogen required for both processes produced by the reforming unit as a byproduct, compression, and recycling of hydrogen required for reforming reactions provided by recycle gas compressor (centrifugal multi-stages compressor), due to the design criteria of this compressor the anti-surge system pass 18000 kg/h, of hydrogen from discharge to suction of compressor with 3" control valve, at the low flow situation during the startup of the unit to avoid the lake of gas flow and avoid overpressure in the discharge of the compressor. Anti-surge system in this compressor contains no inter-stage cooler, the suction temperature of the compressor is designed at 43℃, and the discharge of the compressor is 79℃ when the anti-surge system is involved in the process, the suction temperature of the compressor becomes 70℃, and the discharge becomes 108℃ due to the heat accumulation of recycle gas out of the anti-surge system. In an aim to solve this problem, the outlet of the anti-surge system of the compressor connected with the process heat exchanger, to cool down the hydrogen inlet to suction of the compressor to approximately 46℃ and back to the design limits, the disadvantage of this solution is the absorption of the light end associated with recycle gas posing in the process heat exchanger, which reduces the total molecular weight of recycle gas through the anti-surge system from 13.336 to 10.51 kg/kg mol at start of the run, and from 16.155 to 12.15 kg/kg mol at the end of the run. [ABSTRACT FROM AUTHOR]

The thermal interaction between cooling facilities and the ground is most often discussed in terms of the appropriate insulation of building partitions. Unfortunately, there is little information about the potential of using ground thermal accumulation to support the shaping of the microclimate in cooling facilities by embedding them in the ground. This problem is particularly important in the context of striving to reduce the energy demand of buildings. The article discusses a new scientific problem related to the effect of vegetable cold storage floors being recessed into the ground on the surrounding land's impact range and on its energy management. Validation of the numerical model was performed based on actual year-round field surveys. These surveys were conducted in a free-standing vegetable cold storage facility located in southern Poland. The results of the study allowed us to determine the contribution of the land to the energy balance of the cold storage. A floor recessed into the ground doubled the ground's contribution to the energy balance. The most important research results showed that the range of thermal impact on the surrounding ground also increased by 2.0 m more than that of a building with the floor located at ground level. An evaluation of the heat flow between the cold storage and the ground in the cases analyzed was also carried out. The analysis of the ground heat exchange balance on an annual basis showed high energy gains of 2055 kWh. The total energy demand for cooling was 1723 kWh, while it was 1204 kWh for heating. The results of the analysis of the heat exchange intensity between the indoor air and the ground showed that the ground contribution accounted for 16.6% of the total energy balance of the cold storage. The highest energy gains from the ground were found in October and amounted to 478 kWh. Due to the summer shutdown, there was an intense heat flow to the ground in July, which amounted to 588 kWh. [ABSTRACT FROM AUTHOR]

In the context of directed energy deposition (DED), the production of complex components necessitates precise control of all processing parameters while mitigating undesirable factors like heat accumulation. This research seeks to explore and validate with various materials the impact of a geometry-based analytical model for minimizing heat input on the characteristics and structure of the resultant DED components. Furthermore, it aims to compare this approach with other established methods employed to avoid heat accumulation during production. The geometry of the fabricated specimens was assessed using a linear laser scanner, cross-sections were analyzed through optical microscopy, and the effect on mechanical properties was determined via microhardness measurements. The specimens manufactured using the developed analytical model exhibited superior geometric precision with lower energy consumption without compromising mechanical properties.

The capability to produce complexly and individually shaped metallic parts is one of the main advantages of the laser powder bed fusion process. Development of material and machine specific process parameters is commonly based on the results acquired from small cubic test coupons of ∼10 mm edge length. Such cubes are usually used to conduct the optimization of process parameters to produce dense materials. The parameters are then taken as the basis for the manufacturing of real part geometries. However, complex geometries go along with complex thermal histories during the manufacturing process, which can significantly differ from thermal conditions prevalent during the production of simply shaped test coupons. This may lead to unexpected and unpredicted local inhomogeneities of the microstructure and defect distribution in the final part, and it is a root cause of reservations against the use of additive manufacturing for the production of safety relevant parts. In this study, the influence of changing thermal conditions on the resulting melt pool depth of 316L stainless steel specimens is demonstrated. A variation in thermographically measured intrinsic preheating temperatures was triggered by the alteration of interlayer times and a variation in cross-sectional areas of specimens for three distinct sets of process parameters. Correlations between the preheating temperature, the melt pool depth, and occurring defects were analyzed. The limited expressiveness of the results of small density cubes is revealed throughout the systematic investigation. Finally, a clear recommendation to consider thermal conditions in future process parameter optimizations is given. [ABSTRACT FROM AUTHOR]

Results on the ablation of stainless steel using ultra-short single, double and quadruple pulses as a function of the fluence and the time delay between each laser pulse are presented. The investigations focused quantitatively on the ablated volume and the resulting ablation efficiency, and qualitatively on the topography of the structures produced, providing insights about physical mechanisms such as shielding, re-deposition of ablated particles, and accumulation of heat or energy. The results indicate a significant influence of fluence in combination with the time delay on the ablation process and the resulting ablation topography. [ABSTRACT FROM AUTHOR]

Plants have always been able to adapt to climate change by reacting through various responses, mainly at the phenological level. The aim of this work is to investigate the behavior of specific tree species located in two phenological gardens in central Italy in relation to the temperature increases recorded in recent years. Specifically, four main phenological phases, BBCH_11, BBCH_19, BBCH_91, and BBCH_65, were monitored during a 14-year time period. The data of the weeks corresponding to the first appearance of each phenological phase and the respective heat accumulations for each species were cross-referenced with the meteorological data recorded by the stations in the two considered areas. Based on average temperature, calculated over reference periods, the species were divided by creating "warm" year groups and "cold" year groups so as to better highlight any differences in the behavior of the same species. In addition, a strong correlation was shown between the maximum temperatures in February and the advances of phenological phases BBCH_11 and BBCH_65. Most of the tree species have shown strong adaptation to climate warming, changing the period of occurrence of the phases themselves. [ABSTRACT FROM AUTHOR]

The operating principles of Circulating Fluidized Bed (CFB) boilers involve a significant amount of heat accumulation, which forms the thermal inertia of the boiler and hinders the improvement of its variable load response rate. This study aims to characterize the thermal inertia of CFB boilers by evaluating the change in the boiler's heat accumulation corresponding to the change in unit power generation. The thermal inertia of a 330 MW CFB boiler was determined through the collection of operating data under four different operating conditions of 30%, 50%, 75%, and 100% load. The study proposes to substitute the existing refractory material with a metal grille to reduce the thermal inertia of the boiler. The effect of the metal grille on heat transfer was confirmed through verification on a 440 t/h CFB boiler, and its performance change and thermal inertia reduction were further predicted. The results indicate that over 50% of the total thermal inertia of CFB boilers originates from the refractory material. The use of metal grille in place of refractory material improved heat transfer in the furnace, resulting in a decrease of the furnace chamber temperature by 13°C in the 330 MW CFB boiler. This reduction of thermal inertia by 30%–35% will facilitate faster load lifting and lowering of the boiler, fulfilling the requirement for flexible peaking. [ABSTRACT FROM AUTHOR]

Commonly sold bioethanol fireplaces can represent significant heat source, however due to their intermittent operation the heat energy output is strongly uneven. The aim of this study was to determine the possibilities of heat energy accumulation by individually built ethanol fireplace intended for commonly sold ethanol burner installation. For the measurements of heat energy output, long term tests of the individually built ethanol fireplace with 1, 2 and 3 consecutive combustion periods in a unique calorific room were performed. Accumulation ethanol fireplace has proven high ratio between accumulated heat energy after the ethanol burner last burn-out reaching from 21.4 to 48.4% according to the number of consecutive fuel doses. By usage of the described ethanol fireplace the time of heat energy releasing was increased from approximately 1.15, 2.35 and 3.55 h in case of ethanol burner usage in a non-accumulation fireplace for 1, 2 and 3 fuel doses to 6.5, 11 and 15 h in case of accumulation ethanol fireplace usage. This was also strongly connected with average heat output ranging between 2.54 to 2.47 kW in the case of ethanol burner usage in a non-accumulation ethanol fireplace and 0.38 to 0.59 kW in the case of accumulation ethanol fireplace usage.

In order to explore the relationship between welding thermal cycles and the thermal field during the repair process of dies, a numerical simulation software (SYSWELD) was employed to construct a thermo-mechanical coupled model. The influence of various inter-layer cooling times was investigated on heat accumulation, residual stress, and deformation of the repaired component. The results showed that the numerical simulation results agreed well with experimental data. The temperature within the cladding layer gradually rose as the number of weld beads increased, leading to a more pronounced accumulation of heat. The residual stress exhibited a double-peak profile, where the deformation of the repaired component was large at both ends but small in the middle. The less heat was accumulated in the cladding layer with a prolonged cooling time. Meanwhile, the residual stress and deformation in the repaired component experienced a gradual decrease in magnitude. The numerical simulation results demonstrated that the microstructure of the repaired component predominantly consisted of martensite and residual austenite at the optimal cooling time (300 s). Furthermore, the microhardness and wear resistance of the cladding zone significantly surpassed those of the substrate. In conclusion, this study suggested the prolonged cooling time mitigated heat accumulation, residual stress, and deformation in repaired components, which provided a new direction for future research on the die steel repairments. [ABSTRACT FROM AUTHOR]

Monitoring the climatic conditions of crops is essential for smart agriculture development and adaptation of agricultural systems in the era of global change. Thereby, it is possibly better to understand the stages of development of the crop, thus adopting management practices more efficiently and planning the harvest with greater accuracy. This study was developed to analyze the growing degree-hours and degree-days in two management zones (MZs) for each phenological stage of wheat (Triticum aestivum L.) and the application of low-cost agroclimatological stations to monitor the climatic conditions of the field production. The study was developed in a Ferralsol in Céu-Azul/Brazil. Ten low-cost agrometeorological stations were installed in two MZs delineated based on elevation data using the web platform AgDataBox. Data on solar radiation, atmospheric pressure, wind speed, precipitation, relative humidity, air, and soil temperature were evaluated over two wheat crop seasons. Our results showed different climatic conditions, especially humidity and temperature, between MZs and crop seasons, which could probably cause yield variability. By the low-cost agroclimatological stations, it is possible to collect data on the thermal accumulation by the culture in growing degree-hours, which is a more accurate parameter than the growing degree-days (commonly used in similar studies). With the growing degree-hours data, it was possible to follow the development of the phenological stages of wheat. In conclusion, the results obtained suggest the importance of evaluating agroclimatological parameters in monitoring wheat crops. However, more studies are needed in regions with greater slopes, which may have microclimates that intensely influence the crop. [ABSTRACT FROM AUTHOR]

Achieving high surface integrity of micro features on the silicon wafers is highly challenging, owing to the inherent material properties like higher reflectivity, brittleness, and low toughness. In the present work, ultrashort pulse laser micromachining is used to create high-depth microchannels in silicon. Utilization of high average power ultrashort pulse laser for producing high-depth microchannels in silicon causes adverse effects on the feature quality. To investigate this, repetition rates from 10 to 500 kHz produce average power from 0.18 to 9 W at a minimum constant pulse energy of 18 μJ and peak fluence of 0.28 J/cm2. Surface integrity is evaluated in terms of surface roughness, melting thickness, and crack formation. The ablation depth of 18.24 μm is obtained in silicon at high average power of 9 W. The influence of heat accumulation is dominant at high repetition rates. The temporal separation between pulses decreases with an increase in repetition rates. This induces residual stress at the ablated region, eventually leading to the formation of a crack. Higher melting thickness, surface roughness, and presence of crack were significantly detected at high repetition rates from 333 to 500 kHz. The optimum surface integrity was obtained at a repetition rate of 200 kHz with a pulse energy of 18 μJ. The outcomes from the present research work are highly significant for manufacturing MEMS components. The fabrication of higher-quality micro-scale features on silicon wafers is still considered the most important area of research due to its wide range of industrial applicability. [ABSTRACT FROM AUTHOR]

Laser surface texturing (LST) is one of the most promising technologies for controllable surface structuring and the acquisition of specific physical surface properties needed in functional surfaces. The quality and processing rate of the laser surface texturing strongly depend on the correct choice of a scanning strategy. In this paper, a comparative review of the classical and recently developed scanning strategies of laser surface texturing is presented. The main attention is paid to maximal processing rate, precision and existing physical limitations. Possible ways of further development of the laser scanning strategies are proposed. [ABSTRACT FROM AUTHOR]

During the cold period, the heat transferred through the building's external boundaries to the environment changes the naturally established heat balance between atmospheric air and soil layers. The process of the heat transfer into the ground was investigated experimentally in the cases of the relatively high and low levels of the water table. The first part of each experiment was the research of the heat transfer into the soil from the heating surface. The second part was monitoring the heat dissipation in the ground until the return to the initial natural thermodynamic equilibrium after the heating is intercepted. The heating device was installed into the clay at a one-meter depth, and its surface temperature was kept constant at 20 degrees Celsius. The ground was warmed up in contact with the heating surface. The heat spread to other soil layers and transformed the temperature distribution. A new thermodynamic equilibrium was reached six days after the heating started at an initial temperature of 4.4 degrees Celsius. The intensity of the heat flux density approached a stable value equal to 117.4 W/m2, which is required to maintain this thermodynamic equilibrium, as the heat was dissipating in the large volume of the surrounding soil. The heating was turned off, and the natural initial heat balance was reached after two weeks. [ABSTRACT FROM AUTHOR]

Thermoelectric devices may have an essential role in the development of fuel-saving, environmentallyfriendly, and cost-effective energy sources for power generation based on the direct conversion of heat into electrical energy. A wide usage of thermoelectric energy systems already exhibits high reliability and long operation time in the space industry and gas pipe systems. The development and application of solar thermoelectric generators (TEGs) arelimited mainly by relatively low thermoelectric conversion efficiency. Forthe first time, we propose to use the direct energy conversion of solar energy by TEGs based on the high-performance multilayer thermoelectric modules with electric efficiency of ~15%. Solar energy was absorbed and converted to thermal energy, which is accumulated by a phase-change material (aluminum alloys at solidification temperature ~900 K). The heat flow from the accumulator through the thermoelectric convertor (generator) allows electrical power to be obtained and the exhaust energy to be used for household purposes (heating and hot water supply) or for the operation of a plant for thermal desalination of water. [ABSTRACT FROM AUTHOR]

This publication is provided with the author’s suggestions regarding modification of the basic criterion – heat transfer coefficient. According to the author, the basic criterion of building thermal protection should be extended in such a manner that it will be simple and easy to evaluate a building’s capacity to recover thermal energy accumulated in the wall structure.

Identifying the growth stages on oilseed rape accurately is essential for effective crop management. Two commonly used methods for identifying growth stages are growing degree days (GDD) and BBCH scale, by measuring the heat accumulation on daily temperatures and describes the growth stages of plants. The main goal of this research is using a combination of these methods, where can identify the growth stages in production period. The three-year field experiments 2015/16 - 2017/18 were located in the Skopje Region, with two genotypes in 30 variants and 4 replications. Sowing was on October 1, with 8 kg ha-1 seeding rate. BBCH scale for oilseed rape was used to register the stages of development. Growing degree days - GDD were determined by the formula with corrections for Tmax and Tmin values calculated. Germination (09 BBCH), was 7 days in the first and third year and 79 °C - 65 °C GDD and 8 days in the second year - 65 °C GDD. The flowering (63 BBCH), begins at 202 days in the first, - 809 °C GDD, 199 days in the second year – 649 °C GDD, and 198 days third year with 633 °C GDD. Senescence (BBCH 97), began on days 254, with accumulate 1530 °C GDD, days 258 – 1577 °C GDD, and days 265 with 1542 °C GDD in 3, 1 and 2 years. All data obtained from the research are aimed at meeting the needs of producers and researchers related to rapeseed production in order to ensure optimal production. [ABSTRACT FROM AUTHOR]

The present paper deals with the evaluation of the unique design of the thermal energy storage unit and its impact on the overall heat exchange efficiency. The proposed thermal energy storage unit consists of a gyroid thermally conductive structure, the voids of which are filled with sodium acetate trihydrate. The presented concept is focused on the use in the field of heavy machinery, where it is possible to accumulate and re-use waste heat from internal combustion engines from the cooling liquid or lubricating products. The evaluation of designs took place through numerical simulations on three models characterized by different levels of the introduction of the gyroid structure into the design. From the design point of view, the gyroid structure was considered as an object produced by additive manufacturing methods from a thermally conductive filament based on a thermoplastic polymer, which enables considerable simplification of production compared to the use of suitable anti-corrosion metals. A comparison of the essential thermophysical parameters in the process of charging and discharging of the proposed thermal energy storage unit quantified a significant increase in the rate of the charging, respectively, of the discharging process, manifested by a rapid increase in the temperature of the sodium acetate trihydrate volume, respectively, of the output temperature of the heat transfer medium that removes the accumulated heat for further use. [ABSTRACT FROM AUTHOR]

Values of energy supply and demand vary within the same timeframe and are not equal. Consequently, to minimise the amount of energy wasted, there is a need to use various types of energy storing systems. Recently, one can observe a trend in which phase change materials (PCM) have gained popularity as materials that can store an excess of heat energy. In this research, the authors analysed paraffin wax (cheese wax)'s capability as a PCM energy storing material for a low temperature energy-storage device. Due to the relatively low thermal conductivity of wax, the authors also analysed open-cell ceramic Al2O3/SiC composite foams' (in which the PCM was dispersed) influence on heat exchange process. Thermal analysis on paraffin wax was performed, determining its specific heat in liquid and solid state, latent heat (LH) of melting, melting temperature and thermal conductivity. Thermal tests were also performed on thermal energy container (with built-in PCM and ceramic foams) for transient heat transfer. Heat transfer coefficient and value of accumulated energy amount were determined. [ABSTRACT FROM AUTHOR]