Effect Of Heating Research Articles

Machine Learning Approach to Predict the Effect of Metal Foam Heat Sinks Discretely Placed in a Cavity on Surface Temperature

Machine Learning Approach to Predict the Effect of Metal Foam Heat Sinks Discretely Placed in a Cavity on Surface Temperature

Assessing the Spurious Impacts of Ice-Constraining Methods on the Climate Response to Sea Ice Loss Using an Idealized Aquaplanet GCM

Abstract Coupled climate model simulations designed to isolate the effects of Arctic sea ice loss often apply artificial heating, either directly to the ice or through modification of the surface albedo, to constrain sea ice in the absence of other forcings. Recent work has shown that this approach may lead to an overestimation of the climate response to sea ice loss. In this study, we assess the spurious impacts of ice-constraining methods on the climate of an idealized aquaplanet general circulation model (GCM) with thermodynamic sea ice. The true effect of sea ice loss in this model is isolated by inducing ice loss through reduction of the freezing point of water, which does not require additional energy input. We compare the results of freezing point modification experiments with experiments where sea ice loss is induced using traditional ice-constraining methods and confirm the result of previous work that traditional methods induce spurious additional warming. Furthermore, additional warming leads to an overestimation of the circulation response to sea ice loss, which involves a weakening of the zonal wind and storm-track activity in midlatitudes. Our results suggest that coupled model simulations with constrained sea ice should be treated with caution, especially in boreal summer, where the true effect of sea ice loss is weakest, but we find the largest spurious response. Given that our results may be sensitive to the simplicity of the model we use, we suggest that devising methods to quantify the spurious effects of ice-constraining methods in more sophisticated models should be an urgent priority for future work. Significance Statement The potential effects of Arctic sea ice loss on midlatitude weather have been investigated using climate models where sea ice loss is artificially induced, without increasing greenhouse gas concentrations. Recently, this approach has been challenged because the artificial heating used to melt sea ice may also have direct effects on climate, which are not caused by sea ice loss. We run simulations with a simplified climate model that allows us to separate the “spurious” direct effects of the artificial heating from the “true” effect of sea ice loss. In our simulations, the responses of temperature and atmospheric circulation are amplified by spurious effects. Consequently, we argue that previous studies using more complex climate models may overestimate the effect of sea ice loss on climate.

Effects of heat, elevated vapor pressure deficits and growing season length on growth trends of European beech

In recent decades, continued growth decline has been observed in various beech forest regions of Central and Western Europe, especially in the warmer lowlands, which is not necessarily linked to increased mortality. While earlier dendrochronological studies have shown that a deteriorating climatic water balance in the course of climate warming can drive negative growth trends, less is known about the effects of climatic extremes on tree growth, notably heat and rising atmospheric vapor pressure deficits (VPD). Through climate-growth analysis, we analyzed the influence of summer heat duration (frequency of hot days with Tmax > 30°C) and elevated VPD on the basal area increment (BAI) of dominant beech trees in 30 stands across a precipitation gradient in the northern German lowlands. Summer heat (especially in June) and elevated VPD are reducing BAI in a similar manner as does a deteriorated climatic water balance. While growing season length (GSL), derived from thermal thresholds of growth activity, has substantially increased since 1980, BAI has declined in the majority of stands, demonstrating a recent decoupling of tree productivity from GSL. We conclude that heat and elevated VPD most likely are important drivers of the recent beech growth decline in this region, while growing season length has lost its indicative value of beech productivity.

Heat wave: a new characterization in terms of energy

Heat waves (HW) are prolonged periods of excessively hot weather that can cause severe socioeconomic and environmental impacts. This study aims to evaluate the differences in stored heat and turbulent flux partitioning during a heat wave event in Mexico City, using observations from an eddy covariance tower during the period from 14 June to 21 June 2023. During this period, net radiation (Rn) and sensible heat flux (H) increased significantly, particularly from noon to evening, reflecting stable atmospheric conditions. The air temperature showed a noticeable increase in the afternoon and evening, whereas absolute humidity decreased. We found that during the heat wave, the Bowen ratio (β) increased by 80% during daylight hours and 65% over a full 24-hour period compared to the pre-heat wave period. This heat release at night prolonged warm conditions, intensifying heat stress. The partitioning of net radiation for latent heat (LE), sensible heat (H), and heat storage (ΔQs) showed significant changes; during the heat wave, 51% of Rn was allocated to H and 34% to ΔQs, compared to pre-heat wave values of 49% and 27%, respectively. This study introduces a new characterization of heat waves in terms of energy, emphasizing the significant shifts in energy flux partitioning and storage. The new characterization highlights the critical role of urban heat storage and its release in exacerbating heat stress during and after heat wave events. This approach provides a comprehensive understanding of the energy dynamics during heat waves, which is essential for developing effective mitigation strategies to combat the adverse effects of extreme heat in urban environments.

Fast ion studies in the extended high-performance high βP plasma on EAST

Abstract Comprehending and optimizing fast ion behaviors is critical for the enhancement of performance in Experimental Advanced Superconducting Tokamak (EAST). This study explores the potential benefits of several factors that can improve the fast ion confinement. First, experiments show the change in the direction of the NBI2 from counter-I p to co-I p leads to a significant reduction in fast ion losses. TRANSP/NUBEAM simulation and tomography results based on fast-ion D-alpha measurements reveal that after the neutral beam injection (NBI) upgrade, the beam ion prompt loss is reduced by approximately 50%. Second, the upgraded ion cyclotron resonant frequency (ICRF) antenna at the N-port features twice the coupling resistance of the original antennas at EAST. This improved ICRF power coupling has enhanced the synergistic heating effect of NBI + ICRF, where the ICRF wave field accelerates beam ions at the harmonics. Experiments demonstrate that NBI + ICRF synergistic not only enhances plasma neutron yield and β P, but also accelerates beam ions to hundreds of keV. Further, the electron density and the neutral beam voltage have been optimized to reduce the fast ion slowing-down time and beam ion losses. Experimental and simulation results indicate that increasing the electron density reduces beam ion losses and enhances the bootstrap current fraction. While higher beam voltage results in a slight decrease in beam power absorption, it can increase the fraction of bootstrap current. With the understanding of these optimization of fast ion confinement, experiments have demonstrated fully non-inductive operation at high density (n e/n G ∼ 0.67, β P ∼ 3.1, β N ∼ 2.1, H 98,y2 ∼ 1.2) even without the support of co-I p beam NBI2. This investigation presents a potential regime to enhance fast ion confinement and extend performance in the high β P plasma for future experiments.

Integration and Design of Cryogenic Hydrogen Fuel Systems for Sustainable Commercial Aviation

The transition to hydrogen-powered aircraft offers an opportunity to significantly reduce carbon emissions in commercial aviation. The use of renewable hydrogen in commercial aviation has the potential to significantly reduce the carbon footprint of the industry. Aviation currently accounts for around 3% of global carbon emissions, a figure that is projected to grow without the adoption of sustainable fuels like hydrogen [1]. Hydrogen can be stored as a compressed gas at high pressure and as a liquid at cryogenic temperatures. However, the unique properties of hydrogen, particularly its low density and cryogenic storage requirements need a complete redesign of aircraft fuel systems. The low density of hydrogen necessitates larger storage volumes compared to conventional fuels, and cryogenic storage requires maintaining extremely low temperatures to prevent boil-off, which can lead to significant fuel loss [2]. This research aims to develop innovative fuel system designs that can efficiently store and deliver cryogenic liquid hydrogen. Numerous tank designs including cylindrical, spherical, and double-walled configurations will be explored. Cylindrical tanks are commonly used for high-pressure gas storage and must be designed to withstand pressure loads effectively. Spherical tanks offer a lower surface area-to-volume ratio, which is advantageous for reducing heat transfer and boil-off. Double-walled configurations provide additional insulation and structural integrity, essential for maintaining cryogenic temperatures [3]. Additionally, effective heat management is crucial in hydrogen fuel systems. The research will explore strategies to recover waste heat from fuel cells or combustion processes, which can be utilized to improve overall system efficiency. This is particularly important in preventing excessive boil-off in cryogenic tanks, which can lead to increased pressure and potential safety issues. By conceiving aircraft designs optimized for either direct liquid hydrogen combustion or fuel cell propulsion, this research aims to create sustainable aviation solutions. Furthermore, this study will develop a detailed thermodynamic model to simulate the behaviour of cryogenic hydrogen fuel systems under various operating conditions, including heat transfer, phase changes and boil-off effects. The goal is to optimize the design and operation of hydrogen fuel systems to achieve maximum efficiency and safety. The findings from this research aim to provide a comprehensive framework for the future of hydrogen-powered commercial aviation. By addressing the unique challenges of hydrogen storage and fuel system design, the study seeks to contribute to the development of sustainable aviation solutions that can significantly reduce the carbon footprint of the airline industry.

Enhancing Heat Transfer Efficiency Through Controlled Magnetic Flux in a Partially Heated Circular Cavity Using Multi-Walled Carbon Nanotube Nanofluid and an Internal Square Body

Applications including aircraft systems and electronics cooling depend on effective heat transfer. This study investigates magnetohydrodynamic (MHD) free convection and thermal radiation for heat transfer in a circular cavity filled with multi-walled carbon nanotube (MWCNT) nanofluid and containing a square obstruction. This study examines the impact of the internal geometry on heat transfer and fluid flow dynamics under three distinct boundary conditions, and it presents a comprehensive analysis based on a wide range of Hartmann (Ha) and Rayleigh (Ra) numbers. MWCNT nanofluid with high thermal conductivity was employed to enhance heat transfer efficiency, using a solid volume fraction (SVF) of 4% for MWCNTs and assuming Newtonian behavior for computational simplification. Magnetic properties were imparted to the nanofluid by assuming the dispersion of carbon nanotubes in a base fluid containing magnetic nanoparticles. Other walls were insulated, the bottom wall was heated, and a magnetic field (MF) with Ha ranging from 0 to 100 was applied. It was observed that raising Ra from 103 to 106 improved the Nusselt number (Nu) from 0.08 to 7.1 using the Galerkin finite element method. Ha increased from 0 to 100 and reduced Nu by 35%. Three boundary conditions for the square body showed that the heated conditions provided the largest Nu. By means of an increase in SVF from 0 to 0.04, the MWCNT nanofluid improved heat conductivity by 18%. Radiation effects with the radiation parameter Rd = 0.5 increased heat transmission by 22%. These results underline the importance of considering MHD and nanofluid characteristics in maximizing heat transfer for commercial purposes, and the approaches employed in this study contribute to a deeper understanding of the behavior of thermal systems under the influence of MHD and internal geometry.

Experimental Study on Seasonal Ground-Coupled Heat Storage and Harvesting in Cold Regions

In recent years, global efforts toward sustainable energy have intensified, aiming to reduce carbon emissions and boost energy efficiency. Heating in winter and hot water for hygiene are essential, especially in cold climates where heating demands significantly impact household energy consumption. This study examines a city in western Inner Mongolia, characterized by a severe cold climate and unique geology. A test system with dual U-shaped buried pipes for ground source heat storage and extraction was constructed, utilizing two layout schemes. Drilling tests measured formation parameters, highlighting how pipe layout and soil characteristics influence heat storage. Short-term 5-day cycles and cross-seasonal 60-day cycles were tested. Results showed upper soil suited for frequent short-term storage, while lower soil favored long-term energy retention. Increasing buried pipes raised soil temperature and storage capacity, enhancing thermal stability in short-term cycles. However, while the long-term storage capacity improved, heat loss also rose. Effective ground source heat pump design in cold regions should consider environmental temperatures, pipe optimization, soil characteristics, and heat storage duration to achieve stable, efficient operation.

Probing the heating of the neutral atomic interstellar medium in the Dwarf Galaxy Survey through infrared cooling lines

Star formation in galaxies is regulated by dynamical and thermal processes. In the Milky Way and star-forming galaxies with similar metallicity, the photoelectric effect on small dust grains usually dominates the heating of the neutral atomic gas, which constitutes the main star-forming gas reservoir. In more metal-poor galaxies, the lower dust-to-gas mass ratio together with the higher occurrence and luminosity of X-ray sources suggest that other heating mechanisms may be at play. We aim to determine the contribution of the photoelectric effect, photoionization by UV and X-ray photons, and ionization by cosmic rays to the total heating of the neutral gas in a sample of 37 low-metallicity galaxies. In particular, we wish to assess whether X-ray sources can be a significant source of heating. We also attempt to recover the intrinsic X-ray fluxes and compare them with observations when available. We used the statistical code MULTIGRIS together with a photoionization grid of Cloudy models propagating radiation from stellar clusters and potential X-ray sources to the ionized and neutral gas. This grid includes physical parameters such as metallicity, gas density, ionization parameter, and radiative source properties. We describe a galaxy as a combination of many 1D components linked by a few physical hyperparameters. We used infrared cooling lines as constraints to evaluate the most likely combinations and parameters. We constrained the heating fractions for the main mechanisms for the first time in a low-metallicity galaxy sample. We show that for the higher metallicity galaxies, the photoelectric effect dominates the neutral gas heating. At metallicities below $1/8$ the Milky Way value, cosmic rays and photoionization can become predominant. We computed an observational proxy for the photoelectric effect heating efficiency on polycyclic aromatic hydrocarbons (PAHs) using the total cooling traced by We show that this proxy can match theoretical expectations when accounting for the fraction of the heating due to the photoelectric effect according to our models. Finally, we show that it is possible to predict the X-ray fluxes reasonably well in the $0.3-8$\,keV band from the gas cooling lines for most of the galaxies observed in this band. With the current grid and assumptions, determining the exact heating fraction due to cosmic rays remains difficult, but we speculate that heating from X-ray sources is more important. As expected from the low abundance of dust and PAHs in metal-poor galaxies, heating mechanisms other than the photoelectric effect heating must be accounted for. Bright X-ray sources may deposit their energy on large scales in such transparent, dust-poor interstellar medium, and thus they represent promising avenues to understand the physical properties of the main star-forming gas reservoir in galaxies. The modeling strategy adopted here makes it possible to recover the global intrinsic radiation field properties when X-ray observations are unavailable, such as in early universe galaxies.

Research on the Estimation of the Flexural Capacity of EPS Lightweight Concrete Panels

Expanded Polystyrene (EPS) lightweight concrete possesses numerous special characteristics, including exceptionally low weight, good sound insulation, effective heat insulation, great fire resistance, and low water absorption. Consequently, it has garnered significant attention for research and practical applications in the construction industry, particularly in the development of soundproofing and thermal insulation components, as well as lightweight elements to reduce the superstructure weight, such as external wall panels, floor slabs, roof panels, and base materials. The primary objective of this study is to analyze and estimate the flexural capacity of EPS lightweight concrete panels through both experimental and numerical methods. Furthermore, the influence of the longitudinal reinforcement ratio, strength, and thickness of EPS lightweight aggregate concrete panels on their flexural capacity is thoroughly investigated and evaluated. The findings demonstrate that the Abaqus software, with an appropriate material model for EPS lightweight aggregate concrete, can reliably predict the flexural capacity of EPS lightweight concrete panels reinforced with longitudinal rebars.

Effect of microwave irradiation on the breaking and linear cutting of hard rock

Microwave technology, emerging as a novel approach to rock-breaking, holds significant promise in the realm of auxiliary mechanical pick rock breaking. In view of the problems existing in the hard rock breaking such as low efficiency and difficulty in one-time cutting, this study conducted experimental research using a method combining microwave irradiation and linear cutting with conical picks. The comprehensive temperature distribution of the rock is reproduced by 3D technology after microwave irradiation, defined the high-temperature zone and calculated the surface area. Moreover, analyzing the relationship between temperature and cutting force. And the effect of microwave-assisted conical pick rock breaking was quantified in terms of cutting force, rock breaking effect, and energy consumption. The results indicate that microwave irradiation induces heating in hard rock, leading to the formation of fissures and even partial fragmentation of rocks. The thermal damage effect of microwave is determined by the differences in the physical and mechanical properties of different rocks. In the experiment, basalt has the best heating effect and sandstone has the best fracturing effect. Compared to non-microwave, microwave (6 kW,60 s) irradiation reduces the cutting force, improves the effect of rock breaking, and reduces the work done (E) by the cutting force and the mechanical specific energy (MSE). Microwave irradiation-assisted mechanical rock breaking is better for sandstone, moderate for basalt, and inferior for granite in this study.

Boundary layer flow and heat-mass transfer of shear-thinning nanofluid past a thin needle: electroperiodic magnetic field and thermo-diffusion effects

Heat and mass transfer in a boundary layer flow (BLF) of shear-thinning nanofluid (NF) around a thin needle has various practical applications including industrial processes, like medical devices, complicated cooling systems, high-efficiency thermal control in microelectronic devices, and chemical reactors designs. With a focus on its practical applications, this work investigates the heat and mass transfer effectiveness in a BLF of shear-thinning fluid containing alumina-copper nanoparticles around a thin needle subject to electroperiodic magnetic field in a nonlinear radiative environment. A comparative analysis is done for heat-mass transfer performance of alumina-copper-water-tangent hyperbolic fluid and water-tangent hyperbolic in order to optimize thermal and mass transmission efficiency by highlighting the importance of latent heat, nanomaterial load and thermo-diffusion processes. This work is novel because such comparative investigation on heat-mass transfer for alumina-copper-water-tangent hyperbolic fluid and water-tangent hyperbolic is not taken yet. The governing model for a BLF around a thin needle are solved using Runge Kutta fourth order (RK-4) method. The findings shows that the action of electroperiodic magnetic field greatly improves mass transfer and heat transfer performance. Latent heat effect and needle thickness enlargement improve the rate of heat-mass. Elevating the Weissenberg number modifies the flow dynamics. Adding more alumina-copper nanoparticles to the mixture increases its thermal conductivity and as a result increases the heat transfer rate. The Dufour number had a positive effect on temperature distribution. The activation energy, and Soret numbers all worked together to significantly alter the concentration profile. The mixture () show better heat-mass transfer efficiency as compared to () fluid.

Synergistic effects of carbon and heat under disturbance of human activities: Evidence from a resource-based city of China.

For resource-based cities, the rapid development of industrialization and urbanization has led to significant carbon emissions (CEs), accelerated the rise of urban land surface temperatures (LSTs) and hindered sustainable urban development. This study constructed a model to measure the carbon-heat relationship to clarify the complex relationship between LSTs and CEs in resource-based cities. The results show that:1) High-temperature areas are primarily concentrated around the urban center and large industrial zones, with average LSTs reaching a peak of 35.7°C in 2015, indicating severe temperature polarization; 2) CEs exhibited an overall upward trend with a diffusion effect, particularly pronounced in the urban center and industrial zones. Areas with extremely significant, strong significant, and generally significant growth in CEs accounted for 4.64%, 3.81%, and 81.35%, respectively, showing a concentrated increase in the urban center; 3) A positive correlation between CEs and LSTs of the city was identified, and the distribution of urban heat island and the high value area of CEs are concentrated and similar; 4) The synergistic effects between LSTs and CEs varied between urban center, suburban and peripheral areas, due to human activities. Areas with a high positive correlation between CEs and LSTs are concentrated in urban centers and peripheral areas, while for urban suburbs, the correlation is weak or even absent. To mitigate the negative effects of carbon-heat accumulation, urban centers should avoid high population concentrations, and the carbon sink potential of green spaces near industrial zones and peripheral areas should be fully utilized. These insights provide actionable strategies for sustainability of resource-based cities, particularly in the governance of urban thermal environments and the mitigation of CEs.

Effect of micro-explosion and puffing on combustion interactions of multi-component fuel droplet array during flame spread

Micro-explosion is a potential scheme to increase the combustion rate of engine spray and reduce emissions. The present study investigates the effects of micro-explosion and puffing on the combustion interaction of multi-component fuel droplet array using a magnified high-speed backlit illumination technique. The mechanisms of micro-explosion and puffing in droplet array combustion were proposed. The results indicate that droplet array combustion primarily consists of two droplets burning in the same flame, three droplets burning in the same flame, and independent flame combustion. Three droplets burning in the same flame lasts the longest at droplet spacings of 2 and 3, accounting for 97.14 % and 72.06 % of the total combustion time, respectively. The total combustion duration of the droplet array is shortened by 34.1 % and 40.3 % at droplet spacings of 2 and 3 compared to the theoretical combustion time. However, the total combustion duration of the droplet array is 1.9 % and 7.4 % longer than the theoretical value at droplet spacings of 4 and 5. Most importantly, the interaction factor first increases and then decreases with increasing droplet spacing. The third droplet has the smallest interaction factor. This is mainly determined by the combined effects of hypoxia, flame heating, and vapor cooling.

Applied Sunnah During Hot Weather And Rainy Season: The Philosophy Of Faith And Mitigation Measures

The Sunnah of Prophet Muhammad (PBUH) encompasses various aspects of life. This paper aims to elevate the role of the Sunnah as a source of knowledge, while also applying it as a guide for life. The Sunnah guidance during hot weather and rainy season is among the important practices should be applied to gain the promising rewards for following the Sunnah, and also to provide benefits for daily life activities. This paper, based on thematic hadith research, gathers several hadiths related to the chosen topic, using the dorar.net/hadith application. This application was chosen because its credibility and authenticity have been proven through studies at the higher education level. All collected hadiths are ensured to be authentic, either classified as sahih or at least hasan in which are accepted as sharia evidence in Islamic law. If there is a difference of opinion among hadith scholars regarding the status of a hadith, prioritization will be made based on hadith methodology. The Arabic text of the hadith is included to receive blessings and for personal reflection. If the hadith text is long and contains various issues, the focus will only be on the desired issue from the sub-topic provided, without addressing other issues. The study found that the Sunnah of Prophet Muhammad (peace be upon him) related to hot weather and rain is highly significant, comprehensive, and suitable to be applied in human life. The Sunnah of Prophet Muhammad (peace be upon him) teaches humans to be aware and have faith in Allah (S.W.T.), in His power and to believe in the unseen, the Angels, and the Day of Judgment. Additionally, the application of the Sunnah, such as seeking shade, pouring water over the head, drinking cold beverages, avoiding crowds, and keeping oneself clean and fragrant, are very practical mitigation steps to reduce the negative effects of extreme heat. Meanwhile, the Sunnah's application in fostering awe toward natural phenomena, allowing raindrops to touch the body, praying, performing salah, expressing gratitude, not complaining, and avoiding superstitious beliefs reflects a deep sense of dependence on Allah (S.W.T.) and is very practical for spiritual aspects.

Exploration of Arrhenius activation energy and thermal radiation on MHD double-diffusive convection of ternary hybrid nanofluid flow over a vertical annulus with discrete heating

The primary objective of this article is to examine the effect of discrete heating on MHD double-diffusive convection and thermal radiation of ternary hybrid nanofluid flow heat and mass transfer in a vertical cylindrical annulus along with Arrhenius activation energy and chemical reaction. In this study, the cavity inner wall has two distinct flush-mounted heat sources, while the outer wall is isothermally cooled at a lower temperature. The top and bottom walls are thermally insulated. The ensuing equations that govern the physical framework are solved using the implicit Crank-Nicholson finite difference technique. As the heater advances upward, the flow intensity decreases, leaving a part of the fluid static at the bottom of the cylinder. Because more heat induces high buoyant flow in the annulus, the absolute value of axial velocity and wall temperature rises as the length of the heat source rises. Enhancing the activation energy parameter values drops the Arrhenius energy function, elevating the pace of the generative chemical process and hence the concentration. Increasing the thermal radiation parameter lowers the surface heat flux while enhancing the nanofluid temperature. The Brownian motion parameter corresponds to the random motion of nanoparticles in a fluid, and this irregular movement augments the collision of nanoparticles with fluid particles, causing the particle's kinetic energy which leads to thermal energy and hence increases temperature, a 10% increment in Brownian motion parameter leads to 26% rise in the temperature. Also, the heat and mass transfer characteristics are forecasted and analyzed by considering the Levenberg–Marquardt backpropagating artificial neural network technique.

Holistic numerical simulation of a quenching process on a real-size multifilamentary superconducting coil

Superconductors play a crucial role in the advancement of high-field electromagnets. Unfortunately, their performance can be compromised by thermomagnetic instabilities, wherein the interplay of rapid magnetic and slow heat diffusion can result in catastrophic flux jumps, eventually leading to irreversible damage. This issue has long plagued high-Jc Nb3Sn wires at the core of high-field magnets. In this study, we introduce a large-scale GPU-optimized algorithm aimed at tackling the complex intertwined effects of electromagnetism, heating, and strain acting concomitantly during the quenching process of superconducting coils. We validate our model by conducting comparisons with magnetization measurements obtained from short multifilamentary Nb3Sn wires and further experimental tests conducted on solenoid coils while subject to ramping transport currents. Furthermore, leveraging our developed numerical algorithm, we unveil the dynamic propagation mechanisms underlying thermomagnetic instabilities (including flux jumps and quenches) within the coils. Remarkably, our findings reveal that the velocity field of flux jumps and quenches within the coil is correlated with the cumulated Joule heating over a time interval rather than solely being dependent on instantaneous Joule heating power or maximum temperature. These insights have the potential to optimize the design of next-generation superconducting magnets, thereby directly influencing a wide array of technologically relevant and multidisciplinary applications.

Impacts of HVAC cleaning on energy consumption and supply airflow: A multi-climate evaluation

Energy-efficiency interventions are crucial for sustainable building operations to accommodate emerging indoor air quality (IAQ) criteria into their engineering life cycles. While several studies have addressed building energy consumption and IAQ considerations separately, few provide integrated analysis of these aspects in response to building hygiene practices. In response, this study evaluates the effectiveness of routine heating, ventilation, and air conditioning (HVAC) cleaning on energy consumption and supply airflow patterns in non-residential public buildings. This study juxtaposes HVAC energy consumption and ventilation performance before, during and after routine HVAC cleaning, across buildings situated in four different climate zones, while operating in cooling mode. Each site had nearly identical HVAC systems serving similar architectural features and occupational loads; these were segregated into an intervention (cleaned HVAC system) that could be compared to an otherwise identically operating HVAC (control system), which was not cleaned. Following prescriptive cleaning, HVAC systems exhibited significant energy consumption reductions and delivered higher airflows compared to their uncleaned counterparts. On average, intervention systems saved between 41 % and 60 % on conveyance (fan/blower) energy, with one exception, and supplied 10 % and 46 % more airflow compared to their uncleaned counterparts. This research demonstrates how a new generation of low-cost HVAC system monitors can compile Internet of Things (IoT) archives to show immediate energy consumption benefits associated with cleaning HVAC components and their associated ductwork serving relatively high occupancy commercial and educational spaces.

An investigation on the effect of latent heat on the hygrothermal performance of earth building materials

An investigation on the effect of latent heat on the hygrothermal performance of earth building materials

Aerosol ignition in iron powder flames stabilized on a new type of jet-in-hot-coflow burner

A novel Jet-in-Hot-Coflow burner for the combustion of solid metallic particles is presented. This system features an electrically preheated coflow to ignite particles without the need for a pilot flame, mimicking exhaust gas recirculation, a method often used in industry to suppress NOx emissions and stabilize or control a combustion process. Two different iron powder samples with different particle size distributions were combusted, and their combustion products were analyzed using quantitative XRD to study the effect of particle size and interparticle heating on the ignition temperature of a suspension. It was found that a large fraction of the larger particles failed to ignite, probably due to insufficient heating during the residence time in the hot coflow. An increase in the dust concentration, expected to increase local temperatures and interparticle heating effects, did not significantly decrease the suspension ignition temperature for these powders.