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The oxidation states of dissolved iron (Fe) and sulfur (S) in silicate melts were studied experimentally by heating Hawaiian olivines containing S-bearing melt inclusions (MIs) in a 1 atm gas-mixing furnace. The MIs are closed with respect to S and C, but equilibrate with the oxygen fugacity (ƒO 2) and water fugacity (ƒH 2 O) of the furnace. We also conducted experiments using a S-free synthetic Hawaiian MI composition held on Pt-loops. Experiments were run at 1225 °C for 8–96 hr in H 2 -CO 2 gas mixtures corresponding to ƒO 2 values that varied over seven orders of magnitude and then drop-quenched into water. Time-series experiments show that MI Fe3+/Fe2+ and S6+/S2− ratios reached constant values within ∼24 hr. The H 2 O contents of the Pt-loop glasses and the dehydrated MIs overlap and are proportional to the f H 2 O in the furnace gas. The slope of log 10 (Fe3+/Fe2+) vs. log 10 ƒO 2 is 0.25±0.02(2σ) for the Pt-loop glasses and 0.23±0.01(2σ) for the quenched MIs; the slopes of the two sets of experiments are consistent with equilibrium having been reached via the reaction FeO + ¼ O 2 = FeO 1.5. S-bearing quenched MI glasses have Fe3+/Fe2+ ratios that are systematically low compared to ratios measured in the S-free Pt-loop glasses run at the same T and ƒO 2 ; this may reflect an effect of S on Fe3+/Fe2+, although further experiments are needed to explore this possibility. S6+/S2− ratios in the experimental melt inclusions vary systematically as a function of ƒO 2 , and the measured ratios agree with independent calculations of S oxidation state in basaltic melts. After being held at 1225 °C for 24 or 48 hr, a subset of olivine-hosted MIs were cooled at rates of 1700–40,000 °C/hr and quenched at temperatures between 900 °C and 1150 °C to explore whether Fe and S speciation are modified during cooling. Fe and S speciation in isothermal and cooled MIs held initially at the same ƒO 2 overlap within uncertainty, suggesting that the T dependence of the homogeneous reaction 8Fe3+ + S2− = 8Fe2+ + S6+ is small and/or its kinetics are sluggish relative to cooling rates required to quench basaltic liquids to glasses. The centers of unheated, naturally quenched MIs from Papakōlea, Hawaii with syneruptive cooling rates ranging from ∼50 to 12,000 °C/hr were also measured for Fe and S speciation. MIs that experienced the lowest cooling rates have higher Fe3+/Fe2+ and S6+/S2− ratios relative to rapidly cooled inclusions of comparable size. The increase in Fe3+/Fe2+ is due to olivine crystallization on the inclusion walls during cooling and diffusion of the resulting oxidized boundary layer into MI interiors. Diffusive modification is minimized in MIs that have been rapidly cooled and/or are sufficiently large such that the oxidized boundary layer is restricted to a narrow region adjacent to the inclusion walls. Our experiments and their comparison to naturally quenched MIs show that measurements of Fe3+/Fe2+ and S6+/S2− ratios in quenched basaltic glasses and in the centers of rapidly cooled and/or large MIs are likely to be representative of the redox state in the melt at magmatic temperatures prior to quenching to glass. [ABSTRACT FROM AUTHOR]

Heatstroke (HS), associated with the early activation of the coagulation system and frequently presenting with thrombocytopenia, poses a significant healthcare challenge. Understanding the relationship of nadir platelet count (PLT) within 24 h for adverse outcomes in HS patients is crucial for optimizing management strategies. This retrospective cohort study, conducted in six tertiary care hospitals, involved patients diagnosed with HS and admitted to the emergency departments. The primary and secondary outcomes included in-hospital mortality and various acute complications, respectively, with logistic regression models utilized for assessing associations between nadir PLT and outcomes. The PLT count change curve was described using a generalized additive mixed model (GAMM), with additional analyses involving body temperature (BT) at 2 h also conducted. Of the 152 patients included, 19 (12.5%) died in-hospital. The median nadir PLT within 24 h was 99.5 (58.8–145.0)*10^9/L. Notably, as a continuous variable (10*10^9/L), nadir PLT was significantly associated with in-hospital mortality (OR 0.76; 95% CI 0.64–0.91; P = 0.003) and other adverse outcomes like acute kidney and liver injury, even after adjustment for confounders. GAMM revealed a more rapid and significant PLT decline in the non-survival group over 24 h, with differential PLT dynamics also observed based on BT at 2 h. Nadir PLT within 24 h were tied to in-hospital mortality and various adverse outcomes in HS patients. Early effective cooling measures demonstrated a positive impact on these associations, underscoring their importance in patient management. [ABSTRACT FROM AUTHOR]

In order to explore the thermodynamic characteristics of the gradual cooling and liquefaction process of hydrogen, a small-scale open hydrogen liquefaction system with stepwise cooling is proposed, designed and experimentally tested. The fabrication and practical cooling operation of the hydrogen liquefaction system are conducted under the premise of pre-test of neon and safety precautions. The cooling capacity required for hydrogen cooling is continuously provided by two Gifford-Mcmahon (G-M) refrigerators and the returned cold hydrogen. The hydrogen gas is gradually cooled to about 21 K through two pre-cooling heat exchangers (PHEX) and three counter-flow heat exchangers (CHEX) and then throttled to about 120 kPa. Hydrogen gas with a mass flow rate of 0.2 kg/h can be liquefied to meet the design requirements in this system and the experimental results are compared with the Hysys simulation. The comparative analysis reveals that the measured data of key nodes are in good agreement with the simulation results, and the maximum deviation is around 8.70%, which proves the effectiveness of the experimental system and provides validation for the simulation. In addition, the design of the heat transfer module including the structure of the PHEX and the cold shield is reasonable and feasible. In conclusion, the designed experimental system and results can provide a technical reference for the corresponding equipment selection and operating experience in hydrogen liquefaction experiments. • A small-scale open hydrogen liquefaction system with stepwise cooling is proposed. • The temperature is divided into three zones and the throttling process is retained. • A heat transfer module is designed to enhance the heat transfer performance. • Standard operation procedures and safety precautions are conducted to ensure safety. • The experiment data and simulation results are compared to verify the feasibility. [ABSTRACT FROM AUTHOR]

Challenges in drilling nickel-based superalloys, such as Inconel 718 (IN718), are multifaceted. High requirement of hole surface quality in drilling such alloy must deal with extreme material properties and complex process condition in drilling operation. This paper presents an experimental investigation on the effect of PVD coated solid carbide drills under different internal cooling schemes on hole quality in drilling IN 718 alloy. Three types of solid carbide drills were used in the series of drilling experiments, including PVD coated and uncoated drills, and different design in the number of internal cooling channels, two channels and four channels. The objective of the investigation is to assess the effect of coating and efficiency of internal cooling on surface quality in drilling IN718 alloy. Surface quality on drilled holes in terms of roughness, burr formation, subsurface deformation and strain hardening has also been measured and analyzed on the machined specimen. The roughness and burr size on drilled holes demonstrated little differences among the three types of testing drills. Surface roughness was severely deteriorated by the chip trapped in the hole leaving scratch and smears on the surface. Nevertheless, the scheme of internal cooling channels and PVD coating exhibited noticeable influence on quality of drilled hole surface. [ABSTRACT FROM AUTHOR]

Ocean temperature, redox state, circulation, and nutrient levels regulate the marine nitrogen (N) cycle, yet their specific impacts during greenhouse intervals remain poorly understood. Here, we examined the Smithian–Spathian hyperthermal event (∼250.5 Ma) during the Early Triassic greenhouse using stable N isotopes (δ15N) from sedimentary records in the Nanpanjiang Basin and Northern Yangtze Basin of South China. The δ15N profiles in both basins reveal consistent trends that correspond to fluctuations in temperature across the Smithian–Spathian transition. The Smithian hyperthermal interval exhibited low δ15N values (mostly <+2‰), indicating N deficiency and enhanced biological N 2 fixation. Bacterial blooms and the release of the potent greenhouse gas N 2 O, enhanced by high temperatures, may have triggered positive feedback mechanisms that sustained the warming and contributed to the late Smithian extinction. During subsequent cooling across the Smithian–Spathian transition, δ15N increased to a range of +3‰ to +7‰, likely reflecting signals of partial denitrification based on reconstruction of the NO 3 − inventory associated with oceanic cooling and oxygenation. The prevailing increases in sedimentary TOC/TN ratios signify heightened deamination (removal of amino groups) and N recycling across the Smithian–Spathian boundary. This transition is likely attributed to cooling-driven amelioration of seawater stratification and anoxia from the Smithian to the Spathian, which resulted in increased nitrate availability in the photic zone. Eukaryotic algae thrived while prokaryotes declined during the Spathian, evidenced by elevated δ15N and Δ13C carb-org (the difference between carbonate and organic carbon isotopes). The proliferation of eukaryotic algae had a positive impact on environmental conditions and facilitated biotic recovery due to more efficient burial of organic particles. A notable latitudinal gradient in the N cycle response was observed, with low-latitude regions showing a more pronounced response to cooling compared to mid-latitude areas. This significant gradient may suggest that the rapid recovery of nutrient cycles, despite relatively small decline in high temperature, was a key factor in the amelioration of climate and recovery of life in low latitudes. These findings highlight that the marine N cycle is highly sensitive to temperature changes, particularly in low-latitude regions, and that changes in N cycle under high-temperature conditions may be a critical life-limiting factor. [ABSTRACT FROM AUTHOR]

Both composition and temperature play a crucial role in determining the NO radiative cooling in lower thermosphere as observed by TIMED/SABER. In this work, we present a detailed investigation of seasonal variation in thermospheric NO radiative cooling. We have carried forward the investigation of Li et al. (2018) regarding the variations in local nighttime peak NO radiative cooling and its altitude during solar maximum and solar minimum conditions. By analyzing latitudinal changes over quiet times for each month in year 2018, it is evident that both the investigated parameters exhibit summer-winter variability. The qualitative contribution of different species (i.e., NO, and O), and temperatures in determining the vertical profile of NO radiative cooling for different latitudes is investigated by utilizing the NRLMSISE-00 estimated parameters, and SNOE observed NO density. The temperature, NO density, and compositional variations due to asymmetrical solar heating and associated summer-to-winter circulation in both the hemispheres during solar minimum conditions seem to be the dominating factor in controlling the NO radiative cooling during different seasons. The altitudes at which maximum cooling by NO occurs exhibits an inverse correlation with the amount of radiative cooling. The region of enhanced NO densities (polar and summer hemispheric low-mid latitude regions) have larger NO radiative cooling with lower peak altitudes in comparison to other regions (equatorial to winter hemispheric low-mid latitude regions), where NO radiative cooling is low with higher peak altitude values. [ABSTRACT FROM AUTHOR]

Elastocaloric cooling is emerging as a promising alternative to conventional vapor compression systems due to its potential for energy savings and significant temperature lift compared to other solid-state cooling technologies. This technology harnesses the latent heat associated with the martensitic phase transition of shape memory alloys to generate the desired cooling or heating effect. This paper comprehensively reviews the fundamentals of elastocaloric cooling systems, including the thermodynamics cycle and various materials used. It also presents the latest advancements in elastocaloric systems, focusing on heat transfer enhancement, actuator development, and prototype summaries. Additionally, this paper introduces a new non-dimensional performance parameter to evaluate different elastocaloric prototypes and discusses key aspects necessary to achieve potentially high-performance elastocaloric devices. Finally, we propose an approach for future elastocaloric device development. [ABSTRACT FROM AUTHOR]

In the present work a numerical analysis is presented to identify the separate effect of cooling by radiation and convection, in evaporative meat weight loss during beef carcass cooling process. A transient heat and mass transfer model is proposed using a 3D beef side geometry. Water activity variations are incorporated in the model. Convective coefficients are obtained from correlations by considering buoyancy effect due to temperature and vapor concentration gradients, and forced air flow. For the purpose of model water mass diffusion into the carcass, a first approximation of the meat layer thickness affected by drying is obtained from an analytical analysis as a semi-infinite solid. The model is solved numerically and it is validated with experimental data from the literature. Results of heat load and weight loss are compared to models proposed by other authors. Temperature and surface water activity evolution, and temperature and water content profiles are analyzed also. Finally, a sensitivity study is carried out on the main result of the model, total evaporated mass, varying heat convection coefficient and radiative cooling. It is found that there is a convective heat transfer coefficient that maximize the evaporative losses, so it is important to operate far from this point in order to reduce the evaporated mass. Furthermore, radiation during the meat cooling process turns out to be an interesting method to rapidly cool meat without increasing the evaporated mass (radiation cooling). Results shows that combining properly the convection and radiation heat transfer, evaporation losses can be reduced. • A simplified model to predict beef side weight loss is validated. • Both natural and forced convection are relevant during meet chilling process. • An upper limit of meat thickness affected by drying is analytically estimated. • There is a convective coefficient value that maximizes weight loss. • Theoretically a reduction in evaporated mass might be achieved by radiative cooling. [ABSTRACT FROM AUTHOR]

Zirconolite (CaZrTi 2 O 7) glass-ceramic is considered as a potential stable matrix for the immobilization of Pu or minor actinides (Np, Am, Cm). In this work, the phase combination and evolution of glass (SiO 2 –Al 2 O 3 –Na 2 O–CaO–ZrO 2 –TiO 2 –B 2 O 3) with La as an actinide surrogate were investigated during the process of heating and cooling. By employing controlled cooling process, the zirconolite glass-ceramic with a controllable crystal size was successfully fabricated in borosilicate glass. The results demonstrate that heating and cooling exhibit distinct phase combinations. Both crystallization temperature and duration exert a significant influence on the composition of crystalline phases and microstructure. During the cooling of the melt, an increased degree of supercooling leads to an enhanced crystallization of zirconolite and a significant reduction in crystal size. The experimental results demonstrate that the optimal condition for preparing zirconolite glass-ceramic is held at 950 °C, for 4 h by one-step method, at which time the crystal exhibits a slender acicular morphology with a size of about 30 μm. Most of the simulated nuclides are enriched in crystals, and the rest are dissolved in glass. Zirconolite exhibits thermodynamic instability at elevated temperatures (1000 °C–1100 °C). Following the phase transformation, a proportion of Zr sequestered by titanite, while any excess Zr is either remain dissolved in the glass or gets precipitated as baddeleyite. For La, Al and other elements previously fixed in zirconolite, they are re-released to the glass and partially fixed by titanite, which may be detrimental to the long-term release behavior of the waste forms. In the aqueous durability test, both zirconolite glass-ceramic and phase transformation samples exhibited a low leaching rate, with LR Si , LR Zr , and LR La values of approximately 5 × 10−3, 4 × 10−6, and 6 × 10−6 g·m−2·d−1, respectively, after 28 days of leaching. By controlling the cooling process (one-step method), this paper provides useful information on the preparation of zirconolite glass-ceramic. [ABSTRACT FROM AUTHOR]

• To improve data center performance, it must be efficiently cooled. • This paper undertakes a detailed examination of the most recent cooling optimization techniques. • Several methods are discussed like regular air conditioning, free cooling, and liquid cooling. • An assessment of overhead and underfloor air delivery technologies is presented. • The effects of baffles, variable airflow control, and server placement are investigated. In order to increase data centers' efficiency and performance, a proper cooling system should be applied. This article provides a comprehensive assessment which explores current cooling optimization technologies for data centers. Standard traditional technologies like air conditioning, free cooling, and liquid cooling are investigated. Their limitations as well as proposed improvements are thoroughly discussed. The article also delves into underfloor and overhead air supply technologies, presenting their advantages and drawbacks. The review introduces novel approaches at the rack level cooling, including baffles, variable airflow management, and optimal server placement. Key findings stress the efficacy of optimized airflow systems and innovative rack-level cooling, underlining their role in reducing energy consumption and enhancing overall performance. Notably, potential energy savings of up to 67.2 % compared to traditional methods are demonstrated. The adoption of advanced cooling technologies, such as direct and indirect natural cooling, liquid-cooling cold plates, submersion, heat pipe, and thermosiphon-based cooling, exhibits promising energy efficiency gains and reduced Power Usage Effectiveness (PUE) values. Research into content-specific efficiency enhancements, adaptable energy-saving tactics, and all-encompassing server power consumption models is necessary. To work toward future sustainable, energy-efficient data centers, researchers should investigate how CRACs and server fans interact, find ways to integrate thermal and power management, and how artificial intelligence can be used to cool servers in an eco-friendly way. [ABSTRACT FROM AUTHOR]

Thermal energy storage using coupled metal hydride reactors is attractive because it offers several advantages such as one-time hydrogen loading, high thermal storage density, compactness and possibility of simultaneous heating and cooling. This study presents experimental investigations on a coupled metal hydride based thermal energy storage system. Based on compatibility criteria of hydrides described in this work, LaNi 4.25 Al 0.75 for thermal energy storage and La 0.75 Ce 0.25 Ni 5 for hydrogen storage were chosen. The study employed two novel cartridge type coupled reactors with enhanced heat transfer surfaces. The effects of heat source and ambient temperatures on the system performance were investigated. The study reveals that coupled hydride systems with suitable pairs of hydrides can deliver high energy storage capacities at good thermal efficiencies. The heat output of 227.7 kJ was achieved with a heat transfer rate of 130.7 W at 55.7 % efficiency. The hydrogen storage alloy exhibited good compatibility with the energy storage alloy with fast hydrogenation and dehydrogenation. It also produced a cooling effect of 171.8 kJ while desorbing hydrogen. • Coupled LaNi 4.25 Al 0.75 -La 0.75 Ce 0.25 Ni 5 reactors for thermal storage were experimentally studied. • A procedure to determine the optimum initial state of coupled hydrides is provided. • Energy density of 135.14 kJ. kg MH - 1 at an average heat transfer rate of 130.7 W was achieved. • In addition to hydrogen storage, La 0.75 Ce 0.25 Ni 5 produced a cooling effect of 102 kJ. kg MH - 1 . • Effects of charging and discharging temperatures on thermal performance are investigated. [ABSTRACT FROM AUTHOR]

As a passive heat transfer superconductor for proton exchange membrane fuel cell (PEMFC) cooling, the heat transfer performance and temperature uniformity of flat-plate closed loop pulsating heat pipe (CLPHP) are the key factors to determine its application efficiency. Based on the geometric structure and working medium thermophysical properties of flat-plate CLPHP, this study establishes segmented and integral thermal resistance theoretical models for the heat transfer properties of each section of the flat-plate CLPHP. The calculation accuracy of the segmented and integral thermal resistance models is compared through experimental verification. The results show that the segmented thermal resistance model's temperature variation and temperature uniformity are more accurate than that of the integral thermal resistance model when the flat-plate CLPHP is started, operated stably, or at higher heating power. However, the model calculation error is relatively large when the heating power is relatively high at 400 W, but the calculation accuracy of the segmented thermal resistance model in temperature and temperature uniformity is 2.32 and 5.99 times that of the integral thermal resistance model. The segmented thermal resistance model provides a theoretical basis for improving the calculation accuracy of flat-plate CLPHP coupled PEMFC cooling. • A segmented thermal resistance model of flat-plate CLPHP is proposed. • The segmental and integral thermal resistance simulation models of flat-plate CLPHP are established. • The segmented thermal resistance model has higher temperature calculation accuracy. • Segmented thermal resistance model optimizes simulation calculations for flat-plate CLPHP integrated PEMFC cooling. [ABSTRACT FROM AUTHOR]

Wire Arc Additive Manufacturing (WAMM) consists in the manufacture of metallic preforms from the deposition of multilayer weld beads on a substrate, that is, from a three-dimensional model, the object is divided into layers defining the trajectories in which the addition of metal will be made, with the use of a robotic manipulator. The objective of this work is to study the influence of the addition of cold wire and the effect of interlayer temperature in the WAAM process, comparing it with the deposition made with a single wire, observing mechanical properties such as tensile strength, hardness, in addition to the cooling time for different interlayer temperatures and the geometry of the manufactured parts. A GMAW (Gas Metal Arc Welding) system was used coupled to a robotic manipulator, with multiple wires of 1.6 mm in diameter for the energized wire and 1.0 mm for the cold wire, both classified as ER70S-6. In order to manufacture the specimens for the tensile test, 20 layers were superimposed in a straight line, forming a wall, varying the interlayer temperature between each layer, using 100°C, 150°C and directly, with no waiting interval between layers. In general, a shorter cooling time was observed for the walls manufactured with the addition of cold wire when compared to depositions with a single wire. In addition, it was noted that the cold wire also influences the height and thickness of the pieces. In the mechanical tests, the cold wire did not significantly influence the hardness values. The highest values were found in the 100°C samples. For the tensile tests, it was observed that, in general, the addition of cold wire tended to increase the maximum tensile strength of the samples. [ABSTRACT FROM AUTHOR]

The current manuscript reports the experimental results of a closed loop metal hydride (MH) based compressor driven cooling system (CDCS) employing large-scale reactors. Two identical tube bundle reactors (TBR) with 19 MH tubes were designed, constructed and packed with 26.5 kg La 0.8 Ce 0.2 Ni 5 alloy each for the experiments. The TBR modules were coupled with a custom-built compressor to provide cooling effect in quasi-continuous mode of operation. The compressor was tested to operate smoothly up to a hydrogen flow rate of 0.5 g. s−1 in the temperature range of 10–35 °C, yielding pressure ratio up to 12.8. Test runs were performed by altering refrigeration temperature (10–20 °C), sink temperature (30–35 °C), and half-cycle time (120–600 s). The maximum cooling power attained at 20 °C refrigeration temperature and 30 °C sink temperature was 1.44 kW, generating 537.3 kJ cooling within 600 s. The corresponding mean coefficient of performance (COP) and specific cooling power (SCP) were 0.95 and 36.4 W.kg−1 for 480 s half-cycle time. To avoid overheating of the compressor base, the half-cycle time was restricted to maximum of 600 s. [Display omitted] • A large scale compressor operated MH based cooling system was developed and tested. • A pair of tube bundle MH reactors was packed with 26.5 kg La 0.8 Ce 0.2 Ni 5 each. • The compressor operated on a maximum flow rate of 0.5 g.s−1 giving a PR up-to12.8. • At 20 °C, the peak cooling power was 1.44 kW yielding a cooling effect of 537 kJ. • The maximum system COP obtained was 0.95. [ABSTRACT FROM AUTHOR]

Load managing and price optimizer are significant elements in triple models and combined cooling, heating, and power (CCHP) models. In this study, a new CCHP model utilizes a fuel cell as the main drive with a heat recovery system, a 5-kW PEMFC pile, a small immersion chiller, a humidifier, and a gas compressor is considered. The system has been assessed regards to environment, thermodynamics, and economics in terms of view. A developed type of Honey Badger Optimizer has been suggested to optimize the effectiveness of the model. The system productivity has been assessed by the exergy, energy, yearly price, and pollutant release decrease. According to model studies, low operating temperatures, high intake gas pressures, and high relative humidity all contribute to improved system efficiency and a reduction in greenhouse gas emissions. Based on simulation data, the electricity efficiency at the final optimized point is found to be 69.77%, which is a significant improvement over the baseline efficiency of 63.3% before optimization. Furthermore, the optimized system resulted in a yearly reduction of greenhouse gas emissions by 1.47e7 g, which represents a notable improvement over the 1.20e7 g reduction achieved by the standard system. • New CCHP model is proposed for a fuel cell as the main drive with heat recovery system. • System is analyzed based on environment, thermodynamics, and economics terms of view. • Developed version of Honey Badger Optimizer to improve the system efficiency. • Productivity is by the energy, exergy, yearly price, and pollutant release decrease. [ABSTRACT FROM AUTHOR]

The current study aims to design a new parabolic trough collector (PTC) operated polygeneration system to produce freshwater, hydrogen, cooling, and electricity in a residential society. Dowtherm A (a heat transfer fluid) is used to transfer the heat from PTC to the Organic Rankine Cycle, which is used to produce electrical power. The produced electrical power is utilized in three different ways, namely, to run the home appliances, to produce hydrogen (via water electrolysis), and to produce cooling (through a vapor compression cycle). The cooling produced by the vapor compression system is utilized to preserve the food, milk, and to operate the freezing desalination process. Effects of several factors, such as direct normal irradiance, evaporator temperature, and seawater inlet temperature, have been analyzed on the overall system behavior. Thermodynamic study results show that for a PTC area of 2000 m2, an electrical output obtained is 72 kW, the cooling rate is 112 kW, and the mass flow rate of fresh water produced is 18.4 l/day and 10.8 kg/day of hydrogen for mean solar irradiation of 700 W/m2. The energy efficiency of the system is found to be 17.5%, and the exergy efficiency of the system is around 10.9%. • A new PTC based energy system for a society in remote area is thermodynamically assessed. • Dowtherm A is used as a heat transfer fluid for PTC. • Study results show that for PTC area of 2000 m2, an electrical output obtained is 72 kW. [ABSTRACT FROM AUTHOR]

A systematic and hierarchical multi-physics coupling simulation method is proposed to model the combustion, combustion-gas transonic flow, coolant transcritical flow, and transient heat transfer phenomena inside the regenerative cooling thrust chamber subsystem of a LOX/methane rocket engine. By combining this algorithm with a self-developed platform, two distributed parameter modules are developed. Based on the ground test conditions of a LOX/methane engine, a verification case is established, and transient simulation studies are conducted. Comparisons with steady-state test data show that the calculated errors for coolant temperature rise and pressure drop are not higher than 4%. The simulation results reveal the locations where the transition from liquid to supercritical state occurs within the cooling jacket and provide three peril points of wall temperature on the thrust chamber. This study comprehensively reveals the occurrence of transcritical transient processes inside the cooling channels during the regenerative cooling process, laying the foundation for future entire system simulation. • A finite volume model system for system-level transient transcritical fluid flow. • Fundamental equation of state. • Transonic flow, transcritical flow, heat transfer, and combustion multi-physics coupled. • Modeling regenerative cooling thrust chamber of a LOX/methane rocket engine. [ABSTRACT FROM AUTHOR]

In this work, the effects of TiCN and γ-Al 2 O 3 nanoparticle (NP) addition on the microstructural evolution of cast AZ91 alloys at the cooling rate ranging from 15 to 120 K/s have been systematically investigated. Experimental results reveal that grain coarsening occurs in cast AZ91 alloys when the cooling rate exceeds 90 K/s, while it can be effectively inhibited upon addition of NPs. The marked inhibition effect may originate from the formation of TiCN or γ-Al 2 O 3 NP-induced undercooling zone ahead of solid/liquid (S/L) front of α-Mg, which not only can restrict grain growth effectively, but also can reactivate the native nucleants that are inactive in AZ91 melts to participate in nucleation events. And if possessing high nucleation potency, NPs can also promote further nucleation events and lead to significant grain refinement. An analytical model has been established to quantitatively account for the restriction effect of NPs on grain growth. The present work may shed a new light on the grain coarsening of cast alloys during fast cooling and provide an effective approach to circumvent it. [ABSTRACT FROM AUTHOR]

• Thermodynamic analysis of absorption cooling-assisted CO 2 systems. • Performance enhancement over simple CO 2 system is analysed. • Simple CO 2 system with IHX coupled with DEDHVARS performs better at high T gc. • Enhanced COP and exergy efficiency. Studies have shown appreciable improvements in system performance by subcooling the working fluid in transcritical CO 2 refrigeration systems. The use of a dedicated vapour absorption refrigeration system (VARS) for subcooling the high side working fluid downstream of the heat rejection device is proved to be a viable option. The heat available in the discharged gas downstream of the compressor in the transcritical CO 2 system is used to drive a LiBr-H 2 O VARS. This study examines the performance of an absorption cooling-assisted transcritical CO 2 system. Three different configurations of the absorption system are considered, namely, single effect (SE), series double effect (DE), and series double effect with dual heat input (DEDH). The performance analysis is carried out for gas cooler exit temperatures (T gc) ranging from 30 to 50 °C and evaporation temperatures ranging from -10 to 5 °C. The average COP improvement of the CO 2 system is found to be 29 and 27% using SE and DEDH systems respectively. [ABSTRACT FROM AUTHOR]

The focus of this paper is to investigate the practicality of incorporating immersion cooling methods to mitigate the temperature elevation of motors utilized in hybrid aircraft. Air cooling, oil jacket cooling, slot-channel oil cooling and immersion cooling techniques are each applied to a permanent magnet synchronous motor. When a hybrid aircraft is operating, the amount of fuel it carries is limited and decreases over time. In this case, the normal operating time of the motor is investigated in this paper. The study shows that for the motors in this paper, immersion cooling is the most effective with a limited amount of coolant and takes the longest time to reach the upper temperature limit, which can be improved by 5.6 times compared to slot-channel cooling. This paper serves as a reference for the design of motors for hybrid aircraft utilizing immersion cooling technology. [ABSTRACT FROM AUTHOR]

This figure shows the results from the CoolPINNs framework for forward and inverse problems. Heat is supplied to the bottom of the plate, and the top surface is free to convect and radiation. A flowing fluid through an embedded vasculature—in the shape of a sine wave—regulates the plate's temperature. The forward problem calculates the temperature field, whereas the inverse problem predicts thermal conductivity using noisy temperature data. [Display omitted] Emerging technologies like hypersonic aircraft, space exploration vehicles, and batteries avail fluid circulation in embedded microvasculatures for efficient thermal regulation. Modeling is vital during the design and operational phases of these engineered systems. However, many challenges exist in developing a modeling framework. What is lacking is an accurate framework that (i) captures sharp jumps in the thermal flux across complex vasculature layouts, (ii) deals with oblique derivatives (involving tangential and normal components), (iii) handles nonlinearity because of radiative heat transfer, (iv) provides a high-speed forecast for real-time monitoring, and (v) facilitates robust inverse modeling. This paper addresses these challenges by availing the power of physics-informed neural networks (PINNs). We develop a fast, reliable, and accurate Scientific Machine Learning (SciML) framework for vascular-based thermal regulation—called CoolPINNs: a PINNs-based modeling framework for active cooling. The proposed mesh-less framework elegantly overcomes all the mentioned challenges. The significance of the reported research is multi-fold. First , the framework is valuable for real-time monitoring of thermal regulatory systems because of rapid forecasting. Second , researchers can address complex thermoregulation designs since the approach is meshless. Finally , the framework facilitates systematic parameter identification and inverse modeling studies, perhaps the most significant utility of the current framework. [ABSTRACT FROM AUTHOR]

Perform a systematic review of the literature and present the results of randomized clinical trials (RCTs) pointing out under which conditions and forms of administration menthol is really capable of improving performance in endurance exercise. Thirteen studies met the eligibility criteria. The sample size ranged from 6 to 12 athletes and the studies were evaluated between 5 and 9 on the PEDro scale. Six studies evaluated menthol mouth rinse, of which three demonstrated an increase in time to exhaustion between 6% and 9% and two demonstrated a decrease in time trial (2.7% and 3.5%). Five studies evaluated the topical application but without modification of physical performance variables. Two studies assessed the oral intake, of which in one of them there was a decrease in the time trial between 5.2% and 8.2%. Current data point to a good perspective on the determination of menthol as an ergogenic resource, provided that further studies form a body of evidence on each of the forms of administration. The available evidence suggests that physical exercise practitioners who use menthol orally seem to be able to promoter sport advantage, but these results need to be weighed due to the evidence level is considered to be of low quality due to small sample size, heterogeneous supplementation and exercise protocols and low volume of studies. [ABSTRACT FROM AUTHOR]

During the braking process of a car, the temperature of the brake system increases continuously, and if the cooling performance of the brake system is insufficient, accidents can occur. For this reason, in this study, the experimental method of the Taguchi design was used to optimize the design of a ventilated brake disc with radial vanes using three design parameters (i.e., number of vanes, vane thickness, and steering angle), and the airflow and temperature distribution around the brake disc and tire were simulated using finite elements. The simulation results show that the solution in this study can increase the ventilation gap from 10 to 14 mm, the bending angle of the blades from 29° to 37°, and the cooling effect after emergency braking by 6.1% and 8.8%, respectively, when dissipating heat for 100 s at a driving speed of 60 km/h. [ABSTRACT FROM AUTHOR]

In this paper, we utilized a eutectic gallium-indium liquid metal (LM) with high thermal conductivity to immerse carbon-based phase change material (PCM) capsules to acquire a PCM-LM composite. This produced a scalable, thermally stable, mechanically reliable, high thermally conductive, and leakage-free material. This composite was then applied as a heat mitigator for CPU cooling. Results demonstrate that clear improvements could be made compared to traditional pin-fin heat-sink cooling. Here the continuous full-load operating time could be prolonged by 414.3%. Moreover, the temperature difference between the idle and full-load operating states could be significantly decreased, and prevent damage from thermal stress. Significantly, a 23% energy-saving performance was attained because of the thermal buffering effect and high responsive ability of the composite. Guidelines for an effective match between the heat absorption of the composite and the heat generation from the CPU could also be established. Here the proposed PCM-LM composite can be applied to other PCM-based energy storage industries and efficient temperature control applications, contributing to carbon neutralization and global warming mitigation. [ABSTRACT FROM AUTHOR]

In the current study, a state-of-art biogas-driven poly-generation power plant is presented, evaluated and optimized. For assessing the multi-aspects feasibility of the proposed plant, exergy, energy, exergoeconomic, and environmental evaluations are applied as the robust tolls to the assessment of the plant. Also, to enhance the hydrogen production by the system, the steam reforming technology and proton exchange membrane are incorporated into the plant. Based on the obtained results, the designed plant can generate 86.04 kW, 0.9662 kg/s, 958.2 kW, and 704.573 kg/h of electricity, fresh water, cooling, and hydrogen, respectively. In this plant, the energy efficiency is approximately 33.5%, while the exergy efficiency is about 31.2%. Also, some unit cost of the product and environmental penalty cost rate are calculated at about 23.7 $/GJ and 141.7 $/h. Analyzing sensitivity helps identify which parameters affect the system's performance and determine the most effective optimization mode. The multi-objective optimization mode result improves the exergy and energy efficiencies of the plant by 19.9% and 24.5%, respectively. [ABSTRACT FROM AUTHOR]

The salt swelling destruction in arid sulfate saline soil areas represents a severe problem in road, railway, and foundation engineering. It is imperative to explore a potential solution to solve the salt swelling for the sulfate saline soil. However, vaporous water has a large effect on the forms of sodium sulfate present in the soil, which has not been taken into account by existing models. This work proposes an improved heat-water-vapour-salt based salt swelling model by considering the vaporous water effect. Experiments on unsaturated saline soils were conducted to validate the accuracy of the model. Besides, the effects of temperature, water content, relative humidity, and solute concentration on salt swelling were reasonably analyzed. The results show that the salt swelling rate increases to 64% when the relative humidity reaches 60–90%; once the relative humidity exceeds 90%, the swelling rate will decline to 0%. Moreover, the salt swelling rate follows an upward convex curve along the relative humidity and decreases with increasing liquid water content. When the liquid water content is above 10%, the salt swelling rate is stable at around 0.3. Overall, the improved model is more accurate in predicting salt swelling than the existing model, which shows exceptional promise in providing useful insight into understanding the mechanism of salt swelling and the prevention of salt swelling in saline soils. [ABSTRACT FROM AUTHOR]

In the recent years, radiative cooling has emerged as a promising technology for space cooling applications. Nevertheless, radiative cooling phenomenon is dependent on weather conditions and it presents some performance limitations, meaning that the cooling capacity is limited in some climates. The radiative cooling potential is the maximum theoretical limit that can be achieved. In this study we analyse the evolution of the radiative cooling potential in Europe under the context of climate change. Radiative cooling potential maps for the period 2020–2050 are provided. The results reveal that radiative cooling potential remains constant for this period, evidencing a resilience of this technology during the following decades. We also provide a seasonal study of the potential by regions. Summer, when cooling needs are higher, is the season with the least nocturnal energy potential and the second with the highest nocturnal power potential. Shifting to all-day radiative cooling, the energy potential increases by 1.64 in winter; 2.97 in spring; 4.03 in summer and 2.2 in autumn. [ABSTRACT FROM AUTHOR]

To date, the tunnel lining GHEs have encountered issues with the relatively low heat exchange rate and the rapid decline of heat exchange rate with time. This is because the huge heat accumulation around the tunnel lining GHEs obstructs the heat transfer between the absorber pipe and the surrounding rock during the GHEs operation. Hence, to improve the heat accumulation and enhance heat exchange rate, the two-phase closed thermosyphon (TPCT), an efficient device for long-distance heat transfer, was employed in the tunnel lining GHEs to build a thermally induced channel between absorber pipes and the surrounding rock, accelerating heat transfer between the absorber pipe and surrounding rock. The heat transfer model of the tunnel lining GHEs using TPCTs was built to analyze the thermal performance enhancement mechanism of tunnel lining GHEs using TPCTs for building cooling with different thermal conductivities of primary lining concrete and surrounding rock, and convective heat transfer coefficients (CHTCs) on tunnel internal walls. The results showed that throughout a 90-day operation, TPCTs dramatically boosted the heat injection rate of tunnel lining GHEs from 16.5 to 27.0 W/m2 with an increase of 63.6%. Thermal conductivities of the primary tunnel lining concrete have significant effects on the heat injection rates of the GHEs with TPCTs. The heat injection rates increased from 27.0 to 36.4 W/m2 as thermal conductivities of the concrete increased from 1.85 to 10.7 W/m K, and the enhancement rate ranged from 63.6% to 94.7% when compared to tunnel lining GHEs without TPCTs. The enhancement rate of tunnel lining GHEs with TPCTs decreased with increasing thermal conductivity of surrounding rock and CHTC, reaching up to 122.1% under the thermal conductivity of 1.4 W/m K and CHTC of 0 W/m2 K. Overall, TPCT greatly enhances the heat injection rate of tunnel lining GHEs, implying that it is a promising technology. [Display omitted] [ABSTRACT FROM AUTHOR]

The map of radiative cooling potential shows that the radiative cooling power can reach up to 100 W/m2 for its application in different climatic zones. However, the effect of building deployment on the city-scale application of radiative cooling is generally ignored in majority of existing studies, which overestimates the cooling benefit. This paper investigates the cooling benefit of implementing radiative cooling on a city-scale by considering building deployment. To determine the effect of building deployment on the radiative cooling potential, the city of Xi'an in China is modeled using COMSOL and verified with real weather data. Then, the thermal response of buildings with radiative cooling envelopes is discussed in detail. Finally, carbon emission reduction is derived at the city-scale by applying radiative cooling considering building deployment. The results show that the estimated radiative cooling power is approximately decreased by 14.7% for the ideal broadband surface and 47.1% for the ideal selective surface on the selected day by considering building deployment on a city-scale. Furthermore, carbon emission reductions of 0.52 gCO 2 /(m2⋅h) and 0.16 gCO 2 /(m2⋅h) can be achieved from the roof and walls on the selected day by applying radiative cooling material on both the roof and walls. This study can provide guiding significance for the large-scale application of radiative cooling in cities. [ABSTRACT FROM AUTHOR]

• Influence of heat sink temperature on PWM ejector and system performance is studied. • Influence of compressor speed and evaporator overfeeding is also studied. • PWM ejector with overfed evaporator shows COP increases up to 15.1% over basic unit. • PWM ejector shows COP enhancements up to 10.2% compared to passive ejector. • PWM ejector offers higher COP improvements than its currently available competitors. Ejector-equipped transcritical R744 condensing units are believed to lead to a low-to-zero commercial refrigeration sector. In order to overcome the persisting barrier to their wider adoption represented by the lack of an affordable ejector control technique, the novel pulse-width modulation (PWM) ejector, being low cost, simple and invulnerable to clogging was recently implemented. However, additional experimental evaluations are needed. Therefore, in this experimental work the performance of two PWM ejector-equipped transcritical R744 condensing units, i.e. with and without overfed evaporator, was carried out. The experimental assessment was implemented at the medium temperature (MT) of about -5 °C, heat sink temperatures from 30 °C to 40 °C and compressor speeds from 40 Hz to 60 Hz. The outcomes obtained revealed that the PWM ejector can effectively control the high pressure in transcritical operating conditions, regardless of the selected heat sink temperature and compressor speed. In addition, at the same cooling capacity, the PWM ejector-equipped R744 system was found to permit energy savings between 7.0% and 11.1% without overfed evaporator and between 11.5% and 16.3% with overfed evaporator compared to the standard R744 unit (i.e. with vapour by-pass valve and without ejector), respectively. Finally, higher values of coefficient of performance (COP) were found to be offered by the PWM ejector compared with its today's available competitors. [ABSTRACT FROM AUTHOR]

All-day passive radiative cooling is a promising cooling technique achieves cooling without any energy input, thereby attracting tremendous attention. Most of the studies focus on building applications, but there remains a lack of information on other potential applications of radiative cooling systems. Herein, we report an application of a polymeric passive radiative cooling coating (PRCC) on the exterior surface of chemical storage tanks, which is often overlooked but exhibits great potential to efficiently control the evaporative loss of the chemicals. The PRCC exhibits strong solar reflectivity (96.2%) and emissivity (95%) in the mid-infrared wavelength range. According to the results of an outdoor test on a small-scale chemical storage container, the PRCC achieves 81.4%, 54.1%, and 19.8% of chemicals saved compared with a raw container, container painted with commercial white paint (CWP), and the shaded raw container, respectively. A numerical simulation is also conducted to estimate the chemical standing loss from an industrial large-scale chemical storage tank. It is found that the PRCC can achieve a saving of over 50% of the chemical compared with commercial white paint for a chemical storage tank, showing a promising potential to be applied on chemical storage systems. • Excellent optical properties of spectral selectivity for radiative cooling. • Achieved all-day sub-ambient cooling on both clear and cloudy days. • Evaporation loss is investigated experimentally and numerically. • Over 50% of chemicals can be saved via the radiative cooling technology. [ABSTRACT FROM AUTHOR]

Passive radiative coolers can preserve the surface temperature below ambient by simultaneously reflecting incoming solar radiation and emitting thermal radiation to the sky. Apart from thermo-optical properties of the materials, radiative cooling performance is affected by various environmental factors which determine the atmospheric transmittance. As such, field investigations lack convergence and completion. And energy balance consideration, which aids in interpreting the field investigative results, is a deterministic cogitation on convective and radiative heat transfer by the radiative cooler that ignores the uncertainties abundant in field study. In this work, we examine the cooling performance of radiative cooling materials under different subtropical weather conditions in Hong Kong and approach the problem based on probabilistic regression modelling as an alternative. At nighttime, the response variable of surface temperature reduction can be correlated with a single predictor variable of sky temperature difference, which is a lumped parameter of ambient temperature, relative humidity, and cloud fraction. At daytime, it should be parametrized with an additional variable regarding solar intensity. The regression analysis reveals that, the higher the thermal emissivity, the larger is the temperature reduction at nighttime, especially obvious for large sky temperature difference. And heavy solar heat load is absorbed by the coolers at daytime even they feature reasonably high solar reflectivity. In this regard, further increment in solar reflectivity poses the top priority in improving daytime radiative cooling performance. [ABSTRACT FROM AUTHOR]

• TiO 2 -PVDF fiber film has the hierarchical structure as sky radiative cooling material. • TiO 2 -PVDF fiber are prepared by the polymer assisted electrospinning technique. • The TiO 2 -PVDF fiber film possesses high solar reflectivity of 99.01% (Vis band), 97.20% (NIR band) and high emissivity of 89.91% in atmospheric window. • In the outdoor testing, the maximum sub-ambient cooling temperature of 6.9℃ under sunlight, and 4.4 ℃ at night are achieved. Radiative sky cooling is a passive cooling method without consuming any additional energy. Here, we propose a kind of hierarchically structural and particle-enhanced TiO 2 -PVDF fiber film as the radiative sky cooling material. TiO 2 -PVDF fibers are prepared by the polymer assisted electrospinning technique. The hierarchical structure encompasses polymer fibers, inorganic enhanced particles and pores formed by interlacing fibers. In this work, the effect of TiO 2 adding on the morphology, structure and spectral performance of hierarchically structural fiber film are discussed. By introducing the inorganic TiO 2 particles with high refractive index into polymer fiber matrix, the refractive index difference among the hierarchical structure can increase the scattering and solar reflectance, and phonon polariton resonance will increase the infrared emission. The obtained TiO 2 -PVDF fiber film possesses the optimal high solar reflectivity of 99.01% (Vis band), 97.20% (NIR band) and infrared emissivity of 89.91% within the atmospheric window band. In outdoor testing in Wuhan (temperate climate) during October, the maximum sub-ambient cooling temperature under sunlight can reach 6.9℃, and 4.4℃ at night. Thus, this TiO 2 -PVDF fiber film can become a promising all-day cooling and energy saving material. Furthermore, it can be used in the more cooling and thermal management fields to greatly improve the comfortability of people's living and life. [ABSTRACT FROM AUTHOR]

This paper presents a promising solution to superheat of stratospheric airship with radiative cooling envelope, which has no change in pneumatic profile, structural weight, and power consumption. In this study, a multilayer nanoparticle-polymer metamaterial (MNPM) is hierarchically designed to provide reflectivity across visible wavelength and emissivity in atmospheric window. In this paper, the specimens and ball models are firstly fabricated, the cooling performances of which are tested for ground experiments. The temperatures of MNPM and silica/Ag specimens are 6.7 °C and 10.8 °C at noon in Tianjin. The inner gas and surface temperatures of MNPM scale ball are 11.7 °C and 14.6 °C, lower than silica/Ag by 4.5 °C and 4.6 °C, respectively. Subsequently, the flight experiments verify the cooling performance of MNPM, the maximum temperature of which is lower than the control group by 15.4 °C in stratosphere. Finally, the FLUENT simulations illustrate the cooling performance of stratospheric balloon and airship equipped with solar panel. The MNPM has a better cooling capacity for the internal helium and top surface throughout the day and a weak warming capacity for the bottom surface at night. Considering solar panels, the MNPM reduces the helium temperature by 8.1 °C, and the day-night superheat of the helium temperature is only 19.8 °C. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess effects on milk yield (MY), rumen temperature, and panting score when lactating dairy cows were cooled during the day only or during the day and night. The study was conducted over 106 d during using 120 multiparous Holstein-Friesian cows assigned to 2 treatments (60 cows/treatment; 2 pens/treatment): (1) day cooling (DC): overhead sprinklers (large droplet) and fans while in the dairy holding yard only, shade and fans at the feedpad, and a shaded loafing area; and (2) enhanced day+night cooling (EDN): overhead sprinklers (large droplet) and fans in dairy holding yard, ducted air blowing onto cows during milking, plus thorough wetting (shower array) on exit from dairy; shade and fans at feedpad (turned off at night); and shaded loafing area + ducted fan-forced air blowing onto cows at night. The ducted air at night was manually activated at 2030 h when the maximum daily temperature-humidity index exceeded 75 and remained on until 0430 h the next day. The cows were fed a total mixed ration ad libitum, and feed intake was determined on a pen basis. Rumen temperature and cow activity were obtained from each cow at 10-min intervals via rumen boluses. Panting scores were obtained by direct observation 4 times a day at approximately 0430, 0930, 1530, and 2030 h. Cows were milked twice daily: 0500 to 0600 h and 1600 to 1700 h. Individual MY were obtained at each milking and combined to give individual daily totals. The EDN cows had greater daily MY (+2.05 kg/cow per day) over the duration of the study compared with DC cows. Rumen temperature during the third heat wave was lower for EDN (39.51 ± 0.01°C) than for DC (39.66 ± 0.01°C) cows. During the most severe heat wave (heat wave 3), MY for the 2 groups was similar, but over the 6 d following the heat wave, EDN cows had greater daily MY (+3.61 kg/cow per day). Rumen temperature was lower for EDN (39.58 ± 0.01°C) than for DC (40.10 ± 0.01°C) cows. [ABSTRACT FROM AUTHOR]

The thermal load of the cutting tool is an important process state parameter that directly influences tool wear and thus the dimensional accuracy of the workpiece. Due to limited accessibility and sensor configuration, it is difficult to monitor tool temperature during the machining process, hence cutting parameters cannot be optimally adjusted to the thermal loads. In order to solve this problem, analytical models of tool temperature are increasingly applied in practice. So far, the available temperature models only consider dry process conditions, and the effects of convective cooling in non-continuous heat sources have not been addressed. Therefore, a new 3D temperature model for cutting tools that incorporates the cooling effect is proposed in this work. This model has a simple expression and is easy to solve. To evaluate the applicability of the model, orthogonal cutting tests were performed under both dry conditions and with high-pressure cutting fluid supply. The accuracy of the model for temperature prediction has been demonstrated by comparing the experimental and simulated temperature distributions. In addition, the thermal properties of the tool material on the temperature development were also analyzed. [ABSTRACT FROM AUTHOR]

• A novel structure for the active pressure management of a storage tank is proposed. • The evolutions of temperature and flow during the whole process are illustrated. • A heat-pipe-like and a redistributor work mode are uncovered in different zones. Inevitable evaporation process occurring in liquid hydrogen storage may bring about safety risks associated with over-pressure and hydrogen discharge. Using a cryogenic refrigerator to compensate for the heat leakage is expected to eliminate the risk of hydrogen vent, realizing long-term lossless storage. Presently, active lossless storage technology applied on civil fields has rarely been studied. This paper presents a numerical study on the dynamic evolution process within an active cooling system of a liquid hydrogen tank. The accuracy of the model is validated with an average deviation of 0.47%. During the self-pressurized process, the maximum temperature difference is more than 26 K in the ullage zone. After cooling capacity being introduced, a three-stage depressurization process appears. Minor cooling capacity that is less than heat leakage can still realize pressure management. Further analyses show two operating modes similar to gravity heat pipes and thermal redistributors occurring in the ullage and the liquid zone, respectively. This work suggests the effectiveness of active cooling on controlling the ullage pressure, which may be applicable to future hydrogen refueling stations and intercity hydrogen transportation. [ABSTRACT FROM AUTHOR]

The requirement to reject heat within a small envelope has stunted the development and deployment of high heat flux applications. Thermochemical cooling is a new innovative approach, inspired by engine cooling in aircraft. In aircraft, sensible heat is often rejected to the fuel, without altering its chemical composition, and dissipated through the wings. However, sensible heat absorption is limited to 431 kJ/kg for JP8. Using endothermic reactions, JP8 can absorb as much as 11,688 kJ/kg of heat when converted to hydrogen, carbon monoxide, and other gases. A common refrigerant, such as R134A has an enthalpy of vaporization of 209 kJ/kg. However, after evaluating multiple fuels and reforming literature, it was determined that optimum lower temperature performance could be achieved with a methanol water mixture. This endothermic reaction is a strong candidate for heat absorption. Preliminary test data demonstrated heat absorption as low as 300 °C, with peak absorption at 400 °C. At its peak (R = 400 °C), the reactor is capable of absorbing 3411 kJ/kg. Future efforts will evaluate the use of JP8, which has a larger endothermic reaction potential. • Cooling using endothermic steam reforming technology. • System was able to absorb up to 3411 kJ/kg of heat at peak performance. • Lower temperature conversion promoted greater heat absorption. • Higher temperatures promoted methane formation which suppressed heat absorption. [ABSTRACT FROM AUTHOR]

In the current study, a renewable system with two potential wind and solar energies for electricity production, cooling, and heating has been investigated. The proposed system included reverse osmosis, heat pumps, fuel cell subsystems, wind turbines, photovoltaic/thermal panel units, battery storage, and a hydrogen storage tank. Given Iran's high potential for renewable energy, a performance analysis of six cities, Esfahan, Zanjan, Bandar Anzali, Ahvaz, Bandar Abbas, and Tabriz was done to determine where the proposed power plant should be located. Six decision factors were analyzed for system performance: solar panel angle, solar panel count, wind turbine count, cooling capacity, heating capacity, and fuel cell power. The findings demonstrate that the number of solar panels, wind turbines, and fuel cells significantly influences power, fuel consumption, and system costs. Finally, the outcomes were analyzed by the Response surface method to choose the best system that can satisfy the demand for residential units for one year. To evaluate the effectiveness of the suggested method, a 100-unit apartment building with a 196-square-meter floor space was considered. The results also showed that the combination of hydrogen units and battery storage reduced variations in supply and demand and correctly stabilized the stored energy during a drop in output. The suggested system has a life cycle cost of 674278.4$/h and the capacity to generate 225694.8 kWh of surplus power for residential units with a thermal comfort index. According to the optimization results, the system's optimal panel count was 106, the optimal angle was 26°, the optimal fuel cell power was 65.6 kW, the ideal wind turbine count was 24, the ideal heating capacity was 20.2 kW, and the optimal cooling capacity was 48.7 kW. [ABSTRACT FROM AUTHOR]

[Display omitted] • High thermal emissivity of 0.95 and a sunlight reflectivity of 93%. • Temperature drop of 18.0 °C under direct solar irradiation is achieved. • Outstanding cooling performance even when stretching to 450%. • A model to link sunlight reflection with the microstructure is built. Passive radiative cooling materials (PRCMs) has arose widespread concern with the advantage of cooling a surface by radiating heat to the cold outer space and reflecting sunlight. However, the cooling effect sharply deteriorated in the stretching state. Besides, widespread reflectivity within visible light (VIS) and near-infrared (NIR) range remained a huge challenge for the structure design. Herein, we proposed a porous thermoplastic urethanes (TPU) membrane with a high thermal emissivity of 95% and a sunlight reflectivity of 93%. Abundant hierarchical pores with submicro and micro sizes generate when the solvent of the TPU sol is exchanged by water, which tremendously strengthens the sunlight-reflecting behavior of the porous TPU membrane, especially in the NIR region. By covering the porous TPU membrane on the top, the temperature of the substrate, model house, and hood of the car cool up to 8.8, 16.3, and 18.0 °C, respectively, compared to the bare state. Moreover, the porous TPU membrane shows outstanding elastic cooling properties that the damage of IR emissivity and sunlight reflectivity was minimal even in a tensile strain of 450%. [ABSTRACT FROM AUTHOR]

• A heat and mass transfer model of droplet for artificial snow-making was established. • The critical droplet size for artificial snow-making under different environments was obtained. • The relationship between gas-liquid mass mixing ratio and snow-making density was studied, and the optimal gas-liquid mass mixing ratio suitable for artificial snow-making was obtained. This study investigates the heat and mass transfer of liquid droplets freezing in the process of artificial snow-making, and emphatically analyses the effects of droplet size, ambient temperature and relative humidity on the evaporative cooling and freezing of liquid droplets by establishing a theoretical model. On this basis, the critical droplet size for snow-making under different environmental conditions is obtained, and the accuracy of the droplet freezing model was verified by artificial snow-making experiments. Finally, by analyzing the density of artificial snow under different environmental conditions, the optimum gas-liquid mixing mass ratio (GLR) suitable for snow-making is obtained. The results show that the liquid droplets could be frozen under the action of self-evaporation and convection heat transfer with ambient. The time required for the droplet to be frozen completely shows a positive correlation with ambient temperature, relative humidity and droplet size. In the evaporation cooling stage, the droplet cooling rate increases with the decrease of ambient temperature, and in the phase transition stage, the time for the droplet resists the latent heat of phase transition increases with the increase of the droplet size. When the droplet size is smaller than the critical size for snow-making, the artificial snow can be achieved at a maximum temperature of 3 °C. The snow density decreases with the increase of GLR. And when the GLR is greater than 0.15, the snow density tends to be stable. [ABSTRACT FROM AUTHOR]

• Developing a novel scalable polymer-based radiative cooling coating. • Manufacturing process of aqueous coatings without volatile organic compounds emission. • Excellent cooling capability of achieving sub-ambient temperatures in high humidity region. • In-depth evaluation on the cooling power of the developed cooling paints in a variety of cities. Passive daytime radiative cooling (PDRC) is an emerging technology that dissipates heat from terrestrial objects to the cold universe directly via the atmospheric transparency window. Along with the advancement of PDRC materials, fabrication methods by precision lithography or phase change chemistry are no longer a preferred option due to the concomitant hazardous organic solvents. Instead, it is desirable to develop radiative coolers by aqueous processing-based and cost-effective methods so as to promote their mass production and applications. Herein, we report a new scalable polymer-based aqueous paint without volatile organic compounds (VOCs) emission. By using the simple mechanical agitation-based synthetic method with mixing polymer emulsion as the matrix and glass beads as the functional additive, the cooling paint exhibits an average infrared emissivity of 92% and a solar reflectivity of 94%. A detailed field experiment was conducted in sub-tropical climates to verify the practical cooling performance of the developed cooling paint, and the experimental results showed that the achievable sub-ambient cooling temperature was up to 6 °C under high humidity conditions without any solar shading or convection cover. Meanwhile, in-depth evaluation on the cooling power of the developed cooling paints in a variety of cities was conducted, which shows its wide application potential in building roof across varying climate regions. [ABSTRACT FROM AUTHOR]

AZ31 Mg alloy with heterogeneous bimodal grain structure (smaller grain size of 5–20 µm and coarser grain size of 100–200 µm) was subjected to accumulated extrusion bonding (AEB) at 250 ℃ combined with two-stage artificial cooling in this work, viz. local water cooling and artificial cooling. The microstructure developed consecutively as a result of discontinuous dynamic recrystallization (DDRX) for the AEBed samples. {10–12} tensile twinning also played an important role for the AEB with local water cooling at the initial extrusion stage in the container. Local water cooling could further reduce the DRXed grain size to ∼2.1 µm comparing that without water cooling. And the grain growth rate was reduced by artificial cooling out of extrusion die. Under the combination of two-stage cooling, the fine DRXed grains at sizing band were almost retained with average grain size of ∼2.3 µm after the sheet out of extrusion die, and the unDRXed grains with high residual dislocation density accumulation were also reserved. The tensile tests results indicated that a good strength-ductility balance with a high ultimate tensile strength (319 MPa vs. 412 MPa) and fracture elongation (19.9% vs. 30.3%) were obtained. The strength enhancement was mainly owing to the grain refinement and local residual plastic strain reserved by the artificial cooling. The excellent ductility originated from fine DRXed microstructure and ED-tilt double peak texture. [ABSTRACT FROM AUTHOR]

[Display omitted] • The decrease in liquid fraction determines the slag's electrical conductivity (EC). • The slag's EC during cooling can be well described by the empirical Archie's model. • An online assessment of slag solidification by in-situ EC measurement. • A theoretical basis for the development of industrial online monitoring technology. Large volumes of steel slag are produced annually, leading to significant environmental protection and sustainable development issues. An online technology to monitor the solidification process of steel slag can assist in obtaining the right mineralogy to valorize these slags or render them harmless. For this purpose, we investigated the electrical properties and microstructural relationships of a CaO-Al 2 O 3 -SiO 2 -MgO (CASM) slag during cooling using an innovative setup. The electrical impedance was determined over the frequency range of 20 Hz to 300 kHz at two cooling rates, and the solidification behaviour was observed simultaneously by confocal scanning laser microscopy (CSLM). Four zones can be distinguished in the conductivity-temperature curves for the slag cooled at 10 °C/min, whereas only two distinct zones are visible at 100 °C/min. The liquid fraction of the slag has a significant impact on the slag conductivity during cooling. The electrical conductivity is, therefore, an accurate indicator of the solidification degree. Different theoretical and empirical models were evaluated on their ability to relate the bulk conductivity of the slag to the liquid fraction. The empirical Archie's model proved to be the most suitable model for relating the bulk conductivity of the slag to the liquid fraction. In-situ electrical conductivity measurements during cooling can provide an online assessment of the slag solidification process, including indicating the appearance of solid precipitates, monitoring the growth of crystals, indicating complete solidification when no liquid phase remains, and indicating the cooling rate. [ABSTRACT FROM AUTHOR]

In this study, not only conventional and advanced exergies, but also advanced exergoeconomic, extended exergy and combined extended-advanced exergy analyses are firstly applied to the novel ejector-based CO 2 transcritical Combined Cooling, Heating and Power (CCHP) system powered by geothermal energy. It is found that the evaporator and domestic water heater (DWH) components should be focused to increase system efficiency. For the vapor generator (VG), evaporator (EV) and DWH, avoidable exergy destruction rates are found as 26.334 kW, 0.323 kW and 8.288 kW, while their unavoidable exergy destruction rates are 11.206 kW, 0.276 kW and 1.410 kW, respectively. The extended avoidable exergy destruction rates are determined as 89.068 kW, 5.174 kW and 12.385 kW, while their unavoidable exergy destruction rates are 36.846 kW, 3.079 kW and 1.992 kW for the VG, EV and DWH, respectively. Improvement potential of VG, EV and DWH are endogenous, it means they should be focused on these components themselves. DWH is strongly connected to condenser which has important role on exergy destructions of it and condenser should be focused on improving DWH. According to mexogenous exergy destruction results, the condenser's exergy destruction is equal to −0.468, which means DWH's exergy destruction can be reduced. [ABSTRACT FROM AUTHOR]

• Augmented performance of solar still was evaluated via integrating evaporation and condensation enhancers. • Synthetic nanocomposites were developed, characterized, and used with different concentrations. • Thermo-economic performance was investigated compared to conventional solar still. • Productivity, energy efficiency, and average exergy efficiency augmentations reached 113.72, 96, and 167.62 %, respectively. This work aimed to develop the thermo-economic performance of solar still (SS) via various additives. On the one hand, to improve the thermophysical properties of the basin saline water, two nanocomposites were utilized in the modified SSs (MSSs). In MSS1, chitosan @ graphene oxide (Cs@GO) was used, whereas chitosan @ nickel oxide (Cs@NiO), was provided in MSS2. The concentration influence on the yield was investigated considering three ratios (0.1, 0.2, and 0.3 wt%). The selected concentration (0.3 wt%) was used for the upcoming cases being better than others. At this weight ratio, the yield was augmented by 72.7, and 57.5 % for MSS1, and MSS2, respectively, compared to CSS. In the first case (Case I), a glass lid cooling unit was attached to the MSSs to boost the condensation rate. In the second case (Case II), top and bottom external reflectors were fixed on the MSSs. Then, Case III contained both cover cooling and reflectors. In addition to these enhancers, ultrasonic atomizers were placed on the basin of MSSs in Case IV. In each experiment, both MSS1 and MSS2 were simultaneously compared to conventional SS (CSS). All cases showed good thermo-economic performances. The best performance was obtained, especially in terms of yield, from MSS1 in Case IV, at which the production, energy, and exergy efficiencies were improved by 113.72, 96, and 167.62 %, respectively. [ABSTRACT FROM AUTHOR]

Water flooding causes severe degradation of the performance and lifetime of proton exchange membrane fuel cell (PEMFC). In this study, a novel PEMFC stack with in-built moisture coil cooling was designed and the effects of moisture coil cooling on water management in the new PEMFC stack under various operating conditions were investigated. The result showed that the performance of the PEMFC stack was significantly improved due to the moisture condensation under high current density, high operating temperature, high relative humidity and high operating pressure. The output power was increases by 21.62% (525.71 W) at 1600·mA cm−2 while the increased parasitic power was no more than 35W. Moreover, degradation of the cathode catalyst layer after 100 h operation was also reduced by using moisture coil cooling. Compared with the situation without moisture condensation, the maximum decay rate of the cathode catalyst layer thickness after 100 h operation was reduced by 13.01%. Accordingly, the novel design is valuable and can be widely used in the future design of PEMFC. Sketch of moisture condensation. [Display omitted] • An innovative PEMFC stack with in-built moisture coil cooling is designed. • Performance of every single fuel cell in the stack is greatly improved. • The performance is increased by 490.71 W at 1.6A·cm−2. • The performance degradation after 100 h is reduced by moisture coil cooling. [ABSTRACT FROM AUTHOR]

A three-dimensional simulation of the rotating detonation engine (RDE) with film cooling is conducted. The aim of this study is to analyze the fluid dynamics and heat transfer of the detonation flow field under the influence of cooling flow from the film holes. Results suggest that when the rotating detonation wave sweeps the film holes, the shape of the wave structure will deform, and the detonation products will invade and block the outflow from the film holes; however, this only occurs temporarily. The structure of the detonation wave will quickly restore to its stable form and, meanwhile, the cooling flow also recovers rapidly and provides adequate protected area on the wall surface and effective thermal protection time in a full propagation cycle of the detonation wave. A parametric analysis indicates that the effective outflow time improves with the increase of the mass flow rate of the cooling flow; on the other hand, the cooling efficiency is more significant downstream from the inlet of the combustor to the outlet. In addition, the thrust and specific impulse of the RDE are also examined under the influence of film cooling. • Film cooling is implemented in rotating detonation engines for thermal protection. • The self-sustained rotating detonation wave (RDW) can be achieved with film cooling at various working conditions. • The film cooling effectiveness and interactions between the RDW and cooling flows are analyzed. [ABSTRACT FROM AUTHOR]

Harvesting energy from the hot sun and the cold universe is being investigated and has attracted much attention due to its clean utilization. Herein, a broadband selective absorber/emitter (BS-A/E) is designed and fabricated for the hybrid utilization of diurnal solar thermal and nocturnal radiative cooling. The BS-A/E exhibits high photon absorption in the solar band (i.e., 0.3–3 μm) with a weighted solar absorption of ∼0.83, a strong thermal emission mainly within the atmospheric window (i.e., 8–13 μm), and a low thermal emissivity in other infrared wavelength bands. The outdoor experiment demonstrates that the stagnation temperature of the BS-A/E is 11.6 °C greater than black paint under sunshine and 0.6 °C lower than that of black paint under darkness, showing considerable solar thermal and radiative cooling performance. In addition, thermal prediction also reveals that the BS-A/E can not only achieve solar heating during the day but also obtain sub-ambient cooling phenomenon during the night, indicating that the BS-A/E is capable of providing continuous heating and cooling for humans in various potential applications, such as all-day thermoelectric power generation and thermal storage-based space heating/cooling. [ABSTRACT FROM AUTHOR]