With the development of thermal management needs and technologies, flexible inorganic composite phase change materials have attracted the attention of researchers in the fields of battery thermal management. In this paper, based on the melt mixing method, the composite flexible phase change material S(1) was obtained on spandex cloth (SF), and the cesium-tungsten bronze (CsxWO3) particle coating was used to composite with it, and the flexible and improved sodium acetate/sodium hydrogen phosphate dibasic composite phase change material — functional fabric (FCPCM) was obtained. The structure, physical and chemical composition, thermal properties, stability, and normal temperature properties of S(1-5), S(1)-SF and FCPCM were systematically studied. S(1) had the highest enthalpy of phase change of 109.9 J/g, and the temperature point of phase change was 33.3 °C. The thermal conductivity of S(1)-SF was 0.401 W/(m·K), which decreased to 0.298 W/(m·K) when the surface was covered with CsxWO3. Compared with untreated SF, FCPCM has significant thermal management capability and thermal cycling performance. The thermal management system of lithium battery based on FCPCM provides a way for the in-depth application of flexible composite phase change materials in the future.

Abstract Well layout configuration is critical for gas hydrate production as it dictates pressure spreads and dissociation front propagation. This study conducted numerical simulations for single-well, two-well, and several multi-well layouts. Gas production rate, water production rate, and volume ratio of gas to water were calculated to describe production behavior based on the geological conditions of the SH7 site in the Shenhu Area, northern South China Sea, to investigate multi-well development dynamics. A synergistic effect coefficient (Sec) was introduced to quantify the production enhancement per well in multi-well systems. Results demonstrate that while increasing well count enhances total recovery, the gains are inherently nonproportional, revealing a distinct synergistic effect limitation. Well layout and spacing significantly control performance; specifically, the ring layout and larger well spacing outperforms others by establishing a more homogenized pressure distribution. Mechanistic analysis reveals that while inter-well pressure superposition expands the effective dissociation region, the increasing competition among flow pathways and phase redistribution progressively constrain further enhancement. These coupled processes govern the nonproportional evolution of synergistic effects. These findings provide a mechanistic basis for optimizing well spacing and architecture in large-scale hydrate commercialization.

Food waste (FW) is a challenging biowaste with high moisture content, complicated composition, and low calorific value. Hydrothermal conversion (HTC) emerges as a promising way to mimic the natural formation of humic acids (HAs) from FW. However, the incomplete biowaste conversion in the conventional single-stage processes often results in the low HAs yield. To address this challenge, stepwise thermal hydrolysis and HTC were proposed to promote the staged transformation of biowaste components. The influence of temperature and feedwater pH in hydrolysis stage, as well as the slurry mixture pH in HTC stage on HAs formation was examined. Results show that both alkaline and acidic environment favors the hydrolysis of FW. So does the high hydrolysis temperature. However, the optimal hydrolysis temperature is determined as 150°C in terms of HAs yield. The maximum HAs yield reaches 33.8% by acidic hydrolysis and alkaline HTC. The formed HAs has a lower aromatization degree and higher relative molecular weight than the commercial HAs. A positive correlation between HAs yield and total phenolic compounds (0.71) and soluble protein (0.88) is observed. The fluorescent components of C1, C2, and C3 in hydrolysis stage are associated with the HAs formation in alkaline HTC stage. This study provides an alternative way to enhance HAs formation from FW.

The flexible substrates with high activity are limitedly utilized for the Surface Enhanced Raman Spectroscopy (SERS) detection of Aflatoxin B1 (AFB1) due to their complex and uncontrollable synthesis. Here, a multistep temperature synthetic strategy is innovatively proposed to facilely and controllably synthesize Ag nanowires loaded on the flexible polyethylene terephthalate nonwoven fabric surface (i.e., Ag NWs@PET). The above strategy can effectively promote the generation and the anisotropic growth of small-sized Ag seeds and thus ensure the uniformity of obtained Ag NWs, providing a valuable reference for the formation of other metal nanowires. Furthermore, Ag NWs@PET is employed as active substrates for the SERS detection of the AFB1 in corns. Ag NWs@PET exhibits superior sensitivity, mechanical stability, reproducibility, and long-term stability. Noteworthy, by means of Ag NWs@PET, the quantitative detection of AFB1 ranged from 10_8 to 10_13 M can be rapidly achieved. Clearly, as-obtained flexible Ag NWs@PET as a promising SERS substrate can pave the way for the expended implications of the SERS detection in food safety.

This study examines the cool storage performance of the R1234yf hydrate system via an integrated experimental and simulation approach. Experimental results show that the system's cool storage performance is improved at elevated charging pressures or reduced initial water temperatures. At the maximum charging pressure of 260 kPa and the minimum initial water temperature of 19 degrees C, the system attained optimal performance, with the total cool storage capacity reaching a maximum of 883 kJ and the average cool storage rate peaking at 0.44 kW. Simulations conducted under the above optimal conditions indicated that an increase in compressor suction superheat from 2 K to 10 K improved the system coefficient of performance (COP) by 2 % and the cool storage capacity by 5 %. An increase in condenser outlet subcooling from 1 K to 5 K led to a 4 % improvement in the system COP and a 42 % rise in the cool storage capacity. Elevating the isentropic efficiency of the compressor from 0.65 to 0.85 enhanced the system COP by 19 %, while the cool storage capacity remained unchanged.

Ice slurry, a promising phase-change fluid for thermal energy storage and transport, exhibits complex flow and melting behaviors that are not fully captured by existing numerical models. A coupled Eulerian-Lagrangian framework is presented to calculate ice slurry phase change in a heat exchanger. This modelling framework comprehensively integrates three heat transfer mechanisms: (i) particle-fluid convective heat transfer, (ii) direct conductive particle-wall contact heat transfer, and (iii) liquid film conduction for particle-fluid-wall thermal exchange. Results show that liquid film conduction contributes 60 similar to 82% of the total heat transfer rate, while particle-fluid convection accounts for 18 similar to 40%, and direct particle-wall contact heat transfer is negligible (<1%). The minimum conduction distance significantly influences melting efficiency, with a reduction from 10(-6) m to 10(-12) m increasing total heat transfer by up to 338 W at a wall temperature of 303.15 K. Axial analysis reveals three distinct melting regimes: uniform, stratified development, and stable melting. This work provides a comprehensive and particle-resolved framework for optimizing ice slurry-based heat exchangers.

Circulating hydrothermal carbonization (HTC) has emerged as a sustainable way for enhancing the formation of humic acids (HAs) and mitigating the concerns of process water (PW) treatment. However, the accumulation of alkali and alkaline earth metals (AAEMs) in PW occurs synchronously. Herein, the influence of AAEMs valence state and concentration on HAs formation was examined. The accumulation of divalent AAEMs in PW significantly increases the hydrochar (HC) yield, while all AAEMs enhance the HAs yield. Among them, Na+ shows the best promotion effect on HAs yield of 9.22%. FTIR analysis shows that the monovalent AAEMs at 1 g L-1 promote the retention of aliphatic structures in HAs, while the aromatic C=C intensity reduces slightly. More aliphatic and aromatic structure in HAs is observed by divalent AAEMs at 10 g L-1. The divalent AAEMs cause a slight blue shift of HAs in 3D EEM, indicating lower aromatic condensation and molecular weight. Parallel factor analysis suggests that the accumulation of Ca in PW decreases the fluorescence intensity of HAs, further causing a shift from high aromatic and large molecular Component 1 to Component 2 with less condensed and more oxygenated fluorophores, indicating lower aromaticity and degree of condensation. This study provides a theoretical insight into the influence of AAEMs in PW on HA formation in the circulating HTC.

Deep cryogenic temperatures were widely applied in various fields such as biomedicine, aerospace, and fundamental physics research. The Auto-cascade Refrigeration Cycle was one of the primary methods for achieving temperature requirements ranging from-40 degrees C to-180 degrees C. However, with the implementation of environmental agreements, the use of refrigerants with lower Global Warming Potential had become a trend in refrigeration system development. To investigate the impact of low-GWP mixed refrigerants on ARC system performance, this paper focused on a typical three-stage self-refrigerating cascade system, selected R600a, R1150, and R50 as refrigerants, analyzed the impact of Hydrocarbons(HCs) mixed refrigerant ratios on evaporation temperature, system refrigeration capacity, COP, and other ARC performance, and compared the characteristics with the ARC system using R600a/R23/R14 mixed refrigerants. The results showed that the mixed refrigerants R600a/R1150/R50 had an optimal mass fraction in the ARC; that is, when the ratio of R600a, R1150, and R50 was 73/15/12, the evaporation temperature was lowest at-125.3 degrees C, and the COP was relatively high at 0.15. The change in the mass fraction of R50 has a greater impact on ARC. A 9 % increase in mass fraction results in a 17 % increase in ARC cooling capacity, but only an 9 % decrease in COP to 2.5 %. The discharge temperature of HCS systems is 15 % higher than that of R600a/R23/R14 systems, but the GWP of HCs is 99.6 % lower than that of the latter. The use of HCs reduces set-up costs(SET) by more than 90 % and reduces carbon emissions by more than 47 %.

Hydrogen holds a prominent place in the future energy structure due to its high energy density, environmental friendliness, and wide range of production pathways. However, the optimal hydrogen storage and transportation method have not been discovered. Hydrate-based hydrogen storage technology has gained substantial attention owing to its advantages of safety, nonpollution, and easy release. Molecular dynamics (MD) simulation is a vital approach for exploring its underlying mechanisms. Based on MD simulation techniques, we can monitor the process of hydrate nucleation and growth at the molecular level. Here, we systematically reviewed the existing studies on hydrogen hydrate formation from a microscopic perspective. We initially explore the microstructure, basic properties, and phase equilibrium characteristics of hydrogen hydrates. Subsequently, we summarize the research progress in pure hydrogen systems and hydrogen-additive binary systems. In addition, we illustrate various key factors affecting the formation of hydrogen hydrates, including cage occupancy ratio, guest concentration, and diffusion. Based on these findings, the development of hydrogen storage technology in the MD simulation area has been further summarized. Furthermore, the hydrogen storage density, hydrogen storage rate and nano confinement effect under different systems have been presented. According to the recent study, the restrictions and future directions of MD simulation on hydrogen hydrates are discussed. This review provides theoretical guidance and insights for the future development of hydrate-based hydrogen storage technology.

Exploring the phase change heat transfer characteristics of sucrose ice slurry in brazed plate heat exchangers is crucial for energy-saving applications in ecologically sensitive industries such as food cold chain. The effects of ice packing factor (0-12 %), particle size (0.35-2.36 mm) and hot water inlet temperature (10-35 degrees C) on pressure drop, heat transfer coefficient, entropy generation, pump power and cooling load were investigated. The results showed that the cooling load of sucrose ice slurry was 7.12-22.16 % higher than that of chilled water, and the pump power was 1.06-1.63 times higher than that of chilled water when inlet water temperture is 30 degrees C. When the ice packing factor is more than 7 %, the latent heat accounts for more than 61 %, which becomes the dominant mechanism. When the particle size is greater than 1.83 mm, the pressure drop increases by 43 %, and it is necessary to avoid particle blockage. Frictional entropy dominates irreversibility at high Reynolds number, while hot entropy is insensitive to IPF. Under low temperature conditions (<25 degrees C), it shows the potential of heat transfer enhancement, and as the temperature decreases, the performance index further increases. The experimental results are helpful to develop the potential application value of sucrose ice slurry in the food cold chain.

With global warming and the depletion of fossil fuels, electric vehicles have emerged. Although their carbon dioxide heat pump systems are environmentally friendly, they face the problem of frosting on outdoor heat exchangers. Previous studies have mainly focused on the internal factors of heat exchangers or specific operating conditions, with limited exploration of frosting behavior in electric vehicles under complex operating conditions, especially in supercritical high-pressure environments of carbon dioxide electric vehicles. This study builds an experimental platform for a carbon dioxide electric vehicle heat pump system, using an infrared thermal imager to capture accurate data on outdoor heat exchanger temperature and frost development. Different environmental temperatures and compressor speeds are set at high humidity levels of 85-95% to study the distribution of frost layer growth in outdoor heat exchangers under different operating conditions. The study also introduced FCR to analyze the changes in heat pump performance parameters in different FCR regions. Finally, under the same environmental temperature, humidity, and speed conditions, the frosting characteristics of R744 and R134a heat pump systems were compared, and the impact of frosting on them was analyzed. The results indicate that in high humidity environments, lower ambient temperatures and higher rotational speeds increase frost coverage. When FCR exceeds 40%, the suction pressure of the compressor significantly decreases, the heating capacity of the system decreases by 26.01% to 31.08%, and the COP decreases by 21.59% to 29.69%. Regardless of the compressor speed, the COP decreases by about 21% after frosting. Under similar conditions, R134a heat exchanger has more severe frosting than R744, which has a greater impact on the suction pressure of R134a compressor. However, frosting reduces the heating capacity of both systems by about 30%.

In this study, a prospective strategy on seed-mediated growth in vacuum is provided and used to prepare flexible silver nanofilms (AC0-3 NFs) with high purity, crystallinity and SERS performance. Noteworthy, AC2 NFs surface is uniformly covered with silver nanoparticles (Ag NPs), following the appearance of numerous nano-gaps between Ag NPs. Through the finite-difference time-domain (FDTD) simulation, it is found that the ultra-small nano-gaps less than 5 nm can generate abundant "hot spots" to amplify the Raman signal. Therefore, the above AC2 NFs as SERS substrates exhibit superior activity for the SERS detection of thiram in tomato juice, with the limit of detection (LOD) of 10- 15 M and the enhancement factor (EF) of 3.7 x 1011. Meanwhile, AC2 NFs show outstanding reproducibility and stability during the SERS detection. Additionally, the calibration curve is established, by which the thiram (10- 7 to 10- 15 M) can be quantitatively detected. Clearly, the as-prepared flexible AC2 NFs have great potential in the SERS detection and analysis.

Falling film evaporators are widely used in the refrigeration and air conditioning industries. However, uneven liquid-film distribution and dry-out issues have long posed critical challenges and bottlenecks to their development. Therefore, this study proposed a spray compensation method that utilises an atomising nozzle to redistribute the unevaporated refrigerant on the surface effectively. In order to test the performance, a visual experimental setup was established to evaluate the flow and heat-transfer characteristics associated with this method. The results indicated that spray compensation effectively improved the working fluid velocity and enhanced the disturbance of the working fluid. Even during dry-out, spray compensation could fill the liquid film, maintaining a coverage rate of over 70 %. Moreover, it was demonstrated that spray compensation significantly enhanced the heat-transfer performance of the test tube, with the average heat-transfer coefficient increasing by a factor of 2.73 compared to the state without spray compensation. Notably, pronounced enhancement was observed in the circumferential position from 120 degrees to 240 degrees, where the local enhancement ratio at 180 degrees was as high as 5.73. These findings suggest that spray compensation can effectively alleviate heat-transfer deterioration caused by dry-out, indicating considerable potential for practical applications in falling film evaporators.

Vapor injection technology represents a highly promising avenue for enhancing the efficiency of heat pump systems within electric vehicles, especially in challenging cold ambient conditions. Although a simplified isentropic process is commonly employed to assess the thermodynamic functioning of scroll compressors with vapor injection (SCVI), it diverges significantly from actual operational dynamics. This study introduces a sophisticated 1D mathematical model that incorporates key factors such as internal leakage and thermal losses, thereby providing a more accurate representation of SCVI's operational realities. The research includes comprehensive performance evaluations of a short wrap profile SCVI, with a specific focus on low-temperature ambient conditions, supported by rigorous experimental validation. Comparative analyses against non-injection scenarios reveal notable enhancements, including a maximum 17.2% increase in mass flow, a 10.5% rise in heating capacity, and a 2.15% improvement in heating COP. Both the simplified isentropic process calculation model and the enhanced 1D mathematical model are utilized to analyze compressor operations. The integration of internal leakage and heat loss considerations significantly narrows the gap between calculated and experimental results for heating capacity and discharge temperature, reducing discrepancies from nearly 20% to a mere 4%. This refined mathematical model demonstrates a high level of alignment with experimental data, achieving an accuracy within 5% when assessing the compressor's real-world operational dynamics.

Biochar-assisted water electrolysis (BAWE) has the potential to reduce the electricity consumption of hydrogen production. However, prolonged electrolysis leads to over-oxidation of biochar, reduced reactivity, and decreasing hydrogen production at cathode. Herein, we proposed the electrochemical activation of biochar via limited biochar oxidation reaction (BOR) and hydrogen evolution reaction (HER) in BAWE process, and the upgraded biochar was employed to remove Cr(VI). Distinct biochar was first pyrolyzed from three kinds of representative biomass components, cellulose, lignin, and their mixture at different temperatures. All of them exhibited excellent BOR activity, especially the biochar derived by the pyrolyzed cellulose and lignin at 800 degrees C (MBC-800) required a potential as low as 1.319 V vs. RHE@1 mA cm(-2) using Pt electrode in 1 M KOH and achieved a Faraday efficiency almost 100% for hydrogen production. BAWE presented an energy-saving electrical consumption of 4.98 kWh Nm(-3) H-2 compared to the conventional water electrolysis of 5.32 kWh Nm(-3) H-2. Electrochemical oxidation enriched the oxygen-containing groups on biochar surface, which significantly improved its reductivity towards Cr(VI) and complexation with Cr(III), leading to the removal rate of Cr(VI) more than doubled. Results showed the achievement of electrochemical activation of biochar by limited electrooxidation. These findings provide a new route for the high-value utilization of biochar and energy-saving electrolytic hydrogen production.

In cold, moisture-rich winter environments, window fogging represents a substantial safety hazard for drivers. Electric vehicles often incorporate heat pump systems to address challenges such as dehumidification and heating specific to cold weather. Therefore, it is essential to evaluate the dehumidification and heating efficiency of these systems through focused research. This study presents a dual-evaporator heat pump system designed specifically for electric vehicles, equipped with two distinct modes for dehumidification and heating. The research examines how factors such as inlet air volume and the degree of opening of the electronic expansion valve affect the system's dehumidification and heating performance. Experimental analyses were conducted to explore the system's response under various conditions of inlet air humidity and compressor speed in both modes. Results suggest that increasing inlet air volume improves dehumidification effectiveness but may reduce heating performance. Likewise, a wider opening of the electronic expansion valve enhances heating but could decrease dehumidification efficiency. Importantly, the study indicates that when the relative humidity of the inlet air exceeds 70 %, a single evaporator mode is more effective for dehumidification. However, when the relative humidity is below 70 %, the dual evaporator mode is more advantageous, showing better heating performance.

Biochar-assisted water electrolysis (BAWE) exhibits potential in reducing electricity consumption for hydrogen production and is beneficial to biochar upcycling. However, it remains a huge challenge to increase biochar oxidation reaction (BOR) kinetics and deliver upgraded biochar with high selectivity. Herein, we demonstrate the correlation between the BOR kinetics and physicochemical properties of biochar, the laws of energy and mass transfer at anode-electrolyte interface, and the evolution of biochar structure during its electrooxidation. The biochar was derived from the pyrolysis of mixed cellulose and lignin at 500-800 degrees C, and based on Pearson correlation analysis, the physicochemical properties such as functional groups abundance, contact angle, and electric conductivity of biochar showed significant influence on electron transfer rate during biochar oxidation. Oxygen evolution reaction (OER) was found the main competition to BOR, only biochar oxidation occurred at potential below 1.6 V vs. RHE, but OER became dominant at potential above 1.6 V vs. RHE. Biochar underwent three stages including oxygen consumption, oxygen enrichment, and deep oxidation during its electrochemical oxidation. The easily-oxidized carboxyl, hydroxyl, and aldehyde were primarily oxidized, followed by the transformation of methyl into hydroxyl and aldehyde, and aldehyde further oxidized into carboxylic acids and CO2. These findings provide new inspiration on electrochemical upgrading of biochar coupled with efficient hydrogen production.

Hydrate blockage always imposes a common problem in oil and natural gas transportation pipelines. The blockage usually occurs at special locations, such as the inlet and outlet of the pump or the slope sections, which are less likely to be detected and more likely to cause serious consequences. A novel fully visual flow loop was used to study the evolution of hydrate formation and blockage in different parts of the pipeline. The results showed that 50% water cut with low liquid loading has the fastest hydrate formation speed. Hydrate usually gathers in the inlet section with some fluid accumulating, which increases the local pressure drop. The hydrate volume fraction at the inlet is higher than at the outlet, and the difference value gradually increases with time and results in hydrate blockage at the inlet parts. Moreover, the results found the most prone location of hydrate blockage in the slope transition section. The rolling hydrate particles in the slug flow at the upslope will backflow due to the action of gravity. It will collide with the fluid and hydrate particles in the horizontal pipe at the junction of the upslope section. This phenomenon results in a negative pressure drop with hydrate blockage in the slope pipes. In addition, the use of an inhibitor (0.5% PVCap) can reduce the hydrate formation speed by more than seven times and the maximum water conversion rate by more than 30%, which can significantly reduce the risk of hydrate blockage.

To fill the research gaps in the study of flow boiling on composite surfaces, four heat exchange tubes with different structures were investigated: an enhanced tube with herringbone teeth (EHT_HB), a tube with a dimple structure (EHT_DIM), a tube with a composite herringbone tooth/dimple structure (EHT_HB/DIM), and a smooth tube as a baseline for comparison purposes. The experimental conditions were set as follows: saturation temperature 6 degrees C, mass flux 50-205 kg/(m(2) center dot s), and vapor quality 0.2-0.8. After confirming the validity of the experimental results, the effects of the mass flux on the flow boiling heat transfer and pressure drop characteristics were examined. Results showed that the flow boiling heat transfer coefficient and pressure drop increase with the increase of the mass flux and the vapor quality in the tested tubes. The EHT_HB/DIM tube was found to combine the advantages of the two structures and to have the highest heat transfer coefficient. The average value of the heat transfer coefficient was found to be 43.75% higher than that of the smooth tube. Also, the average flow boiling heat transfer coefficients of the EHT_HB and the EHT_DIM tubes were found to be 15% and 35% higher than that of the smooth tube, respectively. From the perspective of the frictional pressure drop, it was found that the EHT_HB/DIM tube exhibited the maximum frictional pressure drop. The optimum working conditions of the enhanced tubes were determined by introducing a performance factor that captures the combined effects of heat transfer and pressure drop.

Up to now, the reported methods to regulate the surface morphology of metals are complicated and thus difficult to achieve. Herein, the etching method is optimized and used to change the surface morphology of copper (Cu) wire. By adjusting the amount of HCl as etching agent and the purity of Cu wire as the raw material, the Cu wire covered by uniform submicro-sized cubes (CWC) is successfully prepared and chosen as catalyst for the reduction of 4-nitrophenol. The CWC shows superior catalytic activity, recyclability and stability. Clearly, the as-provided etching method is effective for the surface morphology control of Cu wire, which can be a prospective strategy to obtain the metal materials with special surface morphology.