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This paper presents BubbleID, a sophisticated deep learning architecture designed to comprehensively identify both static and dynamic attributes of bubbles within sequences of boiling images. By amalgamating segmentation powered by Mask R-CNN with SORT-based tracking techniques, the framework is capable of analyzing each bubble's location, dimensions, interface shape, and velocity over its lifetime and capturing dynamic events such as bubble departure. BubbleID is trained and tested on boiling images across diverse heater surfaces and operational settings. This paper also offers a comparative analysis of bubble interface dynamics prior to and post-critical heat flux conditions. [ABSTRACT FROM AUTHOR]

Measurements on heat transfer and critical heat flux of pool boiling cooling of the baseplate of an inverter power module are performed. A refrigerant with low global warming potential, FK-649, is used as coolant. Tests are done for heat fluxes up to 146 kW/m2, with refrigerant saturation temperatures of 36 °C, 41 °C and 46 °C and with refrigerant liquid heights of 1 cm, 6 cm and 17 cm. Both heat transfer rates and critical heat flux increase with increasing saturation temperature. In the range tested, the liquid height had no effect on both the boiling curve and the critical heat flux. The measured boiling curve can be divided in three regions: two regions with a lower slope at heat fluxes just above onset of nucleate boiling and just below the critical heat flux and a region with a higher slope at intermediate heat fluxes. The measured critical heat flux for FK-649 is predicted by the Lienhard-Dhir correlation within 10%. The highest critical heat flux measured is 146 kW/m2, which is lower than the heat fluxes in the most compact power modules. This indicates that methods to increase the critical heat flux are needed for enabling two-phase power module cooling with FK-649. [ABSTRACT FROM AUTHOR]

• Effect of vortex generators on flow boiling oscillation are verified. • Vortex generators suppress the large bubble's formation and reverse flow. • The max increment of limiting oscillation heat flux by vortex generators is 21.1%. • A new correlation for vortex-enhanced limiting oscillation heat flux is developed. Subcooled flow boiling in micro-channels is an effective solution for high-heat-flux electronics thermal management, and the heat flux has a limitation value (i.e., limiting oscillation heat flux) due to flow boiling oscillation. The purpose of this study is to propose a new method to suppress the flow boiling oscillation (i.e., forcing bubbles to leave the channel by installing a vortex generator), experimentally verify the effect of vortex generators on suppression of flow boiling oscillation and increasing limiting oscillation heat flux, and develop a predicting correlation for this heat flux. In the experiments, the vortex generator is a helix wire with a pitch of 1.8 mm, a length of 22.5 mm, a wire diameter of 0.2 mm and a diameter of 1.8 mm; the inlet subcooling degree and mass flux range from 10 – 50 K and 750–1750 kg m−2 s−1, respectively. The results show that, the flow boiling oscillation occurs in the flow channel without vortex generators while it doesn't occur in the flow channel containing vortex generators at the same working condition; the vortex generators can raise the limiting oscillation heat flux with a maximum increment of 21.1%, which indicates that vortex generators can suppress the flow boiling oscillation. A new correlation predicting limiting oscillation heat flux in channels with vortex generators was developed, and its predictions match 95% of the experimental data within ± 20% while the average deviation is 7.6%. [ABSTRACT FROM AUTHOR]

• 1mm chevron depth W-shaped plate has no favor to R32 and slight benefit to R410A. • Convective boiling occurs earlier with decreasing of chevron depth. • Several correlations predict well to R32/R410A flow boiling in microscale plate channel. Brazed plate heat exchanger (BPHE) has gained more advantages of refrigerant inventory reduction and high efficiency due to smaller chevron channel. This paper experimentally investigates the heat transfer and pressure drop of R32 and R410A flow boiling in BPHEs with 1 mm chevron depth and W– and V– chevron patterns. Variations in heat transfer coefficient (HTC) and frictional pressure drop (FPD) with mass flux (15 − 40 kg m−2 s−1 for R32 and 25 − 60 kg m−2 s−1 for R410A) and imposed heat flux (from 6 − 14 kW m−2) are analyzed for each combination of the two refrigerants and two types of plate patterns. The HTC of R32 is approximately 10 % and 30 % higher than that of R410A at same mass flux in W– and V–shaped plates, respectively, which has an equivalent friction factor. The V–shaped plate is found more suited for R32 compared to the W–shaped plate. The existing available transition criterions fail to predict the flow boiling heat transfer mechanism in microscale channel, and convective boiling seems dominant in 1 mm chevron depth channel under the present working conditions, particularly for R32. The HTC correlations of Hsieh and Lin, and Palmer et al. fit the measured data relatively well with 96 and 80 % data within the deviation of ±20 %, respectively. Huang et al. correlation exhibits fare predictability for FPD, with more than 80 % data within the deviation of ±25 %. [ABSTRACT FROM AUTHOR]

Innovative reactor designs like small modular reactors (SMRs) have the potential to operate in a natural circulation (NC) boiling mode, but this mode introduces flow oscillations that pose a risk to nuclear safety. Therefore, it is essential to investigate the effects of various parameters on these oscillations. This study focuses on predicting the operational behavior of the Integral PWR-type SMR Test Rig (iPSTR) when operating in NC and subcooled boiling conditions. The iPSTR replicates an NC boiling loop with a vertical heater, vertical cooler configuration, high-temperature and high-pressure conditions, and nonuniform diameter structure. Using the RELAP5 model, thermal-hydraulic simulations were performed to anticipate how varying degrees of inlet subcooling affects parameters such as mass flow rate and void fraction, with experimental data used to validate the model's accuracy. This investigation covers a range of process conditions, including system pressures from 5 to 20 bars, core input power varying from 8.5 to 14.5 kW, and degrees of inlet subcooling from 1 to 49 K. The results reveal that increasing input power leads to higher average mass flow rates, while at a constant system pressure, higher input power stabilizes flow rates at higher degrees of inlet subcooling. Moreover, reduced and more consistent oscillation amplitudes and frequencies at higher core power result at more elevated system pressure, enhancing the safety of the iPSTR facility. [ABSTRACT FROM AUTHOR]

Ebullition is an important route of methane emission from aquatic ecosystems. Ebullitive CH4 emissions from the wetlands, particularly the mountain wetlands of Eastern Himalayan, are poorly understood. To gain insights into the role of ebullition in CH4 emissions and understand the factors influencing CH4 ebullition, we conducted field measurements of the spatial and temporal variation of ebullition in a freshwater wetland area in floating national park (40 sq. km, 780 m amsl, maximum depth < 4.5) in Northeast India. The average ebullitive CH4 flux ranged from 220.24 to 1889.35 mg m−2 d−1, while the overall CH4 fluxes varied widely ranging from 345.81 to 2240.56 mg m−2 d−1. Methane constituted 90.18% of the gas bubbles produced from the sediment, with CO2 comprising 8.82% of the total sediment gas in the wetland. This suggests that CH4 emission through ebullition plays an important role in transporting biogenic CH4 to the atmosphere. The ebullition rate was markedly higher during summer and lower during winter and exhibited a significant seasonal variation. At a spatial scale, the sites with dense aquatic vegetation growth increase CH4 emission where plants derived autochthonous sediment organic matter, substantiating the supply of carbon substrate for CH4 production. Linear mixed-effect models revealed that water temperature, organic matter, organic carbon and dissolved organic matter are the important factors affecting the ebullitive methane flux. Our results indicate that mountainous wetlands with organic-rich sediments may be potential hotspots for CH4 ebullition. However, the lack of information on these wetlands in the scientific literature emphasizes the need for further research. [ABSTRACT FROM AUTHOR]

Wetlands are active biogeochemical processing sites with conditions that promote carbon storage and the production and release of greenhouse gases (GHGs). Estimates of GHG release from wetlands, including small ponds, are still highly uncertain, and rarely consider diverse pathways of exchange, instead focussing primarily on diffusion. One way to resolve this uncertainty is to quantify and compare multiple pathways of GHG release and to consider specific wetland types. At four natural ponds in the Canadian Prairie Pothole Region (PPR), we investigated four flux pathways (diffusion, ebullition, exposed sediment, and vegetation-mediated) and found distinct differences between pathways for methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O). The highest magnitude effluxes were via exposed sediment for CO2 and N2O and ebullition for CH4, though ebullition was not the dominant CH4 efflux pathway in two ponds. For pathways with potential for high GHG efflux, we used generalized least squares (GLS) regression to investigate physicochemical predictors. We identified significant relationships between air temperature and exposed sediment fluxes of CO2 and N2O, and between sulphate and dissolved oxygen concentrations and diffusive CH4 fluxes. Water temperature may be linked to ebullitive CH4 fluxes, but this was not statistically significant. This research identifies hotspots and physicochemical predictors for GHG efflux in the first study to directly compare four key flux pathways for PPR ponds, highlighting that processes occurring in different parts of the wetland can greatly outweigh their areal extent. This analysis will inform future work to synthesize and upscale GHG fluxes for these ponds. [ABSTRACT FROM AUTHOR]

Thermal conversion of vacuum tower bottoms (VTB) and its narrow‐cut distillation fractions were studied at 530°C between 0.1 and 2 MPa pressure to assess the effect of the reaction pressure on coking. Coke yield in the VTB conversion increased with pressure, which was found to be mostly due to the enhanced coking of the 700°C+ narrow cut. The microcarbon residue in the liquid remained unaffected. The yield of products with a boiling point below 510°C, including distillate and by‐product lights, decreased with the pressure increase. The trend was a cumulative effect of the increased yields from the VTB cuts boiling below 635°C and the decreased yields from the heavier cuts. Admixing different VTB cuts into the VTB feed resulted in the weighted average changes with no synergistic or antagonistic effects. [ABSTRACT FROM AUTHOR]

ABSTRACT This study investigated the effect of different processing methods (boiling, oil boiling, and stir frying) on the flavor of hoki steak soups. The quality of different fillet broths was explored by pH, Thiobarbituric acid reactive substances (TBARS), and color. E‐nose, E‐tongue, and gas chromatography‐ion mobility spectrometry (GC‐IMS) combined with free amino acids (FAAs) were used to analyze the flavor of hoki steak soups. Key compounds were screened by relative odor activity value (ROAV). The variable influence on projection (VIP) was used to identify the differential compounds. The E‐nose and E‐tongue were able to distinguish hoki steak soups. A total of 47 volatile compounds were characterized by GC‐IMS. n‐Pentanal (M) was the key component for the difference between hoki steak soups. There were six substances with ROAV ≥ 1. The results showed that the hoki steak soup boiled for 2 h in the stir‐frying group had a lower fishy odor. [ABSTRACT FROM AUTHOR]

AbstractA complete thermo-hydraulic understanding of condensing and evaporating flows in heat exchangers requires predictive modeling and analysis of not just heat transfer but also the hydraulics of the flow. While modeling the friction factor and pressure gradient yields a quantitative understanding of the pressure drop, only the two-phase multiplier and void fraction, in combination with the Martinelli parameter, help better understand the relative contributions of the liquid and vapor fractions to the overall pressure drop. This article reports the empirical modeling, analysis, and meta-analysis of the two-phase multiplier for condensing and evaporating flows in plate heat exchangers. Over three thousand data compiled from forty-two sources were modeled using various regression techniques to develop correlations for predicting the two-phase multiplier for condensing and evaporating flows in plate heat exchangers. The Weber number for most studies was less than one, indicating that drop condensation and pool boiling were impossible. Further, the Bond number for most studies was also much higher than one, indicating that the buoyancy effects were significant during condensation and evaporation. Meta-analysis for evaporators was statistically significant and positive, strongly recommending plate heat exchangers. [ABSTRACT FROM AUTHOR]

Subcooled flow boiling has important applications in cooling systems with high heat fluxes. Additionally, it has higher heat transfer efficiency and better performance in critical heat flux compared to saturated flow boiling. In this paper, subcooled flow boiling heat transfer of deionized (DI) water under varying heat fluxes was investigated experimentally, in a vertical tube with inner and outer diameters of 4.3 and 6.3 mm, respectively. The heat transfer coefficient (HTC) behavior was studied as the flow transitioned from forced convection in a single-phase state to subcooled flow boiling in a two-phase state, ultimately reaching the critical heat flux (CHF). The curve of subcooled flow boiling of deionized water was presented by explaining the heat transfer mechanism in various boiling regions. Investigation of the effects of various parameters, such as mass flux, pressure, subcooled temperature, the length of the heating tube, and output equilibrium vapor quality (Xe), indicated that CHF increased by 42% and 42.7% with increasing mass flux from 689 to 1148 kg m−2 s−1 and pressure from 1 to 3 bar, respectively. Meanwhile, the critical heat flux decreased by 5% and 24.2% with the increase in subcooling temperature and heating tube length, respectively. Moreover, increasing the mass flux, absolute pressure, and subcooling temperature enhanced the behavior of the heat transfer coefficient. However, as the length of the test section tube increased, the HTC decreased. [ABSTRACT FROM AUTHOR]

R134a was recognized as probably one of the most important refrigerants of the two past decades. Among the proposed alternative fluids, there are certainly isobutane (R600a) and R152a. This article presents about 200 new heat transfer coefficient and pressure drop data obtained during flow boiling of R152a and R600a inside a smooth copper tube having an internal diameter of 4 mm. Three saturation temperatures were considered for each refrigerant, from 5 °C to 20 °C. Furthermore, for each temperature studied, the heat flux was varied between 15 and 30 kW m−2 and the refrigerant mass flux from 100 to 400 kg m−2 s−1. After presenting the new data, a critical comparison was proposed between the performance of these refrigerants and R134a. Finally, some classic correlations available in the literature have been implemented. The deviations between the calculated and experimental values were reported and commented. [ABSTRACT FROM AUTHOR]

The oxidation of 5,5′‐(methylene)bis(6‐hydroxy‐1,3‐dimethylpyrimidine‐2,4(1H,3H)‐dione) monopiperidinium salts with Mn(OAc)3•2H2O was carried out in boiling MeCN, producing 2,4,9,11‐tetramethyl‐2,4,9,11‐tetraazadispiro[5.0.57.16]tridecane‐1,3,5,8,10,12‐hexaones in high yields. A similar reaction using 4,4′‐(methylene)bis(1,2‐diphenylpyrazolidine‐3,5‐dione)s gave 2,3,8,9‐tetraphenyl‐2,3,8,9‐tetraazadispiro[4.0.46.15]undecane‐1,4,7,10‐tetraones in good yields. The structure determination and the reaction mechanism for the formation of the unique tetraazadispiro(cyclopropane)s are discussed. [ABSTRACT FROM AUTHOR]

Deionized water is replacing fluorinated liquids as the preferred choice for two-phase immersion cooling in data centers. Yet, insufficient bubble removal capability at low saturated pressure is a key challenge hindering the widespread application. To solve this issue, this study employs non-ionic surfactant (Tween 20) and asymmetric structures (expanding microchannel) to enhance the boiling performances of deionized water under sub-atmospheric pressure. The research examines the effects of pressure (8.8~38.5 kPa), surfactant concentration (0.1~0.5 mL/L), and heat flux density (10~180 W/cm2) on the boiling heat transfer characteristics and analyzes the mechanism of unusual temperature oscillations induced by surfactants. It was found that the trade-off between the sub-atmospheric pressure, surface tension coefficient, and reduced static contact angle results in pronounced intermittent boiling on the heated surface. Even with the addition of surfactants, the improvement in heat transfer requires demanding conditions. Boiling enhancement throughout all heat flux conditions was achieved when the surfactant concentration was higher than 0.2 mL/L for the expanding microchanneled surface. The heat transfer coefficient reached 6.89 W·cm−2·K−1 under 8.8 kPa, which was 45% higher than without the surfactant. Under the same heat flux and sub-atmospheric pressure, as the concentration increased from 0.1 to 0.5 mL/L, the amplitudes of temperature fluctuation of the plane surface and expanding microchanneled surface decreased from 10 K to 2 K and 18 K to 1 K, respectively. The onset of nucleate boiling and wall superheat of the expanding microchanneled surface gradually decreased with the increase in surfactant concentration, where the onset of nucleate boiling decreased by 10.54 K. When the heat flux is 160 W/cm2, the wall superheat is reduced by 12.8 K. [ABSTRACT FROM AUTHOR]

The production of methane in coastal sediments and its release to the water column is intensified by anthropogenic eutrophication and bottom water hypoxia, and it is still uncertain whether methane emissions to the atmosphere will be enhanced. Here, we assess seasonal variations in methane dynamics in a eutrophic, seasonally euxinic coastal basin (Scharendijke, Lake Grevelingen). In-situ benthic chamber incubations reveal high rates of methane release from the sediment to the water column (74–163 mmol m−2 d−1) during monthly measurements between March and October 2021. Comparison of these in-situ total benthic methane fluxes and calculated diffusive fluxes point towards a major role for ebullition. In spring and fall, when the water column was oxic, microbial removal of dissolved methane occurred aerobically in the bottom water. In summer, in contrast, dissolved methane accumulated to concentrations of up to 67 μmol L−1 below the oxycline. Shifts in δ 13C–CH 4 and δ D-CH 4 towards higher values and the abundant presence of methane oxidizing bacteria point towards removal of methane around the oxycline, likely through both aerobic and anaerobic pathways, with the latter possibly linked to iron oxide reduction. Shifts in δ 13C–CH 4 and δ D-CH 4 to lower values above the oxycline indicate that bubble dissolution contributed to dissolved methane. Methane emissions to the atmosphere were observed in all seasons with the highest, in-situ measured diffusive fluxes (1.2 mmol m−2 d−1) upon the onset of water column mixing at the end of summer. Methane release events during the measurement of in-situ water-air fluxes and model calculations point towards a flux of methane to the atmosphere in the form of bubbles, which bypass the microbial methane filter. The model calculations suggest a potential year-round ebullitive methane flux between 30 and 120 mmol m−2 d−1. We conclude that methane emissions from eutrophic coastal systems may be much higher than previously thought because of ebullition. [ABSTRACT FROM AUTHOR]

• New data of jet impingement boiling on surface modified metal foam were obtained. • Effects of metal foam wettability on boiling heat transfer were analyzed. • Influence on bubble dynamics behavior was analyzed. • New heat transfer coefficient correlation considering wettability was developed. Wettability may have significant influence on jet impingement boiling on metal foam, but the effect mechanism of metal foam wettability remains unclear. In this study, the boiling heat transfer characteristics of distributed jet array impingement on hydrophobic and hydrophilic metal foam covers were experimentally researched and compared with those on uncoated metal foam covers to analyze the influence of wettability. The experimental conditions cover contact angles of 14.0–158.7°, pore densities of 20–40 PPI, porosities of 92 %-97 %, thicknesses of 3.0–5.0 mm, and jet velocities of 0.5–4.0 m·s−1. The results show that, the obtained maximum heat flux and maximum heat transfer coefficient are up to 538.1 W cm−2 and 57.9 Kw m−2 K−1, respectively; the hydrophobic metal foam cover has a 4.8 K lower surface superheated degree at the onset of nucleate boiling, but a 7.5 % lower maximum heat transfer coefficient compared with the uncoated one; the hydrophilic metal foam cover shows a less deterioration after the departure from nucleate boiling but a 5.3 K higher surface superheated degree at the onset of nucleate boiling than those of the uncoated one. A new correlation for boiling heat transfer coefficients was developed with a mean relative error of 9.75 %. [ABSTRACT FROM AUTHOR]

Nanofluid was frequent technique which solved microscale heat and mass transport problems to intensify pool boiling heat transfer. This paper had investigated the effect of nanofluid, ultrasonic field and ribs surfaces on cooperative heat transfer enhancement in pool boiling. A two-step method was applied to prepare Al2O3 nanofluids of different kinds of concentrations and diameters. Group experiments were examined the influences of nanofluid concentration and diameter, ultrasonic power and distance and rib surface type on heat transfer characteristics, respectively. The heat flux and convection heat transfer coefficient were used the performance parameters. The results showed that the concentration and diameter of the Al2O3 nanofluid effected the heat transfer performance on the pool boiling. The Al2O3 nanofluid with an average diameter of 80 nm had the most significant enhancement effect on the pool boiling heat transfer performance, but the Al2O3 with a diameter of 30 nm had the weakest enhancement effect, when the concentration of Al2O3 nanofluid was 0.01 wt%. Meanwhile, the generated acoustic streaming effect and cavitation effect by ultrasonic field can promote the energy accumulation, rupture and regeneration of the bubbles at low superheat stage on nanofluid pool boiling. The heat transfer coefficient (HTC) gradually enhances as the ultrasonic field changes. At an ultrasonic power of 528 W and a distance of 50 mm, the nanofluid pool boiling increased by 44.34% compared to no ultrasonic field HTC. Compared with No rib, the boiling point of the Al2O3 nanofluidic pool boiling of Rib II was reduced by 2°C under the ultrasonic field. The nanofluid pool boiling with ultrasonic field of p = 528 W and Rib II had the best heat transfer effect, and HTC improved more than 50%. This is due to the addition of more nucleation points for bubbles on the heated surface of the Rib II. [ABSTRACT FROM AUTHOR]

Roasted peanuts (OPs) are more often used in daily life than boiled peanuts (BPs); the main reason may be related to the pleasurable flavor in OPs. This study comparatively investigated the effects of boiling and roasting on nutritional components contents, taste, and aroma to reveal the advantages of roasting in terms of the nutrition and flavor of peanuts. Results showed that boiling increased fat content to 54.47% of peanuts, diluted or reduced sugar content to an undetectable level, noticeably changed the contents of poly/monounsaturated fatty acids, and significantly decreased the content of free amino acid (FAA, 1.05 mg/g peanuts) in peanuts. Roasting simply decreased the contents of sugar and FAA to 2.78 and 1.82 mg/g peanuts, respectively. Compared with roasting, boiling had more discernible effects on fatty acids and FAAs. Both BPs and OPs have good dietary lipid quality. In terms of flavor, OPs had more FAAs (2 types) that contributed remarkably to the taste of peanuts than BPs (0 types), more volatile substances (40 types) than BPs (12 types), and a higher number of key volatile aroma components (8 types) than BPs (3 types). That is, roasting induced a relatively small effect on nutritional components and gave peanuts a richer taste and stronger aroma than boiling; therefore, roasting is an ideal peanut processing method. This study proved the different changes in peanuts caused by boiling and roasting on a material basis and corroborated the irreplaceability of roasting in peanut processing. [ABSTRACT FROM AUTHOR]

To investigate the influence of flow rate increment on the solute transport parameter of immobile zones in a karst system, a dye tracer test was conducted in the Downtown Salado Spring Complex (DSSC) comprising three springs: Big Boiling, Anderson, and Doc Benedict springs. The Multiflow two-region nonequilibrium model (2RNE) was used to simulate the breakthrough curve (BTC) of the springs, and changes in the solute transport parameters in response to flow rate increment were observed. The simulation result showed that the 2RNE model was capable of reproducing the BTC of all the DSSC springs, with an R-squared value greater than 0.9 in all flow rate increment scenarios. The research demonstrates that a positive correlation will exist between the flow rate and solute transport parameter of the immobile zones if the tracer transport to the spring is truly influenced by immobile zones. In contrast, a negative correlation will exist between the flow rate and mass transfer coefficient if the immobile zone has less influence. Overall, the research provides insights into contaminant movement in karst by documenting how tracers are retained in the immobile fluid zone. [ABSTRACT FROM AUTHOR]

This work investigates pool boiling heat transfer (BHT) and bubble dynamics from a porous medium. The influence of the porous media structural parameters, such as porosity, pore density, porous medium height, thermal conductivity, and wettability, are mainly investigated. The findings indicate that the presence of porous media can increase the critical heat flux (CHF) by an average of 3.75 times and the BHT coefficient by an average of 3.84 times when porosity varies between 57.5% and 98.0% as compared to the plain surface. It is also found that both the CHF and BHT coefficient increase as the porosity decreases if porosity ε ≥ 71.4 %. However, they drop with the porosity decreases if porosity ε ≤ 71.4 %. On the other hand, the number of nucleation sites, heat transfer area, and bubble escape resistance increase as pore density increases. In addition, increasing the porous media height may enhance BHT performance, but too high a porous media increases the bubble escape resistance and restricts the separation of bubbles. Moreover, the CHF value and the maximum BHT coefficient increase with the thermal conductivity of porous media linearly. Finally, the stronger the wettability, the faster the bubble detachment, and the stronger the BHT performance. [ABSTRACT FROM AUTHOR]

Lakes are important sentinels of climate change and may contribute over 30% of natural methane (CH4) emissions; however, no earth system model (ESM) has represented lake CH4 dynamics. To fill this gap, we refined a process‐based lake biogeochemical model to simulate global lake CH4 emissions, including representation of lake bathymetry, oxic methane production (OMP), the effect of water level on ebullition, new non‐linear CH4 oxidation kinetics, and the coupling of sediment carbon pools with in‐lake primary production and terrigenous carbon loadings. We compiled a lake CH4 data set for model validation. The model shows promising performance in capturing the seasonal and inter‐annual variabilities of CH4 emissions at 10 representative lakes for different lake types and the variations in mean annual CH4 emissions among 106 lakes across the globe. The model reproduces the variations of the observed surface CH4 diffusion and ebullition along the gradients of lake latitude, depth, and surface area. The results suggest that OMP could play an important role in surface CH4 diffusion, and its relative importance is higher in less productive and/or deeper lakes. The model performance is improved for capturing CH4 outgassing events in non‐floodplain lakes and the seasonal variability of CH4 ebullition in floodplain lakes by representing the effect of water level on ebullition. The model can be integrated into ESMs to constrain global lake CH4 emissions and climate‐CH4 feedback. Plain Language Summary: Lakes are highly sensitive to climate change and can produce over 30% of natural methane (CH4) emissions. However, these emissions are not well understood or included in global CH4 assessments. Current lake CH4 models either miss key processes or haven't been tested with observations from different environments. To address this, we improved the Advanced Lake Biogeochemistry Model (ALBM) to better simulate CH4 production, oxidation, and transport. We also created a new data set of CH4 emissions from 106 lakes worldwide to validate the model. Our improved model shows promising performance in simulating observed emissions. Our findings highlight the importance of including CH4 production in oxygen‐rich water, the impact of water level change on CH4 bubble release, and a new method for CH4 oxidation in lake CH4 models. The improved ALBM can now be used in Earth system models to better predict global lake CH4 emissions and their impact on climate change. Key Points: We enhanced and validated the Advanced Lake Biogeochemistry Model for lake CH4 emissions using a new global data setThe model captures lake CH4 emissions across diverse environments and accounts for seasonal and inter‐annual variationsLake CH4 models should include oxic CH4 production, water level impact on ebullition, and a new method for CH4 oxidation [ABSTRACT FROM AUTHOR]

Compared with the traditional mechanical knitting needle, the tubular magnetic suspension knitting needle has the advantages of no friction and flexible control. But the highspeed reciprocating motion of the needle needs to consume a lot of power. The winding temperature is difficult to suppress. The heat dissipation performance becomes the main obstacle restricting the power improvement. In this paper, an integral tubular electric knitting needle is proposed and studied. The heat dissipation area of the needle is increased by the annular thermosyphon in the motor housing. The heat dissipation performance is carefully studied by experiments, and the results show that the heat dissipation performance is obviously improved compared with the original design. Under the power of 17 W, after the annulus thermosyphon is started, the maximum temperature of the winding can be suppressed at about 107 °C. Boiling occurs only at certain points on the surface of the winding, which is related to the structural asymmetry in the winding manufacturing and epoxy injection processes. The heat dissipation performance is best when the winding is located at the bottom of the motor. The axial temperature difference is within 15 °C while the circumferential temperature difference is within 4 °C. [ABSTRACT FROM AUTHOR]

The article analyses the degree of water superheating with respect to the liquid-vapour equilibrium line in experiments on the micro-explosion of a composite droplet comprised of two immiscible liquids. The analyses were carried out for water-in-fuel drops under conditions of high-power heating. This degree is compared with the mechanical effect of droplet decay, involving the formation of daughter droplets. Our attention was drawn to the smallness of the degree of superheating preceding the decay. A model of the boiling up of such a droplet is constructed taking into account the sources of premature boiling up of water inherent in micro-explosive experiments. The dependencies of the boiling up temperature of water on the heating rate obtained in the model turned out to be in accordance with the experimental data across a wide range of heating rates. A hypothesis about the local superheating of the transition layer, which is not detected in the experiment, is formulated. Thus, a step has been taken to clarify the essence of the mismatch of the degree of superheating of water recorded by macroscopic equipment along with a completely satisfactory generation of daughter droplets serving as the basis for advanced fuel technology. [ABSTRACT FROM AUTHOR]

The heat transfer limit of heat pipes is investigated by pool boiling experiments in a standard apparatus with a capillary layer placed on a copper tube. The capillary layer is a hollow cylinder made of bronze with a wall thickness of 2 mm and the test fluids are methanol and n‐pentane. The setting is comparable to high‐flux tubes already investigated in the literature. In dependence on the heat flux, three to four sections with different characteristics are identified. Compared to plain copper tubes, the heat transfer is partially increased by a factor of 12 until the limit is reached at around 70 kW m−2. [ABSTRACT FROM AUTHOR]

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At present, bamboo fiber is mainly prepared by rolling and carding after employing the alkali boiling softening method, which is not friendly to the environment. In order to obtain a green and environmentally friendly pretreatment method for preparing bamboo fiber, this paper starts with the current bamboo softening technology and explores the impact of various experimental factors on fiber extraction of Pleioblastus amarus (bitter bamboo) after application of the saturated steam softening method through studying the relationship between saturated steam temperature, holding time, moisture content of bamboo strips, fiber yield, fiber fineness, and the mechanical properties of Pleioblastus amarus fiber. Single-factor experiments revealed that optimal softening fiber extraction effects were achieved within a steam temperature range of 150–180 °C, a holding time of 10–30 min, and a moisture content of 12%–22%. Based on these findings, an orthogonal experiment was designed using a factorial-level table. Through the analysis of range, variance, and orthogonal experiment results, combined with the fibrillation effect and the practical application of fibers, the optimal process parameters of the saturated steam softening method for fiber extraction were determined: saturated steam temperature 170 °C, holding time 20 min, and moisture content 12%. In contrast to the method of conventional mechanical fiber extraction after alkali boiling softening treatment, bamboo fibers processed utilizing the optimized conditions of the saturated steam softening technique showcase a substantial 63% elevation in fiber yield, a notable 18% reduction in fiber fineness, a commendable 28% enhancement in fiber tensile strength, an equivalent tensile modulus, and a marked 53% decrease in elongation at break. The softening process can provide a green and environmentally friendly treatment method for bamboo fiber extraction and greatly promote the scope of application of Pleioblastus amarus. [ABSTRACT FROM AUTHOR]

The liquid-to-vapor transition can occur under unexpected conditions in nanopores, opening the door to fundamental questions and new technologies. The physics of boiling in confinement is progressively introduced, starting from classical nucleation theory, passing through nanoscale effects, and terminating with the material and external parameters that affect the boiling conditions. The relevance of boiling in specific nanoconfined systems is discussed, focusing on heterogeneous lyophobic systems, chromatographic columns, and ion channels. The current level of control of boiling in nanopores enabled by microporous materials such as metal organic frameworks and biological nanopores paves the way to thrilling theoretical challenges and to new technological opportunities in the fields of energy, neuromorphic computing, and sensing. [ABSTRACT FROM AUTHOR]

This paper presents a model-based PID tuning method for a reactor used in microwave-assisted chemistry. The reactor is equipped with a solid-state source of microwaves and a PID controller capable of increasing or decreasing the delivered microwave power to maintain the reacting substances at the desired temperature. The model has the form of an algorithm applied in numerical simulations of two simultaneous processes: heating a substance by absorbing microwave radiation and cooling it by dissipating heat to the surroundings. It has proven its suitability for tuning the PID controller in a time-efficient manner. Despite some noticeable inaccuracies, the presented approach easily finds PID coefficients that result in stable and repeatable controller operation. In this way, significant time savings can be achieved, as well as minimizing the risks associated with, for example, boiling liquid spills. The article demonstrates that a carefully designed, but still relatively simple, model can yield significant benefits in tuning PID controllers. [ABSTRACT FROM AUTHOR]

Reservoirs are an important source of methane (CH4) emissions, but the relative contribution of CH4 ebullition and diffusion fluxes to total fluxes has received little attention in the past. In this study, we systematically monitored the CH4 fluxes of nine cascade reservoirs (Dahejia, Jishixia, Huangfeng, Suzhi, Kangyang, Zhiganglaka, Lijiaxia, Nina, and Longyangxia) in the upper reaches of the Yellow River in the dry (May 2023) and wet seasons (August 2023) using the static chamber gas chromatography and headspace equilibrium methods. We also simultaneously measured environmental physicochemical properties as well as the abundance of methanogens and methanotrophs in sediments. The results showed the following: (1) All reservoirs were sources of CH4 emissions, with an average diffusion flux of 0.08 ± 0.05 mg m−2 h−1 and ebullition flux of 0.38 ± 0.41 mg m−2 h−1. Ebullition flux accounted for 78.01 ± 7.85% of total flux. (2) Spatially, both CH4 diffusion and ebullition fluxes increased from upstream to downstream. Temporally, CH4 diffusion flux in the wet season (0.09 ± 0.06 mg m−2 h−1) was slightly higher than that in the dry season (0.08 ± 0.04 mg m−2 h−1), but CH4 ebullition flux in the dry season (0.38 ± 0.48 mg m−2 h−1) was higher than that in the wet season (0.32 ± 0.2 mg m−2 h−1). (3) qPCR showed that methanogens (mcrA gene) were more abundant in the wet season (5.43 ± 3.94 × 105 copies g−1) than that in the dry season (3.74 ± 1.34 × 105 copies g−1). Methanotrophs (pmoA gene) also showed a similar trend with more abundance found in the wet season (7 ± 2.61 × 105 copies g−1) than in the dry season (1.47 ± 0.92 × 105 copies g−1. (4) Structural equation modeling revealed that the ratio of mcrA/pmoA genes, water N/P, and reservoir age were key factors affecting CH4 ebullition flux. Variation partitioning further indicated that the ratio of mcrA/pmoA genes was the main factor causing the spatial variation in CH4 ebullition flux, explaining 35.69% of its variation. This study not only reveals the characteristics and influencing factors of CH4 emissions from cascade reservoirs on the Qinghai Plateau but also provides a scientific basis for calculating fluxes and developing global CH4 reduction strategies for reservoirs. [ABSTRACT FROM AUTHOR]

Heat exchange on a heat-stressed surface and the critical heat flow from it in the process of cooling this surface by a system of distributed impact submerged microjets of a dielectric liquid, depending on the velocity of these jets, were investigated experimentally for the case where the initial subcooling of the liquid in the jets to the saturation temperature comprises 40 ± 2°C. The experiments were conducted for 36 jets of the HFE-7100 dielectric liquid with an initial diameter of 174 μm, outflowing from the nozzles positioned at a distance of 1 mm from a cooling surface. It was established that the heat transfer coefficients of this surface and the critical heat flow from it are determined by the velocity of the jets, acting on the surface, and the initial subcooling of the cooling liquid, and that they are much larger than those in the case of pool boiling of the cooling liquid on the surface and in the case of its cooling by a single jet of a liquid with a small subcooling to the saturation temperature. [ABSTRACT FROM AUTHOR]

The upcoming energy scarcity problem has driven research toward developing energy-efficient two-phase heat exchangers essential for various cooling applications. This research is rooted in the principles of pool boiling, essential for effective heat transfer in various heat exchangers. A well-known reported problem in heat exchangers is the dry-out phenomena of heated surfaces due to bubble coalescence. To tackle this undesirable problem, an innovative technique has been introduced in this study, which involves the shearing of bubbles through liquid jet impingement over the heated surface. The study has been carried out in a two-dimensional domain numerically, in the wall superheat range of 9–16 K. To study the underlying physics involved in this pool boiling phenomenon, the bubble dynamics parameters such as departure frequency, bubble diameter, cold spot (bubble base) temperature, and vapor volume fraction have been analyzed. The results show that with the jet shearing effect, a maximum enhancement of 25% in heat transfer rate is observed at higher wall superheat. The investigation also highlights that the liquid jet enhances vapor volume fraction, indicating enhanced steam generation, particularly an enhancement of 27% observed at elevated wall superheat. An early onset necking effect is also observed with the shearing effect, which leads to the formation of smaller bubbles with higher departure frequencies. This study is a benchmark to the fundamental physics of enhancing two-phase heat transfer through bubble shearing, offering promising insights for energy conservation in two-phase heat exchanger design, particularly within the context of pool boiling. [ABSTRACT FROM AUTHOR]

A deeper understanding of the post-impact phenomenology of droplets on cold surfaces is crucial for comprehending and developing anti-icing surfaces for various applications. In the present study, a systematic experimental investigation has been done in a controlled environment with a wide range of subcooled surface temperatures ( T s ∼ 1 ° C − 25 ° C), slightly over the freezing point of water. The inertia force dominates during the spreading phase, and the time for maximal spreading is independent of the surface temperature. However, surface temperature has a major impact on the recoiling phase and governs the post-impact outcome. During the receding phase, the dynamic receding angle varies drastically and is also found to be strongly dependent on surface temperature. It is proposed that the micro-cavity condensation induced water bridge formation and viscous dissipation critically influences the receding dynamics. The retraction becomes partial retraction and finally pins at low temperatures with an enhanced retraction time, thus aiding the proposed mechanism. An empirical relationship is found for the average receding contact angle as a function of surface temperature. A scaling relation for retraction time is proposed that takes into account both the transient and surface temperature dependent variation of receding contact angle variation and the changes in thermophysical properties of the fluid. A theoretical framework has been proposed to predict the pinning to bouncing regimes for drop impact over subcooled superhydrophobic surfaces. The postulated scaling relation and prediction models are in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

Subcooled nucleate flow boiling encompasses intricate simultaneous condensation and evaporation processes. It involves thin liquid microlayers trapped beneath growing bubbles, enabling high heat and mass transfer with fluxes exceeding 1 MW/m2. Understanding microlayer contribution to bubble growth is pivotal for developing reliable boiling models. Unlike previous studies, we account for condensation effects, important in the context of subcooled boiling regime, in estimating microlayer contribution by simultaneously obtaining microlayer dynamics from thin-film interferometry and whole-field temperature from rainbow schlieren deflectometry. We establish that the microlayer evaporation significantly influences bubble growth in flow boiling, contributing up to 60% (in growth phase) in the present study. [ABSTRACT FROM AUTHOR]

The effect of biphilic surfaces on subcooled flow boiling in a horizontal rectangular duct was investigated. Biphilic surfaces were created on an aluminum alloy substrate in the form of juxtaposed Hydrophobic (HPo) and Hydrophilic (HPi) transverse strips. In this regard, two different testing samples with strip widths of 10 and 18 mm were prepared, named pattern I and pattern II, respectively. Using Deionized Water (DIW), the experiments were performed with the two mentioned biphilic patterns and a plain surface. Finally, different cases were compared, and the results were interpreted. The results showed that the biphilic surfaces improve the Heat Transfer Coefficient (HTC) and cause boiling to be initiated at a lower wall temperature. In this regard, pattern I and pattern II represent 22 and 40% improvement in HTC, and boiling initiates 31 and 33.5 °C sooner compared to the plain surface, respectively. In addition, the experiments were also conducted with an Ethylene Glycol/Water mixture (EG/W) in the same manner. The results revealed that EG/W represents smaller HTC values for all cases and shifts the boiling points to higher wall temperatures compared to DIW. It is worth mentioning that the major amount of this HTC reduction is occurred in the single-phase area, in lower wall temperatures. [ABSTRACT FROM AUTHOR]

The precise design of heat exchangers in automobile air conditioning systems for more sustainable electric vehicles requires an enhanced assessment of CFD mechanistic models for the subcooled boiling flow of pure eco-friendly refrigerant. Computational Multiphase Flow Dynamics (CMFDs) relies on two-phase closure models to accurately depict the complex physical phenomena involved in flow boiling. This paper thoroughly examines two-phase CMFD flow boiling, incorporating sensitivity analyses of critical parameters such as boiling closures, momentum closures, and population balance models. Three datasets from the DEBORA experiment, involving vertical pipes with subcooled boiling flow of refrigerant at three different pressures and varying levels of inlet liquid subcooling, are used for comparison with CFD simulations. This study integrates nucleate site density and bubble departure diameter models to enhance wall boiling model accuracy. It aims to investigate various interfacial forces and examines the S-Gamma and Adaptive Multiple Size-Group (A-MuSiG) size distribution methods for their roles in bubble break up and coalescence. These proposed approaches demonstrate their efficacy, contributing to a deeper understanding of flow boiling phenomena and the development of more accurate models. This investigation offers valuable insights into selecting the most appropriate sub-closure models for both boiling closure and momentum closure in simulating boiling flows. [ABSTRACT FROM AUTHOR]

This study introduces a Bayesian spatiotemporal modeling approach to solve inverse heat conduction problems (IHCPs), employing penalized splines within a spatiotemporal forward model. The complexity and ill-posed nature of IHCPs, characterized by potential nonexistence, nonuniqueness, or instability of solutions, pose significant challenges for traditional methods. Addressing this, our study presents a spatiotemporal forward model that incorporates spatial, temporal, and interaction terms, accurately capturing the intricate dynamics inherent in IHCPs and using this information as a leverage to solve the inverse problem. We adopted a Bayesian inference framework for the subsequent parameter estimation problem and developed a Gibbs sampling algorithm to sample from the posterior distribution of the model's parameters, enhancing the estimation process. Through case studies on a one-dimensional (1D) heat simulation and a pool boiling experiment using multisensor thermocouple data for heat flux reconstruction, we demonstrate the model's superiority over traditional methods. The inclusion of the spatiotemporal interaction term significantly enhances model performance, indicating its potential for broader application in solving IHCPs. The application of this method in both simulated and real-world scenarios highlights its effectiveness in capturing the spatiotemporal complexities of IHCPs. This work contributes to the field by offering a robust methodology for addressing the spatial and temporal complexities inherent in IHCPs, supported by a comprehensive Bayesian inference framework and the use of a Gibbs sampling algorithm for parameter estimation. [ABSTRACT FROM AUTHOR]

• Boiling coefficient increased with nozzle inlet pressure and specific enthalpy. • Boiling coefficient ranged from 300 to 4000 in the investigated trans-critical region. • Modified HNB showed an accuracy of 3 % in predicting the nozzle flow rates. • Proposed method for determining saturation pressure was superior to constant value. A modified homogeneous non-equilibrium boiling approach (HNB) was proposed for high-fidelity modelling of the trans-critical flashing process in two-phase R744 ejector nozzles. In the modified approach, the method of determining the metastable liquid saturation pressure was improved by integrating the metastable liquid enthalpy. Experimental tests were conducted on two different nozzles to calibrate the lumped accommodation coefficient in the modified HNB. The calibration dataset consisted of 30 trans-critical test points, with the motive inlet pressure ranging from 7.5 MPa to 11.5 MPa and temperature varying from 21 °C to 45 °C. It was demonstrated that the boiling coefficient was strongly related to nozzle inlet pressure and specific enthalpy. The coefficient was therefore fitted as a function of the operating condition. The modified HNB with the fitted function was then validated against another set of test data composed of 29 test points. The results demonstrated that the relative errors of the nozzle mass-flow rates were within 3 %. Finally, the modified HNB with the improved metastable liquid saturation pressure was compared and discussed with the existing HNB approach in the literature. [ABSTRACT FROM AUTHOR]

The present investigation aims to study the comparative analysis of CNT, GO, and CNT + GO nanoparticle coatings on copper surfaces under a pool boiling situation. Coating on copper surfaces is performed using the dip coating method. Pool boiling experiments are conducted for all the coated surfaces at atmospheric pressure. Water is used as a working fluid. A comparison was made based on the coated surface characteristics and pool boiling behavior of the samples. The results show that CNT + GO coating on copper surfaces is better in terms of critical heat flux (CHF) and boiling heat transfer coefficient (BHTC). It is also observed that CHF and BHTC of the CNT + GO‐coated surface are 129.19% and 194.75% higher, respectively, compared to the bare copper surface. Bubble dynamics studies were also performed for all the samples. [ABSTRACT FROM AUTHOR]

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In this investigation, the performance of coolant in various operating conditions was examined through an energy analysis of experimental data. A novel method was introduced for presenting pool boiling test results, facilitating coolant performance assessment across distinct operational scenarios and enabling comparative energy analyses between transient and steady-state boiling. Leveraging principles of thermal science, distinct correlations were formulated to elucidate pool boiling phenomena in transient mode. analysis was based on experimental results from transient pool boiling tests conducted over predefined time intervals. analysis indicates a direct correlation between the heater's energy output and test duration. Notably, in a steady state, the energy rate produced as a result of Joule heating effects reached its maximum value, which is reflective of the extended duration of this state relative to transient state tests. Specifically, energy yield from the wire heater increased by 75% when the test duration was extended from 1s to 5s. Furthermore, extending duration to 10 s increased energy outputs by 62% and 186% compared to 5s and 1s durations, respectively. Performance decreases as a vapor film forms temporarily, before increasing and becoming nearly constant during film boiling. [ABSTRACT FROM AUTHOR]

A kettle reboiler uses the latent heat from the condensation of high-temperature and high-pressure steam in the tube to produce low-pressure saturated steam in the outer shell. The deposition of particles on the tube may change the boiling heat transfer mode from nucleate boiling to natural convection, thereby deteriorating the heat transfer performance of the kettle reboiler. Therefore, it is very important to explore the deposition characteristics of particles in the kettle reboiler. In this study, the RPI boiling model based on the Euler–Euler method is used to analyze the water boiling process on the surface of the tube bundle. The DRW model and critical adhesion velocity model based on the Euler–Lagrangian method are used to calculate the motion of particles during the boiling process and the deposition (rebound) behavior. The results show that the boiling of liquid water enhances the local flow velocity of the fluid, so that the maximum flow velocity appears around the near-wall region. The local high-speed flow disperses the particles in the wake flow of the tube bundle, which inhibits the impact of particles on the wall. As the particle size increases, the wall adhesion and fluid drag on the particles are weakened, and the gravity effect gradually becomes dominant, increasing the residence time of the particles in the tube bundle and the frequency of particle impact on the wall. The particle deposition ratio first decreases and then increases. Ultimately, most particles will be deposited in the low-speed area at the end of the tube bundle. [ABSTRACT FROM AUTHOR]

The Mn(III)-based oxidation of 1,3-indanedione (1) with 1,1-diarylethenes 2a–c effectively proceeded in boiling AcOH to produce 2,2-bis(vinyl)indanediones 5a–c and 1,2'-spirobi[indene]-1',3'-diones 6a–c via the formation of 2,2-bis(2-acetoxyethyl)indanedione 3 and acetoxyindeno[1,2-b]furan-4-one 4 intermediates. On the other hand, the Mn(III)-based aerobic oxidation of 1a with 2a at room temperature resulted in bis(endoperoxide) 8a and endoperoxypropellane 9a via the production of mono(endoperoxide) 7a. The plausible reaction pathways were also discussed. [ABSTRACT FROM AUTHOR]

Ebullition transports large amounts of the potent greenhouse gas methane (CH 4 ) from aquatic sediments to the atmosphere. River beds are a main source of biogenic CH 4 , but emission estimates and the relative contribution of ebullition as a transport pathway are poorly constrained. This study meets a need for more direct measurements with a whole-year data set on CH 4 ebullition from a small stream in southern Germany. Four gas traps were installed in a cross section in a river bend, representing different bed substrates between undercut and slip-off slope. For a comparison, diffusive fluxes were estimated from concentration gradients in the sediment and from measurements of dissolved CH 4 in the surface water. The data revealed highest activity with gas fluxes above 1000 ml m - 2 d - 1 in the center of the stream, sustained ebullition during winter, and a larger contribution of ebullitive compared to diffusive CH 4 fluxes. Increased gas fluxes from the center of the river may be connected to greater exchange with the surface water, thus increased carbon and nutrient supply, and a higher sediment permeability for gas bubbles. By using stable isotope fractionation, we estimated that 12-44% of the CH 4 transported diffusively was oxidized. Predictors like temperature, air pressure drop, discharge, or precipitation could not or only poorly explain temporal variations of ebullitive CH 4 fluxes. [ABSTRACT FROM AUTHOR]

A microwave discharge inside of a methane bubble in boiling water is modeled in a 0D approximation taking into account the change in the size of the plasma bubble. The process of quenching the reaction products after the bubble detaches from the electrode surface is also simulated. The working pressure is 1 atm. It is shown that the main reaction products are H2, CO2, and CO. The ratio of CO2 and CO concentrations depends on the ratio of the initial flows of water vapor and methane. The calculated concentrations of the main decomposition products of methane and water are in good agreement with experimental data. [ABSTRACT FROM AUTHOR]

The hypervapotron structure was considered to be a feasible configuration to meet the high heat-dissipating requirement of divertors in nuclear fusion devices. In this work, symmetric CuCrZr-based transverse microchannels (TMHC) and longitudinal microchannels (LMHC) with an integrated hypervapotron channel were proposed and manufactured, and subcooled flow boiling experiments were conducted using deionized water at an inlet temperature of 20 °C with a traditional flat-type hypervapotron channel (FHC) for comparison. The LMHC and TMHC obtained lower wall temperatures than the FHC for all conditions, and the TMHC yielded the lowest temperatures. The heat transfer coefficients of the LMHC and TMHC outperformed the FHC due to the enlarged heat transfer area, and the TMHC had the greatest heat transfer coefficient (maximumly increased by 132% compared to the FHC) because the transverse-arranged microchannels were conductive, promoting the convection and liquid replenishment ability by introducing branch flow between fins; however, the microchannels of the LMHC were insensible to flow velocities due to the block effect of longitudinal microchannels. The LMHC obtained the largest pressure drop, and the pressure drop for the FHC and TMHC were comparable since the transverse-placed microchannels had little effect on frictional pressure loss. The TMHC attained the greatest comprehensive thermohydraulic performance which might bring significant insight to the structural design of hypervapotron devices. [ABSTRACT FROM AUTHOR]

As an alternative to surgical excision and magnetic resonance-guided thermal high-intensity focused ultrasound ablation of uterine leiomyoma, this work was aimed at pilot feasibility demonstration of use of ultrasound-guided boiling histotripsy for non-invasive non-thermal fractionation of human uterine leiomyoma ex vivo. A custom-made sector ultrasound transducer of 1.5-MHz operating frequency and nominal f -number F # = 0.75 was used to produce a volumetric lesion (two layers of 5 × 5 foci with a 1 mm step) in surgically resected human leiomyoma ex vivo. A sequence of 10 ms pulses (P +/ P –/ A s = 157/–25/170 MPa in situ) with 1% duty cycle was delivered N = 30 times per focus under B-mode guidance. The treatment outcome was evaluated via B-mode imaging and histologically with hematoxylin and eosin and Masson's trichrome staining. The treatment was successfully performed in less than 30 min and resulted in formation of a rectangular lesion visualized on B-mode images during the sonication as an echogenic region, which sustained for about 10 min post-treatment. Histology revealed loss of cellular structure, necrotic debris and globules of degenerated collagen in the target volume surrounded by injured smooth muscle cells. The pilot experiment described here indicates that boiling histotripsy is feasible for non-invasive mechanical disintegration of human uterine leiomyoma ex vivo under B-mode guidance, encouraging further investigation and optimization of this potential clinical application of boiling histotripsy. [ABSTRACT FROM AUTHOR]

Nucleate pool boiling is known for its exceptional heat transfer coefficients, with the use of cavities further improving bubble nucleation and heat transfer rate. To promote this heat transfer enhancement technique, a thorough understanding of the influence of cavity geometry on single bubble dynamics is required. The influence of depth and radius of cylindrical and conical cavities on the bubble dynamics of nucleate pool boiling of R1234yf were numerically investigated. The cavity radius was varied between 50 and 400 μm and the cavity depth between 100 and 1000 μm at a fixed heat flux of 28 kW/m2. It was found that the maximum equivalent diameter prior to departure was constant for cavities with radii smaller than 120 μm, while it increased linearly when increasing the cavity radius further. Cylindrical cavities exhibited high stability regardless of cavity radius or depth whereas conical cavities showed a decrease in vapor retention with increasing cavity angle. During the necking phase, the bubble interface became pinned at the cavity edge, depending on conical cavity angle, implying that smaller radii allowed for enhanced surface rewetting. Conical cavities could be considered as cylindrical cavities when the cavity angle was less than a quarter of the interface contact angle. When translating the single cavity findings to cavity array design, cylindrical cavities were recommended as they allowed for stable bubble behavior. For increased nucleation zones and rewetting, a sub-critical radius was recommended. Wider cavities were recommended for high superheat conditions as larger bubbles could enhance bubble growth. [ABSTRACT FROM AUTHOR]

Tempeh is a fermented soybean food with high nutritional value, culinary versatility, and palatability. Its popularity is rising because it aligns with the trend towards sustainable and healthy plant-based diets. However, consumers have exhibited a strong preference for local ingredients over soy. Faba bean is a promising raw material in Scandinavia due to its high protein, dietary fiber, and phytochemical content. In this study, we evaluated the effects of soaking media (vinegar, water and sodium bicarbonate with or without lactic acid bacteria (LAB)) on boiling time and physicochemical properties of faba bean-based tempeh. We demonstrated that sodium bicarbonate, with and without LAB, significantly reduces the boiling time of faba beans (7–8 min), while beans soaked in vinegar and water with and without LAB require longer boiling times for tempeh production (>16 min). Texture analysis has revealed notable variations among the samples, with statistically significant differences (p < 0.05) observed across the majority of the measured attributes. Our study has demonstrated that faba beans are suitable for tempeh production and expand the sources of possible raw materials. However, further studies are needed to investigate consumers' preferences and expectations towards faba bean-based tempeh. [ABSTRACT FROM AUTHOR]

Flow boiling with dielectric coolant is not only a highly desirable approach for effective electronic cooling but is also notorious for its poor scalability. Most current flow boiling enhancement strategies are based on silicon substrates with footprint areas less than 1 cm2, which greatly limits their applications to large-size electronics. This study developed a scalable channel configuration to facilitate efficient flow boiling on large copper substrates (∼10 cm2), in which the channel walls are formed by porous pin-fin arrays. This type of hybrid capillary wall makes up for the limitation of conventional machining in creating intricate features, making it scalable and feasible for developing large-size, two-phase cold plates. Moreover, effective two-phase separation and sustainable film evaporation have been realized in the current work. As a result, the proposed structure achieved a 512% increase in heat dissipation when the heating area scales up 480% from the silicon microchannels with micro-pin-fin arrays. Experiments showed a base heat flux of 106.1 W/cm2 was dissipated over a heating area of 9.6 cm2 using the dielectric fluid HFE-7100 at a mass flux of 247 kg/m2 s. It outperformed most existing metallic flow boiling heat sinks using the same coolant at a similarly high coefficient of performance as small-size enhanced silicon microchannels. [ABSTRACT FROM AUTHOR]

Liver fibrosis is a hallmark of chronic liver disease which could lead to liver cirrhosis or liver cancer. However, there is currently lack of a direct treatment for liver fibrosis. Boiling histotripsy (BH) is an emerging non-invasive high-intensity focused ultrasound technique that can be employed to mechanically destruct solid tumour at the focus via acoustic cavitation without significant adverse effect on surrounding tissue. Here, we investigated whether BH can mechanically fractionate liver fibrotic tissue thereby exhibiting an anti-fibrotic effect in an animal model of liver fibrosis. BH-treated penumbra and its identical lobe showed reduced liver fibrosis, accompanied by increased hepatocyte specific marker expression, compared to the BH-untreated lobe. Furthermore, BH treatment improved serological liver function markers without notable adverse effects. The ability of BH to reduce fibrosis and promote liver regeneration in liver fibrotic tissue suggests that BH could potentially be an effective and reliable therapeutic approach against liver fibrosis. [ABSTRACT FROM AUTHOR]