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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]

Given that the onset of flow instability (OFI) and the negative slope steepness of the pressure drop characteristic curve (N-shaped curve) are key factors determining boiling flow system stability, this paper establishes a theoretical model suitable for analyzing the appearance of negative slope in the N-shaped curve. Combined with experimental data, the influence of different experimental parameters on the N-shaped curve is clarified. The results show that the negative slope steepness increases with the increase of inlet subcooling, and the influence of heat flux on the negative slope is relatively small. As pressure decreases, the negative slope becomes relatively accentuated. As the gravity level increases, the negative slope of the curve gradually slows down, and OFI appears at lower mass fluxes, indicating that hypergravity is beneficial for enhancing the stability of the boiling system and delaying the occurrence of boiling flow instability. In addition, the pressure drop prediction method and steps suitable for hypergravity environments have been constructed. This method simplifies the flow state components of the working fluid in the tube, and introduces parameters related to hypergravity and boiling. [ABSTRACT FROM AUTHOR]

This study investigates the boiling characteristics of graphene (GNP) nanofluids, graphene-copper (GNP-Cu) composite nanofluids, and graphene-iron (GNP-Fe) composite nanofluids with mass fractions of 0.001%, 0.002%, and 0.003%. The results indicate that GNP-Cu and GNP-Fe nanofluids can simultaneously enhance the critical heat flux (CHF) and heat transfer coefficient (HTC). Among different mass fractions, GNP-Cu nanofluids with a mass fraction of 0.003% exhibited the highest CHF and HTC. Through the observation of bubbles, the research elucidated that the presence of copper and iron elements is crucial in enhancing heat transfer. Based on the experimental results, this study modified the boiling curve equation of Rohsenow into a linear function. The modified model can predict the boiling curves of GNP-Cu, GNP-Fe, and GNP-Ag nanofluids at various concentrations. Furthermore, the experimental findings indicated a quadratic relationship between the boiling heat transfer coefficient and the heat flux in GNP, GNP-Cu, GNP-Fe, and GNP-Ag nanofluids. As a result, this study investigates the differences in heat transfer and bubble dynamics among GNP nanofluids modified with various metallic elements during boiling. It explores the underlying heat transfer mechanisms and proposes boiling curve equations that are applicable to a range of nanofluids. The findings suggest that acid-mixing treatment and metal-functionalization play a facilitating role in heat transfer of GNP nanofluids. Furthermore, nanofluids loaded with different metallic elements exhibit similar trends in their boiling curve equations. [ABSTRACT FROM AUTHOR]

In large-scale, high-heat industrial applications, surfaces obtained using efficient and cost-effective methods are highly desirable. In this paper, the surfaces are modified through two-step processes, i.e., a chemical etching process to grow CuO thin film on bare copper (Cu) surfaces, and then a Cu-TiO2 composite nanoparticle is deposited over the CuO thin-film copper surface through electrochemical deposition. The experiment is conducted on both the prepared surfaces and the bare Cu surface using deionized water as a boiling fluid. Results reveal that the prepared surfaces exhibit better pool boiling performance than the bare Cu surface due to improved properties like porosity and roughness. The critical heat flux and boiling heat transfer coefficient are found to have 61 and 72% enhancement, respectively, compared to bare copper surfaces. Bubble behavior during boiling is also captured and analyzed for all surfaces through a high-speed camera. [ABSTRACT FROM AUTHOR]

In this study, saturated pool boiling experiments were conducted on copper minichannel and flat surfaces at atmospheric pressure using water as the working fluid. The heat transfer performance was assessed through point measurements with a heater block, cartridge heaters, and thermocouples, as well as field measurements using a thin-foil heater and infrared thermography. Two copper minichannel surfaces with square cross sections of 1 mm (minichannel-1) and 2 mm (minichannel-2) side lengths were tested and compared to a flat surface. Minichannel-1 and minichannel-2 enhanced the critical heat flux (CHF) by 17% and 45%, respectively, and improved the heat transfer coefficient by 24–40% and 51–75%, respectively, compared to the flat surface. Minichannel-2 exhibited the lowest and most uniform boiling surface temperature, making it the best performer among the three. There was no significant change in departure frequency among the surfaces, and no significant change in departure diameter for the flat surface and minichannel-1. However, minichannel-2 had lower departure diameters due to its deeper channels, which prevented bubble coalescence and maintained low departure diameters. Additionally, minichannel-2 delayed vapor film formation by breaking it with its deeper fins, thereby improving CHF and slightly enhancing bubble dynamics. The enhancement in boiling heat transfer is primarily attributed to the increased surface area provided by the minichannels, with a minor contribution from improved bubble dynamics. However, the dominant factor in enhancing pool boiling heat transfer on minichannel surfaces is the increase in surface area. [ABSTRACT FROM AUTHOR]

This study introduces the first metal organic framework using ammelide as the organic ligand, showcasing stability in boiling water and high sensitivity in detecting dichromate ions. [ABSTRACT FROM AUTHOR]

The critical heat flux (CHF) is a vital parameter influencing the safety and efficiency of reactor cores. In this study, the Eulerian two-fluid model coupled with the extended wall boiling model in STAR-CCM+ was employed to simulate the departure from nucleate boiling (DNB) phenomenon in a 5 × 5 pressurized water reactor (PWR) fuel rod bundle channel with spacer grids under non-uniform heating conditions. The transition in boiling curves was used as the criterion of DNB occurrence, while the temperature distribution of rod surfaces was utilized for CHF location predictions. The predicted CHF value and CHF location exhibited good agreement with the experimental data. The deviation between calculated and experimental CHF values was within 15% and the deviation between predicted and experimental CHF locations was within one grid-to-grid span length. The results of this study suggested good prospects for the application of two-phase CFD model in predicting CHF in fuel assemblies with spacer grids. [ABSTRACT FROM AUTHOR]

Hexaconazole, a triazole insecticide, is widely used to control rust disease in Welsh onions. Residue levels of pesticides vary based on the cooking methods. Although studies on hexaconazole residue have involved vegetables such as cabbage, research on Welsh onion is limited. This study investigated the effect of different cooking methods on hexaconazole residues. Welsh onion was processed by common cooking methods such as stir-frying, boiling, and baking, and analyzed for pesticide residues using liquid chromatography with tandem mass spectrometry. The results showed that the removal rates of pesticides after cooking were 40.0–62.9% for stir-frying, 80.0–91.4% for boiling, and 51.4–77.1% for baking. Regardless of cutting thickness (0.8 cm or 5 cm), the reduction rate of pesticide residues increased with time during boiling. Increased reduction rates were also observed with increased time during baking. As stir-frying time increased, the residue amount increased due to water loss. However, the absolute amount of the pesticide decreased with increasing time. Therefore, the residue amount of hexaconazole in Welsh onion was reduced by various general cooking processes. These findings can provide a valuable foundation for research on Welsh onion processing, address consumer concerns about pesticide residues, and provide baseline data for risk assessments. [ABSTRACT FROM AUTHOR]

Enhancing critical heat flux (CHF) and heat transfer coefficient (HTC) by promoting the nucleation, growth, and departure of boiling bubbles has drawn significant attention owing to its wide applications. However, in‐depth understanding and comprehensive manipulation of under‐liquid bubble dynamics from in situ microscale perspectives remain challenging. Herein, in situ observations and analyses of the microsized boiling bubbles of ultra‐low surface tension fluorinated liquids (FLs) are conducted on the superaerophobic silicon surfaces with crisscross microchannels and selective nanowires. It is revealed that deep microchannels yet short nanowires enable ultrafast liquid spreading (<549.6 ms) and ultralow bubble adhesion (≈1.1 µN), while an appropriate spacing (240–600 µm) between microchannels minimizes the bubble departure time (<20.6 ms) due to timely coalescence. By verifying the above bubble dynamics principles through the collaborative enhancement of CHF and HTC, an optimized structure (microchannel depth ≈52.9 µm, microchannel spacing ≈362.9 µm, nanowire length ≈0 nm) is obtained and further implemented onto the exposed Si surface of a commercial CPU chip. Cooled by phase‐change of FLs, the average temperature of CPU maintains ≈64.9 °C even under extreme power loads (≈130 W), far below than those in conventional air‐cooling and water‐cooling operations. [ABSTRACT FROM AUTHOR]

When added to a pot of boiling pasta, a handful of salt grains can create a fascinating and varied pattern of deposits. In this study, we experimentally investigate this phenomenon by examining the deposits, focusing on the radial distribution of clusters of settling spherical particles in a quiescent viscous fluid at an intermediate Reynolds number. We demonstrate that the particle diameter d, the settling height H, and the injected particle volume V inj all influence the particles' radial spread. Additionally, the injection method significantly impacts the deposit's final morphology. The resulting deposit structure emerges from the sedimentation history of the particle cloud, reflecting a complex interplay of various physical mechanisms. [ABSTRACT FROM AUTHOR]

Although the dynamic van der Waals model has great potential in numerically simulating pool boiling, it is still limited to low liquid–vapor density ratios (about 10:1) due to the inherent thermodynamic inconsistency. This study proposes a thermodynamic consistency simplified dynamic van der Waals model to simulate pool boiling with large liquid–vapor density ratios. This model is based on the thermodynamic relationship associating the gradients of temperature and generalized chemical potential with the divergence of the reversible viscous stress tensor. A novel semi-discrete numerical algorithm that satisfies the thermodynamic consistency for this mathematical model is also proposed. The numerical results exhibit excellent agreement with that of analytical, validating the effectiveness and applicability of the proposed model for vapor–liquid coexistence. Compared to the original dynamic van der Waals model, the proposed model and algorithm can effectively reduce the spurious velocity at the vapor–liquid interface, breaking the limitations of low-density ratio and leading to stable simulation at higher-density ratios under low saturation temperatures. The approach is used to model pool boiling at low saturation temperatures with different wettability and liquid–vapor density ratios, and the saturation temperature significantly lower than reported in comparable literature (as low as 0.45 T c and the liquid–vapor density ratio is about 225:1). Compared to low liquid–vapor density ratios, larger liquid–vapor density ratios inhibit bubble coalescence, thereby suppressing the formation of large bubbles. In addition, larger density ratios more effectively maintain the shape of bubbles. [ABSTRACT FROM AUTHOR]

The use of environmentally friendly coolants with low surface tension in boiling applications holds great promise, and the implementation of micro/nanostructures is widely regarded as an effective strategy for enhancing boiling heat transfer. However, as a critical factor influencing the boiling process, the understanding of boiling bubble behavior on micro/nanostructured modified surfaces remains insufficient for the low surface tension fluids. SF-33, with its zero ozone depletion potential and extremely low global warming potential, is gradually gaining attention in the field of boiling as a representative low-surface-tension fluid. Herein, several copper heating surfaces with micro or micro/nanocomposite structures were fabricated using sintering copper mesh and thermal oxidation techniques. The bubble growth and departure phenomena during pool boiling of coolants SF-33 and de-ionized water on these micro/nanostructured surfaces were investigated and comparatively analyzed. The saturated pool boiling experiments were conducted at atmospheric pressure. It was observed that on smooth flat surface and sintered wire-mesh flat surface, SF-33 bubbles exhibited a faster growth rate, higher departure frequency, and smaller departure diameter. However, on the sintered wire-mesh flat surface with nanowires, de-ionized water bubbles demonstrated a higher departure frequency, while the growth rate and departure diameter were similar to those of SF-33 bubbles. In addition, it was found that the influence of microstructures on de-ionized water bubble behaviors is significantly lower than that of micro/nanocomposite structures, while for SF-33, increasing the microstructures alone can greatly affect bubble growth and departure, with further changes induced by the addition of nanostructures being relatively minor. [ABSTRACT FROM AUTHOR]

Owing to their ease of fabrication, oxide nanoparticle-containing nanofluids have been used in the majority of pool boiling investigations. Some investigations have reported a decline in boiling heat transfer. A significant increase in thermal conductivity was seen in the three-dimensional multi-walled carbon nanotube (MWCNT) nanofluids including extremely conducting nanoparticles, which are well-known for their favourable bulk domain heat transfer capabilities. Moreover, whereas many variables affecting the boiling point of nanofluids have been thoroughly investigated, the combined impacts of MWCNT nanoparticle ultrasonication duration and concentration have not yet received enough attention. The ultrasonication duration impact and concentration might have a major, even prevailing, impact on the surface characteristics of the depositing layers, particularly for MWCNTs with an extremely high aspect ratio. These qualities therefore have an impact on the boiling behaviours of MWCNT-based nanofluids. This work used pool boiling tests with heated copper regions in a pool of a water-based nanofluids in an environment of MWCNTs to show the consequences of concentration and ultrasonication duration. The impact of the deposition coatings created by the different MWCNTs on the boiling heat transfer features was investigated by describing the surface features of the boiling spherical surfaces through a series of tests. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the present study, to address the issue of flow rate instability in the flow boiling experimental system, a flow rate adaptive control system is developed using a single-neuron PID adaptive algorithm, enhanced with the whale optimization algorithm (WOA) for parameter tuning. A recursive least-squares online identification method is integrated to adapt to varying operating conditions. The simulation results demonstrate that in step response the WOA-improved single-neuron PID significantly mitigates the overshoot, with a mere 0.31% overshoot observed, marking a reduction of 98.27% compared to the traditional PID control. The output curve of the WOA-improved single-neuron PID closely aligns with the sinusoidal signal, exhibiting an average absolute error of 0.120, which is lower than that of the traditional PID (0.209) and fuzzy PID (0.296). The WOA-improved single-neuron PID (1.01 s) exhibited a faster return to a stable state compared to the traditional PID (2.46 s) and fuzzy PID (1.28 s). Finally, the effectiveness of the algorithm is validated through practical application. The results demonstrate that, compared to traditional PID and single-neuron PID algorithms, the WOA-improved single-neuron PID algorithm achieves an average flow stability of 9.9848 with a standard error of 0.0914394. It exhibits superior performance, including faster rise and settling times, and higher stability. [ABSTRACT FROM AUTHOR]

Often referred to as a law, principle, norm, or rule, reciprocity can be defined as a state or condition of free interchange or mutual responsiveness. This paper considers the importance of reciprocity in organisational settings while identifying three reciprocal exchange behaviours of which leaders should be aware. A Socratic dialogue using the Nelson/Heckmann approach is adopted as a research method, promoting interpersonal sensitivity and stimulating conceptual understanding among participants. The primary methodological concern lies in the axiological field of philosophy, which addresses the nature of value and what is intrinsically worthwhile. This dialogue involves three middle management leaders reflecting on their reciprocal interactions, leading to multiple questions about what is valued in an organisational context. Adopting an inductive content analysis approach, which utilises abstraction to group and reduce data, three key themes emerge from the dialogue transcript: the importance of “small gestures,” “safety and threat,” and “not keeping count.” One conclusion is that from an organisational leadership perspective, “generalised” reciprocal exchange behaviours can create the “durable ties” needed for balanced and thriving organisations. [ABSTRACT FROM AUTHOR]

Copyright of Dirasat: Human & Social Sciences is the property of University of Jordan and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

Aquatic sediments represent a key component for understanding CH4 dynamics and emission to the atmosphere. Once produced in the sediments, CH4 is released either by diffusion at the sediment–water interface or by bubbling out to the atmosphere when total gas pressure in the sediment exceeds local ambient pressure due to high CH4 production. Although bubbling is one of the dominant CH4 emission pathways in lakes, direct measurements of this flux are hampered by its high spatiotemporal variability and methodological limitations. Here, we develop a conceptual approach to quantify CH4 production in lake sediments and particularly its release as bubbles based on simple measurements of bubble gas content and depth. Its main assumptions were empirically tested using > 200 long‐term bubble trap deployments collected from 4 temperate lakes. We then applied the developed methodology to a suite of 408 Canadian lakes to produce the first standardized large‐scale assessment of lakes CH4 ebullitive flux during summer. Our results show that lake sediments produced CH4 at a median rate of 3.3 mmol m−2 d−1 (ranged from 0.2 to 11.8 mmol m−2 d−1), releasing 33% via ebullition to the atmosphere. These rates are remarkably similar in magnitude to other regional estimates in the literature. Moreover, our approach revealed that catchment slope was an important determinant of both the lake‐wide ebullitive fluxes and the fraction of sediment CH4 production released as bubbles. [ABSTRACT FROM AUTHOR]

This study investigates the effects of using laser-textured surfaces in boiling heat transfer during cooling fluid flow in a minichannel. Several laser-textured surfaces, varied in roughness, were created on the heated plate surface that contacted FC-72 during flow in a single minichannel. Infrared thermography was used to measure temperature changes on the untextured side of the plate, while two-phase flow patterns were observed through a glass pane. Three vibration-assisted laser surface textures, previously investigated by the authors, and five novel laser surface textures were tested experimentally. The results were presented as relationships between heated wall temperature, heat transfer coefficient and distance along the minichannel, boiling curves, and flow patterns. The main interest of the authors was to provide a comparative analysis of the heat transfer results at the same value of heat flux supplied to the minichannel heated wall when either a laser-textured surface or a smooth base one was applied. It was noticed that the use of the 90-degree dense grid pattern type 2 (shallow) surface in the research helped achieve the highest local heat transfer coefficient in the subcooled boiling region compared to other surfaces tested. Furthermore, the 90-degree dense grid pattern type 1, characterised by larger maximum depth and height surfaces, performed best in the saturated boiling region. The results obtained for the laser-textured heated plate surface were compared to those collected for the smooth base heated plate surface, generally indicating an intensification of heat transfer processes in boiling heat transfer during FC-72 flow in a minichannel. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the promotion of linoleic acid (OLA)-induced myofibrillar protein (MP) oxidation by boiling treatment. The effect of the boiling treatment on grass carp MP oxidation induced by OLA was investigated. The total sulfhydryl content, fluorescence intensity, and amino acid content were reduced with the increasing OLA concentration after the boiling treatment, while the boiled oxidized MP's carbonyl content (4.76 ± 0.14 nmol/mg) was 2.14 times higher than that of the native MP (2.22 ± 0.02 nmol/mg) at an OLA concentration of 10 mM. Additionally, the secondary structure of MP became more disordered, shifting from an α-helix to random coils and β-turns. When the concentration of OLA was higher than 5 mM, both the surface hydrophobicity and water holding capacity (WHC) decreased with the increasing OLA concentration. Furthermore, the boiling treatment led to a reduction in immobile water and an increase in free water content in the MP gel. These findings establish a theoretical basis for regulating MP oxidation to improve fish quality during boiling. [ABSTRACT FROM AUTHOR]

Boiling noise is a mode of energy release accompanying bubble dynamics, and its noise characteristic is a potential recognition mode of bubble behavior. In this paper, the angular spectrum method is used to calculate the transient sound field and analyze the noise characteristics induced by single bubble deformation and the classical nucleation growth process theoretically. The relationship between the induced noise intensity and the vibration parameters of the bubble surface is obtained quantitatively. It is shown that bubble volume oscillations and deformation are the main sources of noise, while bubble nucleation-induced noise has limited contribution to noise, and the high-frequency information contained in the bubble surface motion plays a key role in the noise intensity. In addition, in order to analyze the noise characteristics induced by boiling bubbles, a boiling correction is introduced based on the Kirkwood–Bethe (K-B) equation. [ABSTRACT FROM AUTHOR]

It is crucially important to understand the dynamics of flash boiling bubbles of liquid fuels in order to achieve optimal fuel spray and mixing performance in realistic combustion engines. In this study, a modified pseudo-potential lattice Boltzmann method was adopted to capture the dynamics of flash boiling bubbles of liquid ammonia. The critical conditions for the flash boiling state of liquid ammonia were determined using isothermal depressurization techniques. Meanwhile, the evolutions of bubble clusters were investigated, allowing for bubble deformation, coalescence, and collapse in different flash boiling stages. The results show that the evolution of flash boiling bubble clusters presents two main stages, i.e., the early rapid expansion stage and the later slow expansion stage, and both stages are highly sensitive to temperature variations. Low-temperature environments can intensify the competition between bubble coalescence and collapse events, thereby changing the density, pressure, and velocity distribution and delaying the transition of bubbles to the eventual equilibrium state. In addition, the evolution of bubble clusters conforms to the Ostwald ripening mechanism, where large bubbles absorb smaller bubbles, promoting the formation and propagation of pressure waves in liquid ammonia. These pressure waves not only disturb the surrounding fluid to form vortices but also cause significant deformation of adjacent bubbles, thereby affecting the overall efficiency of flash boiling processes. [ABSTRACT FROM AUTHOR]

Flow boiling demonstrates superior heat transfer performance and holds significant potential for thermal management applications. In this study, the great effects of aspect ratios of mini-channel on flow boiling heat transfer are reported by the numerical simulation method. Regarding the heat transfer coefficient (HTC), a boiling number threshold of 5.0 × 10−4 is obtained. Below this value, bubble detachment is not yet constrained by the channel, reducing the dry patches and providing better heat transfer at larger aspect ratios. Above this threshold, boiling becomes more intense, bubble size increases, making detachment easier in smaller aspect ratios, which show superior heat transfer performance. For the critical heat flux (CHF), at a flow rate of 0.1 m/s, the CHF for smaller aspect ratios is 77.78% higher than for larger aspect ratios. As the flow velocity increases, inertial forces begin to dominate bubble behavior, reducing the influence of channel size effects, and the differences in CHF gradually decrease. When the flow velocity exceeds 0.5 m/s, bubble behavior becomes similar, and the difference in CHF drops to less than 10%. This research highlights key parameters for optimizing mini-channel design, promoting the refinement and development of mini-channel structures. [ABSTRACT FROM AUTHOR]

The unexpected presence of microbubbles in microfluidic systems typically results in performance degradation owing to their ability to obstruct fluidic pathways, causing pressure fluctuations or shear force variations. To develop or enhance undesired bubble-removal strategies, a solid understanding of the fundamental physics governing the bubble-removal processes is essential. In this context, the present study aims to thoroughly investigate the detachment dynamics of different-sized bubbles, ranging in volume from 3 to 75 μL, from a hydrophobic surface fully submerged in a liquid pool while being subjected to direct current electrowetting (DC EW) actuation. From systematic experimental data on the temporal variations in the base radius of retracting bubbles of different volumes subjected to varying DC EW actuations, empirical relationships between detachment process characteristics (e.g., threshold voltage for bubble detachment and detaching time) and physical factors (e.g., bubble volume and applied voltage) can be determined. These relationships are compared with predictions derived from scaling analysis. The findings will provide valuable insight into the elimination of unwanted bubbles in microfluidic systems for biomedical applications and the rapid removal of bubbles to improve heat transfer rates in pool boiling for thermal management applications, including heat exchangers and cooling systems. [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]

Inadequate adhesion between the multi-walled carbon nanotube (MWCNT) and the substrate's surface, which will raise the intermediate obstruction, is reported to be a key issue for MWCNT coatings over metallic substrates in the published literature. By utilizing an intermediary layer, the adherence between the metallic substance and the CNT may be strengthened. Emphasis on boiling pools of micro-nano-porous (nanopores on micropores) coverings, particularly MWCNTs on micropores, is currently limited. Two nanocomposites (Cu–Cu) intermediate layers were deposited between the CNTs and a foundation polished metal surface in the current study to increase the bonding between the CNTs and the Cu foundation. Moreover, a three-stage sintering process is used to improve the adhesion between the Cu–Cu–MWCNTs layer and the metallic substrate. The pool boiling of DI water was experimentally investigated with respect to heat transport, bubble behavior, and critical heat flux. The Cu–Cu–MWCNTs-coated substrate achieved the highest heat transfer augmentation and critical heat flux of 374 % and 116 %, respectively, in comparison to a smooth bare surface. With the surface coated with Cu–Cu–MWCNTs, the early signs of nucleate boiling were seen. Highest critical heat flux for the Cu–Cu–MWCNTs-coated substrate was achieved by delayed dryout owing to better rewetting nature of the drier area beneath the created vapor bubble. [ABSTRACT FROM AUTHOR]

The nucleation and growth of bubbles on homogeneous wetting surfaces have been extensively studied, but the intricate dynamics on hybrid wetting surfaces remain under-explored. This research aims to elucidate the impact of hybrid wettability on pool boiling heat transfer efficiency, specifically under downward-facing heating conditions. To this end, a series of hybrid wettability surfaces with varying hydrophilic and hydrophobic configurations are meticulously fabricated and analyzed. The study reveals distinctive interfacial phenomena occurring at the boundary between hydrophilic and hydrophobic regions during the boiling process. Experimental results indicate that surfaces with a higher proportion of hydrophilic to hydrophobic interfaces exhibit reduced superheat requirements and enhanced boiling heat transfer coefficients for equivalent heat flux densities. Furthermore, the rewetting characteristics of hybrid wettability surfaces are identified as pivotal factors in determining their critical heat flux (CHF). This investigation underscores the potential of hybrid wettability surfaces to optimize pool boiling heat transfer, offering valuable insights for the design and en-hancement of heat exchangers and other thermal management systems. [ABSTRACT FROM AUTHOR]

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]

The development of enzymes with high-temperature resistance up to 100°C is of significant and practical value in advancing the sustainability of industrial production. Phytase, a crucial enzyme in feed industrial applications, encounters challenges due to its limited heat resistance. Herein, we employed rational design strategies involving the introduction of disulfide bonds, free energy calculation, and B-factor analysis based on the crystal structure of phytase APPAmut4 (1.90 Å), a variant with enhanced expression levels derived from Yersinia intermedia, to improve its thermostability. Among the 144 variants experimentally verified, 29 exhibited significantly improved thermostability with higher t1/2 values at 65°C. Further combination and superposition led to APPAmut9 with an accumulation of five additional pairs of disulfide bonds and six single-point mutation sites, leading to an enhancement in its thermostability with a t1/2 value of 256.7 min at 65°C, which was more than 75-fold higher than that of APPAmut4 (3.4 min). APPAmut9 exhibited a T50 value of 96°C, representing a substantial increase of 40.9°C compared to APPAmut4. Notably, approximately 70% of enzyme activity remained intact after exposure to boiling water at 100°C for a holding period of 5 min. Significantly, these advantageous modifications were strategically positioned away from the catalytic pocket where enzymatic reactions occur to ensure minimal compromise on catalytic efficiency between APPAmut9 (11,500 ± 1100/mM/s) and APPAmut4 (12,300 ± 1600/mM/s). This study demonstrates the feasibility of engineering phytases with resistance to boiling using rational design strategies. [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]

The experiment used oil-tea camellia meal as the raw material and extracted saponins using the inner ebullition method. To improve the extraction rate of tea saponin from oil-tea camellia meal, through the single factor test combined with the Plackett-Burman (PB) test, three key factors that significantly affected the extraction rate of tea saponin were obtained: The concentration and dosage of desorption agent, the time of extraction. Then, according to the Box-Behnken (BBD) central combination design principle, the effects of three main factors on the extraction rate of tea saponin were analyzed and evaluated. This study indicated that the theoretical extraction rate of tea saponin could reach 15.19%, when the concentration of ethanol was 85%, the amount of desorption was 25 mL, the desorption time was 30 min, the solidliquid ratio was 10 mL/g, the extraction time was 15 min, and the extraction temperature at 90 °C. The actual extraction yield of tea saponin was 15.11%, the relative error between the extraction yield and the theoretical value predicted by the model was -0.53%. The study indicates that the extraction process established in this experiment is feasible and can provide theoretical reference for the comprehensive development and utilization of oil-tea camellia meal. [ABSTRACT FROM AUTHOR]

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Inland aquatic systems, such as reservoirs, contribute substantially to global methane (CH4) emissions; yet they are among the most uncertain contributors to the total global carbon budget. Reservoirs generate significant amounts of CH4 within their bottom sediment, where the gas is stored and can easily escape via ebullition. Due to the large spatial and temporal variability associated with ebullition, CH4 fluxes from these aquatic systems are challenging to quantify. To address these uncertainties, six different water storage reservoirs, with average flux rates ranging between 20 and 678 mg CH4 m−2 d−1, were hydro‐acoustically surveyed using a previously established technique to investigate the spatial variability of free gas stored at the sediment surface that could be released as bubbles. Sediment samples and vertical profiles of temperature and dissolved oxygen were also collected to understand their respective influences on sediment gas formation. We found that the established relation used to determine sediment gas storage via the sonar technique, which relied solely on acoustic backscatter (Svmax), tended to underestimate gas storage in shallower, siltier sediment zones and overestimate gas storage in coarser (>2 mm) sediment zones. In response, we introduce an improved model, incorporating gas and sediment type as correction factors for gas attenuation effects on Svmax values. The extended model is able to elucidate patterns within the gas volume data, revealing clearer trends across different sediment types. This research provides valuable data and methodological insights that can enhance the accuracy of greenhouse gas modeling and budget assessments for reservoirs. Plain Language Summary: Inland aquatic systems, like reservoirs, contribute substantially to greenhouse gas emissions, but these systems comprise the most uncertain components of the CH4 budget. Reservoirs can produce significant amounts of CH4 in submerged sediments, which escape slowly through diffusion and quickly through bubbling. However, accurately measuring CH4 emissions from reservoirs is difficult due to significant variability in bubbling patterns over space and time. To better understand these patterns, we surveyed six reservoirs using an established underwater sonar technique to explore the spatial variability of free gas stored in sediments, which could bubble up. We also collected sediment samples and measured dissolved oxygen and temperature at various water depths to study their influence on sediment gas formation. We found that the previously established sonar model used to obtain the amount of gas in the sediments tended to underestimate gas storage in shallower, siltier areas and overestimate it in larger‐grained sediment zones. In response, we introduced a refined model that incorporates gas fraction and sediment type to correct for gas attenuation effects on the sonar output. This extended model clarifies gas volume patterns across sediment types. Our study offers valuable data and methodological insights to refine greenhouse gas modeling and budget assessments for reservoirs. Key Points: Hydroacoustic models relying solely on backscatter underestimate gas in shallow, silty sediments and overestimate in larger (>2 mm) onesAn extension to the current model incorporates gas fraction and sediment type to improve gas predictionsBubble plume mapping reveals ebullition hotspots are tied to gas storage, bottom temperature, dissolved oxygen, and sediment type [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]

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]

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]

In order to research the process of boiling occurring on a porous surface, a model of multiple blocks was developed. The mathematical basis of these blocks is the lattice Boltzmann method in combination with heat transfer equation. The reported complex allows one to obtain the boiling curves for various wall superheats and to find the optimal parameters of a porous heater in terms of heat transfer enhancement. The porous heater structure is specified as a skeleton of square metal heaters located in the lower part of the computational domain. The calculations were performed for the following parameters of the porous heater structure: different number and size of the metal heaters, different distances between them in horizontal and vertical directions, regular and asymmetric packing of the heaters. Using the developed numerical model, parametric studies of the boiling process on porous heaters with different parameters of the porous skeleton were carried out and phase pictures of such a process were obtained. It was shown that the heat transfer coefficient on a porous heater is 3–7 times greater than that on a smooth heater, and depends on the number of heater elements, their size, and location. The results showed a significant advantage of the porous heaters with greater critical heat flux at higher wall superheats compared to that on the smooth surface. [ABSTRACT FROM AUTHOR]

The results of an experimental study on critical heat fluxes (CHF) during the nucleate boiling of the HFE-7100 dielectric liquid in horizontal layers of different heights at atmospheric pressure are presented. The existence of a critical layer height has been established. In layers above the critical layer height, a hydrodynamic boiling crisis occurs; in thinner layers, a surface drying crisis occurs. At a layer height equal to the critical value, a dry spot first appears, followed by transition boiling, which gradually spreads to the entire heating surface. In these experiments, the critical layer height was equal to 6 mm. In a layer of liquid with a critical layer height of 6 mm, a two-dimensional Taylor instability was observed in the transition boiling mode when the ratio of the diameter of the "vapor jets" to the distance between them, as well as the void fractions in the layer (~π/16), corresponded to the main provisions of the Zuber theory. The calculation of CHF using the relations of Zuber's theory, when approaching the crisis from the transition boiling side and taking into account the real geometric dimensions, aligns well with the experimental results. [ABSTRACT FROM AUTHOR]

To date, using biphilic surfaces is one of the most promising methods for enhancing heat transfer and critical heat flux during boiling simultaneously. However, most of studies on the effect of biphilic surfaces on boiling performance have been carried out under atmospheric pressure conditions. In this context, the issues of heat transfer enhancement and stabilization of the boiling process at subatmospheric pressures are particularly critical due to the interesting characteristics of boiling heat transfer and bubble dynamics at subatmospheric pressures and their practical significance including aerospace applications. This paper investigates the effect of the pitch size between hydrophobic spots on a biphilic surface on heat transfer and bubble dynamics during boiling at subatmospheric pressures (from 11.2 kPa up to atmospheric pressure). The data analysis using infrared thermography demonstrated that the maximum heat transfer rate was achieved on a surface with a uniform pitch size (6 mm) at all pressures. In this case, the heat transfer enhancement, compared a bare surface, reached 3.4 times. An analysis of the departure diameters of bubbles based on high-speed visualization indicated that the optimal configuration of the biphilic surface corresponds to the pitch size equal to the bubble departure diameter. Using high-speed visualization also demonstrated that an early transition to film boiling was evident for configurations with a very high density of hydrophobic spots (pitch size of 2 mm). [ABSTRACT FROM AUTHOR]

The parameters of the coolant moving in the channel between the fuel elements in the WWER-1200 core with a design steam content of 0.1 at the outlet are determined. The corrosion of the outer surface of these elements is modeled taking into account the heat and mass exchange between the near-wall layer of the coolant flow (with a thickness of the order of the thickness of the evaporating microlayer under the steam bubble) and its core. It is found that the concentration of ammonia in the near-wall layer of the flow is 0.35 of its concentration in the flow core, and this concentration level is typical of the upper half of the core. A formula is proposed for calculating the thickness of the oxidized layer of the outer surface of the fuel elements taking into account the concentration of oxidizers in the near-wall layer of the coolant flow. An increase in the thickness of the oxidized layer due to the effect of boiling is estimated at 30% compared to the thickness observed upon completion of operation during four annual cycles without boiling. [ABSTRACT FROM AUTHOR]

The paper presents the results of investigation into the crisis heat transfer in subcooled water boiling in macro-, mini-, and microchannels without coating and with porous coating. The equation for calculating the critical thermal load (CTL) in macro-, mini, and microchannels without coating is based on the analysis of arrays of experimental data obtained in investigating critical heat flux in subcooled water boiling in wide ranges of diameters, pressures, mass velocities and vapor contents. The calculation of the critical thermal load during boiling in a channel with porous coating has been conducted according to the previously developed formula for a horizontal 8-mm-diameter tube with a one-side heating. A porous coating in a macro-channel results in an almost threefold CTL rise. For a microchannel with a porous nanoparticle coating, CTL, at comparable mass velocities, is 1.5 times higher than without coating. The suggested equations for both channels without coating and channels with a porous coating describe the experimental data on critical thermal loads in macro-, mini-, and microchannels in the considered ranges of regime parameters with a deviation of no more than 30%. [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]

Hydrophobic tool surfaces have become a hot topic in recent years due to their significant advantages such as anti-adhesion and friction reduction. However, enhancing hydrophobicity would inadvertently decrease the Leidenfrost point of droplets, which diminishes the heat transfer efficiency and compromises manufacturing quality. This issue presents a considerable challenge and underscores the critical need to understand the boiling dynamics when droplets encounter heated hydrophobic surfaces. Herein, we propose a kind of textured hydrophobic tool surface based on laser processing and hydrophobic coating technology, which could achieve gentle film boiling across a wide temperature range. The raised micropillars protect hydrophobic coating with excellent abrasion resistance and stabilizes the droplets in the gentle film boiling regime under harsh conditions. The primary rationale behind this advancement is the reduction in the critical temperature for film boiling and the elevation of the critical temperature for droplet rebound. We have developed a predictive model for the Leidenfrost point, which has been experimentally validated to determine the wall temperature necessary for achieving the gentle film boiling regime. In addition, we found that the textured hydrophobic surface can still inhibit the bouncing and spreading of droplets at high temperatures. This study not only deepens our understanding of the effects of droplets on heated surfaces but also has the potential to improve manufacturing performance by consistently maintaining the hydrophobic properties of tool surfaces during cutting operations. [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]