Search Results (107)

This study proposes a self-condensing water-electrode plasma device in which ambient water vapor is condensed on a cooled needle-tip electrode within a strong electric-field region, forming continuously renewed water droplets, Taylor cones, or water-film interfaces that participate in the discharge process. The effects of ambient humidity, needle-tip temperature, and applied voltage on the self-condensation behavior were investigated. The discharge modes at different applied voltages and discharge gaps, the generation of reactive species, and the inactivation efficacy against Staphylococcus aureus were also analyzed. The results showed that increasing ambient humidity, decreasing the needle-tip temperature, and increasing the applied voltage all promoted water condensation at the needle tip. The electric field shortened the droplet formation time and reduced the droplet detachment size. As the applied voltage increased, the device sequentially underwent water condensation, electrospray, stable Taylor-cone, water-film discharge, and bare-electrode discharge stages, while the boundary voltage of each stage increased with the discharge gap. The ozone concentration remained below the instrument’s limit of detection during discharge with the self-condensing water electrode, whereas hydroxyl-radical generation was significantly enhanced. Compared with a conventional metal electrode, the self-condensing water electrode exhibited greater inactivation of S. aureus at the same applied voltage, with a more pronounced advantage under low-voltage conditions. These findings demonstrate that introducing a self-condensing water interface can regulate the local discharge morphology and reactive-species composition, providing a new strategy for developing low-temperature plasma sterilization technologies with low ozone production and high bactericidal activity. Full article

The performance of coatings, corrosion barriers, photocatalysts, and tribological materials is greatly influenced by in situ surface properties, requiring highly sensitive and reproducible operando surface characterization methods. We previously developed a temperature-programmed photoelectron emission (TPPE) method to clarify electron transfer behavior on light-irradiated metal surfaces. TPPE is sensitive to surface temperature and prior chemical exposure, which affect the total photoemitted electron count (N_T), the photothreshold, and the activation energy derived from Arrhenius plots of N_T obtained during heating–cooling cycles. This study examines the reproducibility of TPPE data and the TPPE mechanisms for Cu₂O/Cu surfaces subjected to mechanical abrasion, cleaning, plasma treatment, and subsequent immersion in organic liquids. The resulting Arrhenius plots reveal both positive and negative activation energies, depending on the treatment conditions. Negative activation energies during cooling are associated with photoredox-mediated emission. TPPE is attributed to oxygen vacancies within the Cu₂O surface layer, which is interfaced with metallic Cu, serving as a direct probe of these vacancy-related states. The TPPE characteristics (N_T intensity and activation energy) following exposure to various polar and nonpolar organic molecules (e.g., acetone, toluene, hexane, and ethanol) correlate with the electronic properties of these vacancies, consistent with previous observations for ambient air, alcohol, and water vapor exposure. Under illumination, Cu₂O vacancy states enhance photocarrier extraction (electrons and holes) and accelerate surface redox reactions within adsorbed thin films, thereby improving photocatalytic performance. Notably, the solvent’s reciprocal dielectric constant significantly influences TPPE, indicative of electrostatic surface–solvent interactions. Finally, the TPPE mechanism is discussed in the context of antiviral inactivation at the metallic copper–environment interface. Full article

This study explores the multifunctional properties of Ni nanoparticles obtained by laser ablation in liquid, with emphasis on the potential use of these nanoparticles in different applications such as cooling fluids or photoelectrochemical ones. The Ni nanoparticles were synthesized by the laser ablation in liquid technique using an Nd-YAG laser and ultrapure water as liquid. The structural, dimensional, morphologic, and stoichiometric characterizations of the nanoparticles were performed using different techniques such as transmission electron microscopy (TEM), energy dispersive X-ray (EDS) and dynamic light scattering spectroscopy (DLS). Nickel nanoparticles with sizes ranging from 5 to 15 nm in diameter were obtained. The experimental measurements were performed to determine the thermal conductivity and viscosity of the obtained nanofluids, essential parameters in the evaluation of the cooling fluid performances. Loading TiO₂ thin films with Ni nanoparticles led to the enhancement of the photoelectrochemical water splitting properties of TiO₂ thin films, the Ni nanoparticles acting on the collecting, transferring and separating the photogenerated charges and ultimately improving the overall anodic and cathodic efficiencies. The results obtained can contribute to the development of innovative, multifunctional solutions based on non-precious metals for cooling and water splitting systems used in industrial, electronics and other applications. Full article

To advance the goals of carbon peaking and carbon neutrality alongside the global energy transition, energy conservation and carbon reduction in refrigeration and air-conditioning systems have garnered widespread attention. Dew-point evaporative cooling (DPEC) represents a promising energy-efficient cooling technology, whose performance is strongly governed by the water supply strategy. This study presents a systematic comparison of falling-film and atomization water supply modes on a counter-flow DPEC test bench featuring 3D-printed palm fiber filament walls. Experiments were conducted over inlet air temperatures of 32–50 °C, velocities of 1.3–4.0 m/s, and a range of water supply temperatures. The results demonstrate that the falling-film mode yields 15–25% higher dew-point efficiency than the atomization mode under baseline operating conditions. Water supply temperature (15–30 °C) exerts a negligible influence on falling-film cooling performance. The hybrid falling-film–atomization mode achieves the highest cooling capacity in the medium-to-low air velocity range, with a maximum wet-bulb efficiency of 1.15, while the falling-film mode yields the highest COP of up to 2.2. These findings offer experimental guidance for optimizing water supply strategies in fiber-wall DPEC systems. Full article

Abrasive flow machining (AFM) is an effective finishing process for complex internal surfaces, particularly cavities, intersecting holes, and micro-channels that are difficult to access using conventional tools. However, when low-viscosity abrasive media is used (here defined, relative to conventional putty-like viscoelastic AFM carriers (with apparent viscosities of 10³–10⁵ mPa·s), as a water-based slurry with an apparent viscosity below 300 mPa·s over the operating shear-rate range), unfavorable flow conditions during the initial polishing stage can induce local over-polishing, erosion depressions, stepped patterns, and cavitation pits, resulting in non-uniform surface quality. The relationship between these flow behaviors and polishing defects remains insufficiently understood. To address this issue, this study investigates the AFM process applied to turbine blade film cooling holes through combined experimental and numerical approaches. The observed defects include erosion depressions, stepped surface patterns, and cavitation pits. The effects of abrasive injection pressure, flow velocity, hole geometry, abrasive viscosity, and particle size on defect formation are systematically examined. The results show that the initial abrasive filling level strongly affects defect distribution by altering the evolution of shear fields and void regions within the hole. Experimentally, at high Reynolds numbers (Re > 2 × 10⁴), intensified local shear and cavitation promote defect formation, while a moderate inclination angle (45–60°) and a higher aspect ratio (>8) are favorable for polishing uniformity. Complementary numerical simulations further indicate that smaller abrasive particles (<5 μm) and a moderate abrasive viscosity (~60 mPa·s) are predicted to improve polishing uniformity. This study clarifies the fluid-dynamic origin of polishing defects in film cooling holes and provides process guidance for suppressing local over-polishing, cavitation, and uneven material removal. Full article

By itself or combining with other cooling technologies, the dew point indirect evaporative cooler (DIEC) will be the preferred solution for cooling buildings. However, there are still some gaps in the research on DIEC performance, one of which is that 3-D (3-dimensional) models and methods are not widely used to comprehensively indicate the cooling mechanism. Most of the available numerical methods adopted 1-D or 2-D models. Existing 3-D models and methods either ignore the water film and plate or are so complicated in the grid system and numerical calculation induced by huge size differences among calculation regions that their attractions are weak. A novel simplified numerical method for DIEC performance is first suggested in this paper, and then, its validity and more efficiency than an existing 3-D numerical method are verified with the help of experimental data and numerical results. Finally, the effects of structure and operating parameters on the performance of a plate DIEC are analyzed by this present method and COMSOL Multiphysics 6.3 software, especially η/η₀ (the reinforcement factor), which was innovatively introduced. Similar results to those of existing literature were obtained, which further indicated the practicability of this simplified method. In the conditions involved in this paper, a channel length of 1.5 m, a width of 4 mm, Re_in (the Reynolds number at the inlet) of 1483, and a (the air ratio) of 0.33 are recommended. In the condition suggested by this paper, η/η₀ is close to 1.2. In the same conditions, this proposed method reduces the number of mesh elements by approximately 58% and the wall-clock computational time by approximately 52% under the reported workstation conditions, and its value would be more obvious for more complicated problems. Full article

To improve the efficiency of jet-based fire suppression for high-rise building façade fires, this study experimentally investigates the liquid film formation characteristics and fire suppression behavior of water jets impinging on insulated vertical surfaces. The effects of operating pressure (flow rate), nozzle-to-wall distance, and jet inclination angle on liquid film spreading morphology, wetted area, and effective water supply rate are systematically analyzed. The results show that increasing the flow rate significantly enlarges the wetted area, while reducing the effective water supply rate. As the nozzle-to-wall distance increases, the liquid film gradually develops a “top-wide and bottom-narrow” morphology. Although increasing the jet inclination angle decreases the wetted area, it enhances the continuity and stability of wall-adhering liquid film flow, thereby improving cooling efficiency near the flame root region. During the fire suppression experiments, low-flow-rate jets exhibit insufficient suppression stability, whereas high-flow-rate horizontal jets are capable of suppressing the flame to a residual burning state near the bottom of the façade. Further increasing the jet inclination angle enables complete flame extinguishment. This study reveals the relationship between jet parameters, liquid film behavior, and fire suppression performance, providing experimental evidence for the optimization of jet-based façade fire suppression strategies. Full article

Hydrotreatment is vital for producing high-quality liquid fuels in petroleum refining and its air coolers are critical components prone to severe corrosion under high-temperature and high-pressure conditions. Ammonium salts from NH₃-HCl and NH₃-H₂S reactions, particularly ammonium chloride precipitated during cooling, readily deposit on tube surfaces. Strong temperature gradients and complex flow conditions may severely affect air cooler inlets and front sections. To enhance the refining process reliability, an experimental setup was established to investigate the water injection removal of ammonium chloride particle deposits in air cooler tube bundles. Results show that water injection effectively removes ammonium chloride particles. Particle size has a minor influence, whereas inlet velocity, temperature, and water injection rate significantly affect removal efficiency. Increasing inlet velocity from 2 to 5 m/s, temperature from 80 to 110 °C, and water injection rate all enhance removal efficiency. Furthermore, differences between two-row tubes were also observed: the second-row tube exhibits a higher removal ratio due to liquid film formation, which increases Reynolds number and shear force, thereby enhancing dissolution. These findings provide experimental support for optimizing water injection strategies to mitigate corrosion, improving hydrotreatment unit reliability and safety, ensuring the continuous operation of the petroleum and fuel processing industry. Full article

This systematic review synthesizes passive and passive-first cooling strategies for greenhouses in hot–arid climates, organizing evidence across four domains: Airflow & Ventilation, Shading & Radiative Control, Thermal Storage & Ground Coupling, and Structural Design & Geometry. Drawing on the project corpus, we analyze 10–13 distinct techniques including ridge and side natural ventilation, windcatchers and solar chimneys, external shade nets, NIR-selective and transparent radiative-cooling films, and dynamic PV shading; earth-to-air heat exchangers (EAHE/GAHT), rock-bed sensible storage, phase-change materials (PCMs), and sunken or buried envelopes; as well as roof slope and shape, span number, and orientation. Across studies, cooling outcomes are reported as peak or daytime indoor air temperature reductions, defined relative either to outdoor conditions or to a control greenhouse, with the reference frame and temporal aggregation specified in the synthesis. Typical outcomes include ≈3–7 °C daytime reduction for optimized ventilation, ≈2–4 °C for shading and spectral covers while preserving PAR, ≈5–7 °C intake cooling for EAHE with winter pre-heating, and up to ≈14 °C peak attenuation for rock-bed storage under favorable conditions. Structural choices consistently amplify these effects by sustaining pressure head and limiting thermal heterogeneity. Performance is strongly context-dependent—governed by wind regime, diurnal amplitude, dust and UV exposure, and crop-specific light and temperature thresholds—and the most robust results arise from stacked, site-specific designs that combine skin-level radiative rejection, buoyancy-supportive geometry, and ground or latent buffering with minimal active backup. Smart controllers that modulate vents, shading, and targeted fogging or fans based on VPD or temperature differentials improve stability and reduce water and energy use by engaging actuation only when passive capacity is exceeded. We recommend standardized composite metrics encompassing temperature moderation, humidity stability, PAR availability, and water and energy use per unit yield to enable fair cross-study comparison, multi-season validation, and policy adoption. Collectively, the synthesized techniques provide a practical palette for improved greenhouse climate management under hot and arid conditions. Full article

Radiative cooling (RC) offers a passive pathway to reduce surface and system temperatures by emitting thermal radiation through the atmospheric window, yet its daytime effectiveness is often constrained by geometry, angular solar exposure, and practical integration limits. This work experimentally investigates the use of passive non-imaging optics, specifically compound parabolic concentrators (CPCs), as enhancers of RC performance under realistic conditions. A three-tier experimental methodology is followed. First, controlled indoor screening using an infrared lamp quantifies the intrinsic heat gain suppression of a commercial RC film, showing a temperature reduction of nearly 88 °C relative to a black-painted reference. Second, outdoor rooftop experiments on aluminum plates assess partial RC coverage, with and without CPCs, under varying orientations and tilt angles, revealing peak daytime temperature reductions close to 8 °C when CPCs are integrated. Third, system-level validation is conducted using a modified GUNT ET-202 solar thermal unit to evaluate the transfer of RC effects to a water circuit absorber. While RC strips alone produce modest reductions in water temperature, the addition of CPC optics amplifies the effect by factors of approximately three for ambient water and nine for water at 70 °C. Across all configurations, statistical analysis confirms stable, repeatable measurements. These results demonstrate that coupling commercially available RC materials with non-imaging optics provides consistent and measurable performance gains, supporting CPC-assisted RC as a scalable and retrofit-friendly strategy for urban and building energy applications while calling for longer-term experiments, durability assessments, and techno-economic analysis before deriving definitive deployment guidelines. Full article

In the context of global climate change and intensified water resource constraints, studying the evolution of the urban–agricultural–ecological spatial structure and the water–heat–vegetation responses driven by large-scale irrigation and drainage projects in arid and semi-arid regions is of great significance. Based on multitemporal remote sensing data from 1985 to 2015, this study takes the Inner Mongolia Hetao Plain as the research area, constructs a “multifunctionality–dynamic evolution” dual-principle classification system for urban–agricultural–ecological space, and adopts the technical process of “separate interpretation of each single land type using the maximum likelihood algorithm followed by merging with conflict pixel resolution” to improve the classification accuracy to 90.82%. Through a land use transfer matrix, a standard deviation ellipse model, surface temperature (LST) inversion, and vegetation fractional coverage (VFC) analysis, this study systematically reveals the spatiotemporal differentiation patterns of spatial structure evolution and surface parameter responses throughout the project’s life cycle. The results show the following: (1) The spatial structure follows the path of “short-term intense disturbance–long-term stable optimization”, with agricultural space stability increasing by 4.8%, the ecological core area retention rate exceeding 90%, and urban space expanding with a shift from external encroachment to internal filling, realizing “stable grain yield with unchanged cultivated land area and improved ecological quality with controlled green space loss”. (2) The overall VFC shows a trend of “central area stable increase (annual growth rate 0.8%), eastern area fluctuating recovery (cyclic amplitude ±12%), and western area local improvement (key patches increased by 18%)”. (3) The LST-VFC relationship presents spatiotemporal misalignment, with a 0.8–1.2 °C anomalous cooling in the central region during the construction period (despite a 15% VFC decrease), driven by irrigation water thermal inertia, and a disrupted linear correlation after completion due to crop phenology changes and plastic film mulching. (4) Irrigation and drainage projects optimize water resource allocation, constructing a hub regulation model integrated with the Water–Energy–Food (WEF) Nexus, providing a replicable paradigm for ecological effect assessment of major water conservancy projects in arid regions. Full article

Thermoelectric generators (TEGs), which can generate electricity simply by floating in water, have high potential for application as power supplies of IoT sensors. However, few studies on single-wall carbon nanotube (SWCNT)-TEGs have examined the effects of the power generation environment. Therefore, we investigated the impact of the relative humidity and temperature on the TEG performance. The SWCNT-TEGs were measured in environments with air temperature controlled at 25–40 °C and relative humidity controlled at 50–90%. Evaporative cooling occurs under environmental conditions with lower relative humidity and higher temperatures, resulting in higher output voltages. The SWCNT-TEG output voltage at 50% relative humidity and 40 °C was 0.26 mV, which was approximately 1.6 times higher than that measured at the same relative humidity and 30 °C, and approximately 1.4 times higher than that measured at 80% relative humidity and the same temperature, because a lower relative humidity and higher temperature increase the amount of water vapor in the air. This facilitates evaporative cooling, increasing the temperature difference within the film, thus increasing the output voltage. These results suggest that environmental factors have a significant impact on the SWCNT-TEGs and that power generation performance can be enhanced through effective use of evaporative cooling. Full article

To scientifically address the low productivity issue of traditional solar desalination systems, the current review intends to investigate the effect of design changes and performance improvement of solar stills with external and internal condensers. This review highlights that elements such as coolant techniques, the geometry of the condenser, and material features (e.g., nanofluids or surfaces of wettability) have a pivotal impact on maximising output. The results show that the combination of external condensers in solar stills is remarkably effective, where the efficiency ranges between 24% and 165% in distillate yield depending on the design modifications, which include the use of nanofluids, reflectors, and phase change materials (PCMs). In this regard, internal condensers explicitly display significant performance advances, with water production improvements of more than 150% in improved stepped designs and 60% in capillary film designs. To guarantee the maximum production of fresh water, this review proposes a number of adjustments to elevate the overall performance of solar stills, such as condensers with enhanced mechanisms of heat transfer or passive cooling strategies, which enable solar stills to be more practical in achieving the sustainable desalination of water across a wide range of climatic regions. Indeed, the enhancement of the efficiency of solar desalination technologies would support the United Nations Sustainable Development Goal 6 (Clean Water and Sanitation), providing access to safe and affordable drinking water for all. Full article

Single-walled carbon nanotube (SWCNT) films are potential materials for thermoelectric generators (TEGs) owing to their flexibility and high thermoelectric performance near 300 K. However, they inherently exhibit low mechanical strength and high thermal conductivity. To address these limitations, SWCNT-based composite films were fabricated by combining SWCNTs with varying amounts of an inorganic-blended acrylic emulsion additive. The resulting SWCNT-based composite films exhibited significantly improved mechanical properties, with breaking strain and tensile strength values approximately thirty and two times higher, respectively, than those of the additive-free SWCNT film. Thermal conductivity decreased from 7.3 W/(m·K) for the additive-free SWCNT film to 2.1 W/(m·K) for the SWCNT-based composite films. Two types of TEGs were fabricated using the composite films: (1) the water-floating TEG, which generated a temperature difference through evaporative cooling; and (2) the standard TEG, which generated a temperature difference when vertically mounted on a heater. The output voltage of the first type of TEGs decreased as the additive amount increased, owing to reduced evaporative cooling. However, the second type of TEGs increased the output voltage by adding the appropriate amount of additive owing to the film’s low thermal conductivity. These findings are significantly helpful in using TEGs with appropriate designs and placements. Full article

Outdoor environments typically require intensive cooling during the day, while nighttime cooling demands are comparatively modest. Conventional radiative-cooling systems deliver strong cooling at night but often underperform during daytime solar exposure. Here, we develop a PCM-integrated radiative cold-storage system (RCSS) that couples a polymer metasurface radiative-cooling (PMRC) film with a paraffin cold-storage tank via a helical-tube heat exchanger, and validate it through outdoor tests supplemented by CFD-based analysis. Under representative outdoor conditions, the RCSS cools circulating water at an average nighttime rate of 3.1 K h⁻¹ and maintains stable performance for initial water temperatures of 25–55 °C. Using PMRC’s cooling power as the benchmark for effective radiative-cooling power, we quantify the system-level heat-transfer pathways and provide design sensitivities with respect to film area, exchanger geometry, and tank dimensions. The results establish a practical route to all-day thermal management by storing “cold” at night and releasing it on demand, thereby facilitating scalable deployment of radiative-cooling technologies. Full article