Effect Of Solar Heating Research Articles

Bioinspired smart dual-layer hydrogels system with synchronous solar and thermal radiation modulation for energy-saving all-season temperature regulation

All-season thermal management with zero energy consumption and emissions is more crucial to global decarbonization over traditional energy-intensive cooling/heating systems. However, the static single thermal management for cooling or heating fails to self-regulate the temperature in dynamic seasonal temperature condition. Herein, inspired by the dual-temperature regulation function of the fur color changes on the backs and abdomens of penguins, a smart thermal management composite hydrogel (PNA@H-PM Gel) system was subtly created though an “on-demand” dual-layer structure design strategy. The PNA@H-PM Gel system features synchronous solar and thermal radiation modulation as well as tunable phase transition temperatures to meet the variable seasonal thermal requirements and energy-saving demands via self-adaptive radiative cooling and solar heating regulation. Furthermore, this system demonstrates superb modulations of both the solar reflectance (ΔR = 0.74) and thermal emissivity (ΔE = 0.52) in response to ambient temperature changes, highlighting efficient temperature regulation with average radiative cooling and solar heating effects of 9.6 °C in summer and 6.1 °C in winter, respectively. Moreover, compared to standard building baselines, the PNA@H-PM Gel presents a more substantial energy-saving cooling/heating potentials for energy-efficient buildings across various regions and climates. This novel solution, inspired by penguins in the real world, will offer a fresh approach for producing intelligent, energy-saving thermal management materials, and serve for temperature regulation under dynamic climate conditions and even throughout all seasons.

Pioneering computational insights into the structural, magnetic, and thermoelectric properties of A3XN (A=Co, Fe; X=Cu, Zn) anti-perovskites for advanced material applications

This study pioneers the utilization of computer-controlled simulations to elucidate the structural, elastic, electronic, and thermoelectric properties of A3XN anti-perovskites (A = Co, Fe; X = Cu, Zn). Starting with the development of a detailed structural model, structural optimization calculations identify the stable Pm-3m cubic phase, aligning with experimental findings. Also, these optimizations indicate the ferromagnetic phase stability of A3XN anti-perovskites, further supported by positive Curie-Weiss constants of 60 K, 80 K, and 100 K for Co₃CuN, Co₃ZnN, and Fe₃CuN, respectively. The spin-dependent electronic properties, including band structure and density of states, are explored using multiple exchange-correlation (XC) functionals—GGA, GGA + U, and GGA + mBJ. The results uphold the metallic nature of the materials, accompanied by significant spin magnetic moments. Specifically, the calculated values of magnetic moments for Co3CuN, Co3ZnN, and Fe3CuN are 5.08 μB, 3.70 μB, and 7.61 μB, respectively. Furthermore, we compute the Curie temperatures for each compound, 942.48 K for Co3CuN, 692.7 K for Co3ZnN, and 1400.41 K for Fe3CuN, which are substantially elevated, indicating robust ferromagnetic behavior that persists well above ambient conditions. Mechanical properties, including stability, deformation behavior, and ductility, are validated through elastic calculations, with various mechanical anisotropy factors examined. From an application perspective, the thermoelectric characteristics of Co3CuN, Co3ZnN, and Fe3CuN are meticulously evaluated, focusing on parameters like the Seebeck coefficient, electrical conductivity, thermal conductivity, power factor and figure of merit (zT). The analysis highlights promising power factor values of 3.0×1011(W/cm.K2), 4.0×1011(W/cm.K2), and 6.0×1011(W/cm.K2) for Co3CuN, Co3ZnN, and Fe3CuN, respectively, suggesting potential for enhanced efficiency in thermopower generation, particularly in waste heat recovery applications. Furthermore, the study provides a comprehensive analysis of the ground-state optical properties of A3XN, including the dielectric constant, photoconductivity, reflectivity, refractive index, absorption coefficient, and extinction coefficient. The reflectivity spectra demonstrate high reflectivity of 45 % across visible and ultravioletregions, suggesting suitability for applications in coatings designed to mitigate solar heating effects.

Colored Radiative Cooling and Flame-Retardant Polyurethane-Based Coatings: Selective Absorption/Reflection in Solar Waveband.

The aesthetic demand has become an imperative challenge to advance the practical and commercial application of daytime radiative cooling technology toward mitigating climate change. Meanwhile, the application of radiative cooling materials usually focuses on the building surface, related tightly to fire safety. Herein, the absorption and reflection spectra of organic and inorganic colorants are first compared in solar waveband, finding that iron oxides have higher reflectivity in NIR region. Second, three kinds of iron oxides-based colorants are selected to combine porous structure and silicon-modified ammonium polyphosphate (Si-APP) to engineer colored polyurethane-based (PU) coating, thus enhancing the reflectivity and flame retardancy. Together with reflectivity of more than 90% in near-infrared waveband and infrared emissivity of ≈91%, average temperature drops of ≈5.7, ≈7.9, and ≈3.8°C are achieved in porous PU/Fe2O3/Si-APP, porous PU/Fe2O3·H2O/Si-APP, and porous PU/Fe3O4·H2O/Si-APP, compared with dense control samples. The catalysis effect of iron oxides in the cross-linking reaction of pyrolysis products and dehydration mechanism of Si-APP enable PU coating to produce an intumescent and protective char residue. Consequently, PU composite coatings demonstrate desirable fire safety. The ingenious choice of colorants effectively minimizes the solar heating effect and trades off the daytime radiative cooling and aesthetic appearance requirement.

Solventless autothermic production of energy-intensive furanic biofuels expedited by photothermal effect

Driving C-C coupling reactions to produce biofuels is usually energy-consuming and requires well-tailored catalysts. Herein, a novel photothermal catalytic strategy was developed to be highly efficient for cascade hydroxyalkylation-alkylation (HAA) of various biomass-derived aldehydes/ketones with 2-methylfuran or acetalization of different bioalcohols with furfural to exclusively afford furanic biofuel molecules (up to 94.8 % yield). The developed bio-based SO3H-functionalized graphene-like catalyst (GLB-SO3H-700) could complete the HAA and acetalization reactions in 10 min under solvent-free and room-temperature conditions. Infrared thermal imaging revealed that the local photothermal effect of interfacial solar heating could in-situ remove water co-product, thereby improving the reaction selectivity and rate as evidenced by kinetic study. Moreover, the GLB-SO3H-700 catalyst exhibited good stability and recyclability. The developed SO3H-functionalized graphene-like photothermal materials hold great potential for catalytic upgrading of biomass into high-quality biofuels under mild conditions.

Solar-promoted photo-thermal CH4 reforming with CO2 over Ni/CeO2 catalyst: Experimental and mechanism studies

Combining solar light and heat in dry reforming of methane (DRM) is a promising technology for reducing CO2 to a valuable syngas and increasing the utilization of solar light in the solar-to-fuel process. The reaction temperature is still high and the mechanism remains unclear in DRM. Clarifying the synergistic mechanism of solar light and heat is pivotal for industrial applications. To this end, a nanoscale Ni/CeO2 catalyst is prepared, and the synergistic effect of solar light and heat in DRM is experimentally investigated. The experimental results show that photo-thermochemistry leads to a 39.74% increase in relative conversion rate of CH4 compared to thermochemistry, while the reaction temperature is reduced by 45 °C. The syngas production rate and the selectivity of DRM are improved by solar light. The in-situ infrared study indicates that solar light enhances the dissociation process of CH4 and the production of HCOO⁎ on the surface of the Ni/CeO2 catalyst. The light response in the catalyst and microscopic enhancement of intermediate products are responsible for the increased DRM performance under photo-thermochemical conditions. These findings contribute to the understanding of the synergistic effects of solar light and heat, and guide the conversion of CO2 into fuel with the aid of solar energy.

Bacterial Cellulose‐Based Janus Films with Radiative Cooling and Solar Heating Properties for All‐Season Thermal Management†

Comprehensive SummaryAdvanced radiative cooling materials with both heating and cooling mode is of pivotal importance for all‐season energy‐saving in buildings. In this work, we report the design and fabrication of bacterial cellulose‐based Janus films (J‐BC) with radiative cooling and solar heating properties, which were developed by two‐step vacuum‐assisted filtration of modified MXene‐doped bacterial cellulose and modified silicon nitride (Si3N4)‐doped bacterial cellulose, followed by hot‐pressing and drying treatments. The as‐prepared J‐BC films show a unique Janus structure where modified MXene nanosheets and cellulose nanofibers are on the bottom surface, and modified silicon nitride (Si3N4) nanoparticles and cellulose nanofibers are on the top surface. The radiative cooling effect of J‐BC films is enabled by the Si3N4‐doped bacterial cellulose due to the high mid‐infrared emissivity of Si3N4 nanoparticles, which shows a high solar reflection of ~98.1% and high emissivity of ~93.6% in the atmospheric transparency window (8—13 μm). Thanks to the enhanced photothermal conversion of the modified MXene nanosheets, a reduced solar reflection (6.6%) and relatively low thermal emissivity in the atmospheric window (71.4%) are achieved, making sure the solar heating effect of J‐BC films. In the outdoor tests, J‐BC films achieve a sub‐ambient temperature drop of ~3.8 °C and an above‐ambient temperature rise of ~14.2 °C. Numerical prediction demonstrated that the J‐BC films with dual modes have great potential of all‐season energy saving for buildings and a corresponding energy‐saving map in China is also created. The work disclosed herein can provide an avenue for the shaping of advanced radiative cooling materials for emerging applications of personal thermal management, sustainable energy‐efficient buildings, and beyond.

Multifunctional magnetic sponge with outstanding solar/electro-thermal performance for high-efficiency and all-day continuous cleanup of crude oil spills

The high-efficient, eco-friendly and low-energy cleanup of viscous crude oil spills is still a global challenge. Emerging absorbents with self-heating function are promising candidates due to that they can significantly decrease crude oil viscosity via in-situ heat transfer so as to accelerate remediation. Herein we developed a novel multifunctional magnetic sponge (P-MXene/Fe3O4@MS) with outstanding solar/electro-thermal performance by facilely coating Ti3C2TX MXene, nano-Fe3O4 and polydimethylsiloxane onto melamine sponge for fast crude oil recovery. Superior hydrophobicity (water contact angle of 147°) and magnetic responsivity allowed P-MXene/Fe3O4@MS to be magnetically driven for oil/water separation and easy recycling. Owing to excellent full-solar-spectrum absorption (average absorptivity of 96.5 %), effective photothermal conversion and high conductivity (resistance of 300 Ω), P-MXene/Fe3O4@MS possessed remarkable solar/Joule heating capability. The maximum surface temperature of P-MXene/Fe3O4@MS could quickly reach 84 °C under a solar irradiation of 1.0 kW/m2 and 100 °C after applying a voltage of 20 V. The generated heat induced a significant decrease of crude oil viscosity, enabling the composite sponge to absorb more than 27 times its weight of crude oil within 2 min (1.0 kW/m2 irradiation). More importantly, by means of the synergistic effect of Joule heating and solar heating, a pump-assisted absorption device based on P-MXene/Fe3O4@MS was able to realize the high-efficiency and all-day continuous separation of high-viscosity oil on water surface (crude oil flux = 710 kg m−2 h−1). The new-typed multifunctional sponge provides a competitive approach for dealing with large-area crude oil pollution.

Mission Concept and Development of the First Interstellar CubeSat Powered by Solar Sailing Technology

Project Svarog is a student-led initiative aiming to reach the heliopause using a solar sail. Orbital models have proven the feasibility of the mission given the mass-to-area ratio of about 9 grams per square meter of the sail for a satellite launched on a piggyback mission to Mars. Solar sailing increases the flexibility of missions to the outer Solar System, as unique planet alignment, which was crucial for gravity assists is no longer required. Long-term missions require a better understanding of thin membrane behaviour since buckling of sail material under solar radiation pressure might cause the spacecraft to tumble unpredictably. Reduced order model of membrane deflection is thus coupled with orbital simulation, resulting in the determination of the operation regime, for which the mission escapes the Solar System. Additionally, vacuum chamber experiments designed to investigate the effects of solar radiation pressure and heating on the transient and steady-state behaviour of the sail have been devised. The system is designed to be built as a 6U CubeSat, being one of the first missions to utilise small-scale platforms for deep space missions. Granted that the first mission is successful, the Svarog system could also serve as a low-cost testbed for new technologies and research opportunities in deep space. Keywords: Satellite, Deep Space, CubeSat, Solar Sail, Orbital Mechanics, Structural Design

Numerical study of thermal enhancement in ZnO-SAE50 nanolubricant over a spherical magnetized surface influenced by Newtonian heating and thermal radiation

ApplicationsThermal conductivity of nanomaterials potentially contributes in heat transport applications. Due to heat absorbing and cooling characteristics, nanoparticles broadly use in environmental engineering, solar plates, computational chemistry, chemical engineering and thermal engineering etc. Thus, it is substantial to identify the nanomaterials with effective heat generating or absorbing properties which have variety of applications in mechanical engineering. Purposeand Methodology: The main focus of this study are to introduce a nanofluid model using ZnO-SAE50 nanolubricant under additional effects of solar thermal radiations, magnetic field and resistive heating. This parametric study will help to maintain the temperature under various ranges of physical parameters which has broad applications in many engineering disciplines. The achieved model analyzed through numerical approach and comprehensive analysis provided in the view of furnished results. Major findingsInvestigation of the results provided that the heat transport is maximize using ZnO-SAE50 nanolubricant while; conventional SAE50 is not good to achieve desired heat transfer rate. Solar thermal radiations and dissipation effects positively act on the temperature role of ZnO-SAE50.

Long-term temperature acceleration effect of solar radiation heating on chloride transport in the CRTS III multilayer structure

The service life of high-speed railway track structures located in coastal areas may be shortened by chloride erosion due to the marine environment. This study aims to simulate chloride transport within the track structure by boundary condition models based on high-precision climate data and structural damage. The established numerical models consider various factors, including structural damage, historical exposure data of air temperature and relative humidity, temporal resolutions, solar radiation history, and the deposition rate of atmospheric chloride. The main conclusions are as follows: The maximum vertical temperature gradient of the track slab is roughly 81K/m, and the daily average temperature differences between air and surface concrete in July and February are around 9.6°C and 4.8°C, respectively. The chloride flux boundary derived from the chloride deposit rate is nearly 1 × 10-9mol/(m2s) to 10 × 10-9mol/(m2s) under a marine atmospheric environment. Step functions of daily average and monthly average temperature can improve almost the same prediction accuracy of chloride diffusion, and increasing the monthly average temperature curve by 10°C can roughly estimate the upper limit of temperature acceleration.

Translucent-Colored radiative coolers based on localized surface plasmon resonances for Energy-Efficient windows

Translucent-colored (TC) windows, employed for both light-gathering and decoration, would inevitably bring about a large thermal load mainly due to the solar heating effect of coloration, but few studies have been performed on minimizing the thermal load of TC windows. Herein, we propose a translucent-colored passive daytime radiative cooling (TC-PDRC) strategy by embedding plain Au or Au@SiO2 core–shell nanoparticles in a polymeric polyvinyl alcohol matrix, simultaneously exciting the localized surface plasmon resonances (LSPRs) with a narrowband solar absorption for coloration and improving the thermal radiation with a high thermal emittance for radiative heat dissipation. Compared with the conventional TC films used in TC windows, the experimentally prepared yellow, red, purple, and blue TC-PDRC films exhibit a higher visible transmittance (≥72.81 %), a lower visible absorptance (≤19.83 %), and a higher infrared thermal emittance (≥92.39 %), facilitating a reduced thermal load. The field measurements show that the temperatures of the testing chamber covered by the TC-PDRC films are 3.6–5.4 °C lower than that of the chamber covered by the conventional TC film during the midday period, as also confirmed by the indoor measurements. This work reveals that the excitation of LSPRs provides a pathway for controlling the thermal load, mitigating the dilemma between energy-efficient applications and aesthetic purposes.

Diurnal Cycle and Dipolar Pattern of Precipitation Over Borneo During the MJO: Linear Theory and Nonlinear Sensitivity Experiments

AbstractThe precipitation anomaly over Borneo features a dipolar pattern under the influence of the Madden‐Julian Oscillation (MJO). To understand the formation mechanisms of this pattern, a linear theory is developed to study the factors controlling its diurnal cycles and the dipolar pattern. The theory predicts that the prevailing wind is primarily responsible for the asymmetry over an idealized island, while the topography plays a critical role in the leeward convergence and convection asymmetry. The results are largely consistent with the observed composites of the dipole at Borneo. Nonlinear cloud‐permitting simulations are further conducted to test the effects of island topography and solar radiative heating in different MJO phases. The results show that the island topography can cause the mesoscale flow to split around the mountain due to the topographic blocking, and favor the development of the lee side sea breeze. These processes strengthen the low‐level convergence and convection at the leeside of the island during the late afternoon and night, which is very important to the formation of island dipolar precipitation anomaly. In contrast, the inland convergence is weakened and the dipole disappears when the terrain is flattened. The diurnal cycle of solar insolation is the dominant factor driving the land‐sea breeze circulation, which intensifies the island convection at the leeside. These results indicate that the MJO wind anomaly, island topography and solar insolation play distinct roles in the formation of the dipolar pattern of Borneo precipitation.

Integrated impacts of solar heating and water evaporation on urban airflows and thermal environments in 2D street canyons

Solar heating affects both airflows and thermal environments. However, the combined effects of turbulent mixing, solar heating and water evaporation remain largely unexplored. Therefore, this study used computational fluid dynamics (CFD) simulations to investigate integrated impacts of turbulent mixing, solar radiation, and evaporation of water bodies on airflow and temperature/water vapor concentration distribution in two-dimensional (2D) street canyons. Standard k-ε model, P-1 solar radiation model, and species transport model were employed. We considered street canyons with various aspect ratios (building height/street width, H/W = 1,3,5) and two water layouts under different solar radiative scenarios (isothermal, ground, leeward and windward heating). The water surface of layout A coincides with the street ground, while layout B is 2 m below the ground.As H/W = 1, one clockwise main vortex appears and evaporation from layouts A and B slightly affects the airflow and temperature. However, under windward heating with layout A as H/W = 3, water evaporation changes original two vertically aligned vortices to three vortices with larger vapor concentration increments and larger temperature reductions (∼2.5 K) near the water surface. From layout A to B, velocity change over water surface due to water layout (13.38%–53.00%) dominates vapor concentration over water surface rather than evaporation rate change (0.32%–8.73%) among aspect ratios (H/W = 1, 3, 5).

Superhydrophobic aerogel blanket with magnetic and solar heating effect enables efficient continuous cleanup of highly viscous crude oil

Rapid cleanup of highly-viscous oil spills the sea is eagerly desired while still remains a great challenge. Hydrophobic and lipophilic adsorbents are regarded as ideal candidate for oil spill remediation. However, traditional adsorbents are not suitable for viscous crude oil, which would block the porous structure and lead to poor adsorption efficiency. In this work, a non-contact responsive superhydrophobic SiO2 aerogel blankets (SAB) with excellent magnetic and solar heating effect for efficient removal of viscosity oils under harsh environments was developed, via assembled MXene and Fe3O4/polydimethylsiloxane layer-by-layer along the SAB skeleton (Fe3O4/MXene@SAB). The Fe3O4/MXene@SAB exhibited excellent compression tolerance (compression stress 70.69 kPa), superhydrophobic performance (water contact angle 166°), and corrosion resistance (weak acid/strong base). Due to high water repellency and stable porous structure, the Fe3O4/MXene@SAB could successfully separate oil-water mixture, while with remarkable separation flux (1.50–3.19 × 104 L m−2 h−1), and separation efficiency (99.91–99.98 %). Furthermore, the responsive Fe3O4/MXene@SAB also showed outstanding magnetic-heating and solar-heating conversion efficiency, which could continuously separate high viscosity crude oil from seawater by pump even under relatively low magnetic fields and mild sun. The superhydrophobic blankets hold great promise for efficient treatment of heavy oil spills.

Microbial protocols for spacecraft: 2. Biocidal effects of Delrin and nylon in sealed compartments may enhance bioburden reductions in planetary spacecraft

AbstractInterplanetary spacecraft are assembled with thousands of parts composed of many diverse materials. Little is known on whether any of the spacecraft materials are biocidal to the typical microbiomes that develop on spacecraft during pre-launch processing. During ongoing experiments to examine the interactive effects of solar UV irradiation, solar heating, ionizing radiation, and vacuum, we observed that bacterial spores of three Bacillus spp. were killed when incubated within small vacuum chambers for 5 days – without exposure to the aforementioned factors. Eight potential spacecraft materials were tested within the vacuum chambers for biocidal activities against spores of B. atrophaeus ATCC 9372, B. pumilus SAFR-032 and B. subtilis 168. All three species were fully inactivated (i.e., no survivors detected) by machined parts manufactured from Delrin®; a thermoplastic polyacetal polymer. Although not tested here, it is known that Delrin can off-gas formaldehyde, and thus, we hypothesize that this volatile organic compound (VOC) was responsible for the biocidal activity of the material. Knowledge of the biocidal nature of routinely used spacecraft materials might offer diverse methods to inactivate deeply embedded or shielded microbiota within spacecraft via the release of biocidal VOCs.

Mixed temperature gradient evaporator for solar steam generation

Solar-driven interfacial water evaporation enables us to build flexible, extensible, and decentralized evaporators with zero carbon dioxide emission. The theoretical limit of evaporation rate is not tolerable for users with large-capacity water requirements. Here, we report how a wicking solar absorber with a columnar structure can generate a counterintuitive evaporation enhancement mechanism: both positive- and negative-temperature gradients, which we term mixed temperature gradient, are generated in the wicking material. This allows a ∼3.8 times equivalent evaporation rate compared with the theoretical limit. We demonstrate that the mixed temperature gradient is a new thermal equilibrium achieved by the combined effect of solar heating and evaporative cooling. Importantly, the sidewall height should be consistent with the capillary height dominated by imbibition and diffusion. Specifically, designing a solar absorber with a balanced water supply and demand allows a higher evaporation rate in both light and darkness. • A mixed temperature gradient of the interfacial solar steam generator is reported • Efficient management of water and heat transportation are synchronously achieved • The underlying evaporation enhancement mechanism is discussed • An evaporation rate of up to 5.62 kg m −2 h −1 under one sun is obtained Li et al. describe the mixed temperature gradient of solar steam generators enabled by solar heating and evaporative cooling. This evaporator demonstrates 5.62 and 2.77 kg m −2 h −1 evaporation rates in light and darkness, respectively, opening up the development of flexible, extensible, and sustainable solar stills to produce clean water.

Quantifying Weathering-Aging Test Parameters of High Viscosity–Modified Asphalt by Establishing a Conversion Relationship with Standard PAV Aging

The purpose of this study was to quantify the weathering-aging degree by establishing a conversion relationship with standard pressure-aging vessel (PAV) aging, thus guiding the selection of environmental parameters in the weathering-aging test. First, the orthogonal test was used to determine the most severe weathering-aging combination. Then the rheological property and chemical composition of high viscosity–modified asphalt (HVMA) after weathering-aging and standard PAV aging were investigated by dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR), Fourier transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC) tests. Afterward, the radar figure was used to establish the conversion relationship between weathering aging and standard PAV aging. The results show that the most severe weathering-aging condition combination is 70°C, 1,000 W/m2, and 70% relative humidity (RH). The molecules from the polymer, asphaltene, and maltene phase exhibit dynamic migration processes of molecular weight during aging, thus leading to the transition from a viscous component to an elastic component in HVMA. Compared with PAV aging, HVMA has more significant chemical changes during weathering aging due to the coupling effect of solar radiation and heat. Most of the performance changes of HVMA are similar in weathering aging and standard PAV aging except for functional groups and R3.2. The 4 days of weathering aging at 70°C, 1,000 W/m2, and 70% RH shows the best accordance to the standard PAV aging.

Investigation of the effect of solar water heating of vacuum tube on heat loss coefficient

In the solar thermal utilization system, it is necessary to study the factors that affect the heat loss of the hot water storage tank. Therefore, the heat loss coefficient of the hot water storage tank in the all-glass vacuum tubular solar water heater is calculated using experiments and measured data in the present study. Then the problem is analyzed in forced circulation and non-forced circulation conditions. According to the results of the investigation, the heat loss coefficient of the thermal storage tank in the forced circulation state is 12.6 times that of the non-forced circulation condition. The heat loss coefficient is impacted by the tank temperature, intake, and exit water temperatures, circulating water flow rate, wind speed, and ambient temperature, as determined by a linear regression analysis of the experimental data. It is found that in the non-forced circulation, wind speed significantly affects the heat loss coefficient, specifically, the heat loss coefficient increases by 0.49 W/(m2·℃) for every 1 m/s increase of wind speed when all other factors are constant. But wind speed can be neglected in the forced circulation condition. Moreover, it is observed that as the inlet water temperature increases, the corresponding heat loss coefficient increases.

Cost effective 24-h radiative cooler with multiphase interface enhanced solar scattering and thermal emission

Passive radiative cooling is an emerging energy-free pathway that radiates the emission of heat from the earth to cold space (3 K) through an atmosphere transparent window (7–14 µm). Recently, this technology has attracted great interest in residential and industrial applications. However, critical challenges remain for 24-h radiative cooling due to the unwanted solar heating effect in the daytime. The complex manufacturing process and high price also result in a cost barrier for large-scale applications. Here, an easy-prepared and cost-effective radiative cooler (RC) was processed which consists of polydimethylsiloxane (PDMS) and SiO2 microspheres based on cellulose nanofibers (filter paper) with a backing silver (Ag) mirror for mass production. This whitish hybrid material exhibited high reflectance of 91% in the AM 1.5 solar spectrum (0.2–2.5 µm) and high thermal emissivity of 90% in the atmospheric window, which was enhanced by the randomized multiphase interfaces. Moreover, it can accomplish 24-h continuous outdoor cooling with an efficient average temperature reduction of 5 °C, especially 6.5 °C in the nighttime. Overall, this work provided a new approach to promote 24-h radiative cooling as a next-generation green energy technology.

Solar thermal catalysis for sustainable and efficient polyester upcycling

<h2>Summary</h2> Although the extraction of value-added products from end-of-life plastics brings significant environmental and economic returns, the current recycling technologies are limited by their low efficiency and high energy consumption. Here, we propose an efficient solar thermal catalysis to recycle various polyesters into high value-added monomer derivatives with low energy consumption and carbon emissions. Compared with the traditional thermal catalysis of homogeneous heating, the solar thermal process exhibits a unique localized solar heating effect, forming a temperature gradient from the solar absorber to the bulk solution. This effect allows a lower depolymerization temperature (150°C), but the recycling efficiency is increased by threefold, unattainable by thermal catalysis. Furthermore, the solar thermal process can reduce energy consumption by 3.7 GJ and CO₂ emissions by 0.4 tons per ton of polyester treated compared with the thermal catalysis. Therefore, solar thermal catalysis opens an efficient, high-profit, and eco-friendly way to reuse waste plastics.