Solar Radiation Heat Research Articles

Numerical simulation of variable density and magnetohydrodynamics effects on heat generating and dissipating Williamson Sakiadis flow in a porous space: Impact of solar radiation and Joule heating

This study is confined to the numerical evaluation of variable density and magnetohydrodynamics influence on Williamson Sakiadis flow in a porous space. In this study, Joule heating, dissipation, heat generation effect on optically dense gray fluid is encountered. The inclined moving surface as flow geometry is considered to induce the fluid flow. A proposed phenomenon is given a mathematical structure in partial differential equations form. These partial differential equations are then made dimensionless using dimensionless variables. The obtained dimensionless model in partial differential equations is then changed to ordinary differential equations via stream function formulation. A set of transformed equations has been solved with bvp4c solver. The numerical fallout of velocity field, temperature field, skin friction, and heat transfer rate are illustrated in graphs and tables with flow parametric variations. Conclusion is drawn that mounting values of density variation parameter confirm the reduction in velocity field and augmentation in temperature of the fluid. When Williamson fluid parameter enhances, both fluid velocity and temperature are rising correspondingly. Growing magnitudes of the magnetic number, radiation parameter, heat generation, and Eckert number rise the temperature of the fluid. A rise in a porous medium parameter weakens the fluid velocity. Skin friction is reducing as radiation parameter and density variation parameter are increased.The present solutions are compared to those that have already been published in order to validate the current model. The comparison leads to the conclusion that the two outcomes are in excellent agreement, endorsing the veracity of the current answers.

Effects of 'Inhaling' and 'Exhaling' of buildings in three-dimensional built environment on Land Surface Temperature

As growing urbanization and land becomes scarcer, vertical architectural development is intensifying the complexity of the three-dimensional (3D) urban landscape, thereby exacerbating the Urban Heat Island (UHI) effect. In contrast to the existing literature that has primarily focused on the 'Inhaling' heat from buildings based on their 3D morphological characteristics through absorbing solar radiation heat and influencing heat exchanges, this research endeavors to shed light on the 'Exhaling' heat from buildings through active heat emissions. This paper aims to investigate the 'Inhaling' and 'Exhaling' effects, as well as their interactive effects based on the 3D morphological characteristics of buildings on Land Surface Temperature (LST), considering various spatial scales and seasonal variations. The results demonstrate that buildings' 'Inhaling' significantly affects LST year-round, while 'Exhaling' primarily influences LST during the winter and spring. The influence of the building's 'Exhaling' effect on LST is more pronounced at smaller spatial scales, gradually diminishing as the spatial scale increases. Furthermore, the 'Inhaling' effect of buildings characterized by average building height and building density, moderates the effect of buildings 'Exhaling' from heavy industry on LST. This study underscores the need to consider the interplay between passive and active heat processes in vertical urbanization for UHI mitigation.

Transparent Sol-Gel-Based Coatings Reflecting Heat Radiation in the Near Infrared.

Thin, flat textile roofing offers negligible heat insulation. In warm areas, such roofing membranes are therefore equipped with metallized surfaces to reflect solar heat radiation, thus reducing the warming inside a textile building. Heat reflection effects achieved by metallic coatings are always accompanied by shading effects as the metals are non-transparent for visible light (VIS). Transparent conductive oxides (TCOs) are transparent for VIS and are able to reflect heat radiation in the infrared. TCOs are, e.g., widely used in the display industry. To achieve the perfect coatings needed for electronic devices, these are commonly applied using costly vacuum processes at high temperatures. Vacuum processes, on account of the high costs involved and high processing temperatures, are obstructive for an application involving textiles. Accepting that heat-reflecting textile membranes demand less perfect coatings, a wet chemical approach has been followed here when producing transparent heat-reflecting coatings. Commercially available TCOs were employed as colloidal dispersions or nanopowders to prepare sol-gel-based coating systems. Such coatings were applied to textile membranes as used for architectural textiles using simple coating techniques and at moderate curing temperatures not exceeding 130 °C. The coatings achieved about 90% transmission in the VIS spectrum and reduced near-infrared transmission (at about 2.5 µm) to nearly zero while reflecting up to 25% of that radiation. Up to 35% reflection has been realized in the far infrared, and emissivity values down to ε = 0.5777 have been measured.

Compaction of the snow base of Vostok station wintering complex

The compaction of the snow base of the wintering complex under construction of the Russian Antarctic station “Vostok” is considered, which was required due to the unsuitability of the natural snow base for the perception of loads from the supports of the foundation of the wintering complex. Technical solutions were developed for snow base compaction on the basis of heating by solar radiation with the use of thermal mat and on the basis of snow vacuuming. The computational justification of the developed technical solutions was performed, which was carried out based on spatial finite element models using the computational software complex ANSYS. In this case, to substantiate the method of snow base compaction by solar radiation heating with the use of thermal mat, the calculated volume was analyzed, including the snow base zone, thermal mat and the space filled with air. When substantiating the method of snow base compaction by snow vacuuming, there was explored the calculation area for modeling the method of vacuuming for the hermetic volume of the excavation pit with immersed columns under the wintering complex foundation supports. The results of the of the calculated research have fully confirmed the assumptions laid down in the technical solutions for compaction of the wintering complex snow base by using of thermal mat and snow vacuuming.

Fine‐grained chondrule rims in Mighei‐like carbonaceous chondrites: Evidence for a nebular origin and modification by impacts and recurrent solar radiation heating

AbstractThe Mighei‐like carbonaceous (CM) chondrites, the most abundant carbonaceous chondrite group by number, further our understanding of processes that occurred in their formation region in the protoplanetary disk and in their parent body/bodies and provide analogs for understanding samples returned from carbonaceous asteroids. Chondrules in the CMs are commonly encircled by fine‐grained rims (FGRs) whose origins are debated. We present the abundances, sizes, and petrographic observations of FGRs in six CMs that experienced varying intensities of parent body processing, including aqueous and thermal alteration. The samples studied here, in approximate order of increasing thermal alteration experienced, are Allan Hills 83100, Murchison, Meteorite Hills 01072, Elephant Moraine 96029, Yamato‐793321, and Pecora Escarpment 91008. Based on observations of these CM chondrites, we recommend a new average apparent (2‐D) chondrule diameter of 170 μm, which is smaller than previous estimates and overlaps with that of the Ornans‐like carbonaceous (CO) chondrites. Thus, we suggest that chondrule diameters are not diagnostic for distinguishing between CM and CO chondrites. We also argue that chondrule foliation noted in ALH 83100, MET 01072, and Murchison resulted from multiple low‐intensity impacts; that FGRs in CMs formed in the protoplanetary disk and were subsequently altered by both aqueous and thermal secondary alteration processes in their parent asteroid; and that the heat experienced by some CM chondrites may have originated from solar radiation of their source body/bodies during close solar passage as evidenced by the presence of evolved desiccation cracks in FGRs that formed by recurrent wetting and desiccation cycles.

Natural convection in vertical solar heat collector nanotextured with reduced graphene oxide and silver nanowires

In this study, a vertical shaft is coated using silver nanowires (AgNWs) together with reduced graphene oxide (rGO) via the supersonic spray-coating technique to enhance the absorption of solar radiative heat for use in solar air heaters. The rGO/AgNW-coated surface induces multiple light reflections, similar to that in a perfect black body inside a Helmholtz jar, thus enhancing the collection of solar radiation. Air fed into the vertical heated shaft ascends owing to buoyancy. The air temperature difference, ΔT, between the outlet and inlet is measured for various mass flow rates to quantify the heat transferred to the air from the solar-heated vertical shaft. The longitudinal air velocity and temperature distributions inside the shaft are numerically simulated using the fire dynamics simulator. Both two- and three-dimensional simulations are performed, and the results are compared with experimental data for various mass flow rates. The results confirm that the trends observed in both the experiments and simulations agree well for all cases. Multiple metal meshes are installed inside the vertical shaft to induce turbulence, which enhances the heat transfer intensity. This turbulence enhancement is confirmed via smoke visualization and infrared images.

Energy and exergy analysis of a cross flow solar air heater for thermohydraulic performance augmentation

This study numerically examines the enhancement of thermo-hydraulic efficiency of a cross flow solar air heater (SAH) for Reynolds number ranging from 3000 to 21000. The thermal performance is investigated for various perforation hole diameters of absorber plate and varying number of rows of holes. Discrete Ordinates radiation model is used to simulate the solar radiation heat interactions within the computational domain. Maximum thermo-hydraulic efficiencies of 86.51% and 85.15% are observed for configurations with 3 rows and 4 rows of perforation holes with hole diameter ratio of 0.06 and 0.07 respectively. The maximum exergy efficiency is found to be 5.28%. The system's enviro-economic analysis shows that the CO2 mitigation rate is 1.12 t CO2/annum, whereas the environmental cost is 16.31 $/year. The exergo-economic parameter is computed as 1.18 kWh/$, while the energy cost is calculated as 0.049 $/kWh. Additionally, it is determined that the energy payback period is 5 months while the exergy payback period is 22 years. The heat map for the various configurations shows the economical operating range of the air heater. The envisaged SAH has the advantage of completely decimating the laminar sublayer throughout the absorber plate due to cross flow movement of air through the absorber plate unlike the conventional SAH.

A newly designed BIPV system with enhanced passive cooling and ventilation

Nowadays, the application of renewable energies such as solar energy in the building sector has increased notably considering the adverse impacts of climate change on human life; hence many studies have focused on the application of photovoltaic panels in buildings. In the current study, a 3D computational fluid dynamics (CFD) model has been developed to evaluate the performance of a newly designed building-integrated photovoltaic (BIPV) system. Given the negative influence of overheating on the lifespan and performance of PV panels, their passive air cooling has been studied. Further, the potential of rooftop-mounted solar panels in passive ventilation of buildings by generating natural convective currents has been explored. The developed CFD model takes into consideration the effects of radiation, conduction, and buoyancy-driven natural convective currents generated by solar PV panels which are heated due to the exposure to solar radiation heat flux. The results suggest that applying a high surface emissivity for the part of the roof beneath the PV panels intensifies the natural convective currents which in turn provides better cooling for PV panels with higher cooling effects at higher solar heat fluxes. Up to a 34% increase in the convective mass flow rate and a 3 K decrease in the mean temperature of the panels were attained by modifying the emissivity of roof surface. Such a 3 K decrease in the operating temperature of the PV panels can enhance their efficiency and lifespan by about 1.56% and 21 %, respectively. Based on the operating conditions and system characteristics, the BIPV system yielded an air change rate (ACH) in the range of 3–13 which was considered to be highly prevalent in providing the required passive ventilation for a wide range of applications. It was also observed that the flow dynamics inside the building were affected by both the amount of solar heat load incident on the solar panels and the emissivity of the roof surface behind the panels.

Mass-balance and ablation processes of a perennial polar ice patch on the northern coast of Ellesmere Island

AbstractIce patches have implications for landscape and ecosystem dynamics in polar deserts, however, the understanding of the driving factors that control their spatio-temporal variability is limited. This study aims to assess the seasonal and long-term evolution of ice patches on Ward Hunt Island (WHI; 83°N, Canadian High Arctic) based on field measurements of surface mass and energy balance. Results show that mass gains of the ice patch systems occur mostly through drifting snow, making them highly linked to the topography as well as the frequency and magnitude of wind events. Summer ablation is primarily driven by net radiation, but the short-term variability in melt rate is driven by sensible heat fluxes. The highest ablation rates occur during the passage of warm fronts that combine strong winds and mild temperatures. Conversely, foggy days reduce fluxes of solar radiation and sensible heat to the snow/ice surface, thereby suppressing ablation. Ice patches are less climate-sensitive than other cryospheric elements due to a feedback between snow accumulation and topography, however, summer ablation is strongly influenced by micrometeorology. Model projections of these factors suggest that conditions will become critical for preserving ice patches at WHI and along the northern coast of Ellesmere Island as early as in the next decades.

Effect of riser-pipe cross section and plate geometry on the solar flat plate collector's thermal efficiency under natural conditions

The current study aims to enhance the thermal performance of the Solar Flat Plate Collector (SFPC). To achieve that, four proposed models of (SFPC) were investigated in terms of thermal response under transient solar radiation using passive techniques. Two of these models simulate the influence of different riser-pipe configurations, namely models A and B, respectively representing semicircular and elliptical cross sections. While, the other two models, -C- and -D- represent the effect of plate geometry, which represent dimples and channel plates, respectively. All geometric models and the numerical simulations were created using ANSYS 19. R3. The results show that there is good conformity between numerical and experimental findings. Moreover, all four proposed models have been found to have a better thermal response than conventional model. Furthermore, model -D- is found to be the better model among all the other models under investigation due to the increased surface area of the collector, which leads to receive more solar radiation (heat flux) and hence increases the heat transfer to the working fluid within the riser pipe, which increases the temperature of the working fluid and the water inside the container. The thermal response of model -D- in terms of working fluid temperature inside the container and water temperature at the exit is approximately 13.2% and 12.3% higher, respectively, as compared to the traditional model. In addition, the overall thermal efficiency of the model -D- collector is approximately 13.7% higher than the conventional model.

Diagnostics of Transmission Bearing Units Based on Thermal Load Study

Abstract. The operating temperature of the transmission unit is noted to affect its reliability and can serve as a diagnostic criterion. It is proposed to diagnose the transmission unit technical condition by the temperature in the friction zone in order to take into account the influence of air temperature, solar radiation heating and adjacent heat-producing objects. (Research purpose) To ensure the bearing unit controllability based on the thermal load study. (Materials and methods) The study uses the results of calculating the nominal and operational load of the rear power take-off shaft of the Belarus-82.1 tractor. The study uses the three-dimensional modeling and finite element analysis of the temperature distribution under steady-state thermal conductivity conditions. To establish the functional relationship between the temperature in the friction zone and the diagnostic temperature, the method of finite element analysis is used under steady-state thermal conductivity conditions. (Results and discussion) The maximum load modes and temperatures in the friction zone were determined for the 60310A bearing of the power take-off shaft gearbox during aggregation with different agricultural machines such as 4300 Newtons and 2.4 degrees Celsius for FS-2.0U garden cutter (540 revolutions per minute); 4126 Newtons and 40.7 degrees Celsius for Rovatti T3K80/90/2 (540 revolutions per minute) irrigation pump; 956 Newtons and 13.0 degrees Celsius for ROU-6 (1000) manure spreader; 2615 Newtons and 36.6 degrees Celsius for KPRN-3.0A (1000) mower-conditioner. The maximum temperatures as a diagnostic criterion are established in the friction zone, which equal to 41.7 degrees Celsius at 540 revolutions per minute engine speed and 31 degrees Celsius at 1000 revolutions per minute. (Conclusions) Since the direct measurement of the temperature in the friction zone is hardly possible without changing the bearings design, it is proposed to measure the diagnostic temperature on the unit used for mounting the temperature sensor. The coefficient of proportionality k=0.53 of the finite element model is determined. In order to implement diagnostics in an automatic mode, an algorithm is developed for a digital transmission malfunction recorder. Its design is based on the ATmega328 programmable microcontroller and TMP36 temperature sensors. It is found that the digital transmission malfunction recorder provides automatic control of up to seven different transmission units simultaneously, taking into account the ambient temperature.

A Review of Radiative Heat Transfer in Fixed-Bed Particle Solar Receivers

A highly efficient receiver is required because re-radiation loss increases dramatically with increased working temperature. Among a large number of receivers, the fixed-bed Particle Solar Receiver (PSR) represents a new pathway to high temperature with maximum overall thermal efficiency. The incoming solar radiation can penetrate deeper into the fixed-bed PSR filled with semi-transparent quartz and ceramic particles (spheres or Raschig rings), resulting in an increased volumetric effect. Reports show that an optimized PSR can realize overall receiver efficiency of around 92% at outlet temperatures above 1000 K, and achieve the annual temperature above 1000 K over 65% annual operating hours integrated with a concentrated solar power (CSP) system. To fully understand radiative heat transfer characteristics and provide deep insight into thermal efficiency, radiation energy is classified as incident solar radiation and radiative heat exchange in two parts. The transfer mechanism, the solution method and the progress of the investigation for each section are summarized and discussed in detail. Then, challenges and future directions, including an innovative design method, an improved experimental approach and an effective simulation method are proposed to put forward this receiver to be a preferred substitute in advanced, high-temperature power cycles.

Experimental and Numerical Study of the Influence of Solar Radiation on the Surface Temperature Field of Low-Heat Concrete in a Pouring Block

With the influence of intense solar radiation heat and the greater temperature difference between day and night, surface concrete with a drastic temperature change can easily experience a great nonlinear temperature difference, which increases the risk of early-age concrete cracking. In this study, a distributed optical fiber temperature sensing (DTS) system is used to monitor the surface temperature gradient of concrete in real time, and a solar radiation heat monitoring test is also carried out based on the Baihetan project. Based on this, a solar radiation loading model and a finite element model of a typical pouring block considering solar radiation are established. Combined with the measured temperature data and different calculation conditions, the surface temperature changes of medium-heat and low-heat concrete experiencing solar radiation are analyzed, and the temperature control effect of surface concrete with different surface insulation measures is further analyzed. The results show that the temperature variation of medium-heat concrete at the same depth is more obvious than that of low-heat concrete. Additionally, the temperature variation of low-heat concrete is noticeable within 20 cm of the top surface. In addition, in an intense solar radiation environment, covering the concrete with a 4- or 5-centimeter-thick polyethylene coil can effectively control the surface temperature gradient and maximum daily amplitude of low-heat concrete, and surface concrete cured by running water has a significant temperature control effect. Therefore, it is suggested that 22–24 °C water temperatures be used for water curing during periods of intense solar radiation during the day and a 4-centimeter-thick polyethylene coil be used for coverage at night. These study results have been employed in the Baihetan project to optimize the temperature control scheme of the pouring blocks.

Ultrasonic Velocity, Viscosity and Thermal Conductivity Studies on Barium Oxide: Silicone Oil Nanofluids

In this study, we focused on the preparation and characterization of Barium oxide (BaO): Silicone oil nanofluids with the assistance of ultrasonication. The purpose was to investigate the potential impact of these nanofluids on solar radiation absorption. To achieve this, six different concentrations (ranging from 0.01 g to 0.06 g) of BaO: Silicone oil nanofluids were prepared. The nanofluids were subjected to various characterization techniques to evaluate their properties. Ultrasonic velocity measurements were conducted to assess the dispersion quality and stability of the nanofluids. Fourier transform infrared (FTIR) spectroscopy was utilized to examine any potential interactions between the nanoparticles and the fluid medium. Ultraviolet-Visible (UV-Visible) spectroscopy was employed to investigate the optical properties of the nanofluids, particularly their ability to absorb solar radiation. Additionally, electron microscopy analysis provided insights into the morphology and size distribution of the BaO nanoparticles. The results obtained from the UV-Visible analysis provided valuable information regarding the solar radiation absorption efficiency of the BaO: Silicone oil nanofluid systems. These findings contribute to our understanding of the potential application of these nanofluids in solar energy harvesting. Furthermore, the ultrasonic studies and FTIR analysis confirmed that there were no significant particle-fluid interactions, indicating the stability of the nanofluids. Thermal conductivity measurements were carried out to determine the heat transfer efficiency of the BaO: Silicone oil nanofluid system at different concentrations. The results revealed an optimal concentration that exhibited the highest heat transfer efficiency, suggesting the potential of these nanofluids for enhancing heat transfer processes. In conclusion, this study successfully prepared and characterized BaO: Silicone oil nanofluids. The analysis of their optical properties, stability, and thermal conductivity provides valuable insights into their potential application in solar radiation absorption and heat transfer systems. Further research can explore the practical implementation of these nanofluids in solar energy conversion and thermal management technologies.

Eksperimen Rumah Pengering Ikan Sarden Model Ultra Violet (UV) Solar Dryer Kombinasi dengan Sistem Solar Air Heater Melalui Variasi Kecepatan Udara Keluar

The technique for preserving a new product is by using a drying technique. The development and utilization of solar energy must continue to be developed with several technologies including the Solar Air Heater. The research method used was an experimental method on Ultra-Violet solar dryer drying houses for drying sardines with additional absorption of solar radiation heat using a solar air heater system. This configuration works by drawing air from the building envelope or from the outside environment and passing it through a collector where the air is warmed by conduction and convection in the absorber. The analysis of this study is regarding the velocity of the airflow coming out of the drying chamber, namely 1.0 m/s, 1.5 m/s and 1.8 m/s, while the airflow velocity in the solar panel (exhaust fan) is 3.5 m/s (constant). The results of the study show that the addition of heat through the solar air heater panel can speed up the drying process in the drying chamber. The temperature difference in the solar panel increases the heat absorbed through the hot air flow which also increases the efficiency of the solar panel. The highest efficiency of the drying house is 48.05 % occurring at the outlet air flow rate of 1.8 m/s. The temperature difference in the drying chamber and the increased ambient air tends to increase the efficiency of the drying chamber where in this study the highest value of 48.05% was obtained at a speed of 1.8 m/s

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

Research on the Flexible Heating Model of an Air-Source Heat Pump System in Nursery Pig Houses

Maximizing the utilization of renewable energy for heating is crucial for reducing energy consumption in pig houses and enhancing energy efficiency. However, the mismatch between peak solar radiation and peak heat load demand in nursery pig houses results in energy waste. Therefore, we investigated a flexible air-source heat pump system (F-ASHP) based on the hourly-scale energy transfer of solar energy. A theoretical calculation model for F-ASHPs in pig houses in the heating areas of northern China has been established through on-site testing and Simulink. This study investigated the heat storage and release of four energy storage materials in pens and the variation in heat load in the house, validating the accuracy of the model. The results show that the F-ASHP can effectively match the peak solar heat and peak heat load in the house. Among the four energy storage materials in pens, the magnesium oxide heat storage brick material performed the best. During intermittent solar periods, it released 3319.20 kJ of heat, reducing the heat load in the pig house by 10.1% compared with that by the air-source heat pump (ASHP). This study provides a theoretical model for flexible heating calculations in pig houses in northern China and aims to serve as a valuable resource for selecting energy-storage pens.

Theoretical and Simulation Analysis of a Thin Film Temperature Sensor Error Model for In Situ Detection in Near Space

Near space environment is the airspace at 20–100 km, where complex conditions such as low temperature, low pressure, high wind speed, and solar radiation exist. Temperature, as one of the most important meteorological parameters, is crucial for space activities. However, the accuracy of traditional temperature sensors is low, and the influence of complex environments makes the error of conventional temperature measurement methods more extensive. Therefore, we designed a new microbridge temperature sensor to reduce solar radiation and achieve a fast response. Additionally, through simulation analysis, we investigated the three factors influencing the temperature errors of Joule heat, solar radiation heat, and aerodynamic heat. Additionally, the influence of temperature error is reduced by optimizing the installation position of the sensor. The error value in the actual measurement value is removed through the temperature error model to realize the high-accuracy detection of the near space temperature.

Wearable, Biodegradable, and Antibacterial Multifunctional Ti3C2Tx MXene/Cellulose Paper for Electromagnetic Interference Shielding and Passive and Active Dual-Thermal Management

An energy-saving scheme that can simultaneously realize electromagnetic interference (EMI) shielding, passive solar radiative heating, and active Joule heating in a single wearable device is still a huge challenge. Here, by combining the unique properties of Ti3C2Tx MXene and biocompatible cellulose nanofibers (CNFs), a flexible, degradable, and antibacterial multifunctional Ti3C2Tx/CNF paper (∼0.6 Ω/sq) is constructed through a facile vacuum filtration strategy. The resultant device not only exhibits an admirable EMI shielding effectiveness of ∼48.5 dB at the X-band and a superior heating property including dual-driven electrothermal and photothermal conversion without energy but also possesses wide temperature range regulation and long-time stability. More impressively, both high antibacterial efficiency (toward both gram-positive and gram-negative bacteria) and good degradability with low-concentration hydrogen peroxide solution can also be achieved in Ti3C2Tx/CNF papers. This study provides a promising platform for practical applications of multifunctional Ti3C2Tx/CNFs in EMI shielding, thermotherapy, heat preservation, and antibacterial protection in harsh environments, satisfying the demands for energy-saving, environmentally friendly, and sustainable development.

Combined numerical approach for the evaluation of the energy efficiency and economic investment of building external insulation technologies

The objective of this paper is to examine the energy efficiency and economic feasibility of different coating technologies used to improve the thermal insulation of external walls in buildings. The comparison is made between traditional coat insulation and ventilated façade, evaluating their impact on energy consumption to maintain a constant indoor temperature throughout the year by means of a combined numerical approach. . Furthermore, the paper investigates the effect of opening and closing the air gap in ventilated façades on thermal insulation during the winter and summer seasons. Energy efficiency calculations are employed to estimate the economic investment required for implementing the different insulation solutions.The paper proposes an innovative combined approach to determine the performance of the building insulation technologies. Firstly, a computational fluid dynamics (CFD) simulation is carried out on the full three-dimensional geometry of the building during two reference days representing extreme temperature and sun radiation conditions during the summer and winter. This modeling includes the effects of solar radiative heat transfer during the day: for a chosen date, time, and geographical location, the model computes sun altitude and azimuthal angles, along with the corresponding direct and diffuse solar fluxes. In addition, the model uses a multiband thermal radiation approach to capture the different nature of radiative heat exchange according to the light wavelengths. The total heat transfer coefficient of the building walls in each scenario is calculated through the computational fluid dynamic analysis and implemented in an in-house developed library based on the open source Open-Modelica platform to simulate the energy requirement of the building throughout the year. This combined numerical approach provides a comprehensive performance analysis of the studied technologies in terms of electric energy and fuel consumption required for maintaining a constant indoor temperature and internal ambient comfort.The results of the simulations demonstrate that by adopting the two proposed solutions, there was a potential to save approximately 37% of the fuel required for the heating system and more than 51% of electric energy required for the air conditioning systems. Finally, the payback period for each scenario is calculated, and it was found that coat insulation offers the best balance between thermal performance improvement and economic effort, with a payback time close to 20 years.