Search Results (92)

The paper presents an analysis of the operating parameters of a solar chimney with a non-selective and selective absorbers. The analyzed system consisted of a rectangular vertical collector integrated with a chimney. The collector surface was 30 m², while the installation was 80 m high. The calculations were performed for the climatic conditions in Katowice, Poland. The work included an analysis of parameters such as air temperature increase and its velocity and mass flow in the solar chimney system. The cumulative amounts of electricity that can be obtained in each month of the year were shown. A comparison of electricity generation in the installation with an absorber covered with a non-selective coating and selective coatings was made. The installation with an absorber with an absorption coefficient of 0.95 and an emission coefficient of 0.05 allowed for the generation of the largest amount of electricity during the year. Full article

The Co-CuCoMnO_x coatings with varying proportions were prepared and investigated to develop a novel metal–ceramic solar selective absorption coating employed at high temperature. The CuCoMnO_x powders were synthesized using the solid-phase reaction method. Subsequently, Co-CuCoMnO_x coatings were deposited on the surface of 316L steels utilizing the atmospheric plasma spraying (APS) technique. The results showed that the synthesized CuCoMnO_x powders were mainly composed of two phases, which were Cu_1.5Mn_1.5O₄ and MnCo₂O₄. The CuCoMnO_x powders had a solar absorptance of 0.929 and an infrared emittance of 0.862, which was considered a good solar absorbent. The synthesized Co-CuCoMnO_x coating had a typical thermal spray layered stacking structure. The chemical phases of the coatings were mainly Co, CoO, and CoCuMnO_x. Due to the addition of CuCoMnO_x inhibiting the oxidation of Co during the thermal spraying process, the 95Co-5CuCoMnO_x (wt%) coating exhibited the optimal quality factor (α/ε) of 2.184, with a solar absorptance α of 0.808 and an infrared emittance ε of 0.370, respectively. Moreover, this specific coating demonstrated a good thermal stability for up to 3 h when exposed to an atmospheric environment at 450 °C. The results indicate its significant potential for high-temperature solar selective absorption coating. Full article

The present work aims to develop the current CubeSats architecture. Starting from the framework of project ARAMIS (an Italian acronym for a highly modular architecture for satellite infrastructures), a new concept of smart tiles has been developed, employing multifunctional structures and lightweight, composite materials. This enables increased CubeSat mass efficiency and payload volume. An embedded battery tile has been designed, built, and tested from a vibration point of view. In the present work, the LiPo batteries selected for the prototype have been tested with the HPPC testing procedure, to extract their equivalent Randles circuit parameters. Thus, the thermal power dissipation from the batteries can be estimated. With these data, Thermal Desktop simulations of a representative ARAMIS CubeSat are performed, considering LEO orbit and hot/cold cases. Firstly, a parametric analysis was conducted to evaluate the thermal behaviors of various design alternatives. A suitable configuration for the CubeSat was then found, enabling the validation of the embedded battery tile from a thermal point of view. The final configuration includes heaters for the LiPo batteries, a commercial CubeSat skeleton made in aluminum alloy, and a top coating for smart tiles with proper solar absorptivity. Full article

Sol-gel coatings are commonly used to prevent corrosion from molten salt mixtures in CSP plants. Until now, they have been driven primarily by cost considerations, without integrating environmental criteria into the modeling and decision-making process. The novelty of this study lies in the development of an evaluation framework that incorporates environmental impact alongside technical and economic factors, providing a more sustainable approach. This work assesses porosity, thermal shock resistance, and thickness to determine the optimal sol-gel coating. For this purpose, the multi-criteria decision-making technique “Analytic Hierarchy Process” (AHP) and the Life Cycle Assessment (LCA) methodology are implemented. The results show that the scores obtained for the 3YSZ-5A (5% mol) coating are higher than those of the 3YSZ (3% mol) and 3YSZ-20A (20% mol) coatings, between 1.52 and 1.69, respectively. The 3YSZ-5A coating (5% mol) is the optimal solution among all the systems analyzed, with a score of 0.61 AHP pt. The coating of the same type and higher molar concentration (20%) achieved 0.55 AHP pt. Finally, the 3YSZ type coating received the lowest rating, with a score of 0.36 AHP pt. The insights generated in this research will support decision-making in the design and maintenance of CSP plants. Full article

The present work introduces a new solar selective absorber coating (SSAC) for the receiver tube of Concentrated Solar Power (CSP) systems, proposing silver as an infrared reflector for application at 550 °C. In the past, the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA) has developed SSACs suitable for applications at 550 °C, featuring solar absorbers based on graded multilayer cermet of WN-AlN and W-Al₂O₃ and an infrared reflector of tungsten. Although these coatings ensured properly stable photothermal performance at 550 °C, due to the low tungsten diffusivity, their hemispherical emittance could be reduced by using metals with higher reflectance in the infrared region, like silver. However, the high diffusivity of silver compromises its use at high temperatures. This last drawback has been addressed by foreseeing two stabilizing layers enclosing the Ag infrared reflector. One W stabilizing layer was placed between the substrate and the Ag infrared reflector, whereas a second stabilizing layer, selected among aluminum nitride deposited with a low and high nitrogen flow and aluminum oxide deposited at a low oxygen flow, was placed between the Ag infrared reflector and the solar absorber. Accelerated aging tests revealed a negligible (not detectable) degradation of the solar absorptance for the new SSACs. Furthermore, the hemispherical emittance at 550 °C increased by 0.75% and 0.42% for solar coatings with aluminum nitride stabilizing layers deposited through a high and low nitrogen flow, respectively. Differently, the increase was evaluated as being equal to 0.08% for the solar coating with an aluminum oxide stabilizing layer deposited through a low oxygen flow. The manufactured solar coating with a stabilizing layer of aluminum nitride deposited with a low nitrogen flow exhibited a solar absorptance of 95%, comparable to ENEA coatings incorporating a W infrared reflector for applications at 550 °C, whereas the estimated hemispherical emittance at 550 °C was 2% lower than that of the best ENEA coating with a W infrared reflector for the same temperature. Full article

This paper continues the mathematical research of the novel glass tube collectors for water heating. The subject of this research is a vacuum solar collector composed of a glass tube and a selective (using the SnAl₂O₃ coating) flat absorber plate. Water heating is performed using gravitational driving force and single-stage direct flow. The thermal performance with the geometric optimization (absorber width and glass tube thickness) of the presented solar collector type was determined using the specially designed iterative calculation algorithm (phase 1) and the double multi-criteria analysis (phase 2). Different operational (absorber temperature, ambient temperature and wind speed), geometric (mass, surface occupation, total surface occupation and volume occupation), economic (manufacturing costs and exploitation costs) and ecological (embodied energy and greenhouse gas emission) indicators were taken into account. The results showed that the useful heat power has an increasing trend if the flat absorber plate width increases, while the thermal efficiency has a decreasing trend. It was also determined that the glass tube thickness and the thermal performance of the solar collector are oppositely dependent. The main conclusion of this paper is that the optimal performance of such non-conventional solar systems is achieved when the absorber plate width is between 85 and 90 mm. Full article

Solar collectors represent an attractive green technology for water heating, where sunlight is efficiently absorbed by a selective coating and the generated heat is transferred to water. In this work, the improvement and scale-up of an electrodeposited black nickel selective coating with a modified silica (MS) film deposited by spray pyrolysis are reported. The MS material was prepared by the sol–gel method using tetraethyl orthosilicate with the addition of n-propyl triethoxysilane to obtain a porous film with an adequate refractive index and enhanced flexibility. The reflectance of electrodeposited selective coatings was characterized with and without the MS film and compared to a commercially available coating of black paint. The MS film increased the solar absorptance from 89% to 93% while maintaining a much lower thermal emittance than the painted coating. The reflectance of the MS film remained unchanged after prolonged thermal treatment at 200 °C (200 h). The fabrication process was scaled up to 193 cm × 12 cm copper fins, which were incorporated in commercial-size flat-plate solar collectors. Three complete collectors of an area of 1.7 m² were fabricated and their performance was evaluated under outdoor conditions. The results show that the electrodeposited selective coating with the MS film outperformed both the commercial black paint system and the system without the modified silica film. Full article

In recent years, third-generation solar cells have experienced a remarkable growth in efficiency, making them a highly promising alternative energy solution. Currently, high-efficiency solar cells often use top electrodes fabricated by thermal evaporation, which rely on high-cost and high energy-consumption vacuum equipment, raising significant concerns for mass production. This study develops a method for fabricating silver electrodes using the screen-printing process, aiming to achieve solar cell production through an all-solution coating process. By selecting appropriate blocking-layer materials and optimizing the process, we have achieved device efficiencies for organic photovoltaics (OPVs) with screen-printed silver electrodes comparable to those with silver electrodes fabricated by thermal evaporation. Furthermore, we developed a method to cure the silver ink using near-infrared (NIR) annealing, significantly reducing the curing time from 30 min with hot air annealing to just 5 s. Additionally, by employing sheet-to-sheet (S2S) slot-die coating, we scaled up the device area and completed module development, successfully verifying stability in ambient air. We have also extended the application of screen-printed silver electrodes to perovskite solar cells (PSCs). Full article

Solar thermal selective coatings (STSCs) are crucial for enhancing the thermal efficiency of receivers in solar power applications. Enhancing the photothermal conversion performance of STSCs is crucial for improving the thermo-economic efficiency of these sustainable high-temperature applications. Wherefore, in this study, we comprehensively review the ongoing technologies and enhanced strategies of solar thermal selective coatings, highlighting their advantages, drawbacks, technological advancements, and mechanisms. This review comprehensively examines the latest advancements in material synthesis, coating structure designs, and induced aging mechanisms of STSCs. It critically discusses the various types of STSCs, and the research techniques employed to assess photothermal performance and enhance thermal stability. Lastly, the limitations and future expectations of STSCs are also highlighted. This paper serves as a detailed guide for planning and implementing various types of STSCs in diverse solar power applications. Full article

Due to climate change, population increase, and the urban heat island effect (UHI), the demand for cooling energy, especially in urban areas, has increased and will further increase in the future. Technologies such as radiative cooling offer a sustainable and energy-free solution by using the wavelength ranges of the atmosphere that are transparent to electromagnetic radiation, the so-called atmospheric window (8–13 µm), to emit thermal radiation into the colder (3 K) outer space. Previous publications in the field of textile building cooling have focused on specific fiber structures and textile substrate materials as well as complex multi-layer constructions, which restrict the use for highly scaled outdoor applications. This paper describes the development of a novel substrate-independent coating with spectrally selective radiative properties. By adapting the coating parameters and combining low-emitting and solar-reflective particles, along with a matrix material emitting strongly in the mid-infrared range (MIR), substrate-independent cooling below ambient temperature is achieved. Moreover, the coating is designed to be easily applicable, with a low thickness, to ensure high flexibility and scalability, making it suitable for various applications such as membrane architecture, textile roofs, or tent construction. The results show a median daytime temperature reduction (7 a.m.–7 p.m.) of 2 °C below ambient temperature on a hot summer day. Full article

This paper proposes a temperature-adaptive radiative cooling (TARC) coating with simple preparation, cost effectiveness, and large-scale application based on a thermochromic powder. To determine the energy efficiency of the proposed TARC coating, the heat transfer on the surface of the TARC coating was analyzed. Then, a typical two-story residential building with a roof area of 258.43 m² was modeled using EnergyPlus. Finally, the energy-saving potential and carbon emission reduction resulting from the application of the proposed TARC roof in buildings under different climates in China were discussed. The results showed that the average solar reflectivity under visible light wavelengths (0.38–0.78 μm) decreases from 0.71 to 0.37 when the TARC coating changes from cooling mode to heating mode. Furthermore, energy consumption can be reduced by approximately 17.8–43.0 MJ/m² and 2.0–32.6 MJ/m² for buildings with TARC roofs compared to those with asphalt shingle roofs and passive daytime radiative cooling (PDRC) roofs, respectively. This also leads to reductions in carbon emissions of 9.4–38.0 kgCO₂/m² and 1.0–28.9 kgCO₂/m² for the buildings located in the selected cities. To enhance building energy efficiency, TARC roofs and PDRC roofs are more suitable for use on buildings located in zones with high heating demands and high cooling demands, respectively. Full article

Thin transparent oxide layers are typically patterned for use in electronic products including semiconductors, displays, and solar cells for applications such as transparent electrodes, insulating films, and encapsulation films. Conventional patterning methods have traditionally been used in photolithography and lift-off processes. Photolithography employs the wet development process, which has disadvantages such as potential undercut effects, swelling, chemical contamination, and high process costs. On the other hand, laser ablation, which has the advantages of high accuracy, high speed, a noncontact nature, and selective processing, can be used to pattern thin films. However, absorption in transparent oxide films is usually low. In this study, experiments were conducted to determine the ablation characteristics of mask layers. The factors affecting ablation, including beam radii, fluences, overlap ratios, and coating thicknesses, were examined; and the parameters characteristic of residue-free ablation, namely the ablation threshold, minimum fluence, and minimum ablation linewidth, were also examined. The experimental results revealed that the beam radius was an important parameter in determining the resolutions of transparent films and substrates. Full article

We introduce a novel method for fabricating perovskite solar modules using selective spin-coating on various Au/ITO patterned substrates. These patterns were engineered for two purposes: (1) to enhance selectivity of monolayers primarily self-assembling on the Au electrode, and (2) to enable seamless interconnection between cells through direct contact of the top electrode and the hydrophobic Au connection electrode. Utilizing SAMs-treated Au/ITO, we achieved sequential selective deposition of the electron transport layer (ETL) and the perovskite layer on the hydrophilic amino-terminated ITO, while the hole transport layer (HTL) was deposited on the hydrophobic CH₃-terminated Au connection electrodes. Importantly, our approach had a negligible impact on the series resistance of the solar cells, as evidenced by the measured specific contact resistivity of the multilayers. A significant outcome was the production of a six-cell series-connected solar module with a notable average PCE of 8.32%, providing a viable alternative to the conventional laser scribing technique. Full article

In its simplest terms, a closed-cavity façade (CCF) is a sealed, unventilated enclosure equipped with motorized shading devices, internal double or triple glazing, and external single glazing. This technology effectively controls solar energy and daylight entry into buildings. This research aims to enhance the thermal efficiency of CCFs in tropical climates using Venetian blinds (VB) and advanced glass coatings. EnergyPlus and DesignBuilder were employed to assess various CCF designs and compare them to a single glazing unit (SGU) with grey coatings. This was inspired by a residential case study on Penang Island, Malaysia. The findings indicate that CCFs surpass SGUs in thermal performance and occupant comfort, particularly in Malaysia’s humid tropical climate. CCFs reduced operating temperatures by a monthly percentage ranging from 33.5% to 68.75% in all operations. On an annual basis, temperature reductions ranged from 27.5% to 80.25%, with maximum decreases between 2 °C and 4 °C and minimum decreases between 0.5 °C and 1 °C compared to SGU units. The results show that CCFs outperform SGUs in thermal performance and comfort, reducing operating temperatures by 33.5% to 68.75% monthly and 27.5% to 80.25% annually. Temperature reductions ranged between 2 °C and 4 °C at maximum and 0.5 °C and 1 °C at minimum compared to SGU. Notably, Venetian blinds with nano-coatings (83/58) and low-E coatings (83/23) (T_vis/T_sol) were the most effective. This study highlights the importance of selecting appropriate coatings for CCFs, and demonstrates their potential in enhancing interior temperatures and comfort in Malaysia’s climate. The findings emphasize the significant impact of innovative glazing technologies on improving operational temperatures and occupant comfort using closed-cavity façades in the tropics. Full article

Asphalt pavements absorb more than 90% of the incident solar radiation, which induces not only high-temperature degradation but also the urban heat island (UHI) effect. In this study, a novel nanoscale non-stoichiometric compound containing tungsten (M_xWO₃) was used for the first time to prepare thermal shielding coatings to reduce the temperature of pavements and mitigate the UHI effect. Coatings with good shielding characteristics were selected for outdoor thermal insulation tests to evaluate their properties. M_xWO₃ (M = K, Na, Cs) exhibited significant thermal shielding, especially Cs_xWO₃. Outdoor thermal insulation tests were performed for the Cs_xWO₃ coatings, and it was found that the greater the doping, the more significant the thermal shielding effect. Compared with untreated pavements, the surface-coated pavement exhibited significant cooling at 5 cm and 15 cm depth-wise, which reduced the overall pavement temperature by 1–2 °C, and the coating thickness affected the cooling effect. Full article