Solar Thermal Energy Conversion Research Articles

Boric acid-free electrodeposition process and solar–thermal energy conversion of and Ni-carbon black nanocomposite coatings

AbstractThis work focuses on the development of a multi-layered system, of bright nickel electrodeposited on a steel substrate, and a second layer composed of black nickel either with or without carbon black nanoparticles (CB NPs), aiming for an efficient conversion of incident solar radiation into heat, for the fabrication of solar collectors. The structural characterization, revealed that the bright nickel film was composed of metallic nickel, while the black coatings contained amorphous nickel compounds. SEM analysis unveiled the presence of pinholes on the surface of the bright nickel film, suggesting that the black nickel coating was ineffective in sealing them. The appearance of cracks with the increase in the deposition time was observed. With the nanocomposite of black nickel and CB NPs, these cracks can be avoided and the pinholes sealed. The CB NPs were found to reduce reflectance, enhancing the conversion of solar energy into heat. Graphical abstract

3D reconfigurable hydroxylated carbon nanotubes-based water evaporators with long-distance transportation for continuous vapor generation

Utilizing solar-thermal power for water purification through interfacial solar steam generation represents an environmentally friendly approach to secure a clean water source. However, it is still challenging to simultaneously overcome short transport distances, low transport rates, and unsatisfactory solar-thermal energy conversion efficiency, as well as the salt accumulation problem. In this work, three-dimensional (3D) reconfigurable water evaporators are developed based on commercial fabric strings and hydroxylated carbon nanotubes. The specifically designed 3D architecture enables the fabric strings to have a long water transport distance and localized focusing of solar light that benefits the fabrication of 3D evaporators and water isolation with low heat loss. Besides, the hydroxylated carbon nanotubes with strong hydrophilicity as well as their inherent black color show high solar-heat conversion efficiency. A high evaporation rate of 3.234kg m-2h−1 is found and a solar-to-vapor efficiency of 123.21 % is also achieved by using a vertical evaporation structure due to the enlarged surface area allowing absorption of heat from the environment. Meanwhile, the accumulated salts do not block the water transport pathway and they can be easily removed in high-salinity water evaporation by employing the assembled rotating evaporator. The results suggest that the fabric rope is a good platform for exploring highly efficient evaporation structures. Combined with hydroxylated carbon nanotubes, as-designed 3D reconfigurable evaporators are promising for efficient freshwater generation.

Solar Selectivity of Silver Nanoparticles Modified Copper Oxide Nanocomposite Thin Films Prepared by Facile Chemical Oxidation Method

AbstractSilver nanoparticles modified copper oxide nanocomposite thin films (Ag‐CuO NC TFs) and pristine CuO TF were successfully synthesized on copper substrates using a chemical oxidation route. X‐ray diffractometry (XRD) characterization of Ag‐CuO NC TFs revealed the formation of monoclinic crystal structured CuO. Scanning electron microscopy (SEM) images showed a star‐like grain morphology of the Ag‐CuO NC TFs. Energy dispersive X‐ray spectroscopy (EDX) analysis ascertained the presence of anticipated elements without impurities. Fourier transform infrared spectroscopy (FTIR) investigation confirmed the presence of Ag NPs on CuO in the Ag‐CuO NC TFs. Raman spectroscopy examination indicated the presence of a spinel structure with vibrational and tetrahedral sites. UV‐Vis‐NIR reflectance analysis demonstrated that Ag‐CuO NC TFs with 2.0 wt.% Ag NPs exhibited solar absorptance of 72.39 %, thermal emittance of 4.3 %, and a highest solar selectivity of 16.83 among the prepared thin films. These results suggest that the Ag‐CuO NC TFs could be promising candidates for use as solar selective absorbers in solar thermal energy conversion devices.

Preparation and thermal stability research of oxalic acid dihydrate-glutaric acid/PAMPS phase change gel for solar thermal energy utilization

Thermal energy storage technology based on phase change materials (PCMs) can address the temporal and spatial mismatches in solar thermal energy conversion, thereby enhancing solar energy utilization efficiency. However, the liquid flow and poor thermal reliability of PCMs limit their large-scale application in solar thermal systems. In this study, we employ a simple “one-pot method” to prepare a form-stable and thermally reliable oxalic acid dihydrate-glutaric acid/poly 2-Acrylamido-2-methyl-1-propanesulfonic acid (OAD-GA/PAMPS) phase change gel. The OAD-GA/PAMPS phase change gel melts at 64.5 °C with a phase change enthalpy of 193.6 kJ/kg, the tensile strength is 7.707 MPa, and the compressive strength is 16.940 MPa. By incorporating 5 wt% BN particles, the thermal conductivity of OAD-GA/PAMPS phase change gel reaches 0.63 W/(m·K). After 200 heating-cooling cycles, the phase change temperature of the OAD-GA/PAMPS phase change gel remains nearly unchanged, and the phase change enthalpy decreases by only 5.7 %. The photo-thermal conversion efficiency of the OAD-GA/PAMPS phase change gel is 82.7 %. The high thermal reliability and photo-thermal conversion efficiency of the OAD-GA/PAMPS phase change gel makes it suitable for solar thermal energy storage applications.

Tree-like 3D GNP-rPN composite structure for solar-thermal evaporation and photocatalytic degradation of antibiotic wastewater

To realize high-yield and long-term purification of wastewater containing antibiotic ciprofloxacin hydrochloride (CIP) and seawater, a tree-like 3D GNP-rPN solar-driven water evaporation and photocatalysis evaporator is developed by preparing and assembling GO/NPDI/PVA (GNP) hydrogel (canopy) and rGO/PU/NPDI (rPN) foam (trunk). The “tree-like” evaporation and photocatalysis evaporator design in this work has the following three characteristics: First of all, graphene oxide (GO) and reduced graphene oxide (rGO) sheets broaden the light absorption range of the photocatalyst perylene imide nanowires (NPDI), which facilitates absorption of more sunlight; secondly, GO and rGO adsorb pollutants in water and provide them to NPDI for catalytic degradation under sunlight irradiation because of their huge specific surface area; thirdly, the excellent photothermal conversion ability of GO and rGO converts solar energy into heat energy, thus facilitating the catalytic degradation of CIP by NPDI. Thanks to the reduced enthalpy of water evaporation by GNP hydrogel, the sufficient top-down water supply, the superior photocatalytic performance of NPDI nanowires, and the efficient solar light absorption and solar-thermal energy conversion of the GO sheets and NPDI nanowires, the resultant GNP-rPN evaporation and photocatalysis system achieves an average water evaporation rate of 2.84 kg m−2 h−1 and a CIP degradation efficiency of 74.04 % within 1 h under 1-sun irradiation. The GNP-rPN system exhibits an optimal degradation efficiency of 74.04 % for a CIP solution with an initial concentration of 10 mg/L within 1 h of irradiation, reaching a degradation efficiency of 96.37 % after 4 h, demonstrating its effectiveness in purifying antibiotic-laden wastewater.

Interfacial enhancement enables highly conductive reduced graphene oxide-based yarns for efficient electromagnetic interference shielding and thermal regulation

Although the coating of conductive graphene onto commercial yarns is promising for scalable production, the resulting conductive yarns are susceptible to the coating detachment, causing reduced conductivity and poor stability. Herein, we propose a scalable and cost-effective interfacial enhancement strategy for fabricating highly conductive yarns with satisfactory mechanical properties by modifying polyamide yarns with polyethyleneimine to enhance their interaction with graphene oxide (GO) sheets and subsequently reducing the GO component with hydroiodic acid. Because the enhanced interfacial interactions of the polyethyleneimine-modified polyamide yarns with the GO sheets improve the loading of GO and the coating stability, the resultant yarns can withstand bending, embroidering, sewing and weaving, maintaining an extraordinary conductivity of 4.7 × 103 S m−1 after 10000-cycle bending. The conductive textiles woven by the yarns reach an excellent electromagnetic interference (EMI) shielding effectiveness of 66.7 dB at the thickness of 0.615 mm along with superior hydrophobicity, satisfactory air permeability, and high electrothermal and solar-thermal energy conversion performances. The EMI shielding effectiveness of the textile is well maintained even after 5000-cycle bending, demonstrating its satisfactory stability. This work demonstrates an interfacial enhancement strategy for the large-scale fabrication of multifunctional yarns that hold great promise for EMI shielding, personal thermal regulation, and deicing applications.

A novel design for conversion and storage of solar thermal energy into electrical energy using a solar thermoelectric device‐coupled supercapacitor

AbstractThe conversion of solar‐thermal (ST) power into electrical power along with its efficient storage represents a crucial and effective approach to address the energy crisis. The thermoelectric (TE) generator can absorb ST power and transform it into electrical energy, making it a highly viable technology to achieve photo‐thermal conversion (PTC). However, the practical application of the pristine TE generator devices on a larger scale is still facing several challenges. On the one hand, the pristine TE generator device has low inherent PTC efficiency, thereby leading to low power conversion. On the other hand, such solar‐thermoelectric (STE) conversion does not provide the functionality of electric energy storage. Herein, an effective strategy has been proposed that employs a CoAl2O4 PTC coating to decorate the pristine TE generator for developing the STE generator device with the remarkable STE performance and then coupling this device with a supercapacitor (SC) for effective storage power. In comparison to the pristine TE generator, the developed STE device exhibited considerable enhancement in both the open‐circuit voltage (Voc) and its maximum power density, displaying more than a 4‐ and 15‐fold improvement, respectively. In addition, the feasibility of coupling this solar‐driven STE generator device in series with a SC for ST conversion and storage was verified, and the working mechanism has been elucidated. This work presents a promising approach to effectively convert and store clean solar power into electrical energy, enabling practical applications of STE generator devices in conjunction with other electrochemical energy storage devices.

Diffusion Behaviors of CaCl2-NaCl Molten Salt under an Electric Field: A Deep Potential Molecular Dynamics Simulation.

CaCl2-NaCl molten salt is one of the widely used electrolytes, and the effect of the electric field on it needs to be considered in the environment of manufacturing metals and alloys as well as in battery applications. To be closer to the state of the CaCl2-NaCl molten salt system in practical applications, this study uses the training-based deep potential, combined with the ionic structure, to analyze the electric field effects on the drift velocity, ionic mobility, ion diffusion, and viscosity of the CaCl2-NaCl system by molecular dynamics simulations. It is shown that the electric field has a stronger effect on the ion diffusion behavior parallel to the direction of the electric field in the CaCl2-NaCl molten salt system. Due to the looser coordinate structure of Na+, the interaction force between Na-Cl is small compared with that between Ca-Cl. Na+ is easily driven and more sensitive to the electric field, whose drift velocity, ionic mobility, and diffusion coefficient are larger than those of the other two ions, with an order of Na+ > Cl- > Ca2+. All ionic drift velocities increase linearly as electric field intensity increases and the ionic mobilities tend to be constant. The diffusion coefficient parallel to the direction of the electric field exponentially increases and the viscosity tends to exponentially decrease with the increase in the electric field intensity. This work is important for accurately predicting the properties and performance of molten salts and their improvement for applications such as solar thermal energy conversion.

Phase change materials encapsulated in graphene hybrid aerogels with high thermal conductivity for efficient solar-thermal energy conversion and thermal management of solar PV panels

Phase change materials (PCMs) have a wide range of applications in latent heat storage and thermal management. However, their practical use is hindered by high leakage rates and low thermal conductivity. To address these issues, polyvinyl alcohol/carboxylated carbon nanotubes/graphene hybrid aerogels (PCG) were carbonized at high temperatures to obtain polyvinyl alcohol/carboxylated carbon nanotubes/graphene carbon aerogels (cPCG). Polyethylene glycol (PEG) was then encapsulated within cPCG to form cPCG@PEG shape-stabilized PCMs (SSPCMs). These cPCG@PEG SSPCMs demonstrated excellent thermal conductivity (0.843 W•m-1•K-1) and superior solar-thermal conversion performance (91.8%). Additionally, the latent heat of cPCG@PEG showed a minimal decrease even after 100 melt-crystallization cycles. An experimental setup was designed to regulate the temperature of solar photovoltaic (PV) panels using cPCG@PEG. The results indicated that cPCG@PEG effectively managed the temperature of solar PV panels under varying light conditions. This study presents a novel approach for enhancing the application of porous PCMs in solar energy utilization and thermal management of equipment.

One-Step Electrochemically Prepared Bionic Hierarchical Nickel Black@Graphene Composite Membrane for Desalination by Solar-Thermal Energy Conversion.

Ingenious microstructure construction and appropriate composition selection are effective strategies for achieving enhanced performance of photothermal materials. Herein, a broccoli-like hierarchical nickel black@graphene (Ni@Gr) membrane for solar-driven desalination was prepared by a one-step electrochemical method, which was carried out simultaneously with the electrochemical exfoliation of graphene and the co-deposition of Ni@Gr material. The bionic hierarchical structure and the chemical composition of the Ni@Gr membrane increased the sunlight absorption (90.36%) by the light-trapping effect and the introduction of graphene. The Ni@Gr membrane achieved high evaporation rates of 2.05 and 1.16 kg m-2 h-1 under simulated (1 sun) and outdoor sunlight conditions, respectively. The superhydrophilicity and the hierarchical structure of the Ni@Gr membrane jointly reduced the evaporation enthalpy (1343.6 kJ/kg), which was beneficial to break the theoretical limit of the evaporation rate (1.47 kg m-2 h-1). This work encourages the application of bionic metal-carbon composite photothermal materials in solar water evaporation.

DFT analysis of Cs2NaBiCl6, Cs2NaBiBr6, and Cs2NaBiI6 perovskites for optoelectronic and thermoelectric applications

In this theoretical study, we examined the structural, electronic, optical, elastic, and thermoelectric properties of Cs2NaBiX6 (X = Cl, Br, I) halide double perovskites. The calculated formation energies are negative, affirming the stability of these compounds and their suitability for experimental synthesis. Our investigation has revealed the presence of strong covalent bonds within the [Bi/NaX6] clusters. The electronic properties demonstrate the indirect bandgap of 1.94, 3.15, and 3.24 eV for Cs2NaBiI6, Cs2NaBiBr6, and Cs2NaBiCl6, respectively, calculated using modified Becke-Johnson potential plus spin–orbit coupling (mBJ + SOC) approximation. In the visible spectrum, Cs2NaBiI6, Cs2NaBiBr6, and Cs2NaBiCl6 exhibit average rate transmittance of 53 %, 83 %, and 84 %, respectively. The absorption spectrum, extending from visible to ultraviolet (UV) wavelengths, reaches 25 × 104/cm in the case of the iodine-based perovskite. The thermoelectric characteristics, involving Seebeck coefficient, electrical conductivity, and power factor, demonstrate the use of these perovskites as a suitable for solar cells and solar thermal energy conversion technologies.

Cost-efficient sunlight-driven thermoelectric electrolysis over Mo-doped Ni5P4 nanosheets for highly efficient alkaline water/seawater splitting

Thermoelectric water spitting to hydrogen systems has great potential in the production of environment-friendly fuel using renewable solar energy in the future. In this work, we prepared porous nanosheet Mo doping Ni5P4 catalysts on nickel foam with efficient hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performance in alkaline media. Density Functional Theory (DFT) calculations and experimental studies have shown that Mo doping deadeneds the interaction between H and O atomic orbitals of transition state water molecules, effectively weakening the activation energy of H2O dissociation. Therefore, Mo doping is favorable for enhancing HER activity with overpotential at 10 mA cm–2 of 93 mV and Tafel slope of 40.1 mV dec–1 in 1 M KOH. Besides, it exhibits high alkaline OER activity with an ultra-low overpotential of 200 mV at 10 mA cm–2. Moreover, this catalyst only needs 1.537 V in a dual-electrode configuration of the electrolytic cell, which is much lower than the commercial Pt/C-RuO2 couple (1.614 V). In addition, we have developed and constructed a solar thermoelectric generator (TEG) that is capable of floating on water. This TEG has a continuous power output and an exceptionally long lifespan, providing a stable power supply to the synthesized catalyst electrolyzer. It can produce a maximum power output of over 90 mW, meeting the requirement of converting solar radiation heat into usable electricity. As a result, the system achieves productivity of 0.11 mL min–1 H2. This solar thermal energy conversion technology shows the possibility of large-scale industrial production of H2 and provides a new idea for exploring heat source utilization.

Photothermal conversion-enhanced thermoelectric generators combined with supercapacitors: An efficacious approach to integrated power generation and storage

Thermoelectric generators (TEGs), which harness and convert solar-thermal energy into electrical energy, possess immense potential within the field of photothermal conversion (PTC). However, the widespread adoption of conventional TEGs in PTC domain has encountered some obstacles, which represent that TEGs have poor inherent PTC performance, resulting in low solar-thermoelectric conversion efficiency, and this solar-thermal-electric conversion method lacks the capability of electrical energy storage. Hence, an urgent imperative exists to develop integrated and synergistic energy technologies that can respond to these underlying challenges. Herein, we reported a novel strategy for employing spinel-type Cu1.5Mn1.5O4 PTC coating to adorn conventional TEG to construct the solar-thermoelectric generator (STEG) which exhibited excellent solar-thermoelectric conversion capability, and then integrating the STEG in series with a supercapacitor composed of synthetic ionic liquid electrolytes and carbon electrodes to fulfill the conversion and storage of solar-thermal energy into electrical energy. The results indicated that, when compared to a conventional TEG, the STEG attained a drastically elevated internal temperature difference due to the excellent PTC capability of spinel-type coating. As a result, remarkable enhancements were observed in both the steady-state voltages (Voc) and maximum output power density (Pmax) of the STEG, exceeding a 6-fold and 40-fold increase, respectively. Furthermore, we conducted experimental validation to ascertain the viability of the solar-driven STEG to charge a supercapacitor, thereby achieving the conversion and storage of solar-thermal energy into electrical energy, and the working mechanism of this integrated system has been revealed. This study offers invaluable insights into the development of highly efficient solar-thermal energy conversion and storage methods.

High performance composite phase change materials enhanced via evaporation-induced hydrogen bond network refactoring

Composite phase change materials (CPCMs) with real-time thermal harvesting are in high demand in the solar-thermal energy conversion industry. However, poor heat conduction, lack of strength and leakage problem severely restrict its availability. In this study, we develop an evaporation-inspired, facile, and versatile strategy for manufacturing shape stable CPCMs from organohydrogels with enhanced thermal performances for advanced thermal energy storage and management. Organohyodrogels contained with graphene nanoplatelets (GNPs) served as the template. By oven-drying the organohydrogel, hydrogen bonding reconstruction would assist in the formation of a dense polymer layer to encapsulate PCMs, forming the non-leakage CPCMs. The strong capillary force generated during the oven-drying process would induce the alignment of GNPs, forming thermal conduction pathways. The as-prepared composite exhibits a high thermal conductivity (1.25 W m-1K−1), satisfactory latent heat storage (171.5 J g−1) and excellent Young’s modulus (8.3 MPa). When subjected to solar radiation, solar energy is converted to heat and stored inside the material, with a conversion efficiency as high as 95.8 %. The robust composite with high performance is expected to be an efficient and reliable thermal management material in solar-thermal energy conversion.

NUMERICAL HEAT TRANSFER ENHANCEMENT OF SOLAR RECEIVER TUBE OF PARABOLIC TROUGH COLLECTOR USING FIBERFRAX 140 COATED WITH AL 2O 3

Parabolic trough collectors (PTCs) play a vital role in solar-thermal energy conversion, with the absorber tube being central to heat collection efficiency. This study investigates the potential for improving heat transfer within the PTC absorber tube using Fiberfrax 140 coated with Al 2O 3 as a novel reflector material. The research is driven by the ongoing pursuit of enhanced PTC performance. A standard modeling approach was employed, utilizing Computational Fluid Dynamics (CFD) analysis with SolidWorks Flow Simulation software, coupled with solar simulations to assess collector performance under varying conditions. Environmental parameters of Bauchi such as temperature, humidity, and wind speed were sourced from the Nigerian Meteorological Agency (NiMet). Optimization techniques were implemented to establish the optimal design configuration. The optimal design parameters were determined as a focal length of 700mm and a rim angle of 90°. Simulations were conducted daily from 8:00 AM to 5:00 PM, encompassing the period of January to June. A mass flow rate of 0.2 kg/s, informed by existing literature, was employed in the simulations. The results indicate improved collector performance throughout the simulated period, with peak thermal efficiency ranging from70%to82%.

Multifunctional flexible composite membrane based on nanocellulose-modified expanded graphite/electrostatically spun fiber network structure for solar thermal energy conversion

To enhance the application range of flexible films, it is crucial to rationally design composite films with high stretchability, excellent thermal conductivity, and water resistance. Flexible composite films with nanocellulose (CNF)-modified expanded graphite and spun fibers loaded with phase change materials as the backbone were obtained by electrospinning method. The prepared materials were characterized by good tensile properties (328.32%), high latent heat (107.0 J/g), good thermal stability, high photo-thermal conversion efficiency, good reusability, flame retardant properties, UV resistance and visible light absorption properties. What's more, the performance of the flexible composite membrane is adjustable. The prepared flexible composite membranes are promising in the fields of solar thermal energy conversion, wearable flexible materials and renewable energy utilization.

Metal-organic framework (MOF) dispersion based fluids for solar-thermal energy conversion

This paper discusses the potential use of metal–organic framework (MOF) dispersion based fluids for solar-to-thermal energy conversion (STEC). For this, the optical and thermal characteristics of MOF dispersion were investigated, with MOFs dispersed in ethylene glycol (EG). This study is focused on three different MOF dispersions, namely ZIF8/EG, CuBTC/EG, and FeBTC/EG, each with varying concentrations of MOF particles. The results showed that FeBTC/EG at a concentration of 0.3 wt% is the optimal fluid for STEC, exhibiting the highest absorption and STEC efficiency compared to the other two fluids. The study also highlights the trade-off between STEC efficiency and cost, as increasing the concentration of MOF particles decreases the specific absorption rate (SAR). Additionally, the paper evaluates the dispersion stability of FeBTC/EG over time, which is critical for practical STEC applications. The novelty of the paper lies in the use of MOF dispersion based fluids for STEC application, which has not been extensively studied before. This study provides valuable insights into the potential use of MOF/EG for STEC and highlights the importance of optimizing the concentration of MOF particles for efficient and cost-effective performance. This study also introduces the novel application of MOF dispersion based fluids for enhanced STEC performance, showcasing FeBTC/EG as a standout for its high efficiency and stability. It marks a significant stride in utilizing MOF materials for sustainable energy, emphasizing practical considerations of dispersion stability and cost-effectiveness in STEC systems.

A high-temperature solar selective absorber based on one-dimensional multilayer nanostructures

Selective absorbers play a crucial role in harvesting solar energy and realizing effective solar-thermal energy conversion in concentrated solar power systems and thermophotovoltaic systems. This study focuses on obtaining a high-temperature solar selective absorber which can well balance its thermal performance as well as structural complexity. Based on this, a selective absorber with simple one-dimensional multilayer nanostructures is designed to adapt to the high-temperature operation environments. The obtained absorber exhibits a total solar absorptance of 0.9504 to the AM1.5 solar radiation. Taking into account the infrared radiation loss, the solar-thermal efficiency of the absorber is found to be 91.2% under 1000 suns at 1273 K, and the total emittance is 0.1504 at the corresponding temperature. The absorber shows high insensitivity to both incident polarization angles and wide-angle incidence. Analysis of impedance and electromagnetic field distribution indicates that the selective absorption performance of the absorber is attributed to its impedance matching properties, resulting from the coupling effect of surface plasmon polaritons and magnetic polaritons.

Mathematical analysis of the solar assisted thermoelectric generator

The direct conversion of solar energy into electrical energy is primarily dependent on the photovoltaic systems. However, in the last few decades, researchers have shown interest to work on the thermoelectric modules for direct conversion of solar thermal energy into electrical energy based on the Seebeck effect. This research paper provides a comprehensive analysis of various Solar Thermoelectric Generator (STEG) designs, focusing on their conversion efficiencies. Despite the comparatively lower efficiency of STEG in comparison to photovoltaic (PV) cells, owing to limitations in the figure of merit value and temperature differences between hot and cold sides of the thermoelectric modules, this study proposes strategies for enhancement. Approaches include the development of materials with higher figure of merit values, design optimization, solar tracking, heat storage systems, and efficient heat sink designs. Also, Mathematical analysis of the power and efficiency calculation of a STEG has been presented on the basis of some fundamental and derived mathematical equations. The overall efficiency of STEG, a product of Opto-thermal Efficiency and thermoelectric module efficiency, is explored, identifying an optimal hot side temperature for maximum efficiency. Module mismatch analyses for series and parallel connections are also derived, underscoring conditions for mitigating power loss. These findings serve as guidelines for designing more feasible and efficient STEG systems, with considerations for economic viability, sustainability and greenhouse gas reduction throughout the life cycle.

Economical and shape-stabilized hydrated salt/bagasse biomass-derived carbon phase change composite for thermal energy storage

Due to their high heat storage density, low cost, and non-inflammability, hydrated salts have significant potential for application in thermal energy storage for buildings. Hydrated salts, however, have a few drawbacks, including high supercooling degree, unstable shape, and phase separation. In general, materials such as graphite, aerogel, and foam metal are commonly used to provide support for hydrated salts in order to mitigate or eliminate their drawbacks. While these currently used supporting materials have expensive and complicated production procedures. In this study, we developed bagasse biomass-derived carbon (BBC) materials to obtain easily accessible, cost-effective, and environmentally friendly support materials. Using the high-temperature carbonization method, the bagasse made from biological waste displayed a highly oriented and stacked lamellar structure. This not only significantly lowered the cost but also made the storage of hydrated salts easier. A straightforward vacuum impregnation technique was used to create SSD-SC/BBC phase change composites (PCCs). In comparison to sodium sulfate decahydrate (SSD), the developed SSD-SC/BBC9 PCCs exhibited a higher thermal storage capacity of 161.5 J/g, along with an exceptionally low supercooling degree. They also demonstrated the higher thermal conductivity of 1.79 W·m−1·K−1, improved thermal reliability, and enhanced solar-thermal energy conversion ability. Compared to other support materials, the economic analysis using static and dynamic payback periods demonstrates that the utilization of biomass-derived carbon as a support material for phase change materials (PCMs) is cost-effective, with lower preparation costs and a shorter payback period. A simple, affordable, and environmentally friendly method for utilizing hydrated salts in thermal energy storage for buildings is provided by SSD-SC/BBC9 PCCs.