Thermal Storage Materials Research Articles

Advancing Solar Rooftop Power Generation: A Review on the Integration of Concentrated Solar Technology and Advanced Materials with Economic Perspectives

Abstract: This review paper offers a thorough analysis of the integration of concentrated solar technology and advanced materials in solar rooftop power generation, with a primary emphasis on optimizing efficiency and economic viability. As the demand for sustainable energy solutions intensifies, harnessing concentrated solar energy on rooftops presents a promising avenue for meeting these challenges. The paper explores current advancements in concentrated solar technologies, including solar concentrators, parabolic troughs, and solar towers, elucidating their working principles and efficiency gains. Concurrently, the integration of advanced materials, such as high-efficiency photovoltaic materials, thermal storage materials, and coatings, is discussed for their role in enhancing the overall performance and durability of rooftop solar systems. A critical examination of the economic aspects associated with these technologies forms a pivotal aspect of this review, encompassing an evaluation of initial investment costs, operational expenses, and potential returns on investment. Economic models and case studies are presented, offering valuable insights into the financial implications and feasibility of widespread adoption.

A Novel Sandwich-Structured Phase Change Composite with Efficient Photothermal Conversion and Electromagnetic Interference Shielding Interface.

Stability and multifunctionality greatly extend the applications of phase change materials (PCMs) for thermal storage and management. Herein, CuS and Fe3O4 nanoparticles were successfully loaded onto cotton-derived carbon to develop a multifunctional interface with efficient photothermal conversion and electromagnetic interference (EMI) shielding properties. 1,3:2,4-di-(3,4-dimethyl) benzylidene sorbitol (DMDBS) and expanded graphite (EG) formed an organic/inorganic three-dimensional network framework to encapsulate 1-octadecanol (OD) by self-assembly. Finally, multifunctional shape-stabilized PCMs (SSPCMs) with the sandwich structure were prepared by the hot-press process. Multifunctional SSPCMs with high load OD (91%) had favorable thermal storage density (200.6 J/g), thermal stability, and a relatively wider available temperature range with improved thermal conductivity to support the thermal storage and management realization. Furthermore, due to the synergistic enhancement of two nanoparticles and the construction of the carbon network with cotton carbon and EG, highly efficient photothermal conversion (94.4%) and EMI shielding (68.9 dB average, X-band) performance were achieved at about 3 mm thickness, which provided the possibility of the multifunctional integration of PCMs. Conclusively, this study provides new insights towards integrating solar energy utilization with the comprehensive protection of related electronics.

Effect of different silicon sources on the properties of in-situ synthesized corundum-mullite composite thermal storage ceramics

Thermal storage materials are typically made of materials with high thermal storage density, high thermal conductivity and high temperature stability. In this study, corundum-mullite composite thermal storage ceramics were prepared by solid-phase sintering using widely available and low-cost α-Al2O3, kaolin, and quartz as raw materials. The effects of silicon source and Al2O3/SiO2 ratio on the physical properties and structural properties of corundum-mullite composite ceramics were investigated. The results showed that the A3 sample (α-Al2O3: 85.77 wt%, kaolin: 14.23 wt%) after sintering at 1650 °C had the excellent performance, with thermal conductivity of 15.01 W (m K)−1 (25 °C), thermal storage density of 965.15 kJ kg−1, and bending strength of 145.9 MPa. The multiple ions introduced by kaolin can effectively promote the liquid-phase mass transfer at high temperatures, accelerate the diffusion rate of Si4+, increase the growth rate of mullite, and accelerate the densification process of the samples, which in turn improves the physical properties of the samples. When used in a solar thermal storage system, the A3 sample per unit volume can provide 911.53 kW h of electricity to the grid, saving 112.12 kg of coal and reducing 358.78 kg of CO2 emissions.

Assessment of solar distillers with cement layer and cement cylinder fins as low-cost and locally available thermal storage materials

ABSTRACT Most regions of the world, including the Algerian desert (southeast of Algeria, the El-Oued region in particular) suffer from pure water scarcity, although there is a huge stockpile of groundwater, it is salty water. Solar stills are one of the best solutions to the problem of freshwater shortages because it depend on solar energy, which is abundant throughout the year in southeastern Algeria. Due to the low productivity of solar stills, the current experimental study aims to create simple and inexpensive solutions to improve the productivity of solar stills. This was done by manufacturing the absorption basin from a concrete layer, with the addition of cement cylindrical fins and which were used as energy storage materials in addition to the use of cylindrical fins helped to increase the heat transfer area between the absorption surface (thermal storage materials) and basin water. To achieve this goal, two single-slope solar distillers were built and tested in this article, the first is Single Slope Solar Distiller with a Cement Layer (2 cm) placed as absorbent at the bottom base of the basin (SSSD-CL) and the second is a Single Slope Solar Distiller with Cement Layer (2 cm) and Cement Cylindrical Fins (SSSD-CL&CCF). Cylindrical fins are made of cement with a diameter of 1.5 cm and a length of 3 cm. The results showed that SSSD-CL&CCF produced drinking water at a rate of 4.52 kg/m2/day while SSSD-CL produced only 3.46 kg/m2/day, which is 30.64% more compared to SSSD-CL&CCF. These results demonstrated that the drinking water produced by SSSD-CL improved by incorporating the cement cylindrical fins with the cement layer as low-cost and available sensible thermal energy storage materials. Also, Cement cylindrical fins were used, which increased the thermal and exergy efficiency by 31% and 56.7%, respectively.

Enhanced performance assessment of an integrated evacuated tube and flat plate collector solar air heater with thermal storage material

The solar air heater incorporating flat plate solar collectors is a straightforward system suitable for domestic use. Nonetheless, it faces challenges with lower thermal efficiency, especially when applied to moderate-temperature purposes. This study aimed to enhance the solar air heater performance by integrating an evacuated tube collector with a flat plate collector and incorporating paraffin C20-C33 as thermal storage material. Inside the flat plate solar collector, the phase change material (paraffin C20-C33) is placed under the absorber surface where the copper air pipes are immersed. Different parameters like outlet temperature, temperature rise, heat gain, thermal efficiency, and pressure drop have been analyzed and discussed for varying weather conditions and mass air flow rates. Also, the system performance is compared by using phase change material (paraffin C20-C33) and without it. The experimental results show that the innovative design achieves higher efficiency, temperature output, and operation hours compared to the standard SAHs. In the presented SAH, the maximum air outlet temperature reached 119 °C at a flow rate of 0.015 kg/s. The maximum ratios of temperature rise to solar radiation at mass air flow rates 0.015, 0.02, and 0.025 kg/s were about 28 %, 26 %, and 25.5 % without PCM and 31 %, 28.5 %, and 27.6 % with PCM, respectively. The average daily thermal efficiency reached the highest values of 47.46 %, 56.12 %, and 64.53 % at air mass flow rates of 0.015, 0.02, and 0.025 kg/s respectively with PCM. The increase in the ratio of accumulated useful energy to average solar radiation through the day was found at 16 %, 14 %, and 13 % with PCM at 0.015, 0.02, and 0.025 kg/s respectively compared to the one without PCM. This developed solar air heater shows promising potential for various applications such as drying and industrial process heating.

Sustainable and clean water distillation by parabolic dish collector and different heat absorber and thermal storage materials: An experimental study

In this study, an integrated solar distillation unit with a parabolic dish collector and a spherical solar water distillation unit is designed. The use of parabolic dish collector increases the evaporation rate of the saltwater in the lower chamber (basin) of the spherical distillation unit considerably. The performance of solar water distillation system is investigated for different types of basin material, including copper, zinc, and iron. In the second part, the gravel is used in the copper basin of solar distillation system as the thermal energy storage material. The thermal efficiency, water productivity, exergy efficiency, and freshwater production cost of the integrated solar distillation system with different types of basin materials are studied. The thermal efficiency of the integrated solar distillation system with the copper, zinc, and iron basins was 13.97 %, 10.72 %, and 9.88 %%, respectively. The water productivity of the integrated solar distillation system with copper, zinc, and iron basins was 2.592 kg, 2.27 kg, and 1.825 kg, respectively during 9 h of experiment. The exergy efficiency of the integrated solar distillation system with the copper basin was better than the zinc and iron basins. The gravel can increase the productivity of solar distillation system up to three times in the sunset and night hours.

Design and heat analysis of basalt glass as a thermal storage material in a concentrated solar power (CSP) system

Design and heat analysis of basalt glass as a thermal storage material in a concentrated solar power (CSP) system

Aspects of energy, exergy, economy, and environment for performance evaluation of modified spherical solar still with rotating ball and phase change material

This study explores advancements in solar distillation, introducing a modified spherical solar still with a rotating ball to overcome traditional limitations of low productivity. The study conducted a comprehensive set of experiments in Kafrelsheikh, Egypt (31.1107° N, 30.9388° E) to compare the performance of the modified spherical distiller with that of the conventional spherical solar still. The evaluation encompassed various aspects, including energy, exergy, economic, and environmental dimensions. Key factors investigated within the study encompassed a range of rotation speeds (0.25, 0.5, 0.75, 1, 1.25, and 1.5 rpm), the introduction of a black jute wick material stretched over the rotating ball, and the utilization of a thermal storage material beneath the rotating ball. Two thermal storage materials were investigated with three arrangements (desert sand, copper grits, and mixture of both). The study's findings have unveiled that the optimal rotation speed for MSSS was 0.75 rpm, where the yield was augmented by 40 %. While incorporating wick material enhanced the distillate of the modified spherical distiller by 57 % when operating at 0.75 rpm. The best operating conditions for the modified spherical distiller were operating at 0.75 rpm and using wick and mixture of copper grits and desert sand, where the distillate reported 7160 ml/m2.day versus 3525 ml/m2.day for conventional spherical distiller, which means that the distillate was improved by 103 % and efficiency reached 59.5 %. Moreover, the exergy efficiencies for the conventional and modified spherical distillers at 0.75 rpm with thermal storage material, are 3.1 % and 4.2 %, respectively. Also, the cost of producing one liter of distilled water for conventional spherical distiller, modified spherical distiller, and modified spherical distiller with thermal storage material was determined to be $0.066, $0.043, and $0.024, respectively. Finally, the environmental parameter for modified spherical distiller with thermal storage material amounted to 27.7 tons of CO2 annually. Furthermore, the enviroeconomic parameter (Z') for the conventional spherical distiller and modified spherical distiller with thermal storage material stood at 335 and 365 per year, respectively.

Synthesis and characteristic analysis of an inorganic composite phase change materials for medium-temperature thermal storage

Composite phase change materials (CPCM) synthesized using inorganic salt (Na2HPO4·12H2O), lime fruit peel biochar (activated), and boron nitride have been explored as a solution for the medium-temperature thermal energy storage systems in this work. The activated biochar and BN concentrations were varied, and the effects of the activated biochar and BN on the thermal properties, chemical, and thermal stability of the phase change materials (PCM) were studied. XRD and FTIR studies confirmed the chemical stability of the synthesized CPCM samples. Leak test results revealed that the addition of biochar and BN has improved the shape stability. TGA studies revealed the superior thermal stability of the CPCM samples. Composite PCM with 2 g of activated biochar and 0.5 g of BN has exhibited better thermal properties with a latent heat of 121.33 J/g, encapsulation efficiency of 55.9%, and thermal energy storage capacity of 98.2% compared to the pure PCM.

A lightweight porous shear stiffening composite foam with excellent mechanical–thermal coupling protection performance

Lightweight SSE-EVA foam (SEF) with excellent compression resilience and mechanical-thermal protection was prepared by foaming. It owned application potential in thermal camouflage and thermal storage materials.

Design and manufacturing of forming molds for thermal storage materials and analysis of their thermal storage structures

In response to the shortcomings of concentrated stress, difficult forming, and short service life of commonly used honeycomb ceramic thermal storage materials with square lattice holes, the author has developed a new type of low stress honeycomb ceramic thermal storage material by studying the structure, forming mold, and extrusion forming material of the thermal storage body. The author introduced the changes in specific surface area and porosity of heat storage materials with different geometric structures, and analyzed and compared the structural characteristics of two types of heat storage materials, namely heat storage balls and honeycomb bodies, under the premise of equal heat storage capacity. The trajectory of air-flow in the heat storage chamber was simulated using CFD software, and the pressure loss and centerline velocity changes of different shapes of honeycomb were analyzed. The flow characteristics, pressure distribution, and heat transfer performance of gas inside different shapes of honeycomb were calculated. The experimental results showed that the closer to the circular shape, the smaller the pressure loss of the centerline. The larger the equivalent diameter, the smaller the resistance along the path. From the perspective of cold pressure loss alone, regular quadrilateral holes and regular circular holes are the best choices for the shape of honeycomb openings. The centerline velocity of the equilateral triangle hole is the largest, indicating that the smaller the equivalent diameter is, the greater the average velocity at the outlet is. The resistance along the path of the round hole is the smallest, the regular quadrilateral hole is slightly larger, and the pressure loss of the equilateral triangle hole is the largest, which exceeds the round hole by nearly 1/3. Taking into account factors such as heat storage, specific surface area, flow characteristics, and heat transfer characteristics, quadrilateral honeycomb cells are the best choice.

Innovative integration: Enhancing solar distillation efficiency with modified spherical solar stills

This study addresses the pressing need for eco-friendly potable water production, exploring the promising avenue of solar distillation. To overcome limitations in traditional systems, the author introduces the modified spherical solar still (MSSS), featuring a rotating ball within the design. A comprehensive experimental investigation compared MSSS performance with reference spherical distiller (CSSS) across energetic, exergetic, economic, and environmental (4E) dimensions. Key factors explored included: rotation speeds (0.2–1.2 rpm), wick material on the rotating ball, and thermal storage material (PCM) beneath the ball (desert sand, copper grits, or their mixture). The optimal MSSS configuration was identified: Rotation speed: 0.8 rpm (40 % yield increase), wick material: 57 % distillate enhancement at 0.8 rpm, and combined, these conditions yielded a remarkable 103 % distillate improvement compared to CSSS (7160 vs. 3525 mL/m2.day) and an efficiency of 59.5 %. Exergy efficiency also surpassed CSSS: 4.2 % for MSSS with PCM vs. 3.1 % for CSSS. Notably, the cost per liter of distilled water dropped significantly: $0.024 for MSSS with PCM compared to $0.066 for CSSS. Environmentally, MSSS with PCM saved 27.7 tons of CO2 annually. Lastly, the enviroeconomic parameter (Z′) rose from 335 for CSSS to 365 for MSSS with PCM.

Guest size effects on a robust structure of semiclathrate hydrates and their thermophysical properties.

The ability to tune the pore size, shape, and functionality of semiclathrate hydrates, host-guest materials formed from aqueous solutions of ionic guest materials and water, makes them attractive materials for thermal storage and gas storage applications. The flexibility of semi-clathrate hydrates and their guest-molecule-dependent reactions produce these unexpected and desirable properties. As an ionic guest, tetra-n-butylammonium cation is known for best-fit in hydrogen-bonded water structures. Few investigations have been conducted for other cations, while there are numerous candidates. Relationships between the molecular structures of ionic guest substances and their hydrate structure and relevant thermodynamic properties are yet to be understood. In this study, the semiclathrate hydrates formed with two variations of tetra-n-butylammonium chloride (N4444Cl) that are n-propyl, tri-n-butylammonium chloride (N3444Cl) and tri-n-butyl, n-pentylammonium chloride (N4445Cl) were investigated. Structure analyses found that both salts formed Jeffrey's type III tetragonal hydrate structure which is the same as that of tetra-n-butylammonium chloride hydrate, although their lattice parameters are significantly different. The present data found that this hydrate structure can cover a wide range of melting temperature compared to the other two main semiclathrate structures. The present N4445Cl hydrate is an example in which its melting temperature was adjusted to be suitable for air conditioning, i.e., ∼282 K, compared to that of the N4444Cl hydrate, the melting temperature of which is slightly too high for this purpose. The results provide insight that the thermal properties of the tetragonal P42/m hydrate structure can be widely tuned by ionic guests for various practical requirements.

A stable and visualized fatty acid-based phase transition material constructed by solid-phase molecular self-assembly for thermal management.

Fatty acids are excellent thermal management materials for thermal storage, release and preventing thermal runaway. However, the leakage of fatty acids leads to instability and prevents their application in thermal management. Herein, a stable and visualized fatty acid-based phase transition material P-S/PA was constructed through solid-state molecular self-assembly strategy from polydiallyldimethylammonium chloride (PDDA), sodium dodecyl benzene sulfonate (SDBS) and palmitic acid (PA). The electrostatic interaction between PDDA and SDBS and hydrophobic interaction between PA and SDBS can prevent PA leakage during phase transition, achieving stability. After 1000 cycles, the changes in the phase transition enthalpy (ΔH M, ΔH C) were less than 1%. The structural similarity also made P-S/PA phase transition visible, and the transmittance changed significantly from 0% to 68% during phase transition. In addition, P-S/PA can be remolded by hot-pressing without performance changes, showing temperature adjustability on varying the fatty acid carbon chain length. Thus, the stable and visualized P-S/PA fatty acid-based phase transition material constructed by solid-phase molecular self-assembly has promising application in thermal management.

Analysis of thermal characteristics and thermal storage performance of energy-saving phase change thermal storage materials in buildings

In order to explore the thermal characteristics and thermal storage performance analysis of energy-saving phase change heat storage materials in buildings, taking the common exterior wall insulation composite wall structure in southwestern China as an example, the influence of insulation board structure thickness design on the total cost of residential air conditioning energy consumption and insulation board cost is studied, thus clarifying the concept and calculation origin of economic insulation thickness. The experimental results show that by drawing mathematical functions of energy consumption cost, total cost, and insulation material cost in the same 2-D coordinate, it is intuitively demonstrated that the minimization of total cost can be ensured when the insulation thickness is in an economic state, and the specific economic thickness can be accurately calculated through example data. Therefore, specific measures for improving external wall insulation from refined insulation structure design are proposed. It has been proven that the design of the exterior wall insulation layer structure is an important way to improve the overall energy-saving benefits of building exterior wall insulation.

Application of performance dynamic equationin numerical simulation and optimization of waste heat utilization and storage system

In order to improve the current situation of double energy loss in waste heat recovery and utilization, according to the factors such as phase change temperature, thermal conductivity, phase change latent heat, economy, and safety of thermal storage materials, 70# phase change thermal storage balls produced by XX company were selected as phase change thermal storage materials, and differential scanning calorimetry was used to test and analyze them, and the melting point, freezing point and phase change latent heat value of PCM were obtained, provide data reference for simulation in the following text. The shell and tube heat exchanger is selected as the core component of the mobile heat storage system, and its heat storage and release processes are simulated using FLUENT software. The results show that when the heat transfer equipment is charged for 7 hours, almost all of the inner-heat exchangers have completed the heat supply, and only the phase change products at both sides and bottom of the heat supply have ?dead zone?, which is the major effect of heat storage. In order to improve the heat storage and release rate and break the ?bottleneck? of heat storage, the heat transfer was strengthened by changing the diameter size, arrangement, and adding fins of the heat exchange tube. The effects of straight fins, T-shaped fins, as well as the number, height, thickness, and width of fins on the heat storage performance were explored. The results indicate that, adding fins cannot only improve heat transfer efficiency, but also inhibit natural-convection. The heat storage and release time decreases to varying degrees with the increase of fin width, thickness, height, and the number of circumferential fins in a single heat exchange tube.

Complex phase behavior of dihydroxyl-functionalized ionic liquids at low temperature.

Here, we have synthesized six dihydroxyl-functionalized ionic liquids for phase behavior studies at low temperature via crystallographic methods, Raman spectroscopy, differential scanning calorimetry (DSC), and density functional theory (DFT) calculations. Phase varieties are observed depending on the direction and strength of hydrogen bonding. Our studies also show that the ILs could be potentially excellent phase-change thermal storage materials with nearly no change of the phase transition enthalpy.

Efficient solar thermal storage of foamy bamboo charcoal-based composite phase change materials

Solid/liquid phase change materials (PCMs) with high phase change latent heat have been widely used in thermal energy storage in recent years, but their own disadvantages such as poor light-absorbing capacity, easy leakage, and low thermal conductivity seriously limit their practical use in solar thermal storage applications. In this study, a series of biomass-derived porous carbons (CB400, CB550, and CB700) were synthesized by combining the template method with the activation method through high-temperature carbonization using bamboo as raw material and Ca(OH)2 as precursor. 1-octadecanol (OC) is selected as the PCM, and four different composite photothermal phase change thermal storage materials (CB550-85, CB550-80, CB550-75 and CB550-70) were prepared by using CB550 as the photosensitizer and support material. The phase change enthalpy of CB550-85 with 85 wt% OC content was 299.8 J/g, the thermal conductivity of CB550-70 with 70 wt% OC content was 0.71 W·m−1·K−1, which is 184 % higher than that of 1-octadecanol. CB550-OC has good thermal and shape stability, excellent solar energy absorption capacity and photothermal conversion performance. This study provides a new technological pathway for the utilization of biomass. CB550-OC has a broad application prospect in the field of solar thermal utilization and thermal energy storage.

Wet Impregnation Method for Synthesis of Phase Change Composite of N-Octadecane in Porous Silica Gel

Thermal energy storage is gaining more interest as people aim to utilization of solar energy. The thermal energy can be stored in the form of latent heat and used for building applications that require increasing energy. This report investigated the wet impregnation method for the synthesis of thermal storage material, namely phase change composite (PCC) for two purposes: to create a simple method for the synthesis of PCC and study behaviors of phase change material (PCM) when confined inside the pore. Particularly, the PCC was synthesized using n-octadecane and silica as PCM and porous matrix, respectively. The characterization of the product was conducted by various analytical methods: N2 adsorption/desorption isotherm, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA). Results showed that the n-octadecane was successfully impregnated into a silica porous network through simple steps of the wet impregnation method. The porosity analysis confirmed the confining of PCM inside matrix pores. The n-octadecane was easily kept inside pores by the capillary and surface tension forces. without any chemical interaction. At maximum impregnation, n-octadecane accounted for 70% of the composite. This sample presented a shape-stability at up to 90 oC, provided a latent heat of 145 J g-1, and was selected as optimal PCC.

Enhanced thermal storage and photo-thermal conversion composite phase change materials based on MOF-derived carbon for efficient solar energy utilization

Composite phase change materials (PCMs) with high thermal conductivity and photo-thermal conversion performance can be employed for the efficient conversion and utilization of solar energy. In this work, a Ni-doped carbon material derived from a Ni metal-organic framework (Ni-BTC) is prepared and used as the supporting material to encapsulate polyethylene glycol (PEG). The Ni-BTC derived carbon (NBC) obtained retained the intrinsic porous flower-like structure which facilitates the encapsulation of PEG. The doping of Ni metal particles enhances both the thermal conductivity and photo-thermal conversion performance of the composite PCM. Additionally, the thermal conductivity of the composite PCM is further enhanced by the addition of a graphene/Ag composite, resulting in a thermal conductivity that is 3.15 times higher than that of pure PEG. The latent heat of the resulting composite PCM is 125.4 J/g, the photo-thermal conversion efficiency is 91.81 %. Moreover, the composite PCM exhibits excellent thermal stability and reliability, indicating its potential for wide-ranging applications in solar energy storage.