Solar Thermal Energy Conversion Research Articles

Visible light driven low temperature photoactive energy storage materials for high rate thermal output system

Development of photoactive chemical heat storage (PCHS) materials that can be isomerized without ultraviolet light and have outstanding storage performance as well as high rate heat output capability under low temperature conditions is a core issue for effective solar thermal conversion. In this study, we report a novel PCHS material by attaching ortho-tetrafluorinated azobenzene (AzoTF) onto reduced graphene oxide (rGO) for photothermal conversion and storage. By applying the strategy of separating the n → π* transition of two different configurations of AzoTF to the field of PCHS materials, this AzoTF-rGO composite not only realizes the isomerization with visible light for two configurations with a long life cycle, but also exhibits excellent fatigue resistance and low temperature high rate heat output capability, which greatly increases its exploitation value. Moreover, the AzoTF-rGO composite also shows remarkable heat storage density (Max. 345.8 kJ kg−1), power density (Max. 2401.4 W kg−1) attribute to the intermolecular hydrogen bond as well as the strong intermolecular interactions arise from the high attachment density. This new AzoTF-rGO PCHS material may paves a new way for more effective and efficient solar thermal energy conversion and storage.

One-step synthesis of graphene-based composite phase change materials with high solar-thermal conversion efficiency

Graphene-based composite phase change materials (PCMs) exhibit great potential applications in the field of solar-thermal energy conversion and storage, recently, due to their attracting capability of endowing the PCMs with superior light absorption ability and preventing the liquid phase leakage during the transition process. However, current synthesis methods of graphene-based composite PCMs usually involve complicated multi‐step procedures, greatly hindering its large-scale preparation for the practical application of the solar-thermal energy utilization technique. Herein, we report a facile and straightforward one-step strategy of constructing graphene-based shape-stable composite PCMs with polyethylene glycol (PEG) in situ filled into a graphene oxide (GO) network structure hydrogel. Using this one-step strategy, we achieve a high PEG loading capacity up to 95 wt% in the graphene-based composite PCMs. The composite PCMs also have a relatively constant phase change enthalpy of 162.8 J/g even after 1000 heating–cooling cycles. Most importantly, the composites exhibit a superior solar-thermal conversion ability with the conversion efficiency as high as 93.7%. Compared with the currently reported synthetic routes, the complicated processing steps are greatly reduced in this one-step synthesis strategy. This work proposes a simple and efficient method of synthesizing graphene-based composite PCMs with superior solar-thermal conversion efficiency, which may have great potential applications in the field of solar-thermal energy conversion and storage.

Phase change materials confined into sunlight capturer sponge towards thermal energy harvesting and storage

Polybutadiene (PB) waste recycling helps to reduce the ever-growing fossil energy demands because it is usually made from petroleum and natural gas. However, designing and developing a facile and low-cost way to achieve the efficient recycling of PB waste is still a formidable challenge because considerable energy is required to break the polymer chains. Herein, a 3D continuous porous sunlight capturer sponge derived from PB and octadecylamine-functionalized reduced graphene oxide (ODA-rGO) via self-sacrificial template strategy is proposed as supporting skeletons and high-efficiency solar-thermal conversion platform to construct a series of novel phase change composites (PCCs). The prepared PCCs are characterized by excellent leak-proof capability and thermal stability with a heat storage capacity as high as 171.5 J/g. More importantly, highly stable and reversible solar-thermal energy conversion and heat storage capacity without heat loss to the surrounding environment for the PCCs are also demonstrated. Hence the developed PCCs have a potential application in solar energy utilization systems and provide an excellent opportunity for the efficient recycling of PB waste.

Transparent silica aerogel slabs synthesized from nanoparticle colloidal suspensions at near ambient conditions on omniphobic liquid substrates

This paper presents a novel sol-gel method to synthesize large and thick silica aerogel monoliths at near ambient conditions using a commercial aqueous solution of colloidal silica nanoparticles as building blocks. To achieve slabs with high visible transmittance and low thermal conductivity, the method combines the strategies of (i) synthesizing gels on an omniphobic perfluorocarbon liquid substrate, (ii) aging at temperatures above room temperature, and (iii) performing solvent exchange with a low-surface-tension organic solvent prior to ambient drying. The omniphobic liquid substrates were used to prevent cracking and ensure an optically-smooth surface, while nanoparticle building blocks were small (<10 nm) to limit volumetric light scattering. Gels were aged at temperatures between 25 and 80 °C for up to 21 days to make them stronger and stiffer and to reduce shrinkage and cracking during ambient drying. Ambient drying was achieved by first exchanging water in the gel pores for octane, followed by drying in an octane-rich atmosphere to decrease capillary forces. The synthesized nanoparticle-based silica aerogel monoliths had thicknesses up to 5 mm, diameters up to 10 cm, porosities exceeding 80%, and thermal conductivities as low as 0.08 W m−1 K−1. Notably, the slabs featured visible transmittance exceeding 75% even for slabs as thick as 5 mm. The as-synthesized aerogel monoliths were exposed to TMCS vapor to induce hydrophobic properties resulting in a water contact angle of 140° that prevented water infiltration into the pores and protected the aerogels from water damage. This simple synthesis route conducted at near ambient conditions produces hydrophobic aerogel monoliths with promising optically transparent and thermally insulating properties that can be adhered to glass panes for window insulation and solar-thermal energy conversion applications.

Three-Dimensional Interpenetrating Network Phase-Change Composites with High Photothermal Conversion and Rapid Heat Storage and Release

Solar thermal energy conversion and storage have gained more attention for solving energy crisis and environment issues. Phase-change materials with excellent thermal conductivity, high photothermal conversion efficiency, rapid heat storage and release, and good stability are required for solar thermal applications. In this study, three-dimensional (3D) interpenetrating network phase-change composites are fabricated by taking graphene-oxide (GO) aerogel (GA) containing a small amount of carbon nanotubes (CNTs) and carbon spheres (CSs) as support materials and vacuum impregnation melting polyethylene glycol (PEG) as the phase-change material. The 3D structure and abundant functional groups greatly improve the stability of phase-change composites. The addition of CNTs and CSs greatly increases the thermal conductivity and photothermal conversion capability of PCMs. Compared with pure PEG, thermal conductivity is increased by 181.58%, and photothermal conversion efficiency reaches 89.3%. Simulated results also confirm that GA-based phase change composites exhibit better thermal conductivity. Less thermal conductivity fillers and more phase-change material (96.4%) exhibit excellent thermal conductivity, high photothermal conversion efficiency, and a greater energy-storage density. The 3D phase-change composites are also applied for thermoelectric generation and show a stable output voltage of 35 mV for 300 s after removing the light source. The 3D interpenetrating network form-stable phase change composites based on black GA shows broad prospects in solar thermal energy applications.

Ultra-Broadband Refractory All-Metal Metamaterial Selective Absorber for Solar Thermal Energy Conversion.

A full-spectrum near-unity solar absorber has attracted substantial attention in recent years, and exhibited broad application prospects in solar thermal energy conversion. In this paper, an all-metal titanium (Ti) pyramid structured metamaterial absorber (MMA) is proposed to achieve broadband absorption from the near-infrared to ultraviolet, exhibiting efficient solar-selective absorption. The simulation results show that the average absorption rate in the wavelength range of 200–2620 nm reached more than 98.68%, and the solar irradiation absorption efficiency in the entire solar spectrum reached 98.27%. The photothermal conversion efficiency (PTCE) reached 95.88% in the entire solar spectrum at a temperature of 700 °C. In addition, the strong and broadband absorption of the MMA are due to the strong absorption of local surface plasmon polariton (LSPP), coupled results of multiple plasmons and the strong loss of the refractory titanium material itself. Additionally, the analysis of the results show that the MMA has wide-angle incidence and polarization insensitivity, and has a great processing accuracy tolerance. This broadband MMA paves the way for selective high-temperature photothermal conversion devices for solar energy harvesting and seawater desalination applications.

Theoretical analysis of efficiency for vacuum photoelectric energy converters with plasmon-enhanced electron emitter

Thermionic energy converters (TECs) convert heat or light into electrical energy based on electron emission in vacuum. By using a cathode consisting of metal nanostructures, plasmonic thermionic energy converters (PTECs) can overcome challenges concerning high operation temperature, which hinders the use of TEC for solar–thermal energy conversion. However, there is lack of theoretical analysis to describe the mechanism behind PTEC and to guide the design of device. In this study, we developed a simple model to calculate the power conversion efficiency of PTEC consisting of metal nanostructure cathodes, also named as vacuum photoelectric energy converter (VPEC) with plasmon-enhanced electron emitter, in this work. The distribution of plasmon-induced hot electrons was calculated using Fermi's golden rule. Under the assumption of ballistic transport and photoemission, the performance of VPEC was analyzed under different operating conditions. The results reveal that the size and shape of the nanostructure cathode influence the hot electron emission efficiency. For a cathode consisting of a single silver nanosphere, an optimal nanosphere diameter of ∼15 nm exists with optimal quantum efficiency and energy conversion of 8.71% and 1.88%, respectively, under the illumination of 339 nm light. Besides, the optimal performance for cathode consisting of a silver nanosphere array is ∼33% of that for the single silver nanosphere. This model provides insights into the dynamics of plasmon-induced hot electrons and guidelines for optimizing hot electron devices for photoelectric conversion applications.

Convection in volumetrically absorbing solar thermal receivers: A theoretical study

While now considered a proven technology, molten salt concentrated solar power systems with tubular surface absorbers are still limited by low capture efficiencies, which contribute to higher levelized costs of electricity. Volumetric receivers have long been proposed as promising alternatives to surface absorbers. They consist of semi-transparent media that are directly irradiated and absorb solar radiation volumetrically. They can tolerate higher solar fluxes and eliminate temperature differences between the absorber and the heat transfer fluid, which in turn reduces heat losses. Until now, no studies have quantified the theoretical limits of the performance of volumetric absorbers due to the complex interaction between radiation, natural convection, and volumetric heating. We present a mechanistic model of liquid-based volumetric receivers for solar thermal energy conversion. The model is benchmarked against computational fluid dynamics simulations with good agreement (<1.7°C difference for bulk temperatures and <9°C for boundary temperatures). The model is applied to study the theoretical limits of the capture efficiency and temperature uniformity of a molten salt nanofluid receiver for a range of design parameters. Three characteristic regimes are identified: single-mixing-layer, triple-layer, and conduction-dominant. We propose a dimensionless volumetric receiver number, RV, that captures the regime transitions for a wide range of operating conditions. The results are summarized in the form of design diagrams, providing guidelines for optimal receiver design. The model’s fast (real-time) computation speed can enable digital twinning for volumetric receivers.

Fluorescent thermochromic wood-based composite phase change materials based on aggregation-induced emission carbon dots for visual solar-thermal energy conversion and storage

Efficient solar-thermal energy conversion and storage is significant to overcome current energy shortage problems. Monitoring solar-thermal energy storage process by an evident and convenient display is conducive to improving energy utilization. Herein, fluorescent thermochromic wood-based composite phase change materials (WPCMs) were constructed for visual solar-thermal energy conversion and storage. It was fabricated by encapsulating polyethylene glycol (PEG) and aggregation-induced emission carbon dots (AIE-CDs) showing blue dispersed emission and red aggregation-induced emission into delignified wood (DW). The DW well-preserved the distinctive anisotropic porous structure and prevented the leakage problem of PEG. The WPCMs possessed great solar-thermal conversion capacity benefitting from strong and broad solar light absorption behaviors of AIE-CDs. Additionally, WPCMs showed real-time and visual fluorescent thermochromic property, it exhibited red AIE, and the fluorescence (FL) decreased and shifted into the blue emission band under solar radiation. The solar-thermal energy conversion and storage led to solid–liquid transformation of WPCMs, which promoted AIE-CDs’ dispersion, thereby changing the FL. It also exhibited a high latent heat of fusion (160.8 J·g−1), favorable stability over 150 heating–cooling cycles, thermal stability below 210 °C and good shape stability. The WPCMs can be extended to applications in energy-saving buildings and optical lighting materials with visual thermal regulation capability.

Hypophosphite tailored graphitized hierarchical porous biochar toward highly efficient solar thermal energy harvesting and stable Storage/Release

• Hypophosphite is used as a multifunctional activator in fabricating porous biochar. • Graphitic porous biochar derived from water chestnuts was developed. • Unique interpenetrating network was tailored via triple effects of hypophosphite. • The porous biochar had high pore volume and effective light trapping ability. • Achieved excellent solar thermal energy harvesting and storage/release capacity. Utilization of renewable solar energy is a promising pathway to relieve the severe energy shortage in current fossil fuel society, for which phase change materials (PCMs) based on sustainable porous biomass carbon materials represent an attractive and enormously potential option. However, structural tailor of hierarchical pores independent of biomass natural structure is still difficult for these carbon materials, thus seriously limiting their efficiency in solar thermal energy harvesting and stable storage/release. In this work, hierarchical porous carbons (HPCs) derived from chestnuts were fabricated by using aluminum hypophosphite (AP) as a multifunctional (dehydrating, blowing, and crosslinking) activator. Different measurements confirmed that unique interpenetrating HPC network structures with continuous channels were tailored via the triple effects of AP. The resulting HPC displays high pore volume and high thermal conductivity. The HPC-stabilized composite PCM with 85 wt% octadecane (Octadecane 85 @HPC) possesses the high transition enthalpy of 216.2 J g −1 and shows high reliability in thermal cycle test. Compared with currently reported similar bio-based PCMs, the Octadecane 85 @HPC shows higher energy storage capacity. Interestingly, the solar thermal energy conversion efficiency of the Octadecane 85 @HPC reaches 96.1%, presenting excellent solar energy harvesting capacity. This work provides a promising strategy to tailor biomass HPC for highly efficient solar thermal energy harvesting and storage/release.

Dual-Functional Aligned and Interconnected Graphite Nanoplatelet Networks for Accelerating Solar Thermal Energy Harvesting and Storage within Phase Change Materials.

Solar thermal energy conversion and storage within phase change materials (PCMs) can overcome solar radiation intermittency to enable continuous operation of many heating-related processes. However, the energy-harvesting performance of current storage systems is always limited by low efficiencies in either solar thermal energy conversion or thermal transport within PCMs. Although PCM-based nanocomposites can address one or both of these issues, achieving high-performance composites with simultaneously enhanced photothermal performance and thermal transport capacity remains challenging. Here, we demonstrate that dual-functional aligned and interconnected graphite nanoplatelet networks (AIGNNs) yield the synergistic enhancement of interfacial photothermal conversion and thermal transport within PCMs to accelerate the solar thermal energy harvesting and storage. The AIGNNs include the naked part as the three-dimensional optical absorber and the incorporated part as thermally conductive pathways within PCMs. First, a phase change composite composed of the AIGNNs and the solid-solid PCM of polyhydric alcohol is synthesized using a facile three-step method, and shows 400% thermal conductivity enhancement for per 1 wt % graphite loading compared to pristine PCMs. After the elaborate surface treatment, a small part of the graphite networks is in situ exposed as the 3D optical absorber to boost the surface full-spectrum sunlight absorptivity up to 95%. This dual function design takes full advantage of the integrated AIGNNs in terms of both photothermal conversion and thermal transport capacities, superior to the traditional coating-enhanced photothermal conversion. This work offers a promising route to accelerating solar thermal energy harvesting and storage within PCMs.

Flexible graphene aerogel-based phase change film for solar-thermal energy conversion and storage in personal thermal management applications

Developing phase change materials (PCMs) with solar-thermal energy conversion and storage for wearable personal thermal management is of significance but challenging, due to the difficulty of overcoming the liquid phase leakage, weak light adsorption, and solid phase rigidity of conventional phase change materials. In this work, a novel flexible graphene aerogel based composite phase change film (CPCF) has been successfully designed and constructed. In this CPCF, the introduction of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) can strengthen the porous framework of graphene aerogel (GA) and endow the graphene aerogel film (GAF) with superior flexibility. The final CPCF has been obtained by impregnating paraffin wax (PW) into the GAF supporting matrix. This GAF-PW CPCF behaves excellent thermal property, long-term cycle stability, advanced flexibility, and outstanding solar-thermal conversion ability. The phase change enthalpy of the GAF-PW CPCF can reach 154.64 J/g and stay almost unchanged even after 500 heating-cooling cycles. Most importantly, the solar-thermal conversion efficiency of the GAF-PW CPCF is evaluated to be 95.98%, indicating its superior ability to convert solar energy into thermal energy. The flexible GAF-PW CPCF can be easily attached on a human model to demonstrate its advanced performance of wearable thermal management. This flexible CPCF developed in this work exhibits great potential to be applicable in the fields of wearable personal thermal management, providing a promising direction for the development of wearable fabric to enhance the adaptability of human body in cold environment.

Energy, exergy, and economic analysis of an integrated solar combined cycle power plant

AbstractIntegrated Solar Combined Cycle (ISCC) power plants based on Parabolic Trough Concentrators (PTCs) are the most efficient way for solar into electrical energy conversion. However, due to operation in several climate conditions, they need more efforts in their adaptation. This paper presents a techno‐economic assessment of an ISCC ‐ PTC system operating at Hassi R'mel site (Algerian Sahara) for which a new thermal storage system is incorporated. The obtained results reveal noticeable enhancements in the solar energy conversion and the overall power plant performance, hence offering better stability to the grid. As shown, the net solar thermal energy conversion ratio may reach up to 14%. Energy and exergy efficiencies are respectively equal to 56.06% and 53.29%, and about 46% of exergy received by the system is destructed. Moreover, the obtained Levelized Cost of Energy (LCOE) is around 9.75 ¢/kWh which is very promising, but still higher compared with a simple Combined Cycle (CC). At this geographical site, the modified ISCC ‐ PTC power plant will allow saving about 30 million $ in natural gas consumption and 13 million $ in emission taxes.

Highly anisotropic graphene aerogels fabricated by calcium ion-assisted unidirectional freezing for highly sensitive sensors and efficient cleanup of crude oil spills

Anisotropic graphene aerogels (GAs) are usually fabricated by unidirectional-freezing with graphene oxide (GO) dispersion as the precursor. However, polymer additives or pre-gelation are usually required to enhance the anisotropic architectures, which often cause attenuations in electrical conductivity and shape control accuracy. Herein, we demonstrate a calcium ion-assisted unidirectional-freezing approach for fabricating highly anisotropic GAs by unidirectionally freezing aqueous suspensions of GO with a trace amount of calcium ions, followed by freeze-drying and thermal reduction. The calcium ions could slightly crosslink GO sheets by coordination, and hence reduce the interaction between GO sheets and in situ grown ice pillars, benefiting vertical alignment of the GO sheets. After freeze-drying to sublime these ice pillars, high-temperature annealing is adopted to thermally reduce the anisotropic GO aerogels by removing their oxygen-containing groups, resulting in highly anisotropic GAs. The lightweight and anisotropic GA exhibits excellent sensitivity and durable reversibility as a piezoresistive sensor because of its highly aligned porous architecture. Furthermore, GA exhibits prominent adsorption capacity for many organic pollutants from wastewaters. Interestingly, the vertically aligned porous structure of GA enhances its solar-light absorption and solar-thermal energy conversion, making GA efficient in decreasing the viscosity of crude oil and thus enhancing its adsorption capacity.

Anisotropy-functionalized cellulose-based phase change materials with reinforced solar-thermal energy conversion and storage capacity

Improving the thermal stability and energy storage density of phase change materials (PCMs) in thermal energy storage systems is a key task for their practical applications in industrial production. Whereas, limited by the inherently inferior heat transfer and unsatisfactory visible light response capability, PCMs exhibit extremely low thermal storage/release capability, inhibiting their developments. Herein, we constructed porous cellulose nanofibril (CNF)/silver nanowire (AgNW) hybrid supporting materials possessing the highly ordered structure and characteristically anisotropic thermal transmission capacity by directional freeze-drying, in order to encapsulate octadecanol (OCO) and octodecane (OCC) by vacuum impregnation method. Profited by the infrequently anisotropic structures and high thermal conductivity AgNWs, CNF/AgNW hybrid materials present dissimilar thermal transmission rates in the transverse and longitudinal directions. The close contact of AgNWs to CNFs allows the energy harvesting by solar-excited AgNWs to rapid transfer to CNFs, which increases the phonon propagation of the cellulosic material lattice and implements the improvement of the thermal transmission ability of the hybrid carriers. The obtained series of composite PCMs show an improved thermal conductivity (enhanced by 72.7%), and thermal enthalpy is comparatively approaching the theoretical value. Rejoicingly, the composites are thermally and durably stable. This novel-innovative targeted functional strategy provides insights into the thermal transmission mechanism in anisotropic supporting materials, and the resulting shape-stable composite PCMs (ss-CPCMs) can be employed as promising candidates for renewable thermal energy storage systems in virtue of their characteristic comprehensive performances.

Multiscale Structural Modulation of Anisotropic Graphene Framework for Polymer Composites Achieving Highly Efficient Thermal Energy Management.

Graphene is usually embedded into polymer matrices for the development of thermally conductive composites, preferably forming an interconnected and anisotropic framework. Currently, the directional self‐assembly of exfoliated graphene sheets is demonstrated to be the most effective way to synthesize anisotropic graphene frameworks. However, achieving a thermal conductivity enhancement (TCE) over 1500% with per 1 vol% graphene content in polymer matrices remains challenging, due to the high junction thermal resistance between the adjacent graphene sheets within the self‐assembled graphene framework. Here, a multiscale structural modulation strategy for obtaining highly ordered structure of graphene framework and simultaneously reducing the junction thermal resistance is demonstrated. The resultant anisotropic framework contributes to the polymer composites with a record‐high thermal conductivity of 56.8–62.4 W m−1 K−1 at the graphene loading of ≈13.3 vol%, giving an ultrahigh TCE per 1 vol% graphene over 2400%. Furthermore, thermal energy management applications of the composites as phase change materials for solar‐thermal energy conversion and as thermal interface materials for electronic device cooling are demonstrated. The finding provides valuable guidance for designing high‐performance thermally conductive composites and raises their possibility for practical use in thermal energy storage and thermal management of electronics.

Cold-Resistant Nitrogen/Sulfur Dual-Doped Graphene Fiber Supercapacitors with Solar-Thermal Energy Conversion Effect.

Although graphene fiber-based supercapacitors are promising for wearable electronic devices, the low energy density of electrodes and poor cold resistance of aqueous electrolytes limit their wide application in cold environments. Herein, porous nitrogen/sulfur dual-doped graphene fibers (NS-GFs) are synthesized by hydrothermal self-assembly followed by thermal annealing, exhibiting an excellent capacitive performance of 401 F cm-3 at 400 mA cm-3 because of the synergistic effect of heteroatom dual-doping. The assembled symmetric all-solid-state supercapacitor with polyvinyl alcohol/H2 SO4 /graphene oxide gel electrolyte exhibits a high capacitance of 221 F cm-3 and a high energy density of 7.7 mWh cm-3 at 80 mA cm-3 . Interestingly, solar-thermal energy conversion of the electrolyte with 0.1 wt % graphene oxide extends the operating temperature range of the supercapacitor to 0 °C. Furthermore, the photocatalysis effect of the dual-doped heteroatoms increases the capacitance of NS-GFs. At an ambient temperature of 0 °C, the capacitance increases from 0 to 182 F cm-3 under 1 sun irradiation because of the excellent solar light absorption and efficient solar-thermal energy conversion of graphene oxide, preventing the aqueous electrolyte from freezing. The flexible supercapacitor exhibits a long cycle life, good bending resistance, reliable scalability, and ability to power visual electronics, showing great potential for outdoor electronics in cold environments.

Thermal performance analysis of free-falling solar particle receiver and heat transfer modelling of multiple particles

Obtaining the detailed transient heat transfer process between particles is one of the most important key factors to comprehensively understand the thermal conversion performance of the solar particle receiver. To present a clear understanding of heat transfer, a detailed two-dimensional transient numerical simulation of the solar particle receiver integrated with the Monte Carlo Ray Tracing method and the Finite Element Method is presented in this paper. The solar radiation flux distribution throughout the free-falling solar particle receiver is simulated by considering Monte Carlo Ray Tracing and the transient heat transfer in the circular particle process in the receiver is calculated using the Finite Element Method. Moreover, based on the coupling model, considering the transient heat transfer process inside the particles, the effects of different particle sizes, radiation fluxes, void ratio, and particle residence time on the temperature distribution and thermal performance of the solar particle receiver are also studied. The results show that the transient heat transfer process inside the single particles slightly affected the average outlet temperature of the receiver and the solar thermal energy conversion efficiency. A better outlet temperature and thermal conversion efficiency can be obtained when solid particles with a diameter of 0.2 ~ 0.4 mm in the experiment are used. This study provides basic theoretical insights and support for further research on the thermal performance, structural design, and optimization of the solar particle receiver.

Quantitative evaluation by scenario analysis on the Feasibility of Low temperature Stirling engine in Solar Hot Water Thermal Energy Conversion

Quantitative evaluation by scenario analysis on the Feasibility of Low temperature Stirling engine in Solar Hot Water Thermal Energy Conversion

Solar thermal control system based on variable frequency heat exchanger control technology

Frequency conversion exchanger control is the critical technology of solar water heaters. It can integrate solar thermal technology and heat pump technology and makes solar thermal energy conversion efficiency higher. Based on this research background, the paper first discusses the principle of the technology. Then, it optimizes the system control strategy based on maximizing the utilization of heat energy and the highest efficiency ratio. Finally, the article established a deep learning model of solar radiation based on different time-sharing. The experimental simulation confirmed that the thermal energy control optimization algorithm model proposed in this paper could effectively predict thermal energy exchange.