Solar Thermal Research Articles

A novel vacuum-photovoltaic glazing integrated thermoelectric cooler/warmer for environmental adaptation: thermal performance modelling

Vacuum-photovoltaic glazing, renowned for exceptional thermal insulation and solar energy utilization, faces limitations in its adaptability to varying seasons. While it effectively reduces heat transmission into indoor spaces during summer, it becomes detrimental during winter. To address this challenge, this study introduces an innovative solution: vacuum-photovoltaic-thermoelectric (VPT) glazing, which integrates vacuum, photovoltaic and thermoelectric cooling/warming technologies. The theoretical models were developed and validated through WINDOW and Fluent simulations. A comparative analysis is conducted considering thermal performance under various environmental parameters. The results demonstrate that VPT glazing exhibits enhanced thermal performance, with interior glass temperature decreased by 3.0–9.6oC in summer while increased by 2.5–6.2oC in winter, accounting for ∼55.0 % reduction in air-conditioning load. Compared to vacuum-photovoltaic glazing, VPT glazing reduces the coupling U-value from 7.88 to 5.87 W m−2 K−1 in summer and increases from −0.31 to 2.61 W m−2 K−1 in winter. The solar heat gain coefficient decreases from 0.37 to 0.30 in summer and increases from 0.24 to 0.29 in winter. These results demonstrate the effectiveness of VPT glazing in adapting to different seasons and achieving better thermal environment performance. This study provides insights into VPT glazing design for environmental adaptation and offers implications for future research and applications in energy-efficient building technologies.

Nickel and Cobalt Selenite Hydrates as Broad Solar Absorbers for Enhanced Solar Water Evaporation

Inorganic black materials possessing hydrophilicity are scarce but can be of great importance in areas such as solar water evaporation and solar steam generation. Herein, for the first time, transition‐metal selenite hydrates (specifically, Earth‐abundant metals Ni and Co) not only possess high solar absorbance (>96 %) in the solar spectral range (UV–vis–NIR) but also excellent hydrophilicity, which plays a key role in water transport in the solar steam generation. The hydrophilic behavior in selenite hydrates originates from trapped “water of hydration” inside its crystal lattice, which can easily form hydrogen bonds with other water molecules, facilitating water transport. Owing to the abovementioned properties, the studied selenite hydrates are tested for solar water evaporation, showing excellent water evaporation rates of 1.83 and 2.34 kg m−2 h−1 for nickel selenite hydrate and cobalt selenite hydrate, exceeding the theoretical limit of 1.47 kg m−2 h−1.

Study of Heat Transfer Characteristics of Heat Pipe Using Water as a Working Fluid

Heat pipes are efficient and versatile thermal management devices widely used in various applications to transfer heat. This study focuses on investigating the heat transfer characteristics of a heat pipe employing de-ionized water as the working fluid. The experiment involved analyzing the thermal performance, heat transport capacity, and operational limits of the heat pipe. The aim of the experiment is to assess the heat pipe's performance under different operating conditions, such as varying heat loads. The study aimed to understand the heat transfer limitations and advantages of water-based heat pipes, which can have practical implications for numerous applications, such as electronics cooling, solar thermal systems, and space technology

Non-similar simulations of Ellis model based ternary hybrid nanofluid flow through porous media

The investigation of nanofluid flow through porous media is an emerging area of research in the optimization of thermal processing and numerous thermodynamic processes. The principal objective of these thermal applications is to examine the movement of ternary hybrid nanofluid across a stretched sheet oriented vertically. The flow being examined is represented mathematically in order to incorporate the influences of magnetic fields, thermal radiation, and viscous dissipation. The ternary hybrid nanofluid thermal performance can be enhanced and surpassed by adding nanoparticles to the base fluid. The non-Newtonian Ellis model takes into account the fluid movement through the porous media. Ferrous oxide ( Fe 3 O 4 ) , Zinc oxide ( ZnO ) , and Molybdenum disulfide ( Mo S 2 ) are regarded as nanoparticles, with ethylene glycol ( EG ) serving as the base fluid. To convert the governing equations into a dimensionless system, suitable non-similar transformations have been established. The local non-similarity (LNS) approach is used with the MATLAB built-in tool bvp4c up to the second truncation level. The physical impacts of dimensionless factors on the temperature and velocity profiles of the studied nanofluids are thoroughly investigated. When the magnetic and porosity parameters change, the velocity profile becomes smaller. The heat transmission rate declines when the assessments of the magnetic number and Eckert number increase. The skin friction coefficient experiences an increase as the estimates of magnetic properties and nanoparticle value rise. The current study holds various practical implications, encompassing Solar Thermal Energy Storage, Waste Heat Recovery, Advanced Cooling Technologies, Enhanced Geothermal Systems, and Enhanced Oil Recovery.

Grid dispatching model and benefit analysis of concentrating solar power plants considering flexibility

Abstract With the increasing penetration rate of renewable energy with volatility and uncertainty, flexibility has become an important factor to consider in the operation of the power system. To study the grid-connected dispatching and benefit analysis of CSP plants considering flexible supply-demand balance in the electricity market, the output level of CSP is modeled according to the internal steady state energy flow relationship. Secondly, we model the supply-demand characteristics of flexible resources. Finally, we establish an optimization dispatching model that considers the penalty of insufficient flexibility. The calculation example verifies the effectiveness of considering flexibility supply-demand balance and CSP plants in improving system flexibility.

Polypyrrole@Pd solar-thermal catalyst for eco-friendly and scalable multiphasic Suzuki coupling reactions

Solar-thermal materials enable the heating of reaction solutions in organic reactions without consuming fossil fuels or electricity. In this study, nanostructured polypyrole@Pd was utilized with solar-thermal, catalytic, and Pickering emulsifier functionalities to successfully demonstrate eco-friendly and scalable Suzuki coupling reactions. Pd-catalyzed multiphasic Suzuki coupling reactions were accelerated with high conversions through solar-thermal heating and the formation of Pickering emulsions in a phase-separated, highly concentrated reaction mixture using polypyrole@Pd. Increasing the interfacial area by forming a Pickering emulsion facilitates mass transfer between the two miscible liquid phases, which is crucial for multiphasic reactions. Gram-scale synthesis under solar illumination over an area of 3.14 cm2 was successfully achieved, and the multiple usability of polypyrrole@Pd was demonstrated over 20 cycles.

Effect of multi‐tubes and eccentricity on melting performance of honeybee wax thermal energy storage system: A comprehensive numerical study and experimental validation

AbstractWhen it comes to solar thermal power systems, a latent heat energy storage unit is one possible solution to the imbalance in supply and demand. On a shell‐tube type heat storage system, computational and experimental research was done to determine how to charge a heat storage system using honeybee wax‐biodegradable phase change material. This paper examines the impact of single, double, and triple inner heat transfer fluid tubes on the melting properties of bee wax in relation to vertical and horizontal eccentricity. Through the experimental examination of a lab‐scale prototype, the computational model was verified. A computational model was used to investigate the impact of eccentricity on different configurations for the melting process. Utilizing multiple tubes significantly shortened the charging time, according to the system analysis. In a vertically downward direction, melting time reduced as eccentricity increased. Compared to the single tube concentric case, the maximum melting time reduction for the single‐, double‐, and triple‐tube cases was 63.7%, 67.0%, and 68.34%, respectively.

Comprehensive performance analysis of CST-PV system based on spectral beam splitting film

Abstract In this paper, a novel linear Fresnel concentrator (LFC) with a rotating platform was constructed, and a novel concentrated solar thermal and photovoltaic (CST-PV) hybrid system utilizing spectral beam splitting was established on the LFC. A spectral beam-splitting film (SBSF) was coated on the PV cell’s inner glass wall, replacing the LFC’s primary reflector. The SBSF can transmit the solar spectrum of 300-1100 nm to the photovoltaic (PV) cells and reflect the remaining solar wavelengths to the absorber to generate heat. The LFC’s cosine efficiency and end efficiency after azimuthal compensation by a rotating platform were calculated through theoretical analysis. The effects of temperature on the efficiency of PV and linear Fresnel solar systems were studied through experimental and numerical simulations. The comprehensive utilization efficiency evaluation method was established. The results show that the LFC’s end efficiency and cosine efficiency in this paper, after azimuthal compensation, increased by 31.7% and 33.7%, respectively, compared with the east-west and north-south axis placement. The comprehensive utilization efficiency of the CST-PV system based on SBS is 61.58%, which increased by 13.47% compared to that of the single fixed PV system.

Enhanced solar-driven steam generation and water purification using 3D arch solar evaporators

Steam generation strategy through solar-driven evaporators has now been widely recognized as one of the effective means to relieve the global fresh water crisis. Reducing heat loss has shown to be an effective way to improve the evaporation efficiency which has been overlooked in three-dimensional (3D) evaporators in the past. Herein, a superhydrophilic photothermal fabric was developed by the layer-by-layer assembly of carbon nanotubes followed by dip-coating with polyvinyl alcohol. The as-obtained photothermal fabric was designed as a 3D arch solar evaporator (ASE). The arch structure allowed the photothermal fabric to achieve double-sided water evaporation and a well-balanced saline water supply by controlling the height of the ASE. The ASE effectively captured the incident sunlight and demonstrated extraordinary thermal management performance, resulting in a saline water evaporation flux of 1.015–3.400 kg m−2 h−1 under 1 sun irradiation for 6 h. In addition, the proposed ASE exhibited excellent water purification for high salinity saline water, colored wastewater, and heavy metal wastewater. This work provides new insights into emerging solar steam generation systems by regulating the saline water supply balance.

Basil seed hydrogel incorporated activated carbon as a Capable, Bio-Based, and Cost-Effective interfacial solar steam generator

Utilization of solar energy for desalination and purification of seawater opens up a state-of-the-art way to meet the water needs all around the world specially in coastal cities. Herein, the eco-friendly, low cost and bio-based basil seed (BS) hydrogel is combined with activated carbon (AC) to synthesize activated carbon merged with basil seed hydrogel (AC-BS) composite material. Due to the photothermal property of the AC, the AC-BS composite was used to design an interfacial solar steam generator (ISSG) for water purification. The AC absorbs the sunlight and converts it to the required heat needed for water evaporation and the superhydrophilic BS hydrogel supplies water to the surface causing the high salt rejection ability of the system, in addition, it decreases the required energy for evaporation. The AC-BS is characterized using characterization methods such as EDX and FESEM. The two-dimensional (2D) AC-BS system containing a cotton fiber used to transfer water from the bulk to the surface, a layer of styrofoam as a heat insulator and AC-BS on the surface shows evaporation rate of 1.93 kg m−2h−1. The three-dimensional (3D) AC-BS, designed to solve the solar irradiation angle fluctuation problem during a day and seasons, shows an evaporation rate of 2.70 kg m−2h−1 and an efficiency of about 91 % under 1 sun illumination. The ability of the AC-BS system for saline water desalination and waste water-contaminated dyes as a pollutant treatment is highly acceptable. The AC-BS ISSG can be studied and used on large scales to provide fresh water from saline water.

Plasma Vacuum-Arc Treatment Technology for the Metal Pipe Surfaces of Solar Thermal Power Plants

Plasma Vacuum-Arc Treatment Technology for the Metal Pipe Surfaces of Solar Thermal Power Plants

Techno-Economic Assessment and Dynamic Simulation of Solar Water Thermal Heating Systems for Village Compound in Egypt

Techno-Economic Assessment and Dynamic Simulation of Solar Water Thermal Heating Systems for Village Compound in Egypt

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.

Economic and operational assessment of solar-assisted hybrid carbon capture system for combined cycle power plants

The paper presents a post-combustion CO2 capture process which involves two configurations for enhancing the CO2 separation driving force in the conventional amine-based Carbon Capture System (CCS): a multi-stage membrane module for selective exhaust gas recirculation (SEGR case) and the combination of turbine exhaust gas recirculation with SEGR (EGR + SEGR case). Furthermore, the stripper reboiler in both configurations is integrated with a parabolic trough solar collector field with a 4-h thermal energy storage to provide the required thermal duty for solvent regeneration. Various system components are designed, simulated, and integrated with an economic model to evaluate the system's techno-economic performance across a wide range of loads. The results show that the proposed designs have efficient part-load performance although efficiency degradation is inevitable during partial-loads. A stable supply of solar thermal energy results during the partial operation of NGCC even during night. The EGR + SEGR case represents the case with the lowest levelized cost of electricity and CO2 avoided cost, 81.43 $/MWh and 101.66 $/tonneCO2, among the CCS-equipped designs, which highlight the advantages of this design over baseline and SEGR case. The proposed hybrid system shows promise for significantly decarbonizing fossil-fuel power plants and increasing power sector flexibility.

Quasi-waffle solar distiller for durable desalination of seawater.

Water purification via interfacial solar steam generation exhibits promising potential. However, salt crystallization on evaporators reduces solar absorption and obstructs water supply. To address it, a waffle-shaped solar evaporator (WSE) has been designed. WSE is fabricated via a zinc-assisted pyrolysis route, combining low-cost biomass carbon sources, recyclable zinc, and die-stamping process. This route enables cost-effective production without the need of sophisticated processing. As compared to conventional plane-shaped evaporators, WSE is featured by extra sidewalls for triggering the convection with the synergistic solute and thermal Marangoni effects. Consequently, WSE achieves spontaneous salt rejection and durable evaporation stability. It has demonstrated continuous operation for more than 60 days in brine without fouling.

A Janus evaporator based on Donnan effect for efficient solar thermal desalination

Interfacial solar steam generation (ISSG) is a solution to alleviate the energy crisis by obtaining clean water at low cost. In order to maintain high evaporation rates in high salinity brines, it is necessary to develop a new ISSG device with controlled heat loss and good salt resistance. In this paper, polyvinyl alcohol (PVA) was used as the backbone to construct ion-selective hydrogel, and hydrogel network with multiple hydrophilic groups was formed using Fe3O4 as a broadband light absorber. Specifically, the evaporator is suspended on the water surface with evaporation rate of 3.04 kg·m−2·h−1 under one sun irradiation. The bilayer hydrogels can permeate Cl− and Na+ selectively. The improved salt resistance is due to the exclusion mechanism of the Donnan effect, with the formed potential difference of 157.4 mV at a brine concentration of 3.5 wt%. Even if it is suspended on the water surface in a high concentration of brine, there will be no salt crystals generated. The developed Janus ion-selective hydrogel-based evaporator shows great prospect for desalination and other advanced solar thermal applications.

Energy Consumption at Accommodation Buildings: A Case Study of a Boutique Hotel-Abdera

Global environmental problems such as decreasing biodiversity, natural disasters, climate change, and energy consumption are among the main concerns of the countries. Approximately 50% of the energy consumed worldwide is spent on architectural construction, use, and operation. The increase in energy consumption in buildings especially has taken the reduction of carbon footprint and the importance of energy efficiency to the fore. Physical environment, climate, orientation, envelope, and material properties are among the different factors in determining energy consumption in buildings. The share of tourism activities in total emissions is estimated to be 5%. However, it is also stated that tourism buildings have a share of 21 % of C02 emissions. This work aimed to research the energy consumption of a boutique hotel in Abdera, Greece. ArchiCAD, Graphisoft, and EcoDesigner software were used in the analysis of findings, and suggestions were put forward. Energy consumption and environmental effects were investigated when active solar systems (Solar Thermal Panel /STP (30 m2), Photovoltaic Panel/PV (30 m2)) were added to the roof surface (total 60 m2 Panel) of the building. The analysis showed that the addition of active solar systems by 30% could reduce emissions. In Greece, which is located in a very favorable region in terms of geographical features, it is very important to use solar potential with integrated systems in buildings to provide energy needs.

Thermal analysis of hybrid nanoliquid contains iron-oxide (Fe3O4) and copper (Cu) nanoparticles in an enclosure

The major aim of this work is to analyze the thermophysical properties of hybrid nanoliquid inside a square lid driven enclosure under the effect of applied magnetic field and mixed convection. The Hybrid nanofluid is considered a suspension of Iron-oxide (Fe3O4) and Copper (Cu) nanoparticles into water. The cavity walls have varying properties such as top adiabatic wall is moving continuously while the lower wall is maintained at a high constant temperature, in addition, the vertical walls are kept at a low fixed temperature. The magnetic field is applied to the right vertical wall in a horizontal direction. Additionally, the effects of buoyancy forces caused by temperature gradients and shear forces caused by continuous lid motion are considered. The mathematical modelling of problem with all assumptions yields the nonlinear partial differential system. First this system is transferred into non-dimensional form and then transformed system is solved by using Galerkin finite element method (GFEM) along with Gaussian elimination method. Results for isotherms, streamlines and average Nusselt number are obtained versus Richardson number (0.1 ≤ Ri ≤ 15), Grashof number (10 ≤ Gr ≤ 10000), Hartmann number (0 ≤ Ha ≤ 100), volume fractions of solid nanoparticles (0.005 ≤ ϕ1 ≤ 0.02) and (0.005 ≤ ϕ2 ≤ 0.02). It is observed that the Richardson number and Grashof number have significant impacts on both flow velocity and temperature. In addition, concentration of hybrid nanoparticles improves the heat transfer performance. The obtained results may be crucial for thermal management in the cooling of electronics, heat exchangers, solar thermal collectors, industrial operations, medical equipment, HVAC systems, food processing, and renewable energy systems.

Master slave game-based optimization of an off-grid combined cooling and power system coupled with solar thermal and photovoltaics considering carbon cost allocation

Analogously to power trading models used by electricity companies, the implementation of an energy retailer can address the trading challenges experienced by end-users with decentralized energy consumption patterns. This research develops an off-grid solar-gas energy system to fulfill the cooling and power needs of buildings. Upon creating thermodynamic models, an innovative energy trading mechanism is introduced through an energy retailer, followed by the application of a master-slave optimization method aimed at maximizing participants' profits while incorporating carbon trading and demand response strategies. Through a case study and comparison of four different scenarios, the findings demonstrate that integrating solar thermal and electrical systems leads to the highest profitability, with the energy system's revenues remaining below 10%. The study determines the maximum selling prices for cooling and electricity as 0.231 $/kWh and 0.232 $/kWh, respectively, and highlights that varying carbon allocation rates have minimal effects on user profits. This work sheds light on the sustainable progression of distributed energy systems and presents motivating implications for a diverse audience interested in such advancements.

Solar-enhanced lithium extraction with self-sustaining water recycling from salt-lake brines

Lithium is an emerging strategic resource for modern energy transformation toward electrification and decarbonization. However, current mainstream direct lithium extraction technology via adsorption suffers from sluggish kinetics and intensive water usage, especially in arid/semiarid and cold salt-lake regions (natural land brines). Herein, an efficient proof-of-concept integrated solar microevaporator system is developed to realize synergetic solar-enhanced lithium recovery and water footprint management from hypersaline salt-lake brines. The 98% solar energy harvesting efficiency of the solar microevaporator system, elevating its local temperature, greatly promotes the endothermic Li+ extraction process and solar steam generation. Benefiting from the photothermal effect, enhanced water flux, and enriched local Li+ supply in nanoconfined space, a double-enhanced Li+ recovery capacity was delivered (increase from 12.4 to 28.7 mg g-1) under one sun, and adsorption kinetics rate (saturated within 6 h) also reached twice of that at 280 K (salt-lake temperature). Additionally, the self-assembly rotation feature endows the microevaporator system with distinct self-cleaning desalination ability, achieving near 100% water recovery from hypersaline brines for further self-sufficient Li+ elution. Outdoor comprehensive solar-powered experiment verified the feasibility of basically stable lithium recovery ability (>8 mg g-1) directly from natural hypersaline salt-lake brines with self-sustaining water recycling for Li+ elution (440 m3 water recovery per ton Li2CO3). This work offers an integrated solution for sustainable lithium recovery with near zero water/carbon consumption toward carbon neutrality.