Effective Use Of Solar Energy Research Articles

Innovative twist design for solar water heaters: Experimental findings and implications

More effective use of solar energy in hot water systems is made possible by optimising heat transfer and flow resistance. In light of this, Research has been conducted to enhance convective heat transfer while analysing flow friction characteristics for best performance, resulting in the design of novel inserts known as customised twists, which increase the efficiency of the solar hot water system. A conventional, plain tube heater is used as a baseline for the study on thermal characteristics, heat transportation and flow friction attributes. A thorough analysis and comparison of the thermal behaviour of the system with customised twist inserts that have been modified using rods and spacers of different lengths is performed. As a result of the induced disturbance in the fluid particle flow pattern throughout the length of risers, a significant improvement in the coefficient of convective heat transfer is observed. The study validated the correlations for the convective heat transfer coefficient and the resistance coefficient against previous research findings. The findings indicated that the thermal efficiency of the full-length twist-inserted system is almost three times greater than that of a plain collector while doubling its pressure drop. The findings of this research could be useful in designing low-cost, compact solar water heaters.

Annual performance analysis of solar-assisted raw-water source heat pumps at low water temperatures

With the increase in energy consumption for building heating and cooling, raw-water source heat pumps (RWSHPs) have garnered strong attention because of their advantages of high efficiency and utilization of a clean heat source. However, RWSHPs exhibit poor performance at low water source temperatures. Thus, this study proposes a solar-assisted raw-water source heat pump (SA-RWSHP) to solve the performance degradation of RWSHPs. The SA-RWSHP can improve performance during the heating period by elevating the entering water temperature (EWT) using solar collectors. During the cooling period, a solar heat source can be used to produce domestic hot water. Optimal design parameters are determined by analyzing the performance of SA-RWSHP using the TRNSYS. Additionally, the performance of SA-RWSHP is compared with that of RWSHP. During the heating period, the unit COP (COPhp) of SA-RWSHP was 12.7% higher than that of RWSHP on average, owing to the increase in the EWT. Furthermore, the annual total system COP of SA-RWSHP was approximately 18% higher than that of RWSHP owing to the high COPhp and effective use of solar energy. Overall, the SA-RWSHP exhibited superior performance throughout the year, resulting in a substantial reduction in building energy consumption.

Nanocosmos of catalysis: a voyage through synthesis, properties, and enhanced photocatalytic degradation in nickel sulfide nanocomposites.

Nanomaterials play a decisive role in environmental applications such as water purification, pollutant monitoring, and advanced oxidation-based remediation processes, particularly in semiconductor and metal sulfide-based photocatalysis. Metal sulfides are ideal for photocatalysis because of their unique optical, structural, and electronic characteristics. These properties enable the effective use of solar energy to drive various catalytic reactions with potential uses in environmental remediation with sustainable energy production. Among them, nickel sulfides (NiS) stand out for their narrow band gaps, high stability, and cost-effectiveness. This review thoroughly analyzes recent advancements in employing nickel-sulfide-based nanostructures for water decontamination. It begins by addressing environmental material needs and emphasizing the properties of nickel sulfide. To improve photocatalytic performance, controlled processes that affect the active structure, shape, composition, and size of nickel sulfide photocatalysts are examined, along with their synthesis methods. The heart of the review article is a detailed analysis of the modification of NiS through metal and non-metal doping, heterojunction, and nanocomposite formation for enhanced photocatalytic performance. The discussion also includes metal-modified nanostructures, metal oxides, and carbon-hybridized nanocomposites. This study underscores notable advancements in the degradation efficiency of NiS photocatalysts, rivaling their costly noble-metal counterparts. The analysis concludes with potential future directions for nickel sulfide-based photocatalysts in sustainable environmental remediation.

Solar and open sun drying of untreated and pretreated banana stalk chips biomass: a sustainable processing of biomass using renewable solar energy

The stalk of banana is an abundant biomass that can be sustainably converted into bioenergy, biofuels, biosorbents, animal feeds and fibers. The moisture content of freshly harvested banana stalk is high, so drying is essential before its storage and prior to some of the conversion processes. Hence, solar and open sun drying characteristics of banana stalk chips were investigated. Untreated (5, 10 and 15 mm thick) and pretreated (hot water, salt water and sulphite) banana stalk chips were dehydrated in a solar dryer and directly in sunlight. The data were fitted to twelve drying models. The moisture diffusivities were also evaluated. Banana stalk dried mainly in the falling-rate phase and the rate of drying increased with decreasing chip thickness. However, the chips dried slower in direct sunlight compared to the solar dryer. The pretreatments significantly (P < 0.05) enhanced the rate of dehydration of the chips in the solar dryer. Diffusivities for the solar and direct sunlight drying of banana stalk chips were 1.28 × 10–9–5.32 × 10–9 m2 s−1 and 1.08 × 10–9–3.65 × 10–9 m2 s−1, respectively. The Weibull model aptly described the solar drying of the chips while the Midilli-Kucuk and Weibull models most properly depicted the open sun dehydration of untreated and pretreated chips, respectively. Solar energy may be more efficiently utilized for drying banana stalk chips biomass by using a solar dryer as well as a very thin layer of chips and by pretreating the biomass prior to the drying operation. The effective use of solar energy for drying banana stalk biomass can reduce its processing cost and enhance the sustainability of biomass utilization.

Analysis of the advantages and disadvantages of BIPV technology

As environmental problems such as the greenhouse effect and glacier melting become more and more serious, the society's awareness of environmental protection is becoming stronger and stronger, which makes the development of green buildings extremely important, and the development of many green building materials and environmental protection technologies is also increasing. more attention. In this article, BIPV (Building Integrated Photovoltaic) will be researched and its development discussed. BIPV is to reduce energy consumption through the effective use of solar energy. It is green, environmentally friendly and non-polluting. However, China started late in photovoltaics and lack of research in this area, which makes the application of BIPV technology in China still have high costs and lack of relevant building specification standards. This paper discusses the suggestions for the future development of BIPV technology, hoping to provide meager strength for the development of green buildings in China and provide direction for the future development of BIPV.

Performance comparison of three supercritical CO2 solar thermal power systems with compressed fluid and molten salt energy storage

In recent years, the supercritical carbon dioxide (sCO2) Brayton cycle power generation system has gradually attracted the attention of academics as a solar thermal power generation technology. To achieve the stable and effective use of solar energy, three sCO2 solar power generation systems were studied in this paper. These systems included a molten salt thermal storage system, a compressed CO2 energy storage system, and a combined molten salt thermal storage and compressed CO2 energy storage system. The thermodynamic analysis model of the sCO2 power generation system is constructed, and a mathematical model of the solar power tower system is produced. The operating conditions, thermal efficiency, exergy efficiency, and economics of these three systems on typical days are investigated and compared. The results indicate that the power generation system coupled with compressed CO2 storage has higher thermal and exergy efficiencies than the other two systems with the same daily heliostat field. The thermal efficiencies can be as high as 6.56% and 5.91% respectively, and the exergy efficiencies as high as 5.76% and 6.22% respectively. The system coupled with compressed CO2 energy storage is more cost-effective and has a shorter payback period than the system coupled with molten salt thermal storage system and the system with both forms of energy storage.

Oxygen vacancies-mediated CuO@N-doped carbon nanocomposites for non-radical-dominated photothermal catalytic degradation of contaminants

Efficient molecular oxygen activation (MOA) is a critical step for most of the environmental catalysis applications for generating reactive oxygen species (ROS), which is often limited by the lack of energy to excite electrons. The emergence of photothermal catalyst provides an opportunity to make effective use of solar energy to energize electrons for boosting activation of molecular oxygen. Herein, CuO nanoparticles wrapped into nitrogen-doped carbon nanocomposites (CuO@NCs) with abundant oxygen vacancies (OVs) were prepared through a facile one-step synthesis using carboxymethyl chitosan hydrogel as a template. The as-obtained CuO@NCs exhibited excellent photothermal catalytic properties under visible-light irradiation to achieve efficient molecular oxygen activation, thus allowing the effective degradation of bisphenol F (BPF) in complex aqueous environments and actual water matrices. Density functional theory (DFT) calculations reveal that both the enhanced properties of OVs for molecular oxygen adsorption and the accelerated properties of graphitic N for electron transfer contribute significantly to the MOA and charge separation efficiency, resulting in a large amount of ROS. Molecular oxygen is converted to superoxide (·O2−) and ultimately to singlet oxygen (1O2), which is the dominant ROS responsible for contaminants degradation. Additionally, a photothermal catalytic degradation pathway of BPF was proposed based on the product detection and theoretical calculations. This study provides an effective method for the in-situ fabrication of metal@N-doped carbon nanocomposite photothermal catalysts and elucidates the mechanism of the photothermal catalytic activation of molecular oxygen for contaminants degradation, providing a promising approach for making effective use of solar energy for environmental remediation.

An enhanced grey wolf optimizer with fusion strategies for identifying the parameters of photovoltaic models

Identifying photovoltaic (PV) parameters accurately and reliably can be conducive to the effective use of solar energy. The grey wolf optimizer (GWO) that was proposed recently is an effective nature-inspired method and has become an effective way to solve PV parameter identification. However, determining PV parameters is typically regarded as a multimodal optimization, which is a challenging optimization problem; thus, the original GWO still has the problem of insufficient accuracy and reliability when identifying PV parameters. In this study, an enhanced grey wolf optimizer with fusion strategies (EGWOFS) is proposed to overcome these shortcomings. First, a modified multiple learning backtracking search algorithm (MMLBSA) is designed to ameliorate the global exploration potential of the original GWO. Second, a dynamic spiral updating position strategy (DSUPS) is constructed to promote the performance of local exploitation. Finally, the proposed EGWOFS is verified by two groups of test data, which include three types of PV test models and experimental data extracted from the manufacturer’s data sheet. Experiments show that the overall performance of the proposed EGWOFS achieves competitive or better results in terms of accuracy and reliability for most test models.

Smart Evaluation Index of Roof SHS Suitability

The instability of solar energy and its resource distribution characteristics make it difficult to judge its suitability in practical engineering applications, which hinders its promotion and application. In order to better promote the effective use of solar energy and promote the solar heating system, it is necessary to put forward a simple method of judging the suitability of the solar heating system for engineering application. This study puts forward “F, Q” as the basis for judging the suitability of solar heating systems built on the roof. Two types of public buildings, office buildings and three-star hotels, are taken as the research objects. DeST software is used to change the heating area of the building by superimposing floors to simulate the heat load of the building when the heating area changes. A dynamic simulation coupling model of solar heating system is established in the TRNSYS software to analyze the operating status of the system under all working conditions. The functional relationship between “F, Q” and solar energy guarantee rate is established, and the solar energy contribution rate is divided into three regions of F &lt; 30%, 30% ≤ F ≤ 50%, and F &gt; 50%. The evaluation standard of the building suitability of the solar energy heating system is established according to the scope of “F, Q” in different regions (An office building for, e.g., if the contribution rate of solar heating system is required to be greater than 50%, the “F” of these four areas should be greater than 0.11388, 0.15543, 0.10572, and 0.04511.), and the effectiveness of “F” is verified through actual cases verified by other scholars in the research. The method proposed in this paper is helpful to judge the suitability of solar heating systems in different regions and different types of conventional buildings, so as to better promote solar heating systems.

Efficient photocatalytic degradation of tetracycline under visible light by AgCl/Bi12O15Cl6/g-C3N4 with a dual electron transfer mechanism

A novel and efficient ternary composite AgCl/Bi12O15Cl6/g-C3N4 photocatalyst was prepared by co-precipitation method. The physical structure and photochemical properties of the photocatalyst were analyzed by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Ultraviolet diffuse reflectance spectroscopy (UV-DRS), Fluorescence spectroscopy (PL). The performance of the prepared photocatalysts was evaluated by performing degradation experiments of tetracycline (TC) under different conditions (doping ratio, dosage, initial concentration and initial pH of solution). Furthermore, the stability of composite was confirmed by cycling experiment. Finally, the mechanism of ternary composite AgCl/Bi12O15Cl6/g-C3N4 photocatalyst for decomposition of TC in visible light was investigated by free radical capture experiment. The photoluminescence spectra showed that the peak intensity of the AgCl/Bi12O15Cl6/g-C3N4 composite was significantly reduced compared to other materials, indicating that the photogenerated electron-hole pairs were effectively separated, which contributed to its photocatalytic activity. The composite showed higher TC degradation activity compared to g-C3N4, Bi12O15Cl6/g-C3N4 and AgCl/g-C3N4, with optimum degradation rate constants of 8.2, 2.2 and 1.6 times that of g-C3N4, Bi12O15Cl6/g-C3N4 and AgCl/g-C3N4, respectively. Furthermore, based on the free radical capture experiment, it was confirmed that the active species playing a major role in the reaction process were·O2-, followed by h+ and·OH. A double electron transfer mechanism was inferred to be formed in the AgCl/Bi12O15Cl6/g-C3N4 composite and a possible pathway for the degradation of TC was postulated. This work provides a new approach for the effective use of solar energy, as well as a new solution strategy for the degradation of TC in wastewater.

Feasibility Study and Deployment of Solar Photovoltaic System to Enhance Energy Economics of King Abdullah Campus, University of Azad Jammu and Kashmir Muzaffarabad, AJK Pakistan

As non-renewable energy sources become depleted, the world is transitioning toward renewable energy sources (RERs), which entail several significant advantages, including cost savings, large-scale availability, and minimal losses. Pakistan is sixth among the countries most affected by global warming and abrupt climatic changes. Severe floods, catastrophic rains, and wind gusts have created new challenges in the country regarding resilient and reliable power supply. Due to harsh weather conditions, the power shut down, blackouts, and prolonged fault in the transmission systems are common and cause millions of dollars in economic losses annually. The main challenge of providing a reliable power supply while satisfying the climatic conditions to use renewable energy resources has a global significance. This article aims to develop a hybrid power network (PV/Battery/Grid) for King Abdullah Campus, The University of Azad Jammu and Kashmir, Muzaffarabad, Pakistan. The results for the proposed system are compared with the existing system while they are supplying the same power to the load. The cost of energy (COE) from the existing on- grid Hybrid system is Rs.27.32/kWh. It can be seen that energy cost is minimized by up to Rs.0.251/kWh by the effective use of solar energy. Optimization results conclude that the on- grid hybrid (PV/Battery/Convertor/Grid) is more efficient than all other configurations. Therefore, it is concluded that the proposed hybrid power system for grid-connected sites is most efficient, stable, cost-effective, and environmentally friendly. The ultimate goal was to design an economically feasible hybrid power system and analyze the techno-socio impacts of the PV hybrid system for the campus. Data were initially collected for the desired site and then simulated via the HOMER simulation tool, which determined the net load and feasibility of the proposed system. This techno-economic analysis of the PV hybrid system will enhance the utilization of solar power in other educational or commercial facilities in the region may follow the path in the future.

A waste biomass-derived photothermic material with high salt-resistance for efficient solar evaporation

Effective use of solar energy to produce steam for solving the problem of global shortage of fresh water is considered to be a promising technology. In this work, we reported a low-cost, high-efficient, waste biomass-derived solar evaporator with Janus structure was readily constructed from porous pomelo peel (PP). This multifunctional photothermal sponge has a hydrophobic top layer and a hydrophilic bottom layer to prevent the accumulation of salt on the surface of the evaporator, ensuring high efficiency and stable water vapor output. After hydrophobic modification of one side of freeze-dried PP, MXene was sprayed on the Janus PP (JPP), the interfacial solar energy driven water evaporation can be effectively realized for seawater desalination. The evaporation rate and solar thermal conversion efficiency of JPP@MXene (JPP@M) under simulated sunlight irradiation with one sun (1 kW m−2) were 1.48 kg m−2·h−1 and 92.3% respectively. Under simulated sunlight irradiation of 1 sun, a high efficiency evaporation performance could be maintained after 50 cycles. In addition, JPP@M could be used to effectively reduce the viscosity of heavy crude oil through solar-assisted heating, resulting in effective purification. Moreover, JPP@M exhibited excellent antibacterial property, which is more important for biomass samples. This cost-efficient, sustainable and eco-friendly photothermic sponge is expected to be used for large-scale wastewater treatment and clean water generation.

Effective Use of Solar Energy with BIM Supported Parametric Methods: Case Study Al-Shaab Stadium

In this study, it is aimed to create an infrastructure that can contribute to the integration of parametric techniques and the joint work of construction and architectural science through an exemplary building design. The ability to respond to changes in data entry in algorithms gives architectural designers the opportunity to optimize structures and form at the same time. At the same time, replacing inputs with parametric techniques saves time in the design process. Otherwise, the design will have to be redesigned from the beginning, depending on the periodic change made in the design. In addition to this, it has been emphasized to build a building design and structure that will provide energy efficiency. In order to create low cost in profit-cost ratios, the possibility of minimizing the inefficient surfaces with the design method by analysing the floats with maximum energy gain due to creating solar plans. The algorithmic design used for this is modelled on the visual and optimizes the geometry to achieve maximum energy efficiency for the building form. To find solar panels suitable for the building geometry design, there is a need to model the actual effect of the sun's rays on the building. One of the key parameters that helped us reach the results of the study is to explore the possibility of using modern guidelines of exemplified stadium designs. This research is based on a method of comparing analysis between two prototype proposals tested to show the effect of the sun on geometry using parametric algorithms. In this case, "Grasshopper 3D" software was used for radiation, daylight hours and shadows to create parametric algorithms in the solar effect simulations process. The purpose of using parametric simulation was to increase energy efficiency for the stadium. Additionally, generative design was used for structural optimization. In this study, generative design was also used to optimize the stadium design structure, which helps to significantly reduce the amount of materials used in the formation of the structure and its costs. In this study, with the help of the Buiding Information Modelling (BIM) program used, solar energy gains affecting the building were investigated and energy gain-loss calculations were made by using environmental data. The obtained data and shell design samples were compared. In the study, Al Shaab stadium in Baghdad was evaluated as an experimental model for modelling the reality.

Concentrated photovoltaics as light harvesters: Outlook, recent progress, and challenges

Concentrated photovoltaics (CPV) is a dawn technology in the field of photovoltaic that helps in escalating the effective use of solar energy. Nowadays, applications of photovoltaic solar cells are catching attention due to the better utilization of solar energy. A huge amount of solar energy is received by the earth from the sun, but a barrier to the large-scale use of photovoltaic solar cells is their higher initial cost and lower conversion compared to other non-renewable energy systems. Concentrated Photovoltaics (CPV) is one of the vital tools that focus solar radiation on the small area of solar cells using optical devices to maximize solar to thermal conversion. Low cost, high efficiency, and climate-friendly are the main advantages of concentrated photovoltaics. The review study presents the outlook of work conducted worldwide on the different types of concentrated photovoltaics. In addition, the effect of various performance affecting parameters, challenges, and recent progress is also part of the study. Most of the CPV have efficiency up to 15% while some have an efficiency range of 25–28% which is still very low. It was found that the CPV gave maximum efficiency of up to 38.5% at optimal solar radiation. The focus of sunlight on a small area of solar cell increases the temperature of concentrated photovoltaic allegedly pernicious for electrical efficiency and the life of CPV. Factors like direct normal irradiance, high cell temperature, soiling, optical design, reliability, and durability are considered as challenges and a concise summary of various studies on these challenges is presented. In this regard, various cooling techniques have been investigated by different researchers for thermal management of CPV systems which are discussed in detail. As CPV technology is still in the development phase, various new optical designs emphasizing novel designs and materials are also summarized in the current study. Finally, some recommendations are oriented which will be very valuable for those who are working or want to work in the field of photovoltaics.

Modelling of a concentrated solar power – photovoltaics hybrid plant for carbon dioxide capture and utilization via calcium looping and methanation

Increasing the share of renewable energies and reducing the emissions of carbon dioxide are two of the major challenges of this century. Effective use of solar energy can contribute to both targets. In this study, it is investigated an integrated process in which concentrated solar power is used to perform carbon dioxide capture from a combustion power plant through the calcium looping cycle in a dual interconnected fluidized bed system. Carbon dioxide is then reacted with hydrogen obtained from water electrolysis to produce methane (power-to-gas). Electrolytic cells may be powered by photovoltaics or excess renewable energies, thus reducing their curtailment. The integrated process was studied by means of model computations. Steady state operation of the different units was considered. Intrinsic variability of the solar energy was managed with implementation of a seasonal and/or daily thermochemical energy storage strategy. Design and operational conditions assumed as a reference were those of a combustion plant of municipal solid waste located in Manfredonia (Italy). Parameters were chosen so as to reproduce realistic conditions. Model results suggest that carbon dioxide capture can range from 30% to 85%. Input thermal power of the concentrated solar power must range between 50 and 175 MWth, for 12 h of operation. A share of this energy can be integrated in the power cycle for electricity generation, upgrading the potentiality of the original combustion plant. Size of cubic storage vessels required for continuous operation of the system ranges from 10 to 70 m according to the implemented strategy. Methane yield ranges within 3–12 × 104 tons per year, and production of H2 needs a photovoltaic field of 4–5 km2 if built in Manfredonia. Altogether, the integrated plant has an overall efficiency of 20–22% and allows, simultaneously, for carbon dioxide capture, continuous integration of solar energy in the energy production cycle and carbon dioxide utilization for methane production.

Estimating Downward Shortwave Solar Radiation on Clear-Sky Days in Heterogeneous Surface Using LM-BP Neural Network

Downward surface shortwave radiation (DSSR) plays an important role in the energy balance of the earth’s surface. Accurate estimate of DSSR is of great significance for the rational and effective use of solar energy. Some parameterization schemes were proposed to estimate DSSR using meteorological measurements given ground-based radiation observation sites are scare and uneven. With the development of remote sensing technique, remotely sensed data can be applied to obtain continuous DSSR in space. Commonly, the spatial resolution of most radiation products is relatively low and cannot meet the needs of certain fields. Moreover, some retrieval algorithms based on the radiation transfer models are complicated for non-professionals. In this study, a back-propagation (BP) neural network method with Levenberg–Marquardt (LM) algorithm (hereafter referred to as LM-BP) was applied to predict DSSR by building the relationship between measured DSSR and high-resolution remote sensing data from the Advanced Space-borne Thermal Emission Reflectance Radiometer (ASTER). The DSSR observations from the four-component radiation sensor installed at the land covered by vegetable, village, maize, orchard, Gobi, sandy desert, desert steppe, and wetland were used to validate the model estimates. The results showed that the estimates of DSSR from LM-BP agreed well with the site measurements, with the root mean square error (RMSE) and the mean bias error (MBE) values of 27.34 W/m2 and −1.59 W/m2, respectively. This indicates that by combining the LM-BP network model and ASTER images can obtain precise DSSR in heterogenous surface. The DSSR results of this study can provide accurate high-spatial resolution input data for hydrological, evapotranspiration, and crop models.

A solar dryer for drying green chili in a forced convection for increasing the moisture removing rate

Abstract The abundant and unpredictable use of fossil fuel accelerate the continuous search in that field of an alternative source. Most of the researchers are attracted to the solar power, that is one of therenewable and sustainable energy sources. Based on the current scenario, in futurethe energy requirement will be tremendously high. The effectiveuse of solar energy can be reduced the problem of huge energy demand in all agricultural, industrial, domestic and power production sectors. In agricultural sector, one of the areas is drying technology. The drying technique is one of the applications of the solar energy. Drying is the process of removing moisture from the agricultural produce. From our ancestor to modern humanbeing, various improvement occurs in the solar drying system. The indirect solar drying with integrated flat plate collector is most popular, simple in design, cost effective, maintenance free and easy to operatevegetable drying system. The flow of air movement, thermal leak proof cabinet structure, flat plate collector’s (FPC) absorber plate design, optimum thickness of selective coating materials, etc. directly affect the efficiency and moisture removing rate of the solar drying system. Here, the 15 kg green chili has been taken for drying in solar drying system. The dryer is integrated with phase change materials (PCM) in drying trays, flat plate collector’s absorbing plate coated with activated charcoal and black board paint, the variable air mass flow rate of the blower. It has been found that, at 0.008 kg/s air mass flow rate the outlet temperature of the FPC is 96 °C and efficiency is 33%. The drying time was 16 h as compared with open sundrying time 28 h for the 15 kg chili. It was compared with indirect solar dryer without thermal energy storage and found that the time required for drying chili with thermal energy storage is 4 h less than the without thermal enrgy storage solar dryer.

Experimental Analysis of the Function of a Window with a Phase Change Heat Accumulator.

The article presents the results of long-term field tests and their mathematical analysis regarding the impacts of innovative phase change materials on the energy efficiency of composite windows with various glazing parameters. Research was conducted on six glazing combinations throughout the heating season in a temperate climate in Rzeszów (Poland). The empirical results obtained during the spring months showed an improvement in the monthly heat balance for windows with phase change materials compared to the reference window by as much as 34.09%. In addition, the empirical results allowed the development and verification of a mathematical model describing the transport and distribution of heat within a window with a phase change heat accumulator. The model was made using equations of non-stationary heat flow and an explicit finite difference method using calorimetric thermograms describing the phase change eutectic mixture used in the research. Carrying out the Snedecor–Fischer test proved the statistical adequacy of the developed model in 4 out of 6 tested combinations of glazing units. Good matching of the empirical and theoretical quantities was also confirmed using the quasi-Newton method. The article is a solution to the problem of the effective use of solar energy within transparent building partitions, while presenting a useful mathematical tool that determines potential thermal gains in various climatic conditions.

Br-doping of g-C3N4 towards enhanced photocatalytic performance in Cr(VI) reduction

Semiconductor photocatalytic technology is widely recognized as one of the most promising technologies to solve current energy and environmental crisis, due to its ability to make effective use of solar energy. In recent years, graphite carbon nitride (g-C3N4), a new type of non-metallic polymer semiconductor photocatalyst, has rapidly become the focus of intense research in the field of photocatalysis because of its suitable bandgap energy, unique structure, and excellent chemical stability. In order to improve its intrinsic shortages of small specific surface area, narrow visible light response range, high electron-hole pair recombination rate, and low photon quantum efficiency, a simple method was utilized to synthesize Br-doped g-C3N4 (CN–BrX, X = 5, 10, 20, 30), where X is a percentage mole ratio of NH4Br to melamine. Experimental results showed that Br atoms were doped into the g-C3N4 lattice by replacing the bonded N atoms in the form of C–N=C, while the derived material retained the original framework of g-C3N4. The interaction of Br element with the g-C3N4 skeleton not only broadened the visible-light response of g-C3N4 to 800 nm with an adjustable band gap, but also greatly promoted the separation efficiency of the photogenerated charge carrier and the surface area. The photocurrent intensity of bare CN and CN–BrX (X = 5, 10, 20, 30) catalysts is calculated to be 1.5, 2.0, 3.1, 6.5, and 1.9 μA, respectively. And their specific surface area is measured to be 9.086, 9.326, 15.137, 13.397, and 6.932 m2/g. As a result, this Br-doped g-C3N4 gives significantly enhanced photocatalytic reduction of Cr(VI), achieving a twice enhancement over g-C3N4, with high stability during prolonged photocatalytic operation compared to bare g-C3N4 under visible light irradiation. Furthermore, an underlying photocatalytic reduction mechanism was proposed based on control experiments using radical scavengers.

Investigation of a solar assisted heat pump wheat drying system with underground thermal energy storage tank

Storage of solar energy in underground Thermal Energy Storage (TES) tank during sunny days and extraction of the energy in the TES tank and its surrounding ground by a heat pump through the year for drying systems is an attractive subject for effective use of solar energy and ground as heat sources. It is possible to store solar energy in the TES tank and ground to use it for heating systems. In this study, modeling of a wheat drying system with a heat pump and underground TES tank charged by solar energy is developed using energy analysis of the drying system to investigate its long-term performance parameters. The drying system has four components, which are wheat dryer, underground TES tank, solar collectors, and a heat pump. The analytical model consists of a solution of unsteady heat transfer problem around the TES tank and energy expressions for the other components. A MATLAB code is developed to examine the performance parameters hour by hour along the years. These parameters are water temperature in the tank, Coefficient of Performances for the heat pump (COP) and system (COPs), Specific Moisture Evaporation Rate (SMER), and energy fractions for the system. When wheat mass flow rate and Carnot efficiency are selected as 50 kg h−1 and 40% respectively, collector area, TES tank volume, COP, COPs and SMER are 70 m2 and 200 m3, 4.43, 4.3 and 6.05 respectively when the system attains periodic operation time from the 5th year onwards for 10 years of operation.