Glass Cover Thickness Research Articles

Design, fabrication, and physical properties analysis of laminated Low-E coated glass for retrofit window solutions

The ever-growing demand for improved energy efficiency in buildings has stimulated a stream of research focused on innovative retrofit energy solutions. Laminated low emissivity (Low-E) type coated glass components can be used in retrofitting window systems for enhancing energy savings provided by the insulating properties of glass laminates containing these heat-mirror-type coatings. In particular, custom-designed double-silver low-E coatings embedded into the laminate structure (directly facing the polymer interlayers during and after the lamination) are of interest due to being protected from environmental exposure, enabling easy component transportation, storage, and window retrofits. In this study, we provide some details on the design of several reflector-type solar control low-E coatings of high environmental stability and demonstrate the feasibility of their fabrication on 3 mm thick glass substrates, followed by the lamination. We describe the optical properties of laminated structural glass components of potential usefulness for retrofitting window applications in new and existing buildings. Several thin-film coatings of a low-E type are deposited by using the RF magnetron sputtering technique and then subjected to lamination by using transparent epoxy and PVB materials, to be protected by a clear glass cover layer. The optical performance characteristics of these coatings (measured before and after lamination) elucidate the effects these lamination materials and cover glass thickness have on the final optical properties (leading to a slight reduction in the optical transmission in the visible spectral range, by around 8–10 % while retaining low thermal emissivity across the infrared spectral range). The outcomes of this research, if industrialized could contribute significantly to the development of sustainable building components and practices, and to acheiving a reduction in building energy consumption by way of enabling window retrofit operations at potentially reduced costs.

Photovoltaic-integrated advancements for sustainable water production: Developing and evaluating an enhanced hybrid solar desalination system

The global water crisis demands innovative solutions, and solar desalination is a promising avenue. However, traditional systems often suffer from low yields. This study centres on the development, assessment, and economic feasibility of the Enhanced Hybrid Solar Still (EHSS), a pioneering approach to sustainable clean water production. Integrating photovoltaic technology, the EHSS targets a minimum daily output of 15 L/m2. Computational Fluid Dynamics (CFD) simulations guide the design optimisation, identifying an optimal configuration of 4 mm basin thickness, a 2 mm glass cover thickness, and a 56° slope. The EHSS is a single component that comprises of passive operation and advanced components integration, including monocrystalline solar panels, a hybrid MPPT inverter, a deep cycle battery, and a custom water heater, to enhance the yield. The EHSS undergoes a comprehensive assessment encompassing distillate quality, efficiency, and economic viability. In passive mode operation (solely using solar radiation), clean water yields range from 4.7111 L/m2·day to 2.1309 L/m2·day. Transitioning to active mode operation (employing photovoltaics and additional components) significantly enhances yields to a range of 19.7 L/m2·day. Impressively, the EHSS consistently delivers an average daily water yield of 16.85 L/m2, and also its purity meets World Health Organization standards for drinking water. The PV systems exhibit a charge rate of 14.28 % per hour on clear days and 9 to 11 % per hour on semi-cloudy days, with the battery depleting at 16.66 % per hour at 70 °C operational temperature. Comparative analysis against traditional systems showcases an efficiency increase from 25.61 % to an outstanding 64.01 % for the optimised EHSS (PV system and appurtenances). A strong correlation (coefficient of 0.9701) between experimental and simulation results indicates robust relationships. Over a 20-year lifespan, cost analysis reveals a per-litre cost of 0.0892 US dollars for the EHSS, compared to 0.0374 US dollars for traditional systems. Extended lifespans further underscore the economic feasibility of the EHSS, emphasizing its role in providing sustainable clean water solutions.

Sustainable Energy Progress via Integration of Thermal Energy Storage and Other Performance Enhancement Strategies in FPCs: A Synergistic Review

Flat plate collectors (FPCs) are the leading solar thermal technology for low-medium range temperature applications. However, their expansion in developing countries is still lacking because of their poor thermal performance. Improving the thermal performance of flat plate collectors (FPCs) is a crucial concern addressed in this review This study comprehensively discussed the performance improvement methods of FPCs, such as design modification, reflectors, working fluid, and energy storage materials, by covering current issues and future recommendations. Design factors such as coating and glass cover thickness, thickness of absorber plate and material, air gap between the glass cover and absorber plate, and riser spacing, along with insulation materials, are examined for their impact on FPC performance. Absorber design changes with selective coatings for improving the heat transmission rate between the working fluid and absorber are critical for enhancing collectors’ thermal output. The nanofluids utilization improved FPC’s thermal performance in terms of energetic and exergetic outcomes in the 20–30% range. Moreover, adding a heat storage unit extends the operating hours and thermal output fluctuations of FPCs. Research suggests that employing turbulators and nanofluids as heat transfer fluids are particularly effective for enhancing heat transfer in FPCs. This comprehensive review serves as a critical tool for evaluating and comparing various heat transfer augmentation techniques, aiding in the selection of the most suitable option.

Proposing and optimization of a parabolic trough solar collector integrated with a photovoltaic module layer

Parabolic trough collector (PTC) is a type of solar system that generates thermal energy by concentrating solar radiation on the surface of a circular receiver tube. However, the overall output of this solar system can be significantly enhanced by the integration of this system with Photovoltaic (PV) modules which is proposed and comprehensively investigated in this research using 3D validated numerical simulation. In the first step of this study, all operating parameters of the new PTC/PV system (i.e. thickness of the air gap, the glass cover thickness, copper nanoparticles mass fraction, and PV cell efficiency) are optimized by employing the Taguchi method. Afterward, it is attempted to enhance further the efficiency of the optimized PTC/PV system by rotating the receiver tube of the system and also installing metal foam inside the fluid channel of the receiver tube. According to the Taguchi method, the maximum overall performance of the PTC/PV system is 71.1%, when the glass cover thickness, air gap thickness, PV cell efficiency, and nanoparticles mass fraction are 2 mm, 10 mm, 21%, and 6%, respectively. Additionally, the numerical simulations show that rotating the receiver tube of the optimized PTC/PV system can augment the overall efficiency of the system from 71.1% to 82.5%, which is due to the improvement in heat transfer rate from the tube to the operating fluid. However, by rotating the receiver tube, the electrical efficiency of the PV cells reduces from 16.0% to 14.9%. Additionally, installing metal foam inside the receiver tube can boost the electrical and overall efficiency of the fixed PTC/PV system by approximately 2% and 13.9%, respectively. It is worth mentioning that adding foam to the rotating receiver tube declines the thermal efficiency of the system by around 0.5%.

Performance Evaluation of a Photovoltaic-Thermal Collector Coupled Stepped Solar Still for Indian Climatic Conditions

Freshwater scarcity is increasing across many parts of the globe; to meet this demand, seawater desalination is the best choice, and the electrical energy consumption is escalating due to urbanization and industrialization. Sustainable production of electricity and freshwater can be met by an integrating photovoltaic-thermal (PVT) module with stepped solar still (SSS). The present study focuses on the theoretical modeling of the PVT-SSS desalination system for evaluating thermal efficiency, energy efficiency, freshwater productivity, and electrical power generation. The solar still productivity will be influenced by the depth of water, insulation thickness, glass cover material, thickness and inclination, and operational factors like preheating the input water supply and water salinity. A comparative analysis has been made of summer, winter, and rainy climatic conditions of Vellore town (12.9165° N, 79.1325° E), Tamil Nadu. In the present work, a thermodynamic model based on mass and energy balance is developed for the PVT-SSS system, and it is solved by a numerical method. A Runge-Kutta technique of 4th order is employed using a Python program for solving the thermodynamic simulation model. The results from the model depict that for summer, winter, and rainy climatic seasons, the freshwater productivity of PV/T-SSS was determined to be 12.18 kg/m2day, 6.67 kg/m2day, and 2.77 kg/m2day. Also, it is found that electrical efficiency for summer, winter, and rainy seasons is 8.91%, 9.135%, and 9.53%, respectively. A maximum and minimum freshwater production of 1668 kg/m2 and 1218 kg/m2 are observed for a depth of 2 cm and 5 cm, respectively.

Enhancing the stepped solar still performance using a built-in passive condenser

In this study, an improved stepped solar still with a built-in passive condenser is proposed and experimentally investigated. In the new design, the solar still body is divided by a central inclined stepped absorber assembly carrying a group of basins into two parallel chambers; The upper chamber is an evaporation chamber, and the bottom chamber is called the condensation chamber and is located on the under of the absorber assembly. Solar radiation heated the saline water and evaporated it. A fraction of the resulting vapor is condensed on the inner glass cover surface while the rest is naturally circulated to the condenser chamber to be condensed there. Air is naturally circulated between the chambers through two slits at the bottom and the top of the absorber assembly. The improved stepped solar still (ISS) was designed and fabricated, and its performance was experimentally evaluated under Kerman climatic conditions in June and October. For comparison, a standard stepped solar still (SSS) with the same size and properties is also constructed and tested. Results show that for the same condition, the daily yield of the improved stepped solar still is 30% to 150% higher than the standard stepped solar still. Also, the daily efficiency of the ISS reached as high as 36%. The influence of brine water flow rate and glass cover thickness on the performance of the stepped solar still is also investigated. Finally, the cost of distillate water for the improved stepped solar still and standard stepped solar still is estimated.

Radiation effects in ultra-thin GaAs solar cells

Ultra-thin solar cells are of significant interest for use in space due to their intrinsic radiation tolerance, which may allow them to be used in particularly harsh radiation environments, where thicker cells would degrade rapidly and enable reduction in cover glass thickness to reduce launch mass. In this study, devices with an 80 nm GaAs absorber layer were irradiated with 3 MeV protons. It is shown that integrated light management in these ultra-thin devices offers enhanced efficiency, in addition to extended lifetime through radiation resilience. Time-resolved cathodoluminescence is employed to map the introduction of radiation-induced defects with increasing proton fluence and characterize a decrease in carrier lifetime from 198 ± 5 ps pre-radiation to 6.2±0.6 ps, after irradiation to 2×1014 cm−2 fluence. Despite the substantial reduction in carrier lifetime, short-circuit current does not degrade up to a proton fluence of 1 × 1015 cm−2, beyond which a collapse in short-circuit current is observed. This exposure correlates with the point at which the carrier lifetime, extrapolated from cathodoluminescence, becomes comparable to the transit time for carriers to cross the ultra-thin device. Variation in current–voltage behavior with carrier lifetime and fluence shows that the recombination statistics are similar to those of a Shockley–Read–Hall single deep-level trap model, but that bimolecular recombination does not fully describe the observed behavior. An implication of these highly radiation tolerant cells for space power systems is shown to offer significant savings in cover glass mass, compared with a thicker cell.

Development of a method for calculating effective displacement damage doses in semiconductors and applications to space field.

The displacement damage dose (DDD) is a common index used to predict the life of semiconductor devices employed in space-based environments where they will be exposed to radiation. The DDD is commonly estimated from the non-ionizing energy loss based on the Norgett-Robinson-Torrens (NRT) model, although a new definition for a so-called effective DDD considers the molecular dynamic (MD) simulation with the amorphization in semiconductors. The present work developed a new model for calculating the conventional and effective DDD values for silicon carbide (SiC), indium arsenide (InAs), gallium arsenide (GaAs) and gallium nitride (GaN) semiconductors. This model was obtained by extending the displacement per atom tally implemented in the particle and heavy ion transport code system (PHITS). This new approach suggests that the effective DDD is higher than the conventional DDD for arsenic-based compounds due to the amorphization resulting from direct impacts, while this relationship is reversed for SiC because of recombination defects. In the case of SiC and GaN exposed to protons, the effective DDD/conventional DDD ratio decreases with proton energy. In contrast, for InAs and GaAs, this ratio increases to greater than 1 at proton energies up to 100 MeV and plateaus because the defect production efficiency, which is the ratio of the number of stable displacements at the end of collision cascade simulated by MD simulations to the number of defects calculated by NRT model, does not increase at damage energy values above 20 keV. The practical application of this model was demonstrated by calculating the effective DDD values for semiconductors sandwiched between a thin glass cover and an aluminum plate in a low-Earth orbit. The results indicated that the effective DDD could be dramatically reduced by increasing the glass cover thickness to 200 μm, thus confirming the importance of shielding semiconductor devices used in space. This improved PHITS technique is expected to assist in the design of semiconductors by allowing the effective DDD values for various semiconductors having complex geometries to be predicted in cosmic ray environments.

Effect of Glass Cover Thickness and Inclination Angle on Distillate Efficiency of Single-Stage Solar Still

Solar desalination is one of many methods to separate excess salt from seawater. In this work, solar energy is applied because of its economical and environmental value. Additionally, solar energy is practical to use in the coastal region. To increase the distillate produced by the solar still, four variations of cover thickness and three variations of inclination angle are applied to the still. The cover thickness and inclination angle used in this work are 3 mm, 5 mm, 8 mm, 10 mm and 25°, 30°, 45°. The type of still that is used in this work is a rectangular-shaped single-stage solar still with an area of 0.8 m2. The desalination processes in this work were done from 09.00 until 16.00 and the data was collected every hour in the processes. The result of this work shows that the distillate efficiency produced by the solar still is 1.03% - 6.91%. The highest solar intensity is 1231.97 W/m2 and the lowest solar intensity is 101.03 W/m2. The most effective efficiency was obtained with the variation of 3 mm cover thickness and 25° inclination angle, while the lowest efficiency was obtained with the variation of 10 mm cover thickness and 30° inclination angle.

Modeling, design optimization and field testing of a solar still with corrugated absorber plate and phase change material for Karachi weather conditions

Solar still has been regarded as one of the cheapest and environment-friendly methods to convert brackish water into drinkable water. Despite being promising, solar still has not been employed on a large scale due to its inferior productivity. This paper presents the modeling, experiments, and analysis to augment the productivity of solar still modified with a corrugated absorber plate and Phase Change Material (PCM), under the climatic conditions of Karachi, Pakistan. A detailed literature review was conducted to ascertain the initial design parameters and the absorber plate configuration. A mathematical model based on the mass and energy balance equations of the solar still elements was developed using MATLAB. A parametric study was performed using the MATLAB model to optimize parameters such as the glass cover thickness for maximum productivity. The model results showed that a solar still with a glass thickness of 4 mm was more productive than that with a glass of thickness of 5 mm and 6 mm. Suitable materials for the absorber plate, still cover, body, insulation, and thermal energy storage were determined using the weighted rating method. Thereafter, the solar still Computer Aided Design (CAD) model was developed using Solid works and after a comprehensive market survey and assessment, the still was fabricated. Testing was performed during a hot spring month from 19th April to 26th April, 2020 (1450 readings, over 120 h). The results showed that the solar still with the PCM produced 4.5 L/day of fresh water at a cost of 42.34 USD/m3. In comparison, the solar still without PCM produced 4.1 L of fresh water per day at 43.6 USD/m3 which indicated that solar still with PCM was more productive and economical. The experimental data was also compared to the MATLAB mathematical model predictions. The temperature trend of still elements (basin, glass exterior, glass interior, water, and PCM) predicted by the MATLAB mathematical model and the experimental data matched fairly well.

Theoretical Investigation for the Influence of Various Parameters on the Performance of a Novel Concentration-Based Solar Desalination System

This study aims to investigate the influence of various parameters on the freshwater yield and efficiency of a novel concentration-based solar desalination system. The system performance under the summer and winter climatic conditions of Rabat city, Morocco is evaluated. The design parameters are glass cover thickness, absorber basin thickness, brackish water mass, and absorber basin material. The climatic parameters are wind velocity, ambient temperature, and solar radiation. Numerical studies on different system parameters are done by examining the effect of system component parameters on the system performance. Through the MATLAB code, the equations for the freshwater yield and efficiency of the new system are constructed and solved. The results show that the system gives the best performance with 6 mm glass cover thickness, 2 mm absorber basin thickness, and 40 kg brackish water mass.

Novel Micro-LED Display Featuring Fingerprint Recognition Without Additional Sensors

This paper proposes a new architecture for a micro light emitting diode (micro-LED) display featuring fingerprint detection without any additional light emitting and sensing devices in mobile applications. This paper proposes that conventional LEDs can be used as photodetectors in active-matrix pixel circuits. In the area where a finger touched, some LEDs are used as photodetectors and others are used as light emitting sources. The photocurrents of reverse-biased LEDs under various illumination conditions were investigated. The active-matrix circuit was fabricated using a conventional p-type low-temperature polycrystalline silicon (LTPS) process. The fabricated pixel circuit could distinguish the intensity of the incident light to the sensing LED. The voltage across the sensing LED (V_LED) was investigated when the pixel density was 400 pixels per inch (ppi) and the cover glass thickness was 30 μm. The experimental results showed that the V_LED changed by 0.5 V for 16.7 ms when red, green, or blue LEDs emitted 150 cd/m², 400 cd/m², or 100 cd/m², respectively. 1×9 LED array with 1.5 mm pitch (p) and 2 mm thick cover glass was fabricated to emulate the LED display with 400 ppi and 30 μm thick cover glass. It is found that an emitting LED affected the sensing LEDs within the distance of 3p by comparing V_LEDs. V_LEDs were measured when the material on the cover glass was air and water with white pigments (water/W). ΔV_LEDs were 0.29 V and 1.13 V for glass-air and glass-water/W cases, respectively. It is found that the lights incident on the sensing LED comprised not only reflected lights by Fresnel reflection at the glass interface but also scattered lights in the water/W. A 75× magnified fake fingerprint was fabricated. Its material was poly-lactic acid with refractive index of 1.465 which is very close to that of a fingertip. Measured ΔV_LEDs at ridges and valleys were 0.48 V and 0.22 V, respectively. The ratio of 0.48 / 0.22 was 2.18 that is very close to 1.91 that is the ratio of light intensity at the ridge to that at the valley obtained by the calculation. This verifies that the proposed micro-LED display distinguishes the ridges and valleys of fingerprint without any help from any additional devices.

Combined System–Trajectory Design for Geostationary Orbit Platforms on Hybrid Transfer

A novel methodology for a combined systems–trajectory optimization for a geostationary equatorial orbit (GEO) platform is proposed to obtain comprehensive design solutions. A combined chemical–electric propulsion system is used to execute hybrid high-thrust/low-thrust trajectory transfer to GEO, thereby balancing the overall system mass and transfer time. A systematic and payload-centric mission design provides a new set of design options to deliver tailored solutions to customized payloads. The hybrid trajectory characterization and spacecraft systems design find the required platform launch mass to deliver a GEO platform with a defined final mass and operational power. Elements of the system design are combined with those of multispiral low-thrust trajectory optimization as well as radiation absorption and solar array degradation to provide a comprehensive design solution. The result is a wide set of solutions to reach GEO, where fully chemical and fully electric transfers represent the boundaries of the hybrid transfer trade space. A payload throughput power of 20 kW entails a spacecraft mass in GEO between 4000 and 4550 kg, an initial thrust-to-mass ratio range of , and a cover-glass thickness between 4 and 24 mils to guarantee a minimum end-of-life/beginning-of-life power ratio of 85%. In addition, all-electric solutions from different injection orbits yield transfers to GEO with a time of flight of 60–150 days and an initial mass for the platform of 4400–5500 kg.

Energy matrices, exergoeconomic and enviroeconomic analysis of air-cooled and water-cooled solar still: Experimental investigation and numerical simulation

The impact of using air and water cooling glass in the double slope solar still have been performed numerically and experimentally. The thermoelectric modules cold side cools a water flow which passes on the glass cover in the water-cooled solar still. On the other hand, the wind velocity was used to cooling the glass cover in the air-cooled solar still. The convection heat transfer coefficient is accounted as boundary conditions of the glass surface. Results show that the good agreement was obtained between numerical model and experimental data. The water productivity in water-cooled solar still was 81.1% more than an air-cooled solar still. Moreover, the effects of glass cover thickness, velocity and temperature of the water cooling glass on performance of a water-cooled solar still are performed. The output results, compared to water-cooled solar still, showed that this modification of water-cooled solar still increases the water productivity by 21.53%. Also, the cost analysis indicated that the cost of produced water for water-cooled and air-cooled solar still were about 0.243 $/L and 0.277 $/L, respectively. Based on the results, the CO2 mitigation of air-cooled, water-cooled and modified water-cooled solar still were about 7.75, 13.09 and 16.27 tons, respectively. The enviroeconomic and exergoenviroeconomic parameters in the modified water-cooled solar still were improved by 24.3% and 632.1%, respectively, compared to the water-cooled ones.

A review on the simulation/CFD based studies on the thermal augmentation of flat plate solar collectors

The flat plate solar collectors (FPSCs) are widely used in heating applications due to their simple design and easy installation. Different methodologies and approaches have been used for efficiency improvement and thermal performance enhancement of FPSCs. Coating and thickness of glass cover; Transmittance and emissivity of glass cover influences the thermal performance of FPSCs. The efficiency of FPSC is reduced due to different type of heat losses occurring because of the temperature difference between absorber and surroundings. Transparent cover and Insulating materials such as CFC free polyurethane foam (PUF) collector are used in the FPSCs to minimize the heat loss. Air gap between the absorber plate and glass cover also affect the efficiency of FPSC due to reduction in natural convection. The insertion of twisted tapes, wire coil and foam are the most effective techniques to improve thermal performance of FPSCs. The insertion of twisted tapes results in increased fluid mixing and friction which increase the heat transfer. Porous materials are used in the solar collector system to enhance the heat transfer material because of their high thermal conductivity. The present work provides an overview of numerical/CFD based studies on various kinds of methods which have been used for efficiency improvement of FPSCs. Use of nanofluids, PCM and polymer, changing absorber plate design and use of inserts and reflector for escalating performance of FPSCs have been discussed. These articles also suggest the scope for future work in the domain of FPSCs.

Experimental determination of the effect of change in relative roughness pitch on the thermo-hydraulic performance of air heater working with solar energy

Solar Air Heater has recently developed the effective utilization of renewable, natural and non-conventional energy for environmental sustainability. It is the most appreciating natural resource available for sustainable development. The current work deals with the analysis of thermo-hydraulic properties of solar air heater with specific parameter variation i.e. Relative Roughness Pitch (RRP). As already diagnosed the effect of relative roughness height, width, etc. using MATLAB. Here the authors have specifically focused on the effect of RRP on the solar air heater’s performance. The system utilized some fixed parameters such as, 0.88 emittance of the glass, 0.9 emittance of plate and transmittance- absorptance as 0.8. Also the 0.004 m single glass cover thickness is considered with thermal conductivity of insulation as 0.037 W/m-K. For the analysis purpose, the range of RRP is kept between 6 and 12. Related to operating parameters, Ambient temperature is kept 300 K (fixed) and Wind velocity 1 m/s (assumed fixed) whereas Insulation is kept in the variable range of 500–1000 W/m2. Finally, the results are recorded and the interpretations are made based on the validated data and the outcome results.

Optimization of production in single basin solar still using Taguchi method - Experimental and theoretical approach

In this study, to enhance the distillate production, an attempt was taken to fabricate a robust design single basin solar still. From earlier research findings, four operational parameters were identified as performance enhancing and they were – basin glass cover thickness, basin water depth, wick material used to wrap the fins and size of heat storage material (blue metal). The next task was to identify the optimum parameter level for each parameter. The 4 parameters and 3 parameter levels were combined as per L9 orthogonal array and the experimental results were analyzed using Taguchi method. The optimum parameter levels were identified using S/N ratio and mean response. The significant parameters and contribution to production were calculated using ANOVA technique. The nature and degree of relationship between independent variables and dependent variable was analyzed using regression technique. The optimum production was estimated and it was compared with theoretical production and actual experimental production. The combination of 4 mm thick glass basin cover, 10 mm basin water depth, fins wrapped with glass wool and 15 mm size heat storage material were identified as optimum combination of parameter levels. Wick materials around the fins and basin water depth played significant role in determining the production. The actual production from solar still designed as per Taguchi method was about 86.82% of estimated optimum production.

Effect of design parameters on performance of passive basin solar stills considering instantaneous ambient conditions: A transient CFD modeling

A transient CFD model is developed to investigate the parameters affecting the productivity of a solar still. Instantaneous weather data is accounted as boundary conditions while the absorption of solar irradiance, as well as radiative heat transfer is considered by DO equation. Evaporation and condensation rates are evaluated by solving species transport equation for water vapor and application of Fick’s law. Latent heats are added to the energy equation as sink and source terms by considering a coefficient that accounts for the latent heat shared between neighboring bodies. Effects of wind speed, glass cover thickness, water depth, water to cover distance and cover inclination on performance of a passive solar still are investigated. Stepped solar stills are also modeled and effects of number of steps and water to cover distance are discussed. Results show that a 14.4% increase in the productivity is observed when the wind speed increases from 1 m/s to 6 m/s, and a 3.5% improvement occurs by decreasing the glass thickness from 4 mm to 2 mm. The optimum values of water depth and water to cover distance are found to be 2 and 8 cm respectively, with the cover tilt equal to the local latitude angle. Moreover, by converting the basin solar still to the appropriate stepped solar still, the productivity increases about 17.4%.

Correlation between structure and magnetic properties of “finemet” type microwires

Effect of geometrical parameters (metallic core diameter, glass cover thickness) on the structure and magnetic properties of glass-coated Fe-Si-B-Nb-Cu microwires is investigated. The structure of as-prepared Fe73.8Cu1Nb3.1Si13B9.1 microwire is nanocrystalline, consisting of α-Fe(Si) crystallites in a residual amorphous matrix. It is shown that great residual stresses arising at the manufacturing processes greatly influence the microstresses and crystallite sizes of α-Fe(Si) crystals. An increasing of stress magnitude results to structure refinement. The size of α-Fe(Si) crystals and crystallized volume fraction decrease from approximately 105 nm and 71 % to 9 nm and 34 %, respectively, with glass cover thickness increasing. Grain size refinement of α-Fe(Si) leads to the considerable decrease of coercivity of microwires from 1800 A/m to 160 A/m.

Energy and exergy analysis of an indirect solar dryer based on a dynamic model

Abstract Sun is a clean and available sustainable energy source. The usage of sustainable energy in various industries such as agriculture is taking into consideration during the early years. One application is dehydration by using an indirect solar dryer, which was adopted in this study. A dynamic model was presented in which the calculation of the solar radiation received in the tiled surface of the collector, temperature variation along the collector, the kinetics of moisture reduction and temperature variation of the drying material were taken into consideration. The model was validated and confirmed with high accuracy by test results in three states of mass flow rates of air. The effects of air velocity, the glass cover thickness and the length of the collector took into consideration in the analysis as effective parameters. The thermal analysis was accomplished by using energy and exergy analysis. To energy analysis, the values of received and used energy were calculated in addition to energy utilization ratio and for exergy analysis, the irreversibility at collector was calculated as well as the exergy efficiency of drying in the chamber. Energy and exergy analysis revealed more stream exergy for higher speed air and hence, lower irreversibility. Besides, the defined exergy efficiency was independent of the material mass despite the exergy destruction or energy efficiency, which means a suitable criterion for the system analysis. The model was in good agreement with the experiments so that the deviation from the best fit line (y = x) in the model-experiments curves were 2.37% for radiation estimation, 4% for the outlet air temperature of the collector, 1% for the material temperature and 4.8% for the moisture ratio of the drying material. The model also revealed two critical moisture ratio of 0.75 and 0.23 in the drying process so that the maximum exergy destruction was observed at the first one and the maximum exergy efficiency was 22% for the dryer.