In the present endeavor, a conventional single-slope solar still has been modified to improve its performance by coupling it with a novel nanofluid-based volumetric absorption solar collector (NBVASC). A low-cost and thermally stable nanofluid (prepared by dispersing functionalized carbon soot nanoparticles extracted from used engine oil into paraffin oil) having high solar weighted absorptivity has been employed to volumetrically absorb the incident solar energy. This additional absorbed solar energy is provided to the solar still by circulating a heat transfer fluid in a closed loop through serpentine type heat exchangers placed inside the NBVASC and the solar still. The experiments were performed from May to July 2020, and the results of the experiments conducted on May 25 and June 9, 2020, are reported. Extensive on-sun experiments reveal that coupling NBVASC to the conventional still could lead to substantial performance enhancements—distillate productivity, thermal efficiency, and night distillate improved by 75.3%, 66.9%, and 33.9%, respectively. More importantly, solar still coupled to NBVASC was found to perform better at an optimum nanoparticle concentration of 1.25 mlL −1 (20.75% higher distillate productivity) than the solar still coupled to a surface absorption-based collector (with paraffin oil as the working fluid)—truly establishing the benefits of volumetric absorption over surface absorption under the given set of conditions. Overall, the present study represents a noteworthy step forward in realizing efficient solar energy-driven desalination systems for remote underdeveloped areas.

A solar powered trigeneration system consisting of tower solar collector, Kalina cycle with the heat exchanger, and ejector-absorption refrigeration cycle is proposed to produce refrigeration below freezing, electricity, and process heat, simultaneously. Simulation through computational fluid dynamics using ansys-fluent package is conducted to examine the effect of coil diameter and inlet oil temperature on the pressure and temperature of solar heat transfer fluid. It is found that, for inlet temperature of 92 °C and direct normal irradiations of 850 W/m 2 , the solar heat transfer fluid outlet temperature increases by 9% when the coil diameter increased from 150 to 400 mm. Trigeneration performance is analyzed after altering hot oil outlet temperature, turbine inlet pressure, and the concentration of ammonia–water basic solution to study their effect on power produced by turbine, refrigeration load, exergy of refrigeration, and efficiencies of trigeneration system. An increase in the concentration of the ammonia–water basic solution is leading toward the significant increase in the turbine power and the elevation of trigeneration system’s energy and exergy efficiencies. Bottoming of the Kalina cycle with ejector-absorption refrigeration cycle shows the distribution of solar energy as energetic output 72.31% and energy lost to environment 27.69%. The solar exergy supplied to the trigeneration system is distributed as follows: 16.23% is the exergy produced, 1.62% is the exergy loss, and 82.15% is the exergy destroyed.

A novel method for pairing surface irradiation and volumetric absorption from Monte Carlo ray tracing to computational heat transfer models is presented. The method is well-suited to directionally and spatially complex concentrated radiative inputs (e.g., solar receivers and reactors). The method employs a generalized algorithm for directly mapping absorbed rays from a Monte Carlo ray tracing model to boundary or volumetric source terms in the computational mesh. The algorithm is compatible with unstructured, two and three-dimensional meshes with varying element shapes. Four case studies were performed on a directly irradiated, windowed solar thermochemical reactor model to validate the method. The method was shown to conserve energy and preserve spatial variation when mapping rays from a Monte Carlo ray tracing model to a computational heat transfer model in ansys fluent .

This article compares the dynamic behavior of solar-assisted novel salt-based ammonia/sodium thiocyanate (NH 3 + NaSCN) and ammonia/lithium nitrate (NH 3 + LiNO 3 ) single-effect absorption refrigeration cycles. An evacuated tube collector (ETC) is attached with fully mixed hot water storage tank to power the absorption system. Variations in ambient conditions are determined for Gujarat Region of India and their effects on absorption cycles are quantified throughout the days for the months of April to September. System performance is investigated and compared on terms of coefficient of performance (COP), refrigeration capacity, efficiency and solar COP (SCOP). At same operating conditions, it is found that the NH 3 + LiNO 3 cycle can achieve much lower evaporator temperature (−13.1 °C) then NH 3 + NaSCN cycle (−7.5 °C) and maximum possible COP for NH 3 + NaSCN cycle is 0.73 and 0.68 for NH 3 + LiNO 3 cycle. The working limit of NH 3 + LiNO 3 cycle is wide ranging and narrow for NH 3 + NaSCN cycle due to high crystallization possibility. SCOP varies from 0.18 to 0.43 for NH 3 + NaSCN cycle and 0.17 to 0.39 for NH 3 + LiNO 3 cycle over the period of 6 months. Based on these findings, the suitable working cycle is justified.

A novel multi-generation system (MGS) that comprises two absorption cycles, two Rankine cycles (RCs), and a hot water (HW) production chamber is studied in this research. It is designed to utilize the waste heat from the first Rankine cycle as a thermal energy input for the second Rankine cycle and a double-effect absorption cycle (DEAC). The waste heat from the second Rankine cycle serves as heat input to a single-effect Rankine cycle. Regeneration and reheat principles are also applied to the Rankine cycles. The objective of the study is to develop an MGS without a gas cycle that can achieve higher energy and exergy efficiencies. Two concentrated solar technologies, namely, parabolic trough collectors (PTCs) and heliostats are used to power the designed system. The environmental benefit of the system is also analyzed. The energy and exergy efficiencies of the novel MGS presented in this study are 73.11% and 50.72%, respectively. The application of solar thermal technologies to power the system reduces the overall energy and exergy efficiencies, respectively, to 56.12% and 38.39% for the solar PTC and 41.89% and 29.06% for heliostats. The energy and exergy coefficient of performances (COPs) are 0.754 and 0.349 for the single-effect absorption cycle (SEAC), respectively. As much as 752.7 kg/h of CO 2 , 2.13 kg/h of NO x , and 4.21 kg/h of SO x will be saved from being emitted to the atmosphere.

This paper describes the development and performance assessment of a tower solar collector driven integrated system operating in trigeneration mode to generate electricity, heating, and cooling, in a carbon-free manner. The proposed system applies a heliostat-based central receiver unit as a base of solar energy input to drive the steam Rankine cycle which is combined with the process heater and the lithium bromide-water operated absorption chiller. An analysis is performed to monitor the behavior of energy and exergy efficiency at various operating conditions of the proposed trigeneration system. The computed results are authenticated with the reported literature. A comparison is made between the present findings and reported results in the form of exergy efficiency, total exergy destroyed, and energy efficiency. Consideration of process heat and cold along with electricity provides a promising increase in energy efficiency from 15.8% to 64.1% while the exergy efficiency is enhanced from 16.9% to 24.4%. Variation in direct normal irradiations from 600 W/m 2 to 1000 W/m 2 results in the significant rise of energetic and exergetic outcomes of the proposed trigeneration system. Out of 100% solar exergy supplied to the proposed trigeneration, 24% is generated as the exergetic output, 1.6% is lost to ambient, and the remaining 74.4% is the exergy destroyed in the system components.

The concentration ratio of the parabolic dish solar collector (PDSC) is considered to be one of the highest among the concentrated solar power technologies (CSPs); therefore, such system is capable of generating more heat rate. The present paper focuses on the integration of the PDSC with the combined cycle (gas cycle as the toping cycle and steam cycle as the bottoming cycle) along with the utilization of waste heat from the power cycle to drive the single effect lithium bromide/water absorption cycle. Molten salt is used as a heat transfer fluid in the solar collector. The engineering equation solver (EES) is employed for the mathematical modeling and simulation of the solar integrated system. The various operating parameters (beam radiation, inlet and ambient temperatures of heat transfer fluid, mass flow rate of heat transfer fluid, evaporator temperature, and generator temperature) are varied to analyze their influence on the performance parameters (power output, overall energetic and exergetic efficiencies, outlet temperature of the receiver, and as coefficient of performance (COP) and exergy efficiencies) of the integrated system. The results show that the overall energy and exergy efficiencies are observed to be 39.9% and 42.95% at ambient temperature of 27 °C and solar irradiance of 1000 W/m 2 . The outlet temperature of the receiver is noticed to decrease from 1008 K to 528 K for an increase in the mass flow rate from 0.01 to 0.05 kg/s. The efficiency rate of the power plant is 38%, whereas COP of single effect absorption system is 0.84, and it will decrease from 0.87 to 0.79. However, the evaporator load is decreased to approximately 9.7% by increasing the generator temperature from 47 °C to 107 °C.

This work aims at providing insight into developmental and operational experience of an innovative milk cooler which uses solar thermal energy for cooling of fresh milk by way of vapor absorption refrigeration system (VARS). The system uses CPC solar collector(s) producing medium temperature that is desired to provide required thermal energy to the generator of VARS. However, mismatch between the time of availability of solar energy and cooling period of milk raises a demand of integrating thermal storage to this system for use of thermal energy at appropriate times. The novelty of this work is the development of experimental setup and its operation as innovative design to meet the requirement and possible model for the industry to operate and grow using the suggested system. The design, while addressing the problem of grass root level people for generation of income, also helps in reducing the carbon footprint of milk industry, and in the world environment as a whole.

A building energy simulation study is carried out to analyze the performance of a triple-hybrid single-effect vapor absorption cooling system (VACS) operated by solar, natural gas, and auxiliary electricity-based cogeneration. A high capacity small office building subjected to different climatic conditions is considered. The system is designed to continuously maintain a specified building comfort level throughout the year under diverse environmental conditions. Simulations are done at different generator temperatures to investigate the performance in terms of total annual electric energy consumption, heating energy, and the coefficient of performance (COP). The performance of the present VACS is compared with the conventional compression-based system, which demonstrates the electric energy and cost saving potentials of the proposed VACS. Simulation outcomes are well-validated against benchmark data from national renewable energy laboratory and energy conservation building code. Interestingly, it is found that beyond a certain collector area, surplus energy savings can be acquired with the present triple-hybrid VACS as compared to the compression-based cooling. Results also show that COP of the simulated system is in line with experimental values available in the literature. Finally, recommendations are given to operate the complete system on solar and biomass resources, which provide encouraging opportunity for agriculture-based countries.

Radiation absorption is investigated in a particle curtain formed in a solar free-falling particle receiver. An Eulerian–Eulerian granular two-phase model is used to solve the two-dimensional mass and momentum equations by employing computational fluid dynamics (CFD) to find particle distribution in the curtain. The radiative transfer equation (RTE) is subsequently solved by the Monte Carlo (MC) ray-tracing technique to obtain the radiation intensity distribution in the particle curtain. The predicted opacity is validated with the experimental results reported in the literature for 280 and 697 μ m sintered bauxite particles. The particle curtain is found to absorb the solar radiation most efficiently at flowrates upper-bounded at approximately 20 kg s −1 m −1 . In comparison, 280 μ m particles have higher average absorptance than 697 μ m particles (due to higher radiation extinction characteristics) at similar particle flowrates. However, as the absorption of solar radiation becomes more efficient, nonuniform radiation absorption across the particle curtain and hydrodynamic instability in the receiver are more probable.

Solar-to-thermal energy conversion technologies are an important and increasingly promising segment of our renewable energy technology future. Today, concentrated solar power (CSP) plants provide a method to efficiently store and distribute solar energy. Current industrial solar-to-thermal energy technologies employ selective solar absorber coatings to collect solar radiation, which suffer from low solar-to-thermal efficiencies at high temperatures due to increased thermal emission from selective absorbers. Solar absorbing nanofluids (a heat transfer fluid (HTF) seeded with nanoparticles), which can be volumetrically heated, are one method to improve solar-to-thermal energy conversion at high temperatures. To date, radiative analyses of nanofluids via the radiative transfer equation (RTE) have been conducted for low temperature applications and for flow conditions and geometries that are not representative of the technologies used in the field. In this work, we present the first comprehensive analysis of nanofluids for CSP plants in a parabolic trough configuration. This geometry was chosen because parabolic troughs are the most prevalent CSP technologies. We demonstrate that the solar-to-thermal energy conversion efficiency can be optimized by tuning the nanoparticle volume fraction, the temperature of the nanofluid, and the incident solar concentration. Moreover, we demonstrate that direct solar absorption receivers have a unique advantage over current surface-based solar coatings at large tube diameters. This is because of a nanofluid's tunability, which allows for high solar-to-thermal efficiencies across all tube diameters enabling small pressure drops to pump the HTF at large tube diameters.

The solar photovoltaic thermal system (PVT) facilitates conversion of incoming solar radiations into heat and electricity simultaneously. The beam split photovoltaic thermal system (BSPVT) is one of the PVT systems. In this system, the incoming solar beam is splitted and used separately for PV and thermal system. The feasibility of water, silicone oil, and coconut oil as spectrum filter for C–Si solar photovoltaic system is reported in the literature recently. However, the changes in the optical behavior of the liquids due to extended exposure to sunlight (aging effect) had not been considered in most of the previous studies. The current study includes the methodology for the selection of liquids for BSPVT systems, estimation of external quantum efficiency (EQE) of a solar cell using liquids, and the aging effect on the liquid spectrum filters. The spectral response of the solar cell is analyzed using BENTHAM, (PVE 300) for 300–1100 nm. In this study, it has been observed that the aging of silicone oil reduces the electrical performance of the solar cell. On the other hand, the aged coconut oil improves the electrical performance of the solar cell as compared to the fresh coconut oil spectrum filter.

Natural dye extract of the saffron petal, purified by solid-phase extraction (SPE) technique, has been studied as a novel sensitizing dye to fabricate TiO 2 nanoparticles-based dye-sensitized solar cells (DSSC). The extract was characterized using ultraviolet–visible (UV–Vis) and Fourier transform infrared (FTIR) spectroscopies to confirm the presence of anthocyanins in saffron petals. The typical current–voltage and the incident photon to current efficiency (IPCE) curves were also provided for the fabricated cell. The saffron petal extract exhibited an open-circuit voltage (Voc) of 0.397 V, short circuit current density (Jsc) of 2.32 mA/cm 2 , fill factor (FF) of 0.71, and conversion efficiency of 0.66%, which are fairly good in comparison with the other similar natural dye-sensitized solar cells. These are mainly due to the improved charge transfer between the dye extract of saffron petal and the TiO 2 anode surface. Considering these results, it can be concluded that the use of saffron petal dye as a sensitizer in DSSC is a promising method for providing clean energy from performance, environmental friendliness, and cost points of view.

In this work, we have chosen the low cost natural dye extracted from Saraca asoca flowers to act as a sensitizer dye for TiO 2 -based dye-sensitized solar cell (DSSC). UV–visible spectroscopic studies of ethanolic extract of dyes have been done in order to understand light absorption behavior of dye. The natural dye extract covers appreciable spectrum of solar radiation, 400–500 nm with an absorption maximum at 450 nm that makes it suitable for use as a photosensitizer in DSSC application. The dye adsorbed onto the semiconductor facilitates electron transfer across the dye/semiconductor interface. FTIR spectra of extract revealed the presence of anchoring groups and coloring constituents. DSSC fabricated with TiO 2 and natural dye extract obtained from Saraca asoca flowers as sensitizer has shown open-circuit voltage ( V oc ) 516 mV, short-circuit current density ( J sc ) 0.29 mA/cm 2 , fill factor (FF) 0.65, incident photon-to-current conversion efficiency (IPCE) 43%, and conversion efficiency of 0.09%. This work briefly discusses the simple extraction technique of natural dye and its performance in DSSC.

A new symmetric nonimaging parametric trough collector (PmTC) for an evacuated circular receiver is proposed having an absorber diameter of 70 mm similar to the LS3/Eurotrough absorber one, and a circular secondary. The optical design method is explained and a sensitivity analysis is conducted with respect to the diameter of the secondary and to the acceptance angle. In the design process, transmission, absorption, and reflection losses are neglected. A secondary mirror radius of 145 mm and an acceptance angle of ±14 mrad were chosen as realistic values. For these values a concentrator geometry having 8.7 m gross aperture and 100% intercept factor for rays impinging on the primary within the referred acceptance angle is obtained producing a net concentration ratio relative to the thermodynamic ideal limit of 0.52 compared to 0.31 for traditional parabolic trough collectors. The new concentrator is composed of a primary discontinuous reflector with two symmetrical portions with parametric geometry, and a central parabolic portion located between the other two. The ensemble secondary receiver can be dressed up with the secondary concentrator manufactured by partially mirroring a diameter adapted glass tube—either internally or externally—or alternatively by means of a commercial evacuated receiver and an independent 145 mm radius arc of circumference external secondary reflector. Monte Carlo ray-tracing results show that only 15% of the rays undergo secondary reflection before arriving to the absorber and a sharp angle transmission curve. The new concentrator is proposed for application in solar thermal energy (STE) trough power plants.

The experimental method is extensively used to determine the temperature of a photovoltaic (PV) module at different hours of a day. In this method, the module temperature is measured using a temperature sensor mounted on the back of PV module. However, the experimental measurements have high cost and are not applicable everywhere. In this study, an optical–thermal model was used to predict all the PV module layer temperatures in two cases: tilted toward the south and fixed on a two-axis sun tracker. The impact of accurate consideration of the wind velocity and the ambient temperature on the PV module temperature was the main strength of the present simulation. This was carried out testing several correlations for prediction of convection heat transfer coefficient in the modeling process. The front and back layer temperatures as well as the silicon (Si) layer temperature of PV module were separately determined. To verify the results of the simulation, the temperatures of four PV modules measured in four different locations of the world, namely, China, Germany, Australia, and Brazil, were used. The results showed that the present study predicts the temperature of PV module more accurately compared to the previous studies. It was also shown that the average temperature errors between the measured and the predicted temperatures relative to the maximum module temperature were 2.19%, 2.3%, and 2.85%, for Australia, Brazil, and Germany, respectively.

Spherical sintered bauxite particles between 200 μm and 700 μm in diameter have been shown to be effective in the direct absorption and storage of concentrated solar energy. These particles are commercially available in large quantities and exhibit as-received solar weighted absorptance (αs) greater than 0.90, which gradually degrades with extended heating in air at 700 °C and above. The degradation mechanism is an oxidation reaction that can be reversed via thermal or chemical reduction, resulting in αs > 0.95 along with enhanced resistance to further degradation for some formulations. Certain metal oxide pigments, added to Al2O3:SiO2, have proven to achieve solar weighted absorptance levels similar to those of the commercially available particles and may be promising alternatives to currently available materials.

Copper oxide (CuO) is a p-type semiconductor having a band gap energy of 1.5 eV, which is close to the ideal energy gap of 1.4 eV required for solar cells to allow good solar spectral absorption. The inherent electrical characteristics of CuO nanoparticles make them attractive candidates for improving the performance of polymer solar cells (PSCs) when incorporated in the active polymer layer. The incorporation of CuO nanoparticles in P3HT/PC70BM solar cells at the optimum concentration yields 40.7% improvement in power conversion efficiency (PCE). The CuO nanoparticles in the size range of 100–150 nm have an effective average band gap of 2.07 eV. In addition, the X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analyses show improvement in P3HT crystallinity, and surface analysis by atomic force microscope (AFM) shows an increase in surface roughness of the PSCs. The key factors namely photo-absorption, exciton diffusion, dissociation, charge transport, and charge collection inside the PSCs which affect the external quantum efficiency (EQE) and PCE of these cells are analyzed.

A conceptual design of the power system for a water–lithium bromide absorption system is presented in this work for a given cooling load. The proposed system utilizes both solar thermal and the photovoltaic (PV) generated electrical energy for its operation. The performance of the power system is analyzed over a complete year for a designed operation strategy. It is found that the proposed system can provide an annual-average surplus of 17.4 kWh of energy per day after meeting the in-house energy requirements. Finally, an economic analysis is performed to calculate the payback period of the system.

Effect of 1,8-diiodooctane on the performance of poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) solar cells with glass/indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/P3HT: PCBM/Ca/Al structure was studied. The morphology and thickness of the active layer were investigated using atomic force microscopy (AFM). The UV-visible spectroscopy and X-ray diffraction (XRD) analysis were used to study the absorption behavior (of the solutions and coated layers) and crystallinity of the active layer, respectively. The results show that the existence of 1,8-diiodooctane reduced the open circuit voltage from 0.81 to 0.52 V and increased the short circuit current by about three folds; the fill factor (FF) and power conversion efficiency were increased from 36.0 to 54.1% and 0.47% to 1.54%, respectively. These changes can be attributed to the enhanced crystallinity of P3HT or the doping effect of 1,8-diiodooctane on P3HT chains. UV-visible analysis demonstrated that the addition of 1,8-diiodooctane to the solution did not change the absorption onset, whereas in the coated layers, the maximum absorption peak shifted to higher wavelengths. The XRD analyses demonstrated the enhancement of crystallinity of P3HT upon the introduction of 1,8-diiodooctane.