Absorber Area Research Articles

Investigation of thermodynamics performance of a heat exchanger-incorporated solar dryer equipped with double-pass flat, v-corrugated, and low-e coated collectors for drying applications

In this study, a solar dryer incorporating a flat plate heat exchanger to recover heat from exhaust air was investigated to explore the usability of different types of collectors in the system. Their usability was further evaluated through economic and environmental analyses. Moreover, the thermodynamic performance of the solar dryers was evaluated under two weather conditions in Nepal. Apple drying experiments were conducted for 8 h from 09:00 to 17:00 from February to April 2023 on solar dryers and with open sun drying (OSD) in Dhulikhel, Nepal. The results showed that the low emissivity (low-e) coated aluminum collector was more efficient in terms of collector efficiency and drying rate than collectors with flat or v-corrugated GI absorbers. The average collector efficiency and drying rate were found to be 89 % and 107 g/(h × m2) using the low-e coated aluminum collectors, while the values were 50 % and 84 g/(h × m2) for the GI sheet collector. The results indicated a slight improvement in the performance of v-corrugated collectors, with values of 53 % and 89 g/(h × m2). The drying rate for OSD was found to be 78 g/(h × m2), which was lower than for the dryers with all collectors used in this study. In terms of economic analysis, the dryer equipped with the low-e coated collector was found to be superior, with a payback time of 1.61 years compared to the dryers with flat or v-corrugated GI collectors. Reducing the thermal losses due to radiation by using the low-e coated absorber was shown to be more important than increasing the absorber area using v-corrugated GI sheets.

The effect of adding layers of date stones on the profitability of brackish water solar desalination process

Lately, there has been a pronounced and alarming up tick in the global demand for fresh water, resulting in a limited availability of this precious resource. Solar desalination emerges as a promising solution, particularly for supplying the sparsely populated desert regions in the southern regions of Algeria, where plentiful solar energy and subterranean brackish water resources are present.The current paper seeks to optimize the performance of traditional solar stills and elevate the quality of distilled water by incorporating layers of blackened date stones as an additional heat storage medium. Date stones, typically discarded post-date consumption, undergo a process of washing and blackening before being introduced in two forms (stone and powder). They are then uniformly distributed across the horizontal surface of solar still’s absorber.Three solar stills of identical design featuring glass sides were designed, manufactured, and subjected to testing to compare their productivity with that of a control unit. Experimental trials conducted at Ouargla University reveal significant enhancements the inclusion of a single layer of date stones (approximately 2.210 kg/ (m2 of absorber area)) leads to a remarkable 45.66 % increase in yield. Conversely, an equivalent amount (≈ 504 g) of date stones in powder form results in a 29.42 % improvement in yield. Notably, the distillate quality is substantially enhanced in both cases contrasted with the conventional setup.

Novel Detection Scheme for Temporal and Spectral X-Ray Optical Analysis: Study of Triple-Cation Perovskites

Multimodal x-ray microscopy is key to assessing the property-functionality relationships of semiconductor devices with the utmost sensitivity and spatial resolution. Here, we report on a novel setup—the “Analyzer of X-ray excited Optical Luminescence Offering Temporal and spectraL resolution” (AXOLOTL)—and demonstrate its use by investigating a series of triple-cation mixed-halide perovskite solar cells (PSCs) with varying Cs content. These PSCs exhibit spatially varying performance and are thus ideally probed by multimodal x-ray microscopy to elucidate the origin of the performance variations. Specifically, our nanoscale characterization of the wrinkled perovskite photoabsorber unveils a segregation of I and Br, which is accompanied by a narrowed band gap and an increased charge-carrier lifetime in thick absorber areas. Overall, we demonstrate with this technique the spatial correlation of compositional inhomogeneities, topography, electrical performance, and optical performance, which is of highest interest for identifying loss mechanisms at the nanoscale in high-performance electronic device development, including solar cells. Published by the American Physical Society 2024

Stabilność struktury gruzińskiego naturalnego heulandytu

Zeolites have a unique set of molecular-sieve, sorption, ion exchange and catalytic properties due to their framework microporous structure, and structural stability is an important characteristic and often a decisive factor in the application and performance of natural zeolites. The aim of our work was to study the processes occurring under the influence of heat, which determine the thermal stability of the zeolite-containing tuff of the Tedzami-Dzegvi deposit, with zeolite phase content up to 90%, consisting of heulandite and chabazite in a ratio of 8:1, and chemical composition |Na0.25K0.06Ca0.19Mg0.15|[AlSi3.6O9.2].3H2O. It was found that as a result of exposure to heat, a slight dealumination of the surface of the calcined (400-500 °C) samples occurs, as well as dehydration and amorphization of the crystal structure are observed. Sample dehydration occurs in several stages: (i) most of the water (≈60% of the total water content) is continuously lost at temperatures below ≈250 °C, (ii) the part of the remainder (≈24%) is slowly dehydrated up to 650 °C, (iii) complete dehydration of the sample is achieved at ≈800 oC. Amorphization of the heulandite phase begins at temperatures above 200 °C, the transition to the metastable heulandite B phase at ≈340 oC is not fixed, but at high temperatures wairakite or another mineral of the 9.GB.05 group and quartz are formed; the chabazite phase is stable up to ≈1000 oC, and at temperatures above 1100 oC, leucite (K,Na)AlSi2O6 and cristobalite SiO2 are formed. The adsorption of water vapor and benzene on heat-treated samples decreases monotonically with an increase in the calcination temperature, following amorphization. Nitrogen adsorption-desorption isotherms show slight decrease of the absorbent surface area with an increase in the calcination temperature and nonmonotonic changes in average mesopore diameters. It is also shown that heat treatment improves the acid resistance of heulandite by reducing dealumination after sample treatment with hydrochloric acid.

Experimental testing on the performance of solar dryer equipped with evacuated tube collector, rock bed heat storage and reflectors

Agricultural products can be dried in an open sun; but such drying method has poor quality of the product causes to grow bacteria and microorganisms and long drying time. In order to alleviate those draw backs of open sun drying, direct solar dryers were developed; but this type of dryer reduces the product quality due to direct exposure of solar radiation. Then, an indirect solar dryer became more important and efficient method. However, the most solar dryers were developed with less efficient flat plate solar collectors. A few solar dryers were developed using efficient solar collector called evacuated tube solar collector (ETC) but they have low overall performance. The goal of this research is to create a dependable solar dryer system for drying agricultural products. It was a solar dryer system with an independent rock bed thermal storage unit and an evacuated tube collector having reflectors. In this case, a rock bed has been a well-insulated with thermal insulation and its top surface is covered by a transparent double-glass. This system is intended to dry potato slice that weigh of 7.5 kg sample having a wet base initial moisture level of 80.1 %, until it reaches the ideal moisture content of 7–13 %. The solar dryer has been developed from drying chamber having size of (length x breadth x height) of 85 cm×61 cm x 62 cm, evacuated tube collector area of 1.3 m2, and rock bed volume of 0.137 m3 (with a solar absorber area of 0.52 m2 and a depth of 0.26 m). The solar dryer system was built and tested with loading slices at various air flow rates and open sun. Here, at a 0.016 m3/s air flow rate as compared to lower and higher air flow rates, more moisture reduction (9.3 % within eight hours and 0.664 kg/h), higher efficiency of the solar collector (62.02 %), more heat production from the system (20.79 MJ, of which 4837.8 kJ was recovered from the rock bed), and higher dryer efficiency (23.87 %) were attained. Compared to open-sun drying, 20 % less time was needed for drying. In addition, the study examined the significance of the reflectors and the rock bed. In comparison to the situation of utilizing ETC alone and 30 % of the drying period in relation to the open sun, the introduction of a reflector on the collector increased the average net heat obtained from the collector by 5.1 %. In another instance, the slice's moisture content was lowered to 12.37 % in under eight hours using ETC alone, while the dryer's efficiency was 29.82 %. However, the drying rate rise by 3.7 % in comparison to the dryer equipped with ETC alone because of the enhanced heat output in the dryer, which used ETC with a rock bed's help.

Preparation and Characteristics of Kluwak Shell Carbon Adsorbent

Kluwak shell carbon (KTK) is a biomass with potential as an adsorbent, containing cellulose, hemicellulose, lignin, and fixed carbon at a content of 92.15%. However, the current utilization of KTK in adsorbing free fatty acids and methylene blue is limited and can be improved through thermal activation at a range of temperatures. The study aims to investigate the impact of activation temperature on CEC by examining the adsorption capacity of methylene blue solution, iodine solution, and surface area. Activation was carried out for 2 hours at temperatures ranging from 500 to 900 C on Kluwak shell carbon. The adsorbent performance of the activated KTKAT was initially tested using methylene solution with a concentration of 50 ppm, a volume of 50 ml, and 0.15 grams of KTKAT. The solution was placed in an orbit shaker for 90 minutes and filtered. The absorbance of the filtrate adsorption results was measured at a wavelength of 662 nm using UV VIS. For the second test, 50 ml of 0.1 N Iodine and 0.5 g KTKAT were stirred for 15 minutes and then centrifuged for approximately 15 minutes. A volume of 10 ml of the resulting iodine solution adsorption filtrate was titrated with 0.1 N Sodium Thiosulfate. The surface area was determined using the BET method. The concentration (ppm) of methylene blue solution was determined by converting the absorbance measurement using the standard curve equation. The iodine number was determined by titrating the iodine adsorption filtrate with sodium thiosulfate (ml). These data show that there is an obvious correlation between activation temperature and methylene blue absorbance, iodine number, and surface area. At 800°C, the methylene blue adsorption is 12.41 mg/g, the iodine number is 875.61 mg/g, and the surface area is 561.404 m²/g.

Physical and Chemical Characterization of Commercial Kappa-Carrageenan with Ammonium Chloride as Electrolyte in Organic Battery Application

In this research, we attempt to investigate the difference in physical and chemical characteristics of commercial kappa-carrageenan and purified kappa-carrageenan as electrolytes in organic battery applications. Kappa-carrageenan was used as a host polymer to prepare biopolymer electrolyte films and ammonium chloride was used to enhance the charge transport process in the electrolyte layer of the organic battery. We characterized the physical and chemical properties of commercial kappa-carrageenan and purified kappa-carrageenan by use of UV-Vis spectroscopy, tensile-test measurement, Fourier Transform infrared spectroscopy and Raman spectroscopy in the form of solution and thin film samples. The results show that commercial kappa-carrageenan shows the absorbance area in Ultraviolet range with a maximum peak at 286 nm, while the maximum absorbance peak of purified kappa-carrageenan is slightly shifted at 288 nm. The chemical characterization of both kappa-carrageenan based on FTIR and Raman spectra show no significant structural change between kappa-carrageenan with or without the addition of ammonium chloride. XRD diffraction confirms that commercial kappa-carrageenan is amorphous and kappa-carrageenan with ammonium chloride has high intensity with sharp peaks around 2θ = 32º. The morphology of the thin film of purified kappa-carrageenan seem has a rougher surface in comparison to the commercial kappa-carrageenan. We found commercial kappa-carrageenan with ammonium chloride has high conducting about 1.55 x 10-5 Scm-1. Tensile test measurements indicate that commercial kappa-carrageenan is more flexible for use as an organic battery than the purified kappa-carrageenan.

Preparation and enhanced photocatalytic properties of Cu31S16/Cu9S5 heterojunction composite

A heterojunction photocatalytic material Cu31S16/Cu9S5 was successfully synthesized through a facile solvothermal method by controlling the reaction temperature. The phase composition, morphology, absorbance and surface area were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis diffusion reflection and Brunauer–Emmett–Teller (BET). Transient photocurrent response and electrochemical impedance spectroscopy (EIS) were measured to support the generation and transfer of the photoinduced charge carriers. The heterojunction Cu31S16/Cu9S5 showed superior separation efficiency of the photoinduced charge carriers. The photocatalytic performance of the Cu31S16/Cu9S5 was evaluated through degrading high-concentration methyl orange (MO) solution under visible light. The degradation rate of MO solution increased to 94.8% in 60 min, showing the most remarkable photocatalytic ability. Moreover, a probable photocatalytic mechanism of the Cu31S16/Cu9S5 was discussed.

Drying gayo coffee under natural processing by using modified Hohenheim solar tunnel dryer in Gayo highland

Gayo highland has relatively low daily temperature which is not effective for drying coffee. The objective of this study was to examine the operation of modified type Hohenheim solar tunnel dryer with 33% absorber area for drying coffee under natural processing in Gayo highland. About 9kg coffee cherries were dried by using the dryer and about 1 kg was dried under sun drying method. Results showed that the drying temperature of modified type Hohenheim solar tunnel dryer was higher about 9 to 14°C than the temperature of sun drying method. However, the relative humidity was about 40% both inside the drying chamber and outside the dryer. In order to reach the moisture below 14%, the drying time of coffee cherries by using the Hohenheim solar tunnel dryer may take for 8—9 days (64—72h) whereas the drying time by using sun drying method needs about 40 days (320h). It was found that the drying rate of coffee cherries dried by using Hohenheim solar tunnel dryer was higher than that of dried by sun drying method. In conclusion, the modified type Hohenheim solar tunnel dryer is promising to be used by farmers in Gayo highland.

Thermal performance improvement in solar air heating: An absorber with continuous and discrete tubular and v-corrugated fins

Solar air heaters (SAHs) are a sustainable and eco-friendly technology that utilizes abundant and free solar energy. Meanwhile, they have poor thermal performance owing to inefficient heat transfer and more heat loss. Efficient heat transfer is achieved by improving absorber area and thermal contact between the absorber plate and air. Thus, the present work uses continuous and discontinuous rectangular tubes and V-corrugated fins on the plain absorber surface to increase absorber area and airflow. An appreciable heat transfer and efficiency improvement is found using the current novel absorber. The SAH with continuous and discrete finned absorbers achievedaverage heat transfer coefficients of 79.2 W/m2K and 67.5 W/m2K, respectively, at a Reynolds number (Re) of 10930, outperforming the plain absorber by87.2 % and 59.3 %, respectively. Nusselt number and friction factorincreased by 100 % and 28.2 % for discrete and 44.6 % and 15.3 % for continuous finned absorbers, respectively. An enhanced heat absorption reduced the heat loss by 6.3–19.5 % and 10.7–23.3 % using a continuous and discrete fin structure. The SAH with discrete and continuous finned absorber reached 82.5 % and 79 % peak energy efficiency at Re of 10930. Though a higher pressure drop, discrete and continuousfinned absorbers have better effective efficiency than plain absorbers, with thermo-hydraulic performance factors of 2.01 and 1.6 at Re 4099. The discrete structure of fins is a vital factor for heat transfer increase in addition to geometry. Therefore, the absorber with combined tubular and v-corrugated discrete fins helps to produce more efficient solar air heaters and promotes sustainable development.

INVESTIGATING THE PERFORMANCE OF A FLAT-PLATE SOLAR WATER-HEATING SYSTEM USING CeO2/WATER NANOFLUID: A HOLISTIC APPROACH

The efficiency of a solar water heater with a flat-plate collector, which had an absorber area of 2 m<sup>2</sup> and utilized a cerium oxide-water nanofluid as the working medium with a fixed volume fraction of 0.01%, was analyzed using a holistic approach. To assess the impact of flow rate on its heat transfer characteristics, the working fluid was systematically circulated through a pump-circulation system at various flow rates ranging from 1 to 3 liters per minute (LPM). The system underwent analytical and field testing, which revealed that it achieves a maximum thermal efficiency of 78.2% at a flow rate of 2 LPM. The heat transfer coefficient underwent a notable enhancement, leading to a 21.5% increase in thermal efficiency compared to a system operating with plain water. A refined artificial neural network (ANN) model was created to forecast thermal performance and outlet temperature. The optimized ANN model is structured with a 3-10-2 architecture and achieves a mean squared error of 8.2 × 10<sup>-3</sup>. The performance of the optimized ANN model was assessed by testing its generalization capacity against experimental results. It was determined that the ANN model predictions aligned closely with the experimental data, exhibiting correlation coefficients ranging from 0.96 to 0.98. This study conclusively demonstrates that the analytical model and ANN can serve as a highly effective design tool for evaluating the performance of innovative solar collectors.

An Absorbance Peak Template for Clinical Assessment of Sound Conduction in Newborn Ears.

Power absorbance measures recorded over a wide range of frequencies allow for clinical inferences about the outer/middle ears' acoustic mechanics. A frequency-dependent feature in the newborn wideband absorbance response, the prominent mid-frequency absorbance peak, has been linked to middle-ear resonance. However, current normative methods were not designed to assess subtle changes in such features. This work aims to develop and validate an absorbance peak template (APT) for assessment of absorbance peaks in newborns. Additional objectives are to compare test performance of absorbance peaks and APTs to existing normative methods, to demonstrate APT-based methods for categorization of abnormal absorbance peaks, and to describe absorbance peak test-retest variability. Peak absorbance and peak frequency were analyzed in a training data set (490 measurements in 84 newborn ears who passed transient evoked otoacoustic emissions [TEOAEs] screenings), and an APT was developed by computing normal limits on these two absorbance peak variables. Split-set analysis evaluated the reproducibility of APT, and test-retest analysis was performed. Test performance analysis, conveyed by area under the receiver operating characteristic curve (AROC) and 95% confidence intervals (CIs), compared absorbance peak variables to absorbance area indices (AAIs) in a validation data set (359 ears that passed distortion-product OAE [DPOAE] screening and 64 ears that failed). APT-based assessment paradigms for normal and abnormal ears were compared to the common absorbance normative range paradigm. Split-set analysis demonstrated a good reproducibility of APT, and test-retest of absorbance peak variables showed that they were stable measures for clinical assessment. Test performance of peak absorbance (AROC = 0.83; 95% CI [0.77, 0.88]) was comparable to the top-performing AAI variables (AROC = 0.85; 95% CI [0.80, 0.90]). APT-based assessment categorized measurements based on their peak absorbance and peak frequency and enhanced the detection of subtle frequency changes that were missed by the normative range method. Analysis of absorbance peaks guided by APT has the potential to simplify and improve assessments of sound conduction pathways in newborn ears and can be used together with or in-place of current methods for analysis of wideband absorbance data.

MHD nanofluid flow with energy transfer over a porous stretching surface by using a second-grade fluid model

The main attention of this research is to examine the nature of the flow behavior of nanofluids and energy transfers past an expanding sheet with second-grade fluid model. The system is also situated in an absorbent area, which affects the effects of heat and mass transport and chemical reaction. The numerical calculations and visualization for various flow parameters are performed using a finite difference code that is developed in the built-in bvp4c solver scheme of MATLAB. This involves adopting a set of new variables to change the character of the governing equations of this study. To the best of the authors’ knowledge, many authors have contributed to this field, but they do not take into account the above fluid model associated with the energy transfers with the influences of Brownian motion, thermophoresis effect, and chemical reaction parameters, etc., in their study. Major findings of this study is to achieve a higher amount of thermal transference using the physical parameters, such as magnetic, visco-elastic, thermophoresis, and Brownian motion parameters, etc. Also, using smaller values of the magnetic parameter can be an effective way to minimize the impact of drag force of the fluid at the surface. The considering fluid model has multifarious industrial applications, such as food and cosmetic industry and pharmaceutical and biomedical industry, etc., due to its versatile rheological characteristics.

Морфометрические критерии оценки качества контейнерных сеянцев хвойных пород

The quality of planted forest crops depends significantly on the qualities of the planting stock. Numerous studies have been carried out to find clear seedling quality criteria and work out methods for their quantitative assessment to optimize the cultivation regime. Indicators of planting stock that are available for measurement under nursery conditions are needed to predict the success of forest crop establishment. This paper provides a review of the studies that applied different morphological criteria to evaluate coniferous planting stock quality and different determination methods. The suitability of planting stock quality indicators is determined by the effectiveness of predicting the outplanting survival rate (%) and growth. The key morphometric attributes of planting stock are the linear dimensions and biomass of whole seedlings and their individual organs: root collar diameter (RCD), seedling height (SH), dry mass of needles (NDM), stem (SBDM), roots (RDM), shoot/aboveground part of the seedling (SDM), seedling’s total dry matter (TDM), number of needles (NN). Effective indicators of seedling quality are morphometric indicators of roots: total length (TRL), volume (TRV), dry mass (RDM), number of first- (FOLR N), second- (SOLR N), and third-order (TOLR N) lateral roots, root surface area (TRS). TRL is a fairly reliable indicator of absorbent surface area. To minimize errors in the use of one or two traits, integrated seedling quality indices based on two or more indices have been developed. Widely used indices include: SQ = SH(cm)/RCD(mm); SDM/RDM ratio; Dickson quality index DQI = TDM/ ((SH / RCD) + (SDM / RDM)). RCD was the most suitable parameter to indicate seedling quality for many species due to its higher correlation level with the Dickson quality index. The SH index proved to be an effective indicator for analysis only when used together with RCD. When studying the formation of frost resistance, a number of morphological parameters are used: initiation of needle primordia, size of primordial shoots, cell volume, mitotic index (MI) of terminal primordia. Despite advances in testing planting stock quality and predicting field performance, not a single test is universally applicable for all woody plant species and environmental conditions. According to the target seedling concept, the application of morphometric criteria for assessing seedling quality in forest nurseries is a prerequisite for predicting outplanting success and maximizing the predictability of the outcomes of highproductivity forest crop planting. For citation: Robonen E.V., Chernobrovkina N.P., Egorova A.V., Zaitseva M.I., Nelaeva K.G. Morphometric Criteria for Assessing the Containerized Conifers Seedlings Quality. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 5, pp. 42–57. (In Russ.). https://doi.org/10.37482/0536-1036-2023-5-42-57

Heat and electric power production using heat pumps assisted with solar thermal energy for industrial applications

Solar thermal devices with large installation areas represent technical, economic, and environmental challenges to design, construct, and operate them. Heat pump assisted with a solar thermal installation (STI) guarantee heat load supply at target temperature of a process, minimizing STI occupied area, environment impacts and associated costs. This paper deals with the design of two heat pumps, each one assisted with a STI. For designing solar network (which together the storage tank makes up the STI), lower irradiance levels than winter period are considered, guaranteeing continuous process operation. For designing each heat pump, two refrigerants with Ozone Depletion Potential of zero and Global Warming Potential of 7 (in one of them) are evaluated. This designing methodology is applied to a second-generation production of bioethanol case study. When heat is generated through a heat pump assisted with STI, the solar network absorber area is reduced by 85%, comparing with required area if only a STI produces heating. The same thing happens to generate electric power. Solar fraction value is one, 81,360 tons/year of not burned bagasse avoids 63,142 tons/year of greenhouse gases emissions. Still always guaranteeing the supply of energy to process, the impacts on environment and soil are minimized.

Numerical and experimental investigation of a novel vertical solar chimney power plant for renewable energy production in urban areas

The main challenge in designing solar chimney power plants (SCPPs) is to improve their performance by employing different techniques. This research aims to propose a new SCPP design for urban areas that can be installed on buildings, which is different from conventional SCPP conditions. The model was then analyzed experimentally and numerically (CFD and energy modeling) in order to prove its competency. For this study, ANSYS-fluent and EnergyPlus softwares were used and the case study building was the Energy Ministry of Iran. Seven parameters including air gap, thickness, slope, solar collector distance from the building's wall, chimney height, and diameter were selected for optimization to achieve maximum power outlet. A 1:50 scale of the building was also prepared for the experiment. The results indicated that increasing the height of the chimney leads to an increase in velocity. Additionally, each SCPP geometry has an optimal chimney diameter for its dimensions. It was also concluded that the operation of the system is affected by temperature and radiation, which causes higher power to be obtained in summers. The results showed that the power obtained from this power plant, which is on the same scale as the Manzanares power plant (absorber area, chimney height, and diameter), was approximately four times higher. The difference of this system compared to conventional systems is its completely vertical collector, which results in higher power with a lower chimney height.

Exergy, energy, and economic analyses of pyramid solar still integrated with solar water heater

ABSTRACT One of the top priorities in the development of solar stills is productivity enhancement. The present study experimentally investigates both passive and active pyramid solar stills. In active mode, the pyramid solar still is integrated with a solar water heater. The tests were carried out with conventional pyramid solar still (CPSS) and active pyramid solar still (APSS) at 1, 2, and 3 cm of water depth, respectively. The experimentation has been carried out in Nagpur (Longitude 21.124042, Latitude 79.002211) from April – May 2022. The finding shows that the pyramid solar still coupled with a solar water heater at a water depth of 1 cm produces the highest productivity of 7.99 L/m2.The hourly thermal efficiency is to be inversely related to the absorber area and the exergy efficiency is inversely related to the absorber area and directly proportional to the still output. Hence exergy and thermal efficiency of CPSS at 1 cm water depth is enhanced by (107.59%) and (49.36%) as compared to APSS, respectively. The cost per liter of fresh water obtained from conventional pyramid solar still and active pyramid solar still are 0.0139$/L and 0.00751$/L respectively. Based on the study, lower basin water depths and secondary heating enhance the solar still’s productivity.

Productivity, thermal, and exergy efficiency analyses of tubular solar still integrated with solar water heater

ABSTRACT Productivity is the primary output of any solar still system, hence solar still technology needs to be improved continuously in order to reduce the price of distillate water. In the current work, we compared the tubular solar still (TSS) with the conventional solar still of the same size and material while conducting experiments and improving performance when implementing a solar water heater. The experiment was conducted in Nagpur, India, in May 2022, at Longitude 21.124419, Latitude 79.002072. Three different water depths, respectively, 1 cm, 2 cm, and 3 cm, were used in the experiment to compare TSS using active solar still with TSS using passive solar still. As part of the investigation, the TSS solar water heater produced the most freshwater, at a rate of 8.76 L/m2, compared to the CTSS solar still, which produced 6.02 L/m2 of water at a depth of 1 cm. For water depths of 1 cm, 2 cm, and 3 cm, respectively, the ATSS increased freshwater highest production at 1 cm depth by 45.51%, in comparison to the CTSS. The costs of producing freshwater, ATSS and CTSS, are 0.015 $/L and 0.011 $/L, respectively. As compared to ATSS, the exergy and thermal efficiency of CTSS at 1 cm of water depth is increased by 130.32% and 24.90%due to the absorber area which is inversely correlated with the hourly thermal efficiency, and the absorber area directly correlated with the still output for the exergy efficiency.

MoS2 Nanosheets Decorated with Fe3O4 Nanoparticles for Highly Efficient Solar Steam Generation and Water Treatment.

The shortage of water resources has always been one of the most difficult problems that perplexes humanity. Solar steam generation (SSG) has been a new non-polluting and low-cost water purification method in recent years. However, the high cost of traditional photothermal conversion materials and the low efficiency of photothermal conversion has restricted the large-scale application of SSG technology. In this work, composite materials with Fe3O4 nanospheres attached to MoS2 nanosheets were synthesized, which increased the absorbance and specific surface area of the composite materials, reduced the sunlight reflection, and increased the photothermal conversion efficiency. During the experiment, the composite material was evenly coated on cotton. The strong water absorption of cotton ensured that the water could be transported sufficiently to the surface for evaporation. Under one sun irradiation intensity, the evaporation rate of the sample synthesized in this work reached 1.42 kg m-2 h-1; the evaporation efficiency is 89.18%. In addition, the surface temperature of the sample can reach 41.6 °C, which has far exceeded most photothermal conversion materials. Furthermore, the use of this composite material as an SSG device for seawater desalination and sewage purification can remove more than 98% of salt ions in seawater, and the removal rate of heavy metal ions in sewage is close to 100%, with a good seawater desalination capacity and sewage purification capacity. This work provides a new idea for the application of composite materials in the field of seawater desalination and sewage purification.

Continuous, Nondestructive Detection of Microorganism Growth at Buried Interfaces with Vascularized Polymers.

Evaluating surface bacterial growth at buried interfaces can be problematic due to the difficulties associated with obtaining samples. In this work, we present a new method to detect signals from microorganisms at buried interfaces that is nondestructive and can be conducted continuously. Inspired by vascular systems in nature that permit chemical communication between the surface and underlying tissues of an organism, we created a system in which an inert carrier fluid could be introduced into an empty vascular network embedded in a polymer matrix. When a microorganism layer was grown on top, small molecules produced by the growth process would diffuse down into the carrier fluid, which could then be collected and analyzed. We used this system to nondestructively detect signals from a surface layer of Escherichia coli using conductivity, ultraviolet-visible (UV-vis) absorbance spectroscopy, and high-performance liquid chromatography (HPLC) for organic acids, methods that ranged in sensitivity, time-to-result, and cost. Carrier fluid from sample vascularized polymers with surface bacterial growth recorded significantly higher values in both conductivity and absorbance at 350 nm compared to controls with no bacteria after 24 h. HPLC analysis showed three clear peaks that varied between the samples with bacteria and the controls without. Tests tracking the change in signals over 48 h showed clear trends that matched the bacterial growth curves, demonstrating the system's ability to monitor changes over time. A 2D finite element model of the system closely matched the experimental results, confirming the predictability of the system. Finally, tests using clinically relevant Staphylococcus aureus and Pseudomonas aeruginosa yielded differences in conductivity, absorbance, and HPLC peak areas unique to each species. This work lays the foundation for the use of vascularized polymers as an adaptive system for the continuous, nondestructive detection of surface microorganisms at buried interfaces in both industry and medicine.