Search Results (13)

This paper presents the development and evaluation of an autonomous solar dryer designed to enhance the drying efficiency of bee bread granules. In contrast to natural open-air drying, the proposed system utilizes solar energy in an oscillating operational mode to achieve a controlled and accelerated drying process. The dryer comprises a solar collector integrated into the base of the drying chamber, which facilitates convective heating of the drying agent (air). The system is further equipped with a photovoltaic panel to generate electricity for powering and controlling the operation of air extraction fans. The methodology combines numerical modeling with experimental studies, structured by an experimental design framework. The modeling component simulates variations in temperature (288–315 K) and relative humidity within a layer of bee bread granules subjected to a convective air flow. The numerical simulation enabled the determination of the following: the time required to achieve a stationary operating mode in the dryer chamber (20 min); and the rate of change in moisture content within the granule layer during conventional drying (18 h) and solar drying treatment (6 h). The experimental investigations focused on determining the effects of granule mass, air flow rate, and drying time on the moisture content and temperature of the granular layer of Bee Bread. A statistically grounded analysis, based on the design of experiments (DoE), demonstrated a reduction in moisture content from an initial 16.2–18.26% to a final 11.1–12.1% under optimized conditions. Linear regression models were developed to describe the dependencies for both natural and forced convection drying. A comparative evaluation using enthalpy–humidity (I-d) diagrams revealed a notable improvement in the drying efficiency of the proposed method compared to natural drying. This enhanced performance is attributed to the system’s intermittent operational mode and its ability to actively remove moist air. The results confirm the potential of the developed system for sustainable and energy-efficient drying of bee bread granules in remote areas with limited access to a conventional power grid. Full article

The drying process plays a crucial role in enhancing the shelf life of food products by reducing moisture content. As climate change contributes to rising temperatures, alternative drying methods, such as solar drying, offer promising solutions for sustainable food preservation. This study investigates the solar drying of eggplant (Solanum melongena L.) slices, with a focus on the effect of salting pretreatment on drying efficiency. Eggplant slices were subjected to salting pretreatment for partial moisture removal prior to drying. Drying kinetics were monitored to construct the characteristic drying curve. The dried eggplant slices were evaluated for their proximate composition and rehydration capacity, as well as textural and thermal properties. The results showed that salting pretreatment significantly enhanced the solar drying process by accelerating moisture removal. Notably, water activity (aw) decreased significantly from 0.978 to 0.554 for the control sample and to 0.534 for the saltedsample. Significant differences were observed between the dried and salted dried slices, particularly in rehydration capacity, which decreased following salting. Additionally, the salted dried samples showedreductions in protein, carbohydrate, and potassium contents. In contrast, ash content and hardness increased as a result ofosmotic pretreatment. These findings suggest that while dry salting pretreatment effectively reduces solar drying time, it may adversely affect several nutritional and textural properties. Full article

In recent years, many spruce (Picea abies (L.) H. Karst., Pinaceae) forests have been severely affected by bark beetle (Ips typographus L., Coleoptera: Curculionidae) outbreaks in the Southern Alps, but their ecological impacts remain poorly studied. We analyzed the distribution, ecological, and floristic–vegetational characteristics of forests recently affected by the bark beetle in the upper basin of the Oglio River (Northern Italy) and developed a MaxEnt model to map forests with a bioclimate more prone to severe insect attacks in the coming decades. The results showed that the spruce forests affected by the bark beetle are located exclusively in the submountain and mountain belts (below 1600 m a.s.l.) and that 85% of them are found in areas with high annual solar radiation (>3500 MJ m⁻²). The predictive model for areas susceptible to severe bark beetle attacks proved highly accurate (AUC = 0.91) and was primarily defined by the mean temperature of the dry winter quarter (contribution: 80.1%), with values between −2.5 and 2.5 °C being particularly suitable for the pest. According to the model, more than 58% of the current spruce forests in the study area will exhibit high susceptibility (probability > 0.7) to severe bark beetle attacks by 2080. The floristic–vegetational and ecological analysis of plant communities of 11 bark beetle-affected areas indicated that more thermophilic and significantly different forest communities (in both floristic and physiognomic terms) are expected to develop compared to those of pre-disturbance. Furthermore, the high coverage of spruce snags/standing dead trees appears to accelerate plant succession, enabling the establishment of mature forest communities in a shorter time frame. Full article

One method of preparing sludge for management and use is solar drying. To intensify the drying process, natural lignocellulosic additives can be used to alter the structure of the sludge and accelerate water evaporation. Light, hard materials with low absorption capacity are best suited for this purpose, e.g., walnut shells, which are unused waste. The aim of the study was to determine the impact of the evaluation of walnut shells on the sludge drying process and to assess the impact of the drying process on the chemical, physical, and fuel properties of the additive. The moisture content, crushing strength, chemical composition, and physical and fuel properties of mixtures were determined. A small addition of walnut shells (25%) was found to accelerate the drying process even in winter and spring (up to 30 days) compared to sludge without additives. Walnut shells retain their chemical composition and strength despite unfavourable conditions and a chemically aggressive environment, indicating they may be reused. The mixture containing sewage sludge and walnut shells has a calorific value of 15.6 MJ/kg, which is similar to wood; it is also fully biodegradable and suitable as a fertiliser to improve soil structure, as it contains approx. 80–90% DM (including approx. 40% carbon, 3% nitrogen, and other elements, such as phosphorus and potassium.) Full article

As one of the main chili varieties in Mexico, Yahualica chili requires year-round availability. This study examines the feasibility of five drying methods (open-air, solar, microwave, freeze-drying and shade drying) used to preserve this culturally and economically valuable product. The results show the drying duration and rate for solar drying with varying air temperatures (40, 50, 60, and 70 °C) and airflows (150, 200, 250, and 300 m³/h) and microwave drying with varying power levels (90, 160, 360, and 600 W). Convection drying efficiency increased with temperature and airflow, according to the findings. Microwave drying significantly reduced drying time, and higher powers further accelerated moisture removal. Open sun and shade drying was the slowest, and open sun drying was also susceptible to factors compromising quality. Total Phenolic Content (TPC), Total Capsaicinoids Content (TCC), and antioxidant activity had a positive effect, since the drying methodologies favored the release of these compounds. Full article

As a by-product of wastewater treatment, sewage sludge can be used for natural, agricultural, or energy purposes. One method of preparing sludge for management and use is solar drying. To intensify the drying process, natural additives can be used to alter the structure of the sludge and accelerate the evaporation of water. This research aimed to evaluate the influences of different organic additives in sewage sludge mixtures on the physicochemical and energy parameters of briquettes. This research was carried out without thermal boosting in a 4 × 2.5 × 2 m plastic tunnel. The tunnel was equipped with three drying stations and control and measuring equipment. In two test series, sludge additives in the form of straw and lignocellulosic materials, sawdust, bark, woodchips, and walnut shells, were used. Briquettes were made from the resulting mixtures and then subjected to physical and chemical analyses. This research showed high variability in the contents of trace elements, nitrogen, and sulphur in relation to an increase in the amount of sludge in the briquettes, which, for the briquettes made from sewage sludge, was nearly twice as high as for the briquettes made from the mixtures. The results of the flue gas analysis for the briquettes with sawdust and wood chip additives were very similar. The briquettes made from sewage sludge with lignocellulosic materials (bark and wood chips) had fuel properties similar to woody biomass, with a calorific value and heat of combustion of 15–16 MJ/kg. Fibrous additives (straw) significantly increased the strength parameters of the briquettes, by more than 50% of the value. The compositions and properties of the mixtures affected the following briquetting parameters: temperature and compressive force. The briquettes made from sewage sludge and additives can be classified according to ISO 21640 as SRFs (solid recovered fuels). In most of the results, the net calorific value (NCV) was 3 to 4; the chlorine content (CL) was 2 to 1; and the mercury content (Hg) was 1. The sewage sludge mixtures facilitated the agricultural and energy use of the briquettes. Full article

Solar drying is an environmentally friendly and sustainable approach to preserve agricultural products, particularly in regions with abundant sunlight. In terms of apricot cultivation, the implementation of solar drying methods can significantly impact post-harvest handling and storage. In the conditions of Uzbekistan, the drying of apricot products in indirect solar dryers is the next stage of development. This research aims to investigate the effectiveness of solar drying techniques for apricots in Uzbekistan, focusing on optimizing drying parameters and assessing the quality of the dried products. This study involves the design and implementation of solar drying systems for apricots. It primarily focuses on comparing and evaluating the drying times of apricots, changes in product moisture, and alterations in apricot color during the drying process using an Open Sun Dryer (OSD) and an Indirect Natural Convection Solar Dryer (INCSD). Various drying parameters such as the temperature, humidity, and drying time are monitored and controlled during the experiment. Additionally, the quality of the dried apricots is evaluated through analyses of their color, texture, and nutrient retention. According to the results, when apricots were dried in a solar dryer at 55 °C and with 35% humidity outside, their moisture content decreased from 85–90% to 12–18% within 15 h. The solar radiation intensity and ambient temperature play a crucial role in the acceleration of the time in the drying process. In general, utilizing equipment-based solar drying methods for apricots in Uzbekistan has the potential to rival traditional drying systems in terms of both quality and drying duration. Full article

Agricultural commodity drying technology aims to maintain and improve the quality of agricultural products. Coffee quality is important for the welfare of coffee farmers, and drying technology plays an important role in determining the quality of coffee. Various drying models can be applied, including the traditional model that is still applied today: drying directly under solar radiation. One drying technology that can accelerate the drying time is varying the air velocity in the drying chamber. In this study, the air velocity was varied by 1–3 m/s over coffee bean samples with an initial weight of 1500 g that were dried in parallel simultaneously. The time required was 25 h, with a maximum radiation of 586.9 w/m² and total solar energy over 3 days of 16.6 MJ/m². It was found that good quality coffee was achieved using drying box 1, with a drying air velocity of 1.0 m/s, with which a final mass of 732.24 g was obtained with coffee moisture content of 12.0%, protein content of 11.7%, carbohydrate content of 21.7%, and free fatty acid content of 0.05%. Higher air velocities resulted in almost the same protein and carbohydrate content, as well as a fatty acid content of less than 0.1%, but a higher moisture content. Full article

The Loess Plateau (LP) is a typical climate-sensitive and ecologically delicate area in China. Clarifying the vegetation–climate interaction in the LP over 40+ years, particularly pre- and post-Grain to Green Program (GTGP) implementation, is crucial for addressing potential climate threats and achieving regional ecological sustainability. Utilizing the kernel Normalized Difference Vegetation Index (kNDVI) and key climatic variables (precipitation (PRE), air temperature (TEM), and solar radiation (SR)) between 1982 and 2022, we performed an extensive examination of vegetation patterns and their reaction to changes in climate using various statistical methods. Our findings highlight a considerable and widespread greening on the LP from 1982 to 2022, evidenced by a kNDVI slope of 0.0020 yr⁻¹ (p < 0.001) and a 90.9% significantly increased greened area. The GTGP expedited this greening process, with the kNDVI slope increasing from 0.0009 yr⁻¹ to 0.0036 yr⁻¹ and the significantly greened area expanding from 39.1% to 84.0%. Over the past 40 years, the LP experienced significant warming (p < 0.001), slight humidification, and a marginal decrease in SR. Post-GTGP implementation, the warming rate decelerated, while PRE and SR growth rates slightly accelerated. Since the hurst index exceeded 0.5, most of the vegetated area of the LP is expected to be greening, warming, and humidification in the future. In the long term, 75% of the LP vegetated area significantly benefited from the increase in PRE, especially in relatively dry environments. In the LP, 61% of vegetated areas showed a positive correlation between kNDVI and TEM, while 4.9% exhibited a significant negative correlation, mainly in arid zones. SR promoted vegetation growth in 23% of the vegetated area, mostly in the eastern LP. The GTGP enhanced the sensitivity of vegetation to PRE, increasing the area corresponding to a significant positive correlation from 15.3% to 59.9%. Overall, PRE has emerged as the dominant climate driver for the vegetation dynamics of the LP, followed by TEM and SR. These insights contribute to a comprehensive understanding of the climate-impact-related vegetation response mechanisms, providing guidance for efforts toward regional sustainable ecological development amid the changing climate. Full article

Experimental studies were conducted on the cultivation of tomatoes (Solanum lycopersicum L.) at Shandong Agricultural University, China, from 2022 to 2023. Three cultivation patterns were designed as follows: a north–south orientation with a row spacing of 1.40 m (NS-1.4m), a north–south orientation with a row spacing of 1.80 m (NS-1.8m) and an east–west orientation with a row spacing of 1.80 m (EW-1.8m). A functional–structural plant model using the open source interactive modeling platform of GroIMP was constructed for the cultivation of tomatoes. The growth of plants as well as the light distribution and light interception capacity of the crop canopy were simulated and analyzed. The impacts of these cultivation patterns on the growth, photosynthetic characteristics, fruit ripening time, quality and yield of tomato plants were analyzed. The studies revealed that compared with the NS-1.4m treatment, the canopy light interception of tomato plants under the NS-1.8m and EW-1.8m treatments increased by 6.08% and 9.80% in a winter–spring crop and 6.80% and 19.76% in an autumn–winter crop, respectively. Their plant height, leaf area, aboveground dry matter accumulation, leaf net photosynthesis rate as well as the lycopene, vitamin C and sugar–acid ratio of the fruit all exhibited increasing trends, while fruit ripening was accelerated. The yield of the NS-1.8m and EW-1.8m treatments increased by 3.92% and 6.18% in a winter–spring crop and 4.17% and 9.78% in an autumn–winter crop, respectively. Structural equation modeling was used to further analyze the data, confirming that the cultivation of an east–west orientation with wide row spacing is beneficial for tomato cultivation in Chinese solar greenhouses. This cultivation pattern maximizes the canopy’s light interception, thus leading to improved fruit quality and yield. Overall, this study provides valuable insights for optimizing the cultivation pattern of solar greenhouse crops. Full article

To clarify the physiological mechanism of different groundwater depths affecting soybean evapotranspiration, photosynthetic characteristics and yield, a field experiment with four groundwater depth levels (1 m (D1), 2 m (D2), 3 m (D3) and 4 m (D4)) was conducted through the groundwater simulation system in 2021 and 2022. In this study, a quantitative analysis was conducted on the groundwater recharge and irrigation water demand and evapotranspiration (ET) of soybean fields with different treatments, and the effects of different treatments on soybean leaf area index (LAI), chlorophyll content index (SPAD), intercepted photosynthetic active radiation (IPAR), photosynthetic gas exchange parameters, dry matter accumulation (DMA) and yield were explored. The results showed the following: (1) Groundwater depth affected soybean ET and the source of ET. With the increase in groundwater depth, groundwater recharge and its contribution to ET gradually decreased, but the amount of irrigation required gradually increased, resulting in the ET as D1 > D4 > D2 > D3. (2) Soybean LAI, SPAD and IPAR were significantly affected by the different groundwater depths, of which the D1 treatment always maintained the maximum, followed by the D4 treatment, and the D3 treatment was the minimum. The photosynthetic gas exchange parameters under different treatments changed synergistically, showing significant differences in the flowering and podding stages, notably D1 > D4 > D2 > D3. Soybean DMA and yield first decreased and then increased with the increase in groundwater depth, and the average DMA and yield under the D1 treatment increased by 27.71%, 46.80% and 22.82% and 20.29%, 29.91% and 12.83% in the two years, respectively, compared to the D2, D3 and D4 treatments. (3) The structural equation model demonstrated that the groundwater depth indirectly affected the growth of soybean leaf area by affecting groundwater recharge, which in turn regulated soybean ET and photosynthetic capacity and ultimately affected DMA and yield. The above results showed that in the case of shallow groundwater depth (D1), the largest groundwater recharge promoted the growth of soybean leaf area and chlorophyll synthesis and increased the absorption and utilization of solar radiation. And it improved the leaf stomata conditions, accelerated the gas exchange between the plant and atmosphere, enhanced the photosynthetic production capacity and ET and achieved maximum DMA and yield. Soybean leaf growth and photosynthesis diminish with the increase in groundwater depth. In the case of deep groundwater depth (D4), the maximum irrigation improved the growth and photosynthetic performance of soybean leaves, which was favorable to ET, and ultimately led to increases in DMA and yield. Full article

In this study, solid olive mill waste (SOMW) was used to obtain antioxidant compounds using solid–liquid extraction. The effect of different extraction methods, namely microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), Soxhlet, and conventional solvent extraction, on the yield, total phenolics, and total antioxidant activity of SOMW extracts was investigated. Untreated and dried SOMW were subjected to extraction with water and methanol. The antioxidant activity of the extracts was evaluated using the DPPH assay, while their total phenolic content was measured using the Folin–Ciocalteu method. For the characterisation of the extracts, HPLC-DAD analysis was performed. The results showed that the extraction yield was significantly influenced (p < 0.05) by the solvent used, the material treatment prior to extraction, the moisture content of SOMW samples, and the extraction time. The optimised parameters were water, as the extraction solvent, and MAE as the extraction technique (extraction temperature of 50 °C and time of 1 h). The evaluation of the antioxidant activity of the extracts indicated that phenolics were the dominant bioactive compounds. The extracts were found to be rich in several hydroxytyrosol derivatives. Therefore, SOMW can be a valuable resource for bioactive compounds using conventional and innovative extraction techniques. Full article

Taking climate and geopolitical issues into account, we must shift our thinking towards “eco” and focus on renewable energy. The accessible solar energy represents 400 times the amount of consumption, while its potential represents 10,000 times the amount of demand. The paper aims to analyze recycled, customized polyvinyl butyral (PVB) with high purity (more than 98%) concerning its physicochemical and mechanical properties and its possible applicability in the photovoltaic industry as an encapsulating material. The detailed investigation on polyvinyl butyral starting from characterizations, homogenization, and moulding process to tensile tests and used exposure testing in laboratory apparatus are performed. Samples of recycled polyvinyl butyral were exposed to ultraviolet (UV) radiation of the value 0.76 W.m^–2.nm^–1 at 340 nm, water spray, drying at 50 °C and condensation for 320 h when the radiation was turned off. The results obtained were more controlled in a laboratory environment than those found in external, uncontrolled environments. These conditions subsequently accelerate any degradation of polyvinyl butyral as a material and subsequent degradation of the final product. Full article