This study experimentally evaluates a natural gas–assisted hybrid greenhouse solar dryer (NHGHD) designed to ensure continuous drying under arid climatic conditions. The system integrates an indirect auxiliary gas heater into a greenhouse dryer and is compared with a conventional greenhouse solar dryer (CGHD) under identical operating conditions using tomato slices.The novelty lies in the combined experimental energy–exergy–economic–environmental assessment of an indirectly heated hybrid greenhouse dryer operating under real arid conditions, together with thin-layer drying modelling.The NHGHD achieved higher energy efficiency (48.9%) than the CGHD (45.4%) and significantly higher exergy efficiency (5.57% vs 1.10%). Drying time was reduced from 1770 min to 990 min. Economic analysis showed a lower payback period for the NHGHD (0.32 vs 0.40 years). However, CO2 emissions increased due to natural gas use, reaching 13.43 tons·year−1 compared with 0.06 tons·year−1 for the CGHD. The Midilli–Kucuk model provided the best fit for drying kinetics. Results highlight a clear trade-off between performance improvement and environmental impact in hybrid drying systems.

Improving internal thermo-fluid performance is essential for enhancing the efficiency and reliability of solar thermal drying systems. While most studies focus on solar collector optimization or external design modifications, limited attention has been devoted to structured internal airflow management within drying chambers. This study proposes a passive thermo-fluid intensification strategy for a mixed-mode solar dryer through the integration of twisted and winglet inserts designed to restructure airflow and enhance coupled convective heat and mass transfer.A combined experimental and three-dimensional Computational Fluid Dynamics (CFD) methodology was adopted. Drying experiments were conducted under real semi-arid climatic conditions, while numerical simulations were performed to analyze airflow distribution, mixing intensity, stagnation zone, and residence time modification induced by the inserts.The results demonstrate that internal flow control significantly improves chamber thermal uniformity and transport processes. The winglet configuration provided the highest enhancement, increasing peak chamber temperature to 54 °C and achieving a maximum thermal efficiency of 82.04%, compared to 47.16% for the baseline configuration. CFD analysis revealed a clear improvement in drying uniformity, where the uniformity index increased from 0.63 in the baseline configuration to 0.80 with winglet inserts. Drying time was reduced by up to 56.25% using winglet inserts and reached 62.5% under optimized airflow conditions. Enhanced drying rates and higher effective moisture diffusivity confirmed improved coupled heat and mass transfer mechanisms.The findings highlight the effectiveness of passive internal flow structuring as an economically viable intensification strategy for low-temperature solar thermal drying systems, with a payback period of six months.

In this study, a solar-powered greenhouse dryer was designed, constructed, and evaluated for drying zucchini slices under semi-arid climate conditions. The system's thermal performance was assessed through temperature distribution, drying kinetics, and drying rate, and compared with the conventional open sun-drying method. Results show that the greenhouse dryer significantly reduced the total drying duration to 2 days, compared to more than 3 days for open sun drying, and provided more stable thermal conditions with peak absorber, air, and product temperatures of 65 °C, 57.5 °C, and 50 °C, respectively. Energy performance indicators demonstrated improved solar utilization efficiency and enhanced moisture removal under controlled greenhouse conditions. Experimental drying kinetics data were fitted to seven mathematical models, with the Midilli-Kucuk model showing the best agreement (R2 = 0.9989 and 0.9996, χ = 1.93×10−4 and 5.71×10−5, RMSE = 0.0139 and 0.0076). These results highlight the potential of greenhouse solar dryers as energy-efficient solutions for agro-food processing in arid regions, contributing to sustainable renewable energy applications in agricultural engineering.

The intermittent drying of dates remains a neglected area in academic research, primarily due to factors such as varying cultivation patterns across regions and limited attention to the valorization of overdried dates. This study investigates the impact of drying parameters: air temperature, air velocity, and intermittency ratio, on the drying time and energy consumption of rehydrated dates using hot air drying. Employing Response Surface Methodology with a Central Composite Design and a desirability function, experiments were conducted within specific ranges of air temperatures (40–70 °C), air velocities (0.5–5 m/s), and intermittency ratios (0.2–1). Results show that while air velocity minimally affects drying time, it negatively influences energy efficiency. Conversely, air temperature is significant for both responses. Reducing the intermittency ratio from 1 to 0.3 resulted in a decrease in total energy consumption by up to 60%, particularly at lower temperatures, with negligible impact on total drying time. The study identifies optimal conditions for minimizing both drying time and energy consumption as an inlet temperature of 66 °C, air velocity of 2.5 m/s, and an intermittency ratio of 0.7. The experimental data were fitted to 7 mathematical drying models, the results indicated that Midilli-Kucuk model gave better performance to define the drying kinetics of intermittent drying of rehydrated dates.

Herbs dried in conventional systems often suffer quality degradation due to direct sunlight exposure and uneven drying. To address this, a novel greenhouse dryer (NGHD) equipped with an integrated drying chamber was evaluated, where the walls consist of two plates separated by a thermal insulating material (sandwich type). The metal plate exposed to the sun is painted black to act as an absorber, while the insulating material helps retain heat inside the drying chamber. This innovative design combines the large capacity of direct dryers with the superior quality of dried materials characteristic of indirect dryers. Experiments, conducted at the University of El Oued, assessed mint drying kinetics, moisture removal, and effective moisture diffusivity. Among nine tested models, the two-term model best described the drying kinetics. The NGHD achieved higher internal temperatures (up to 14 degrees C without load, 10 degrees C with load) than the conventional greenhouse dryer (CGHD), reducing drying time by 32 %. Mint's moisture content dropped from 5.45 to 0.03 kg water/kg dry basis in 390 min (NGHD), compared to 570 min (CGHD) and 920 min (sun drying). Effective diffusivity improved by 27 % in the NGHD. Superior mint quality, retaining color and shape, was achieved in the NGHD. Economic analysis showed payback periods of 0.925 years (NGHD) and 1.004 years (CGHD), with carbon credits of 1927.40 $ over 15 years. The NGHD demonstrates its novelty and sustainability by preserving product quality while offering economic and environmental benefits.

This research aims to experimentally and mathematically study the sorption isotherms and thermodynamic characteristics of wheat cultivated in El Menia, south of Algeria, after thermal and biochemical treatment at three different temperatures (20 °C, 40 °C, and 60 °C). A correlation was established between water activity and water concentration in the product. We chose the gravimetric method with sulfuric acid solutions. Various mathematical models (GAB, BET, Halsey, Peleg, Oswin, Caurie, Smith) have been used to represent and anticipate hygroscopic behavior during drying and storage. The models were read and optimized through the statistical processing of the data obtained. The results of this study can be used to determine characteristic drying curves and optimal storage conditions. The isosteric heat of sorption of wheat was calculated using the ClausiusClapeyron equation.

Enhancing heat transfer is critical across diverse industrial and agricultural applications to optimize operational efficiency and reduce energy consumption by maximizing thermal energy exchange between systems and their surroundings. This study investigates heat transfer enhancement in a direct solar dryer through the strategic integration of obstacles, addressing a significant gap in existing literature that primarily focuses on redesigning drying chambers and enhancing solar air collectors without improving internal performance. The primary objective was to enhance heat transfer efficiency within the drying chamber, which is needed to accelerate the drying process of agricultural products. By strategically placing obstacles, turbulence in the airflow was induced to improve mixing and heat distribution. This approach was validated through experimental observations and Computational Fluid Dynamics (CFD) simulations using ANSYS Fluent. The results indicate that integrating obstacles significantly raised the maximum dryer temperature from 10 degrees C without obstacles to 14.1 degrees C with obstacles. Numerical findings demonstrate improved air distribution within the chamber, generating highvelocity zones near obstacles and enhancing overall air circulation. Furthermore, integrating obstacles reduced drying time by more than 4.5 h and achieved a maximum thermal efficiency of 69.39 %. Additionally, this enhancement contributed reducing CO2 emissions to 36.01 kg per year, underscoring the system's environmental benefits.

The thermal performances and quality attributes of dried onion using stationary solar-electric drying (SED), intermittent solar-electric drying (ISED), and intermittent solar-electric drying with sensible storage medium (ISEDS) were compared. The tempering in processing time by 60 min elevated the drying time and reduced the diffusivity from 3.67 x 10-6 m2/s using SED to 2.06 x 10-6 and 2.11 x 10-6 m2/s using the ISED and ISEDS, respectively. The obtained drying efficiency was 21.05 %, 35.69 %, and 35.39 %, respectively, for the SED, ISED, and ISEDS. The average SEC values were found at 0.76 and 0.66 kWh/kg using ISED and ISEDS, respectively. The sustainability index (Si) and waste exergy ratio (WER) values were Si = 1.99, 1.45, and 1.51 and WER = 0.49, 0.63, and 0.61, respectively for SED, ISED, and ISEDS. The improvement potential (IP) of 1.69, 1.84, and 1.74 W were obtained using SED, ISED, and ISEDS, respectively. For SED, ISED, and ISEDS, the payback period (Pb) values were estimated at 1.08, 0.75, and 0.70 years, with the highest annual savings (Sj) obtained using the ISEDS at 16203.3 CNY. Better visual quality was observed for ISEDS. Compared to stationary drying processes using high-extensive energy dryers, intermittent solar drying is a promising technique for preserving agri-food products.

In Saharan climates, greenhouses face extreme diurnal temperature fluctuations that generate thermal stress, reduce crop productivity, and hinder sustainable agricultural practices. Passive thermal storage using Phase Change Materials (PCM) is a promising solution to stabilize microclimatic conditions. This study aims to evaluate experimentally and numerically the effectiveness of PCM integration for moderating greenhouse temperature fluctuations under Saharan climatic conditions. Two identical greenhouse prototypes were constructed in Ghardaïa, Algeria: a reference greenhouse and a PCM-integrated greenhouse using calcium chloride hexahydrate (CaCl2·6H2O). Thermal performance was assessed during a five-day experimental period (7–11 May 2025) under severe ambient conditions. To complement this, a Nonlinear Auto-Regressive with eXogenous inputs (NARX) neural network model was developed and trained using a larger dataset (7–25 May 2025) to predict greenhouse thermal dynamics. The PCM greenhouse reduced peak daytime air temperature by an average of 8.14°C and decreased the diurnal temperature amplitude by 53.6% compared to the reference greenhouse. The NARX model achieved high predictive accuracy (R2 = 0.990, RMSE = 0.425°C, MAE = 0.223°C, MBE = 0.008°C), capturing both sensible and latent heat transfer mechanisms, including PCM melting and solidification. The combined experimental and predictive modeling results confirm the potential of PCM integration as an effective passive thermal regulation strategy for greenhouses in arid regions. This approach enhances microclimatic stability, improves energy efficiency, and supports the sustainability of protected agriculture under extreme climatic conditions.

This article examines the evolution of agricultural drying under the influence of a variety of interdependent factors. These include the dynamics of national food chains, societal controversies over agricultural models, the recognition of drying as a profession, and advances in rural development. We also analyze the issues related to the innovation and diffusion of this technology. By synthesizing these influences and their implications, we highlight the key parameters for anticipating future trajectories of agricultural drying.

This work presents an original and innovative approach by combining greenhouse cooling with artificial intelligence models to ensure food security.The study is divided into two parts: Experimental and theoretical.In the first part, a cooling system was implemented in a tunnel-type agricultural greenhouse and compared to a control system.The cooling system consists of multiple fans powered by two solar panels.Data was collected using an acquisition system (Arduino) over approximately one month.This data, along with external data, was utilized to predict the internal temperature of the greenhouse using backpropagation neural network models.The results obtained demonstrate the reliability of the model based on all tests, as evidenced by the coefficient of determination (R 2 ) and the mean square error (MSE) for the prediction.

This comprehensive and meticulously researched study delves deeply into the multifaceted intricacies surrounding the implementation, optimization, and ongoing refinement of an innovative evaporative cooling system tailored specifically for agricultural greenhouses. Drawing upon the abundant availability of three locally sourced materials — straw, palm leaves, and wool pads — the study endeavors to establish a robust, sustainable, and eco-conscious cooling infrastructure. The overarching objective is not merely to create a cooling solution, but rather to engineer a sophisticated system capable of adeptly regulating temperature fluctuations within the greenhouse environment, thereby creating and maintaining optimal growth conditions essential for crop productivity and success. At the heart of this ambitious endeavor lies the integration of cutting-edge technology, notably a photovoltaic (PV) generator, strategically deployed to power an array of fans. This energy-efficient setup is further bolstered by an ingenious battery storage mechanism, meticulously designed to ensure seamless operation even during nocturnal hours. The evaluation process employed by the researchers is rigorous and exhaustive, meticulously scrutinizing the efficacy of each material utilized as a cooling pad. Parameters such as their ability to effectively humidify the atmosphere and lower ambient temperatures within the greenhouse confines are carefully assessed. Through a series of meticulously conducted experiments and observations, the study unveils the commendable efficiency and efficacy of the cooling system in significantly curtailing temperature differentials, thus underscoring its pivotal role in enhancing agricultural productivity and sustainability. These findings not only underscore the tangible benefits of harnessing locally available resources but also serve as a testament to the transformative potential of eco-friendly cooling solutions in mitigating the myriad challenges faced by modern agriculture. As the research horizon continues to expand, future endeavors are poised to pivot towards further fine-tuning system parameters, exploring the integration of novel materials, and devising innovative strategies aimed at enhancing cooling efficiency and sustainability within greenhouse environments. This ongoing pursuit of innovation and refinement is essential in ensuring the continued evolution and optimization of agricultural practices in an ever-changing world.

The objective of this study is to determine the sorption isotherms and thermodynamic properties of the Deglet Nour variety of dates harvested in the Guerrara region (Algeria), through experimental and mathematical analysis following thermal treatments at different temperatures (20 °C, 30 °C, 40 °C, and 50 °C) and water activity (aw) ranged from 0.06 and 96.44 %. Specifically, we aim to establish the relationship between the water activity (aw) and the equilibrium moisture content (EMC) of the tested product. The gravimetric method using sulfuric acid solutions has been selected as the preferred technique. To model and predict the hygroscopic behavior during the processes of drying and storage, a total of nine mathematical models have been employed, namely the GAB, BET, Smith, Henreson, Halsey, Igesias, Oswin, Caurie and Peleg. The best-fitting equations were Oswin, Caurie and Peleg. The outcomes of this investigation hold the potential for identifying distinctive drying curves and establishing optimal storage conditions.

This study presents a novel, low-cost material used for solar drying of medicinal and aromatic plants, namely clay. Two solar dryers, one direct and one indirect, were designed, constructed, and experimentally investigated under identical conditions. A set of experiments was conducted under load and no-load conditions. The results show that at relatively low ambient temperatures, an optimum drying temperature of herbs of 49.6 degrees C was achieved. Additionally, at high ambient temperatures, the dryers were capable of maintaining an ideal drying environment below 50 degrees C, attributed to the good insulation provided by the novel material and forced ventilation. Both moringa and mint were dried in the two solar dryers, taking 5.33 and 8.66 hours in the direct dryer and 31 and 41.85 hours in the indirect dryer, respectively, to reach a moisture content below 10% (kg water/kg wet basis). Furthermore, a high drying rate was observed in favor of the direct solar dryer. Additionally, economic efficiency increased by 100%, favoring the use of the direct solar dryer with a low payback period of 6 months compared to 14 months for the indirect solar dryer.

The objective of this study is to investigate how different factors, such as lactic acid bacteria, prebiotics (flaxseed powder, watercress seed powder, okra mucilage), and coagulation temperature influence the final quality of curd by conducting three optimization experiments and implementing a structured experimental plan. In the first phase, milk coagulation was assessed at 45 °C with various combinations of lactic acid bacteria (probiotics) and prebiotics (powdered flaxseed and watercress). In the second investigation phase, the effects of lowered probiotic and prebiotic (powdered flaxseed and watercress) concentrations were examined at the coagulation temperature of 38 °C. We investigated the concentration of lactic acid bacteria at 3 mg/mL of milk and the effects of temperature and prebiotics (okra mucilage and flaxseed powder). We observed short milk clotting time (2 s) using the optimized mixture (0.18 mg of probiotics, 1.5 mg of flaxseed powder, and 1.147 mg of watercress powder) per 10 mL of milk. It contrasts with the classical coagulation way optimized at (5.9 and 9.5 s), which were generated at optimal temperatures of 45 and 45.7 °C, respectively. Our new mixture improves the fermentation process of camembert cheese at 38 °C. This cheese had a high flavonoid content, fewer lactic bacteria and molds, a homogeneous texture, and no outer crust, and exceptional sensory attributes such as a creamy and fluid paste. These attributes suggest its potential benefits as a dairy product for individuals with cardiovascular and gastrointestinal conditions.

This article presents the design, fabrication, and testing of a new solar dryer equipped with a tracking system. The dryer was assisted by a cylindrical-parabolic concentrator which moved along two vertical and horizontal axes. The study was conducted at El-Oued University (latitude 33 degrees 23 ' N degrees 23 ' N and longitude 6 degrees 51 ' E). degrees 51 ' E). The experimental performance evaluation involved drying 10 kg of apricots from 69 % to 8 % moisture content (wb). The thermal efficiency of the dryer was tested under no-load and full-load conditions. The results indicated that the solar dryer achieved a temperature of up to 115 degrees C at the receiver in the focal line and 70 degrees C in the drying chamber, which was sufficient for effective drying of various agricultural products. Additionally, an economic analysis further substantiates the viability of our solar dryer, showcasing a notably low capital cost and negligible electricity expenses. With a substantial difference in the cost of fresh versus dried apricots, our system boasts a reduced payback period estimated at 0.43 years. This research demonstrates the potential of using solar power to dry crops and reduce dependence on fossil fuels.

The production and marketing activity of dried agricultural products is widespread in the Saharan regions due to an antagonism created by an environment that is both favorable and restrictive, specific to this ecosystem. It is a source of food consumption that remains within reach of the poorest populations. Our study focused on diagnosing and studying the factors influencing the socio-economic and technical aspects of the production and marketing of dried agricultural products in the municipalities of the M'zab region (Wilaya of Ghardaïa). Based on a study method combining bibliographic data and the analysis of questionnaires established with all the stakeholders involved, they allowed us to highlight many issues not mastered. Its economic importance means it faces enormous difficulties related to handling, the lack of infrastructure, the inadequacy of the storage system, and the rudimentary processing techniques used. 73 % of retail salespeople had a vague idea of the techniques for processing dried products; 68% did not consider preserving their qualities worthwhile, while 9% made a commercial distinction on the physical appearance of the dried products. It was found that they managed their stocks in a mercantile manner without taking into account the quality. The study also found that 68% of retailers approved of the profitability of this activity and that 73% of them have a primary activity. Regarding educational level, 55% are illiterate and 25% have received so-called “Koranic” instruction. It emerges that 63% of retail salespeople were satisfied with their socio-economic situation and considered themselves in the social environment as “businessmen”.

The processing industry faces a significant challenge in reducing drying times for large quantities of food. To address this issue, a medium-scale direct solar dryer with a 50 kg capacity was designed and built, and its performance was meticulously assessed. The dryer was equipped with a heat recovery system (HRS) and a phase change material (PCM) that stored latent heat, specifically paraffin wax. Locally available materials were used to construct the prototypes, which underwent two sets of experiments under identical conditions. The experiments involved testing empty solar dryers and then drying tomatoes as the load. Results showed that the HRSPCM consistently maintained an average air temperature of 5 °C higher during the day and an extension of 1 to 8 °C higher for 5 h at night compared to the conventional dryer. Moreover, the HRSPCM demonstrated superior thermal efficiency over the non-improved dryer, averaging 21%. Drying tomatoes with the HRSPCM resulted in a 50% decrease in total dehydration time, reducing the moisture content from 93.5% to 13.5% in 20 h, while the non-improved dryer took 40 h for the same quantity. The study also modeled moisture transfer from tomato slices using Fick’s second law and calculated the effective diffusivity. The ‘Verma et al.’ and ‘Two-terms’ models were found to be the most suitable for describing the air-drying of the product in HRSPCM and conventional prototypes, respectively. The study demonstrated the system’s superior capacity for high-volume drying operations compared to existing methods described in the literature, providing strong evidence for its usefulness in large-scale processes.

Smart farming's primary goal is to solve the numerous problems that conventional agriculture faces. These problems relate to precision, resource optimization, and cost reduction. Our project develops an IoT system to overcome some of these challenges by optimizing resource use, improving crop yields, enabling adaptive climate responses, facilitating remote management, and promoting sustainable farming practices. The system employs an ESP32 Wi-Fi Microcontroller as the base station, communicating with sensor and actuator nodes via LoRa technology to monitor and control greenhouse environments in real-time. This three-layered architecture includes a Node Layer that provides distributed sensors and actuators for local data collection and control, a Base Station Layer for managing data transfer between nodes and the central platform, and a Platform/Connectivity Layer for remote monitoring, data aggregation, and analysis. The platform provides farmers with real-time insights to optimize resource use and crop yields, even in remote areas with limited internet connectivity.

In this study, the air temperature inside a semi-arid greenhouse was investigated. The model database was built using greenhouse climatic data from a prototype greenhouse in Algeria's Ghardaia region. Over January month, external and internal climatic data were collected in order to develop and validate models for simulating environmental conditions inside the greenhouse, such as relative humidity (RHext), total radiation (GH), air pressure (P), and external temperature (Text). The main objective of this study is to compare three deep neural network models feed forward networks (FFN), Nonlinear auto-regressive network with exogenous inputs (NARX), and recurrent neural networks (RNN-LSTM) to see which one predicted temperature changes in the environment the best. The results showed that the NARX-predicted results agreed closely with the measurements; additionally, RNN provided satisfactory results, while FFN was the weakest of the three models.