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The drying process in agriculture is energy-intensive and traditionally relies on fossil fuels, which are becoming less reliable and more expensive. This study designed and simulated a hybrid solar hot plate dryer system using the computer to reduce reliance on fossil fuels. The system's main components are a flat plate collector, photovoltaic panels, and a wind turbine. This system was simulated in three cities of Iran, including Bushehr, Kerman, and Shahrekord, from May 22 to October 23. Results showed that Bushehr had the best wind turbine performance, producing 1.35 × 109 W annually. Shahrekord was ideal for solar energy, reaching solar radiation levels of about 4540 kJ/m2hr in September and generating 6660 W of solar-heated water. Finally, by comparing the yearly yield, it was concluded that Bushehr had a higher yield than the other two cities due to its geographical location, which was 0.301. The results of this research indicated that Iran, with its sunny days and wind energy potential, will be a very suitable place for installing and operating the hot plate solar dryer system. Future studies should look at longer-term simulations, use real-time data, and consider cost-benefit analyses to improve system efficiency and applicability. [ABSTRACT FROM AUTHOR]

The drying kinetics and physical and chemical characteristics of Leucaena esculenta seed drying using a forced convection solar dryer are described. The drying kinetics behavior is examined for three experiments under climate conditions of three different winter days in central Mexico, observing significant effects related to the reported pH levels of the seeds with values of 6.34, 5.98, 5.97, 5.82, and 6.07. The airflow measurements inside the drying chamber were observed, including the geometric dimensions, color, appearance, weight, and moisture loss, and the effective diffusivity coefficient D e f f of Leucaena esculenta with values between 1.23 × 10−7 and 8.09 × 10−9  m 2 s . Solar drying, with the technology used in this study, is a viable alternative to give added value to Leucaena esculenta. This study can be the basis for developing alternatives to preserve seeds for animal and human consumption. [ABSTRACT FROM AUTHOR]

The aim of the current research is to dry apples using a solar dryer with a desiccant cycle in two modes: direct radiation -convection and indirect radiation -convection. Two types of drying methods, direct and indirect with desiccant and without desiccant, moisture content, and drying in open air were used. Pre - prepared apple slices (flavored with cinnamon) were placed on a specific -sized mesh, the initial weight of the samples was measured, and they were placed inside the solar dryer with a desiccant cycle in two modes: direct radiation -convection and indirect radiation -convection. During the drying process, the evaporation rate, texture, wrinkling, water reabsorption, vitamin C retention, color changes, and sensory characteristics at different treatment levels (30% sucrose and without sucrose, 0.5%, 1%, and 2% cinnamon) were examined. Additionally, several samples were dried as controls without cinnamon flavoring using the solar dryer. Data analysis was conducted using a completely randomized factorial design and the statistical software SPSS version 26. The results of the study showed that in both direct and indirect methods, with and without desiccant, the moisture removal rate in samples without sucrose was higher compared to samples with sucrose and cinnamon. Comparing control samples in both methods with and without desiccant moisture showed that the evaporation rate of samples with desiccant moisture was significantly higher. Furthermore, in samples with sucrose, the evaporation rate was lower in the desiccant method, and in direct sunlight drying, the drying rate was significantly lower compared to solar dryer drying. The results of evaporation rates in the indirect drying method also indicated that similar to the direct method, the evaporation rate of samples with cinnamon treatment and without sucrose was higher than that of samples with sucrose and controls. Tissue analysis results also indicated that the highest firmness was observed in the direct method without desiccant for samples without sucrose, with no significant difference in means. Cinnamon also increased the firmness in samples without desiccant moisture in the indirect drying method, and samples with sucrose had less wrinkling, with an increase in cinnamon concentration leading to more wrinkling, with the highest increase observed in the direct method without desiccant at 2% cinnamon and in the direct method with desiccant at 1% cinnamon concentration. The water reabsorption rate in both direct and indirect drying methods showed that samples with sucrose had better water reabsorption conditions, and the vitamin C degradation rate indicated that the use of sucrose improved vitamin C retention. Color change analysis also showed that samples with sucrose had more favorable conditions in both methods. Therefore, the results related to sensory evaluation characteristics indicated that samples with sucrose and different cinnamon concentrations received the highest sensory evaluation scores. Hence, it can be stated that samples dried with osmotic solution and sucrose generally had better acceptability in terms of physical appearance, color, taste, and flavor . [ABSTRACT FROM AUTHOR]

Evacuated tube solar collector (ETSC) has gained significant attention due to its high thermal efficiency and ability to harness solar energy more effectively as compared to flat plate solar collector. The present review analyzed the in-depth mechanism of analytical modeling of ETSC, different factors influencing the performance, and applications in drying of Agri-commodities. Evacuated tubes with and without heat pipes are used for air heating purposes. ETSC with tracking and non-tracking, selective coating techniques, and for reducing heat loss during drying operations are reported. The system performance is greatly influenced by the ETSC design, absorber coating, heat transfer fluid, mass flow rate of working fluid, inclination or tilt angle, collector size, and distance between tubes. Moreover, Computational fluid dynamic (CFD) simulations of the various ETSC-based drying systems were compiled to investigate their flow patterns, heat transfer characteristics, and overall system performance. This literature inherently provides the way for the development of evacuated tube-based innovative and sustainable solar dryers in small and industrial scale. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive review of the most significant and recent technologies that have been integrated with solar dryers, demonstrating a notable enhancement in the performance of solar dryers. The majority of review articles in this field that have been published have concentrated on the application of solar drying for food preservation in agricultural industries. Numerous researchers have found gaps at the component level and suggested different modifications to solar thermal collectors to enhance drying efficiency. Various technologies that have been created and put into use have effectively and efficiently optimized the energy requirements. Nevertheless, there are not many studies that concentrate on the possible integration strategies in different industries where drying is a crucial step in the production process. This study presents a comprehensive overview of the key drying processes used in different industries to provide readers a sense of the current status of existing technologies and the on-going research being done in the topic of sun drying. To develop innovative drying systems for large-scale enterprises that can be used to other industrial settings, it has been suggested that solar drying be integrated with the current drying techniques. This paper discusses how solar energy is used in the food sector, with a focus on solar air heaters and how they are integrated into solar drying processes. This will help industries and researchers make the drying process compatible with solar energy. This study also offers an alternative viewpoint by examining and contrasting solar dryers based on the many designs that are employed, as well as strategies to increase the solar dryer's efficiency, shorten its drying time, and improve its overall performance. Additionally, this study shows how various solar drying methods such as using gravel, sand, paraffin wax, etc. affect the rate at which moisture is removed based on sensible and latent heating. [ABSTRACT FROM AUTHOR]

Cardamom, also known as the "Queen of Spices," is the world's oldest recognized spice with a high market value for its dried final product. In this work, the drying kinetics of small cardamom (cv. Njallani) has been studied using a solar and a heat pump dryer. Before drying, the produce was pre-treated in sodium carbonate (Na2CO3) at 1%, 2%, and 3%. The treated small cardamom samples are dried as a single and double layer at 40, 45, and 50 °C. The maximum temperature observed inside the solar dryer is 80 °C, resulting in a faster drying rate than the heat pump dryer but poor quality and greenness ((a*) − 0.8 to − 3.25) even after being pre-treated with Na2CO3. The heat pump dryer showed a constant and falling rate drying period at all the temperatures, with the highest drying rate at 50 °C. It required at least 12 h to dry the cardamom samples from 455.5 to 10.2% moisture content as a single layer. The temperature and the bed thickness have the maximum influence on the water activity of dried cardamom (0.54–0.64). A higher greenness value and essential oil percentage are obtained from the small cardamom dried in the heat pump dryer at 45 °C.The COP and SMER are found best at 50 °C. Four different models are used to predict the moisture ratio curve of the dried cardamom, with the quadratic model having the highest R2 value. [ABSTRACT FROM AUTHOR]

Tea is an important industrial crop. It is the second most popular among all the drinks. The drying operation in the tea industry fulfills the aim of enzyme inactivation and reducing the moisture content to the desired level. The energy consumption in drying operation in the tea industry is mostly in the form of thermal energy. Drying consumes a greater amount of energy than other processes in tea industries. Thermal energy needs are met mainly through fossil fuels. Renewable energy sources such as bioenergy and solar energy are also being adopted but at the minute level. Further, addressing problems such as stewing and case hardening (arises due to improper drying conditions) during drying is necessary to avoid quality loss. In this study, mass transfer modeling of drying of crush tear curl (CTC) tea particles is conducted considering natural convection around the tea particle. A finite difference method with an explicit scheme is used to solve the equations for mass transfer modeling of drying. The effect of drying air temperatures on moisture content, moisture ratio, and drying rates are computed. Drying air temperatures such as 80, 90, and 100°C have not shown effective drying. However, drying at air temperatures of 110, 120, and 130°C are recommended for drying times of 1500 s, 1200 s–1500 s, and 1200 s, respectively. Additionally, the effect of the size of the particles is studied and the lower size of tea particles is recommended for better drying characteristics. The current drying model can be used for single tray/conveyor dryers and indirect natural convection single tray solar dryer. Practical applications: The present research work demonstrates the important information for the hot air drying of CTC tea particle in single tray dryer. The drying modeling results can be used to set the proper temperature level of drying air being sent inside the dryer to avoid the under and over‐drying of tea particle and achieve the desired level of moisture content in the tea particle. Thus, the present study helps in deciding drying conditions such as drying temperature, drying duration for CTC tea particle in single tray dryer, slow speed conveyor dryer, and also in indirect natural convection single tray solar dryer. [ABSTRACT FROM AUTHOR]

Solar dryers are a convenient option for drying fruits and vegetables, but they largely depend on climatic conditions. Climate dependency makes them vulnerable to dry products and maintain the quality of the products accurately. To mitigate this problem, an electric auxiliary heating system (AHS) was designed, constructed, and tested for a solar dryer in Bangladesh. The developed system had three parts: an auxiliary heating unit, an air duct, and hot air convection pipes. The performance testing of the AHS was done in three experimental trials. The average air velocity from the auxiliary heating unit was found to be between 3.57 and 3.80 m s−1. Trial runs showed a maximum drying temperature of 66.97°C, while the average value remained between 35.10 and 43.26°C. During the off‐sunshine hours, the AHS rose the average temperature by 1.00–12.84°C above ambient and continued the drying operation. Overall, the solar dryer with AHS saved 30%–36% sunshine hours than open sun drying, and its efficiency was estimated as 14.55%–21.9%. Regression analysis showed that the Page and Modified Page models were suitable for predicting the drying kinetics of cabbage samples. Through the results of the study, the developed AHS showed potential for significantly improving the solar drying process. It could be an effective measure for establishing a weather‐independent drying solution to reduce the postharvest losses of perishable agro‐products. Further improvements to the auxiliary heating unit, implying an Internet of Things (IoT)‐based control system will facilitate an improved and user‐convenient drying operation. Practical Applications: Postharvest losses are prevalent for perishable agricultural products (fruits and vegetables) in Bangladesh and are considered a prime reason for the inhabitants to consume a less nutritious diet than recommended. An appropriate dry chain technology that is affordable, weather‐independent, continuous, and fast in operation could be the optimal solution to this problem. Numerous types of solar hybrid dryers with different additional heating sources (electricity, biomass, LPG, etc.) have been investigated around the world. However, the extent of these research endeavors is very limited in Bangladesh. The study was thus conducted to develop a novel auxiliary heating system for a solar dryer in Bangladesh and check its technical viability. Our results indicate that an electric auxiliary heating system can be an efficient option for drying fruits and vegetables irrespective of the weather and can substantially reduce postharvest losses in Bangladesh. [ABSTRACT FROM AUTHOR]

The application of solar dryer through greenhouse (GH) model as drying method for crops-based product is extremely important in industrial scale agriculture, especially in developed country. The drying model is considered environmentally friendly since it utilizes solar power as the main drying energy. However, the fundamental operational aspect of the basic GH is less discussed according to the drying mechanism of the dried product. In this work, three small-scale drying model are evaluated: open drying (OD), natural convection GH (NCGH), and forced convection GH (FCGH). The drying product is potato, which can be taken as an essential agricultural product in modern world. The OD model has the lowest mass loss rate which less than 50 % of the water from product can be evaporated. The operation of both GH is satisfactory, resulting more than 60 % moisture evaporation. The drying characteristic indicates the two-step failing rate which makes the mass loss fluctuation from the process. The highest mass loss is observed during the constant rate period around 21 % for FCGH and 18 % for NCGH. In addition, the detailed analysis on the effect of each process is discussed in this work. For example, the presence of hair-like structure and the movement of the pith of dried potato during the process. Also, a higher drying rate from NCGH and FCGH initiate the gelatinization and compartmentalization, resulting a substantial water evaporation of the product. It confirms the important correlation of the drying process and water diffusion mechanism of the dried product. The finding from this study can be taken as a vital reference for improving the operation of GH solar dryer. [ABSTRACT FROM AUTHOR]

Drying process has been employed since ancient times to preserve agricultural products by reducing the moisture content. Solar dryer is one of the most commonly used dryers due to its availability, reliability, and environmentally friendly nature. It is practical in rural areas since solar dryer can be fabricated with a simple design. Despite its potential, designing a long-term, feasible solar dryer is challenging without a good understanding of its performance parameters, such as energy, exergy, economic, environmental (4E) aspect, and its impact on product quality. Therefore, many attempts have been dedicated to conducting these analyses. Nonetheless, the information obtained is only one-dimensional, and they do not reflect the actual behaviour of a solar dryer. This paper aims to provide a comprehensive and critical review of the additional 3E parameters, namely energoeconomic, exergoeconomic, and enviroeconomic. Moreover, the effect of solar drying on product quality parameters (Q) will be discussed. Furthermore, a new idea to perform energy, exergy, environmental, economic, energoeconomic, exergoeconomic, and enviroeconomic (7E) and quality analysis (7E + Q) is proposed and outlined to improve the operability of the solar dryer. It is envisaged that 7E + Q analysis will pave the way for more effective and efficient solar dryers. [ABSTRACT FROM AUTHOR]

Fruits and vegetables are an important part of human diet. In the present study, the thermal performance of a solar greenhouse dryer for drying Solanum lycopersicum (Tomatoes) was analyzed. The drying pattern at various locations of the drying chamber and different levels of the dryer was evaluated. The life cost analysis for drying the tomatoes in the dryer for 25 years of service was evaluated. The greenhouse solar dryer was developed with a structure base of galvanized iron pipes and a covering of a 2 mm thick polycarbonate sheet. The experiment was carried out for drying the tomatoes at various locations in the dryer using the trays and trolley system. The maximum thermal efficiency of the dryer is 26.66 % while drying out 5.8 kgs of tomatoes in one day. The economic analysis of the greenhouse solar dryer shows that the payback period of such a system can be attained in only 1.6 years which terms the dryer feasible and economically viable in the current agro-drying market. The embodied energy for the dryer was calculated at 3154.71 kWh for the system. The CO2 emission for the greenhouse solar dryer was found to be around 6.62 tonnes for a lifespan of 25 years. The net CO2 mitigation was calculated at around 41.62 tonnes which would generate an earning from 46766 INR to 62355 INR worth of carbon credits. [ABSTRACT FROM AUTHOR]

The world population is more than 8 billion and about 20-25 percent people does not have enough food to eat. It has been estimated that world as a whole more than 30-50 percent vegetables, fruits etc. are lost before it reaches to the consumers. To overcoming spoiling problems of vegetables and fruit; various preserving methods are used and renewable sources are best for this purpose by which we can save energy for preservation and keeping the product in their natural flavor by drying it. Drying is one of the oldest methods of preserving food. The solar drying system utilizes solar energy to heat air and to dry any food substance. It brings about a substantial reduction in weight, volume, minimizing packing, storage, and transportation costs, and enables storability of the product under ambient temperatures. This paper present the Construction of Continuous solar dryer which can be used for drying various fruits and vegetables products in rural areas under hygienic conditions. The Continues solar dryer was constructed consisting of a solar collector cum drying chamber. The overall dimension of the continues solar dryer is 1830x300x620mm and the drying chamber was painted black to absorb maximum solar radiations. The glass was covered, it permits the solar radiation into the system but resists flow of heat energy out of system and product were moving continually from inlet to outlet through chain conveyors. This chain conveyors was connected to the Rollers and the roller was connected to belt pully to reduction motor and VFD to control the chain conveyor from inlet to outlet to dry the product at required moisture content. [ABSTRACT FROM AUTHOR]

This research addresses the improvement of the performance of a solar dryer equipped with a PVT unit by integrating a heat exchanger into the drying system. The results indicated that introducing a heat exchanger into the drying process had a positive impact on enhancing and raising the drying temperature by harnessing the amount of free energy dissipated after the drying operation. The absorbed energy ranged from 30 J/s to 275 J/s from the hot air emitted throughout the drying process during the day, depending on the drying temperature. This paper also discusses the influence of the drying room design on the thermal balance within the room. Consequently, four different designs for the drying room were developed and studied with the COMSOL software. The findings revealed that the design-4, which optimally places two air inlets (one at the bottom and one at the top) on one side, whereas the opposing side has a centralized air outlet, utilizing a fan to ensure effective air circulation, is the best solution in terms of thermal balance and distribution of the drying air inside the drying chamber. [ABSTRACT FROM AUTHOR]

Fruits and vegetables are nutritious and good in minerals, vitamins, and fib. Most fresh fruits and vegetables contain a minimum of 70% of moisture content which causes the formation of bacteria, fungi, and viruses to affect and cause the items to rot. But dried fruits contain only less than 20% of moisture content. So drying the fruits and vegetables helps to preserve the items for longer use without causing them to rot. Dried fruits have a great source of antioxidants and help in health benefits like improving blood flow, and reducing the effects of many diseases. Compared to fresh fruits, dried fruits are good in nutrition and have less weight for packaging and transportation usage. For drying materials, various types of solar dryers are used. Natural or open sun drying methods comparatively consume more than 12 h to dry material, whereas, direct and indirect drying methods would enhance the efficiency and dry the products quicker than open drying. For the consideration of quality drying and to increase efficiency, various modifications of solar dryers are designed and fabricated. In this review, we discussed the most appropriate developments in the drying of food items, required phase change materials (PCMs), performance, and environmental analysis of SD, and also reported the various designs of the solar drying techniques. [ABSTRACT FROM AUTHOR]

The assessment and enhancement of any drying system for optimal drying processes relies on critical parameters, namely moisture diffusivity and activation energy. In this study, medicinally beneficial kohlrabi of 40‐mm diameter and 6‐mm thickness samples were dried under three different drying methods, namely open sun drying (OSD), natural air‐circulation mode (NACM) single slope direct solar dryer (SSDSD), and forced air‐circulation mode (FACM) SSDSD. The experimental results showed that the drying chamber operating temperature and air velocity played significant roles in the moisture diffusion process and activation energy required to dry the kohlrabi sample. The FACM exhibited the highest average moisture diffusivity values at 7.29 × 10−10 m2/s, surpassing both NACM (5.65 × 10−10 m2/s) and OSD (3.28 × 10−10 m2/s). The activation energy needed for the drying process was the lowest in FACM at 27.44 kJ/mol, followed by NACM at 31.37 kJ/mol and OSD at 35.29 kJ/mol. This is due to the uniform temperature distribution and high airflow rate in the case of FACM. Additionally, 10 thin‐layer models were tested for all three experimental conditions. The statistical analysis showed that for OSD and NACM, the Midilli et al. model, and for FACM, the Page model was best suited for representing drying kinetics with lowest χ2 and root mean square error and highest R2 values. Furthermore, the energy and exergy assessment guaranteed an evaluation of the solar drying system's efficiency. Practical applications: This research provides valuable insights into optimizing solar drying methods for kohlrabi preservation. Understanding how temperature and air velocity influence moisture diffusivity and activation energy allows practitioners to enhance drying efficiency. Forced air‐circulation mode (FACM) single slope direct solar dryer (SSDSD) emerges superior, with higher moisture diffusivity and lower activation energy. The study also identifies appropriate drying kinetics models for each method, aiding the accurate prediction of drying behavior. Emphasizing efficiency, the research highlights FACM's superior thermal efficiency and natural air‐circulation mode's higher exergetic efficiency. These insights empower practitioners to make informed decisions, potentially improving agricultural product preservation, reducing energy consumption, and promoting sustainability. Moreover, the research's findings hold significant implications for industrial food processing and preservation applications, suggesting the direct implementation of optimized solar drying techniques in large‐scale settings for kohlrabi and similar agricultural products. [ABSTRACT FROM AUTHOR]

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The paper proposes a solar collector with sensible heat storage materials for crop drying applications. The materials used were pebbles and gravels. The experiments were conducted under the meteorological conditions of Ujire, Karnataka, India. The bed thickness of pebbles and sand was 20 cm, and air velocity for pebbles and sand as absorbers was 4 m/s and 2 m/s. The experiments were started at 9 o'clock and stopped at 17 o'clock; for every one-hour interval, readings were recorded. Experimental and theoretical heat transfer analyses were carried out and the results were discussed with the help of characteristic curves. The collector with pebbles as absorber showed better performance than the collector with sand as absorber. This is due to surface roughness and higher Reynold's number. The maximum theoretical and experimental values of temperature resulted for pebbles were 344 K and 321 K, and for sand 334 K and 322 K, respectively. The average theoretical efficiency obtained with pebbles as absorber was 39%, and for sand 28.5%. The average value experimental efficiency with pebble as absorber was 25%, and for sand 11%. The developed collector system with pebbles and sand as absorber provides moderate temperature heat and is best suited for drying of crops. [ABSTRACT FROM AUTHOR]

Aloe Barbadensis Miller, commonly known as Aloe vera, has been widely used in different applications, such as medicinal treatments and cosmetic products. However, its transportation and handling present challenges due to oxidation and property loss caused by direct environmental exposure. A strategy to mitigate these effects is dehydration, where different industrial-scale methods such as freeze-drying, spraying, refractory windows, and convective drying can be applied. Despite their effectiveness, those dehydration techniques are both energetically and economically costly. Solar drying technology offers a cost-effective, lower-energy alternative addressing sustainability, socioeconomic, scientific progress, and integrated sustainable development challenges. Nevertheless, solar drying through direct sunlight exposure has been minimally explored for drying high-water-content products like Aloe vera, potentially due to the inherent challenges of drying under uncontrolled environmental conditions. In response, this paper introduces a methodology for pre-treating and pre-drying Aloe vera gel using a low-cost solar dryer prototype, achieving up to 50% water activity reduction in experimental tests under uncontrolled conditions in Colombia, South America. The proposed prototype features a drying cabinet with energy autonomy and forced convection. The experimental evaluation compares the quality of pre-dried Aloe vera gel with freeze-dried samples, demonstrating comparable attributes under favorable environmental conditions. The results demonstrate the feasibility of pre-drying Aloe vera gel within 13 to 48 h, with a maximum drying rate of 0.38 g/min. During this process, water activity decreased from an initial value of 0.975 to a final value ranging between 0.472 and 0.748. Furthermore, the quality of the dehydrated gel was assessed through color analysis, comparing it with a freeze-dried sample. Subsequent color analysis of the freeze-dried samples revealed minor changes in product quality compared to those dried using the proposed solar drying method. These results demonstrate the effectiveness of the proposed solar dryer in pre-dehydrating Aloe vera gel, yielding characteristics similar to those achieved through conventional methods. [ABSTRACT FROM AUTHOR]

Uneven drying is the key drawback of a conventional multi-tray dryer. Therefore, an improved active solar dryer with and without integrated sensible heat storage (SHS) was proposed. A unique feature of this dryer is its movable walls from the sides of the dryer to transform it to an indirect or mixed-mode as and when necessary. Garcinia Pedunculata (GP) is a local seasonal medicinal fruit in Northeast India. Drying kinetics of GP, the dryer performance and economic analysis of dryer were evaluated in the indirect solar dryer without SHS (Exp. I), mixed-mode solar dryer without SHS (Exp. II), indirect solar dryer with SHS (Exp. III), mixed-mode solar dryer with SHS (Exp. IV), and open sun drying (OSD). The dryer's average efficiencies were 18.12%, 22.37%, 21.74%, and 24.46% for Exp. I, Exp. II, Exp. III, and Exp. IV, respectively. The moisture content of GP was reduced to 12.09% in wet basis (w.b.) from 87.99% (w.b.). The overall drying time for Exp. I, Exp. II, OSD, Exp. III and Exp. IV were 31, 26, 53, 28, and 10 h, respectively. From the eleven drying models, the Two-Term model was the best-fitted model for Exp. I, Exp. II, OSD and Exp. III, and Midilli and Kucuk model was for Exp. IV. The final product's fragrance and colour are better for Exp. IV. Developing this dryer for Exp. I, Exp. II, Exp. III and Exp. IV, the price required was around 25,000, 27,000, 26,000, and 28,000 INR (1 US$ = 74.57 INR), respectively, while the economic payback periods are 1.6 years, 0.9 year, 1.4 years, and 0.59 year, respectively. [ABSTRACT FROM AUTHOR]

Open sun drying is the predominant process used for food preservation by smallholder and subsistence farmers (SHSFs), and their families, globally constituting about 2 billion people on about 475 million farms. The major problems with this process are the slow, unreliable speed of completion, rain-caused loss of vital food sources, risks from mycotoxin accumulation, environmental contamination, and loss of nutritional quality. SHSFs represent the poorest and least educated human demographic, whose survival is largely ignored by Governments, untouched by international aid programs, and with limited access to basic utilities. Solar drying systems can greatly improve the preservation of safe and nutritious food, but current systems deployed put this technology beyond the reach of the demographic which needs it most. Here, our objective was to develop the technology for the simplest low-cost drying system, which would minimize all risk factors, particularly eliminate mycotoxin accumulation, and which could be practically deployed by SHSFs. [ABSTRACT FROM AUTHOR]

Drying is one of the crucial processes in agricultural production, especially in grain processing. The drying process can improve grain quality and affect the grain content. However, maintaining the temperature is a challenge in the drying process. Because it can influence the drying performance and produce a low-efficiency reduction of water content, in this study, the hybrid drying system is proposed to improve the performance of the forced convection dryer system. The proposed system used a proportional integral and derivative (PID) control system to obtain the optimal temperature. The proposed system was compared with natural drying and forced convection methods. The experimental result showed that the proposed system performed excellently for three performance evaluations. The average temperature was obtained as the highest of the other methods, with 54.68 °C and 54.55 °C for coffee and cocoa beans. The water content can be reduced by an average of 27.38% and 42.67% for coffee and cocoa beans. Then, the proposed system also had the highest reduction efficiency of water content than the other methods, with 62.71% and 36.94% reductions for coffee and cocoa beans, respectively. The results indicate that the proposed hybrid system performs better than the other methods. [ABSTRACT FROM AUTHOR]

Drying is the process of moisture removal which is applied to many foodstuffs including fruits and vegetables for preservation and storage purposes. Since solar energy is one type of environmentally friendly renewable energy, open-type solar dryers, natural convective type solar dryers and greenhouse type solar dryers were designed and fabricated in this study for the preservation of fruits and vegetables. A comparative study among various solar drying methods was performed to study the drying performance by maintaining the quality and texture of the dried foodstuffs. Factors such as solar radiation, ambient temperature, moisture in the air, materials used for glazing, inclination, etc., were considered during the fabrication of the solar dryer so that a better estimate of the performance of the solar dryer could be obtained. The lowest drying rate was observed when convective drying was used as an indirect mode of heating. The maximum drying rate observed in open drying was 0.088 kg/kgh, whereas in convective drying under the same conditions, it was 0.03 kg/kgh, which was almost 65% less. This in turn also resulted in the dried samples displaying a better texture and better color. The shrinkage effect on the samples was less pronounced for those samples in the convective dryer than it was for those in the open and greenhouse dryers, as the method uses indirect drying. Comparing convective and greenhouse drying, more shrinkage and a greater browning effect were observed for the open drying method. Out of three types of solar dryers, the greenhouse dryer was selected to study thermal performance because of its better drying rate. DHT11 sensors controlled through Arduino programming were employed in this study to record the temperature and moisture at various locations in the greenhouse dryer setup. The range of energy efficiency of the greenhouse solar dryer was estimated to be from around 15% to 25% on average. This might be due to a greater extent of energy losses. No significant difference was observed in the energy efficiency with respect to the samples used for drying. [ABSTRACT FROM AUTHOR]

In geopolymer bricks (GPBs), fly ash content, which is waste from power plants, is converted into bricks by chemical treatment. GPBs can be dried by using appropriate curing methods. Conventionally, electric oven curing is one of the prominent methods. Using a solar dryer instead of an electric oven provides the added advantage of saving high-grade electrical energy. So, in this work, a solar dryer with the phase change material (PCM) paraffin wax and without a PCM is used for curing applications. GPBs gain an added advantage when compared to conventional bricks like cement and sand bricks in terms of strength. A GPB has been taken as a specimen for comparing the compressive strength, tensile split strength, and flexural strength of electrical-energy-based curing and solar-energy-based curing. It has been experimentally observed that solar-energy-based curing with and without a PCM exhibits higher compressive strength, higher tensile split strength, and flexural strength when compared to electrical-energy-based curing. Solar curing with a PCM shows higher compressive strength, higher tensile split strength, and higher flexural strength when compared to solar curing without a PCM. Open solar curing is a traditional technique, but nowadays, aggressive climatic conditions can lead to severe damage to geopolymers. The novelty of this work is the study of the effect of PCMs like paraffin wax in solar drying on the curing time and the mechanical properties of GPBs. [ABSTRACT FROM AUTHOR]

The preservation of perishable foods through their transformation is always a major challenge for producers. Several methods are applied for this purpose, and progresses are recorded by improving these processes or by finding new means. In our work, the method of dehydration and natural drying of tomatoes using a natural dryer with indirect solar energy with air circulation by extractor is used to describe and then predict the process of obtaining the finished product in the form of tiny dried fragments or powder. This is the novelty of this research, which uses the unconventional design of experiments. This consists of finding a mathematical model based on the interaction of 3 parameters that interact with each other, namely the trays temperature, the drying speed and the relative humidity in the solar dryer. The interference of the values of one of these 3 parameters on the 2 other parameters acts directly on the result of the drying process. The matrix treatment of the data of several carried out experiments in the resolution of 13 equations gives us the required responses and permits us to draw the graphs, the contours and the responses surfaces that access us to a more detailed analysis. [ABSTRACT FROM AUTHOR]

This research presents the prediction of temperatures in the chamber of a solar dryer using artificial neural networks (ANN). The dryer is a forced-flow type and indirect. Climatic conditions, temperatures, airflow, and geometric parameters were considered to build the ANN model. The model was a feed-forward network trained using a backpropagation algorithm and Levenberg–Marquardt optimization. The configuration of the optimal neural network to carry out the verification and validation processes was nine neurons in the input layer, one in the output layer, and two hidden layers of thirteen and twelve neurons each (9-13-12-1). The percentage error of the predictive model was below 1%. The predictive model has been successfully tested, achieving a predictor with good capabilities. This consistency is reflected in the relative error between the predicted and experimental temperatures. The error is below 0.25% for the model's verification and validation. Moreover, this model could be the basis for developing a powerful real-time operation optimization tool and the optimal design for indirect solar dryers to reduce cost and time in food-drying processes. [ABSTRACT FROM AUTHOR]

Food industry being one of the world's largest energy intensive industries, lack of proper preservation and storage techniques have led to huge amount of food losses and wastage. Dehydration of food and vegetables has been an effective technique of preservation as this reduces post-harvest losses, make them easier to transport, store and can prevent the growth of microbes. Abundant solar energy being available for free of cost, solar drying is desirable in terms of environment friendliness, economic benefits and is compatible for remote locations. Solar dryers optimize this process with efficient utilization of solar energy and provides higher quality products. Different configurations of solar dryers with diverse configurations and applications have been designed and implemented over the years. Based on the difference in supply and utilization of solar energy, the most prominent solar dryer configurations are direct and indirect solar dryers. This work intends to review the features, design and performance of existing direct and indirect solar dryers. Major challenges such as intermittency and unsteady availability of solar energy has been addressed through thermal energy storage by many research studies, which has also been effectively reviewed. Materials used for construction, design constraints, thermal energy storage integration and experimental results have been discussed and tabulated. The review revealed highly efficient solar collectors such as tube type absorber and evacuated tube collectors, solar concentrators employed dryers capable of achieving elevated temperatures, greenhouse and solar tent dryers with huge capacity and novel dryer and collector designs of superior performance. Various integration techniques of different thermal energy storage materials and their enhancement in performance were eminently observed in the review. As a source of technological attributes and constructional features, this review paper intends to aid the development of solar dryers and food preservation employing renewable energy. [ABSTRACT FROM AUTHOR]

In the present work, performance of solar dryer having evacuated tube collector was enhanced by artificial roughness with circular rib for agricultural applications. The influence of roughness geometry parameters i.e. relative roughness pitch (P/e) of 12 and relative roughness height (e/Dh) of 0.057 on Nusselt number and friction factor has been investigated. Reynolds number considered for investigation varied from 2500 to 8000. Rughened solar evacuated tube collector performed better than smooth solar evacuated tube collector. Nusselt number augments with the increase in Reynolds number while friction factor shows an opposite trend with increase in Reynolds number. Maximum enhancement ratio of Nusselt number and friction factor is 1.54 and 2.43, respectively, obtained at Reynolds number of 8000. The value of thermo-hydraulic performance parameter for circular rib roughened solar evacuated tube collector varied between 1.09-1.15 over the entire range of Reynolds number. [ABSTRACT FROM AUTHOR]

Solar energy provides desired thermal energy for diverse applications, including industrial heating, domestic cooking, power generation, desalination, and agri-food preservation. Despite extensive research on solar drying from the scientific community, there are limited practical applications for small-scale use. This review attempts to analyze the design features of three specific types of dryers for food drying applications: solar evacuated tube dryers, biomass dryers, and hybrid solar dryers. The thermal performance of the three dryers is evaluated in terms of drying time, moisture removal, and temperature attained during drying. The review also assesses the prospects of solar dryers, highlighting the need for further research into innovative designs and advanced drying capabilities. The study provides valuable information for enhancing dryer performance with various integrated solutions. [ABSTRACT FROM AUTHOR]

Due to the expansion of residents, the consumption of non-renewable energy increased enormously, thus indirectly increasing pollution and affecting the surroundings. To reduce pollutions in the surroundings, it is recommended to choose non-conventional energy sources. By satisfying this, we can probably decrease the non-renewable sources of energy, by consuming the solar power in day-to-day life in the application of food drying process. In this review article, we have discussed the classification of solar dryer and the impact of design modifications performed in the components of solar dryer and assessed the various types of solar dryer performance, cost estimations and designs performed in solar dryer of food applications which were not discussed in the earlier research. The primary and critical task in designing the solar dryer is to achieve higher efficiency at minimum cost. Hence, proper analysis of drying application, selection of suitable components and suitable design must be carried out to attain efficient dryer. Considering these characteristics, this paper primarily focuses on the effective design parameters incorporated with various efficiency enhancement processes of the solar dryer in the applications of food drying techniques. Thus, this review paper delivers the various classifications, design parameters, performance enhancement methods, properties and valuable assets of solar dryer, which helps to develop the sustainable green eco-friendly environment most primarily, in the application of food drying process. This review article concreted the way for upcoming considerations and provided the techniques for the studies to convey the work for promoting method enhancements. [ABSTRACT FROM AUTHOR]

In the central jungle region of Peru, within the wet processing of coffee, the coffee pulp is discarded. This objective is to design a dual solar and gas dryer with continuous operation, for the dehydration of waste from wet processing of coffee for human use. The proposed objective is part of a broader project to apply the circular economy in the use of waste from wet coffee processing financed by Pro Ciencia. The following procedure was followed. At first, a 100 kg/Bach capacity gas and solar system dryer was designed applying the proposed technology development methodology in mechanical engineering and secondly arriving at the construction of the prototype. The results are to have a design methodology and the built prototype of the dual dryer (solar and gas) of continuous and semi-automated operation that has a control panel to allow programming and monitoring the drying process in real time. At the end of the project, the proposal will allow a continuous dehydration of the coffee pulp with quality, low cost and the industrialization of its by-products such as coffee pulp flour, filters and functional drinks. [ABSTRACT FROM AUTHOR]

The heat and moisture sensitivity of spices and a consistent supply of electrical energy is the challenging factors in developing a relevant drying system for rural applications. A novel solar‐assisted fluidized bed dryer was developed for drying locally harvested unique spices like bird's eye chili (Capsicum frutescens L.). The chili was pretreated by the osmosonication method prior to drying to expedite the elimination of intercellular and intracellular moisture. In order to make the dryer more reliable, the recirculation strategy and dehumidified air supplied by liquid desiccant were acclimatized to constrict the heat loss through outflowing moist drying air. The experiments were conducted up to the permissible water activity (0.4–0.6) under variable drying conditions (50–70°C). By raising the ambient inlet temperature (maximum 25.9°C), the developed solar FBD was able to supply the drying air up to 50°C (in continuous mode) and a maximum of up to 65°C without aiding any heat energy sources except solar. It was found that osmosonication opened up the possibility of reducing the required drying temperature (↓10°C) and energy consumption (up to ↓31.7%). The dried red chili was fortified by pretreatment, as it could retain more capsaicin (>6%) and reddishness (>5%) compared to untreated samples. The Fourier transform infrared (FTIR) analysis showed the structural integrity of pretreated samples. The relative humidity of the drying air could be reduced by as much as 5% using the composite lithium chloride and calcium chloride (35% + 5%) desiccant dehumidifier. Dehumidification of air was found advantageous, with an inclination to shorten the drying duration (about ↓0.5 h) and energy (↓12.43%). Practical Applications: There are various commercially valuable unique agro‐products that are exclusively being produced in rural areas. The inaccessibility of relevant drying technology and inconsistency of grid electricity are the main constraints in the value addition of those products. Open sun drying is most popular in rural areas; however, it is not reliable, and the product quality can't maintain. The developed solar‐assisted fluidized bed dryer utilizing dehumidifying air and integrated with osmosonication pretreatment could be a relevant technology for drying heat and moisture‐sensitive products like spices. Cost‐effective drying using locally accessible solar energy compared to open sun drying and superior dried product quality can be achieved by using the current drying system. [ABSTRACT FROM AUTHOR]

Agriculture contributes to large export earnings for many countries and provides food all over the world. However, most agricultural products need some post-harvest processing, such as drying, to extend their shelf life while still maintaining their respective nutrient quality. One popular post-harvest processing method is drying using solar energy. It is a type of renewable energy that is abundant and free. Conventional dryers use grid electricity and can be expensive to operate. Consequently, there is a growing need for cost-effective solar-powered agricultural dryers that is reasonable for smaller-scale farmers. Although current solar dryers are still not on par with modern electricity-powered dryers, solar dryers have lower running costs and are sustainable and able to generate electricity. They can also be used practically anywhere with abundant solar energy. As numerous solar drying technologies have been proposed over the past decade, it is necessary to assess the current state of solar drying technology in the agricultural sector to identify current advancements and potential research gaps. In this paper, a review of existing solar dryers mechanism and the state of the art of solar drying technology research for agricultural products is presented. [ABSTRACT FROM AUTHOR]

Solar drying represents an attractive way to implement an efficient and green development strategy. The viability of open sorption thermal energy storage (OSTES) can compensate for the inherent shortcomings of intermittency and instability of solar energy for ensuring the continuity of the drying process. Nevertheless, the existing solar-powered OSTES technologies only allow a batch mode while being severely restricted by sunlight's availability, thereby heavily limiting the flexibility in managing OSTES on demand. Herein, a novel proof-of-concept that a standalone solar dryer integrated with a reversible solid-gas OSTES unit is presented. Using in situ electrothermal heating (in situ ETH) could rapidly release adsorbed water of activated carbon fibers (ACFs) in an energy-efficient manner to achieve a charging process with faster kinetics. Applying electrical power by a photovoltaic (PV) module, particularly during sunlight-absent or insufficient time, allowed multiple OSTES cycles to proceed. Moreover, ACFs cylindrical cartridges can be flexibly interconnected in either series or parallel, forming universal assemblies with well-controlled in situ ETH capacity. The mass storage density of ACFs with a water sorption capacity of 570 mg/g is 0.24 kW·h·kg-1. The desorption efficiencies of ACFs are higher than 90%, corresponding to 0.057 kW·h maximum energy consumption. The resulting prototype can diminish the fluctuation of air humidity along the night and provide a relatively steady and lower air humidity for the drying chamber. The energy-exergy and environment analysis of the drying section for both setups are estimated, respectively. [ABSTRACT FROM AUTHOR]

This present work deals with experimental investigation of photovoltaic thermal collector design and development with solar dryer (PVTCSD). An solar experimental investigation is done on coriander seeds by natural, forced and open sun drying to estimate different parametric investigations such as solar radiation intensity, removal of moisture and the air outlet in the collector. Solar radiation is utilized as a source of energy to propel the photovoltaic thermal collector dryer; which was analysed in a drying testing chamber temperature in the range of 32°C to 59°C to dry 4 kg of coriander seeds. From the experimental study, it was understood that coriander seeds posses much more starting moisture 68% by weight and also the results proved that final moisture content has been decreased by 9% by weight during six bright days in the month of May 2021. The PVTCSD was used during the 9 a.m. to 4 p.m. In terms of understanding PVTCSD, solar sun drying with the forced convection achieved superior results than other two modes of operation. [ABSTRACT FROM AUTHOR]

The drying process is considered an effective technique for preserving foods and agricultural products from spoilage. Moreover, the drying process lessens the products' weight, volume, and packaging, which prompts a reduction in the products' transportation costs. The drying technique with solar energy represents an ancient method, still alluring due to solar energy abundance and cost‐effectiveness. In this article, the previous manuscripts concerned with studying and analyzing indirect solar dryer systems that utilize innovative solar air heaters (SAHs) are reviewed. The results and conclusions are discussed intensively to clarify the significance of utilizing this type of drying technique. The effect of many parameters on the thermal performance and efficiency of the dryer systems has been investigated. The investigated parameters included the incident solar radiation, air flow rates, outlet solar air heater temperature, absorber plate material, moisture content of the agricultural products, and the shape and configuration of the SAH. Moreover, the manuscript outlines the drying rate mathematical models that were used to validate the experimental findings. Based on the review, it is found that solar dryer systems with modified SAHs designs rather than flat plate SAH have considerable effects on enhancing thermal performance and efficiency. [ABSTRACT FROM AUTHOR]

Copyright of Eurasian Physical Technical Journal is the property of E.A. Buketov Karaganda University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Solar dryers are equipped with photovoltaic panels to increase energy efficiency, profitability and independency on nonrenewable energy. Also, these dryers need to be assessed from economic, environmental, and energy-exergy perspectives to determine whether the devices are cost-effective and feasible on a large scale. This study has performed energy, exergy, economic, and environmental evaluations on the newest solar dryers equipped with photovoltaic panels and photovoltaic thermal collectors. In this regard, solar dryers with hot air collectors, concentrating solar dryers, photovoltaic thermal dryers, infrared, greenhouse, and heat pump solar dryers equipped with photovoltaic panels and photovoltaic thermal collectors were investigated. Then, studied dryers were categorized. Initially, this classification was carried out regarding the dried products and subsequently, their economic-environmental and energy-exergy were compared. Despite the short drying time of infrared and heat pump solar dryers, these dryers' construction and energy costs are relatively high. Comparatively to other solar dryers, concentrating solar dryers have high energy efficiency and short drying times. [ABSTRACT FROM AUTHOR]

India like other developing countries adopts many food preservation technologies using fossil fuels. But the fossil fuel resource depletes over the years and is non-renewable. Therefore, solar drying technology is preferred as a sustainable method for food preservation. The present study is aimed at a sustainable livelihood initiative for drying fruits and vegetables through solar technology intervention using an indirect forced convection type solar dryer. Such a dryer of 15 kg capacity has been designed and fabricated for drying mangoes. Performance indicators such as instantaneous collector efficiency, drying efficiency, drying rate, COP, heat utilization factor, and moisture content on a dry basis are evaluated as 59%, 32.25%, 0.15178 kg/hr, 0.77, 0.229, and 2.55, respectively by considering maximum outlet collector temperature, drying chamber temperature and atmospheric temperature. Economic indicators such as pay-back period and cost-benefit ratio are also evaluated as 1.439 and 2.0008, respectively. The dryer can be used by rural people of Odisha for earning their livelihood. [ABSTRACT FROM AUTHOR]

In the present analysis, a novel four-mode solar dryer was developed and tested for the drying of Garcinia pedunculata. The four combinations considered were indirect-mode solar dryer without storage (ID-WOS), mixed-mode solar dryer without storage (MX-WOS), indirect-mode solar dryer with storage (ID-WS), and mixed-mode solar dryer with storage (MX-WS). The feature of this dryer that sets it apart is its capability to convert the drying cabinet into various modes simply by sliding the walls of the four sides of the cabinet. The storage system is made space efficient, by filling the gravel up to the surface of the absorber plate inside the solar air collector. For ID-WOS, MX-WOS, ID-WS, and MX-WS, respectively, the drying durations were 30 h, 25 h, 28 h, and 8 h, and the drying efficiencies were 18.55%, 24.03%, 20.32%, and 29.94%. In ID-WOS, MX-WOS, ID-WS, and MX-WS, the average exergy efficiency was determined as 47.08%, 65.10%, 52.46%, and 68.07%, respectively. Environmental impact was studied for all four cases. The energy payback periods for ID-WOS, MX-WOS, ID-WS, and MX-WS were 1.47, 1.61, 1.48, and 1.62 years, respectively. The study indicated that MX-WS outperformed the other three configurations in all aspects. [ABSTRACT FROM AUTHOR]

The paper develops a Mixed Mode Solar Crop Dryer (MMSCD) using blackcoated pebbles. The experiments were conducted in Ujire, Karnataka, India. Potato slices were used for test sample with an air speed of 4 m/s. Open Sun Drying (OSD) was used and the working temperature range of MMSCD was 36-64 o C, which is suitable for drying a wide variety of fruits and vegetables like green peas, cauliflower, chillies, apples, sweet potatoes and grapes. The dryer was able to provide hot air from 9:00 to 19:00 hours in a day. The overall maximum efficiency of the dryer was 56%. To reduce the moisture content from initial (75%) to storable level (below 10%), MMSCD took 6 h. However, 24 h (3 days of sunshine) were taken under OSD to attain the safe moisture content. [ABSTRACT FROM AUTHOR]

Copyright of Eurasian Physical Technical Journal is the property of E.A. Buketov Karaganda University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Misr Journal of Agricultural Engineering is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The treatment and disposal of sewage sludge is one of the most important and critical problems of wastewater treatment plants. 8.7 million tonnes of dry matter of sewage sludge were produced annually in the European Union in the year 2020. Due to the fact that sewage sludge contains a large number of substances that are not beneficial for human health, the conditions for sludge management will be significantly tightened in the EU countries. One option for sludge liquidation is the production of biofuel in a form of granules or pellets from sewage sludge enriched by waste celluloses. The achieved results show that the resulting quality of such alternative biofuel is fully comparable to conventional fossil fuels. The economic analysis is based on the simulation of cash flows associated with the implementation of the project over the lifetime and the calculation of levelised cost (LCOE). Results shows (under the current economic situation) that solar dryer technology ensures the lowest LCOE at the level of 26 EUR/GJ in fuel. If the LCOE of the alternative biofuel includes the price of the saved emission allowance and the future costs of sewage sludge disposal, the resulting price is directly competitive with lignite. The results thus clearly show that there is an ecological and economically competitive substitute for solid fossil fuels, which may be an important step for the future use of local combustion sources such as district heating plants. [ABSTRACT FROM AUTHOR]

Goji berries (Lycium barbarum) a shrub belonging to Solanaceae family, are also known as wolfberries or Chinese boxthorn. These berries are characterized by their bright orange-red ellipsoid fruits, measuring 1-2 cm in length. The versatility of goji berries lies in their suitability for consumption in both fresh and dried forms, rendering them available throughout the year. The objective of this study was to assess the quality attributes of both fresh and dried goji berries. Specifically, the research focused on the JB2 variety of goji berries, which were subjected to drying using a solar dryer. In preparation for the drying process, the berries underwent distinct pretreatment methods, aimed at determining the optimal approach for retaining quality characteristics post-drying. The pretreatment methodologies encompassed the following: berries without pretreatment (control); immersion of berries in boiling water followed by cooling, succeeded by immersion in a 1% ascorbic acid solution for a duration of 5 minutes; immersion of frozen berries in a 1% ascorbic acid solution for 5 minutes. To determine the quality traits of both fresh and dried goji berries, a comprehensive array of chemical analyses was undertaken: total dry matter, water, total acids, ash, total sugars, vitamin C, cellulose, proteins, total oils and total polyphenols. The sensory properties were estimated by using the scoring method (max. 20). It was estimated that goji berries, variety JB2, have good quality properties, in terms of their nutritional composition and sensorial characteristics. The application of solar drying has shown good results, both from an economic and ecological point of view, as well as in terms of preserving the chemical components of the goji berries. [ABSTRACT FROM AUTHOR]

In this research, a closed-flow solar dehydrator with a refrigeration moisture extraction system was evaluated, likewise, the dehydration temperature time was optimized by evaluating three types of heat transfer fluids. The dehydration equipment included devices to absorb thermal energy from incident sunlight, such as a trombe wall and a parabolic cylindrical collector, and a thermo bank system. In addition, the influence of three types of heat transfer fluids (water, oil and oil nanofluid + silver nanoparticles) was evaluated. This dehydration system was applied to process the Pouteria lucuma fruit. The results indicate the reduction of the dehydration time by 58.19% using nanofluid. This treatment prevents the modification of the physicochemical properties of the product and helps preserving its organoleptic properties. [ABSTRACT FROM AUTHOR]

In the present work, a forced convective hybrid photovoltaic thermal (PV-T) solar dryer assisted with an evacuated tube collector (ETC) is set up to investigate the thin layer drying of potato slices. The drying experiment is compared with the traditional sun drying method without PV-T system under the meteorological conditions of Thanjavur, Tamilnadu. The initial moisture content of potato slices used for the study is 91% (wb). The drying experiment was carried out at different air temperature levels of 50, 55 and 60 °C. Nine numerical models are used to study the drying kinetics of untreated potato slices. Using IBM SPSS 23 statistical package, non-linear regression analysis was performed to estimate correlation coefficient (R2), reduced chi-square (χ²) and root mean square error (RMSE). The model developed by Midilli et al., is the most appropriate one to describe potato slices thin layer drying behavior in a hybrid dryer. The effective moisture diffusivity (Deff) determined using Fick's second law of diffusion was found to vary from 2.12463×10-8 to 2.79233×10-8 m²/s. The activation energy (Ea) determined using the Arrhenius equation was found to be 16.4276 KJ/mol for drying of potato slices. [ABSTRACT FROM AUTHOR]

The current study examined reduction of moisture from agricultural energy and food crops in a conventional oven to a solar dryer at various treatment periods at temperature between 40 ± 10 °C. Sugarcane bagasse and Phragmites Australis had initial moisture of 50.8 % and 6.07 % by dry weight, respectively, with higher heating values (HHV) 6548.5 kJ/kg and 17653.02 kJ/kg respectively. The moisture content of bagasse and phragmites were decreased by 51.31% and 68.69% respectively using oven drying, while the moisture content of bagasse and phragmites was reduced by 48.01% and 66.22% respectively, using solar drying with 5 hrs treatment time. Corresponding increase in HHV's observed in bagasse to 11195.6 KJ/kg (oven drying) and 10998.1 KJ/kg (solar drying), while HHV of phragmites increased to 18706.79KJ/kg (oven drying) and 18685.36KJ/kg (solar drying). Green chillies had a moisture content reduction by 33.69 % (oven) and 8.28 % (solar), whereas grapes had a reduction by 31.20 % (oven) and 7.88 % (solar) with 5 hrs treatment time. The oven drying approach revealed higher carbohydrate content in food crops when compared to solar drying, while both treatments showed a similar drop in protein, fat, and vitamin C contents. Statistical and energy analysis observed that comparing solar drying; the oven drying eliminates slightly higher moisture content and have less drying energy requirements. The amount of heat energy required for drying unit mass of bagasse was 0.476 kJ/kg (oven) and 0.556 kJ/kg (solar), for phragmites it was 0.074 kJ/kg (oven) and 0.092 kJ/kg (solar), for chilles 0.524 kJ/kg (oven) and 0.576 kJ/kg (solar) and for grapes 0.123 kJ/kg (oven) and 0.157 MJ/kg (solar). According to the results solar drying required greater quantity of heat energy than oven drying. Mass transfer analysis showed drying constant of bagasse and phragmites were higher initially, then showed reducing trend with respect time. Furthermore, it was observed that the effective diffusivity and mass transfer coefficient were found reducing with respect to increasing drying treatment time. The research findings of renewable solar drying, on the other hand, are comparable to those of oven drying, demonstrating that there is still enough untapped heat energy available for its utilization in biomass thermo-chemical conversion methods. [ABSTRACT FROM AUTHOR]

Date palm (Phoenix dactylifera L.) fruits are widely grown in rural areas of arid Rajasthan of India. The grown date palm fruits are generally dried in forced convection mode. However, given the socio-economic status of farmers, dryer facility affordability has become crucial. Additionally, there is a critical need for a simple winnower, especially with its operation. To address the highlighted issues with the dryer and winnower and given a location already receiving abundant solar radiation, a solar photovoltaic (PV) winnower cum-dryer was designed and developed. The developed winnower cum-dryer was tested in actual conditions to realize the performance. First, the drying experiment for dehydrating date palm fruits and, second, the winnower experiment for separating grains from straw were carried out. The date palm fruits used for experimentation have a moisture content of 65% on a wet basis. During the drying trial, the dryer reduced this moisture content by 39% in 6 days. In contrast, in the open sun drying, it took 8 days. The drying chamber's temperature gradient was reduced to 2–3 °C from 6–8 °C in the system provided with a preheater, resulting in uniform drying. The observed effective moisture diffusivity and the dryer's efficiency are 4.34 × 10−9 m2·s−1 and 16.1%, respectively. A high IRR of 57.4% and a shorter payback period of 2.10 years were found in the economic analysis, indicating that the dryer is cost-effective. The winnower operation results suggest that about 200–300 kg grains could be separated daily when used as a winnower without natural wind. Overall, the developed winnower cum-dryer produced better-quality dried date palms in a shorter time than open drying by efficiently using solar energy and separating the grains from straw to enhance the utility throughout the year. [ABSTRACT FROM AUTHOR]

Using the solar thermal system in the agricultural area to conserve fruits and vegetables has shown to be a practical and economically feasible approach. In this research paper, the performance analysis of indirect solar dryer was investigated. Using various heat-absorbing materials, heat can be stored in the form of internal energy during the day time, and same heat can be used in night conditions to get desired results as per requirements. The onion and garlic were dried in the indirect natural solar dryer under three different cases like conventional, granite with silica gel and nitrate salt (also called sodium nitrate salt: NaNO3) with silica gel method. The mentioned heat storing material and desiccant material's effect on drying of onion and garlic were studied in each case. The relative humidity drop was observed around 1–2% due to silica gel. The maximum temperature achieved was 52.30°C in granite with silica gel case. Moisture content of the onion was reduced from 86% to 15% in 24 h in solar dryer in case of nitrate salt with silica gel method. For onion drying, moisture content was reduced in case of conventional and granite with silica gel cases up to 25 and 18% respectively, in the same time period (24 h). Moisture content of garlic was reduced from 70 to 56% in 24 h in solar dryer in case of nitrate salt with silica gel. For garlic drying, moisture content was reduced in conventional and granite with silica gel cases were from 70 to 60% and 70 to 57% respectively, in same time period (24 h). Hence the nutrients, color, and taste that are lost in the conventional method was preserved in the solar dryer. The experimental data were fitted for six different mathematical models. Statistical tools like root means square error, chi-square, and correlation coefficients were used to analyze the fitting curves. The logarithmic model showed the best-fitted model to describe the drying of onion and garlic. [ABSTRACT FROM AUTHOR]