Solar Tunnel Research Articles

Mathematical Modeling of Solar Tunnel Dryer for Ginger Drying

Mathematical Modeling of Solar Tunnel Dryer for Ginger Drying

Design, Fabrication and Performance Evaluation of Mixed-Mode Solar Tunnel Dryer for Buffalo Meat by Forced Convection

In the context of Nepal, the consumption, as well as preservation of meat products, has been in practice for ages. The primitive approach - open sun drying technique- a technique for preserving meat for longer, can contaminate the meat. In addition, the meat in direct contact with UV rays also degrades the quality of meat which may not be suitable for consumption. Exposing the meat to the open air causes the evaporation of its moisture, leading to a decline in flavour and an extended duration for the dehydration of the meat product. The alternative technique - mixed mode solar tunnel dryer - is a revolutionary method to undertake the challenges, which uses both solar heated air and direct solar energy. This paper majorly includes the design, fabrication and performance evaluation of a solar mixed-mode tunnel dryer by forced convection for buffalo meat. The purposed system was designed for drying 4 kg of meat for humid sub-tropical climatic conditions with an estimated design drying time of 7 hrs 44 mins. The designed system includes a collector of area 2 m2, a drying chamber, and a DC fan. The recorded parameters were incident solar irradiance, air temperature, relative humidity of the air, and moisture content of meat at equal intervals. Reducing the moisture content in buffalo meat to 26.78% by weight in the month of November, took a total of 14 hrs with maximum collector efficiency of 29.79%.

Enhancement of thermal and techno-economic performance and prediction of drying kinetics of paddy dried in solar bubble dryer

The development and performance evaluation of a solar Bubble drier (SBD) for drying agricultural produce are presented in this study. In order to evaluate the solar bubble dryer's performance in terms of drying characteristics and end-product economics, it was compared to the solar tunnel dryer (STD). A solar tunnel dryer is a structure with a tunnel-like shape that is covered in UV-stabilized polythene sheet so that industrial and agricultural items can be dried off. While there was no load, the maximum temperatures inside the solar bubble dryer and solar tunnel dryer were 56.25 and 49.30 °C, respectively. When there was a full load, the maximum temperatures inside the dryer were 49.55 and 33.20 °C, respectively. For solar bubble dryers, the average final moisture content ranged from 13.07±0.335 % to 18.74±0.716 % (w.b.), while for solar tunnel dryers, it ranged from 13.60±0.575 % to 20.60±0.751 % (w.b.). The mean drying rate also varied depending on the drying air temperature and air flow mode, ranging from 0.081±0.020 to 0.006±0.005 kg/kg dm-h for solar bubble dryers and 0.056±0.025 to 0.005±0.002 kg/kg dm-h for solar tunnel dryers. The thermal efficiency of the developed dryer was found to be 58.39% for solar bubble dryers and 48.09% for solar tunnel dryers, which are significantly higher than that of other general Sun drying (36%). However, the drying rate varied between 0.081 to 0.006 g of water evaporated per g of dry matter per hour when solar bubble dryer was adopted and 0.014 to 0.007 g for solar tunnel dryer. Economic analysis showed that the SBD and STD had payback periods of 3.23 and 2.54 years, respectively. However, the cost of drying came lower for the SBD than the STD, which were Rs. 1.51 per kg and Rs. 1.76 per kg.

Performance evaluation of solar tunnel dryer and electric tray dryer for drying date palm fruit (Pheonix dactylifera L.) in arid region of Rajasthan

Date palm (P. dactylifera, L.) is an important fruit of arid and semi-arid regions.In Western Rajasthan the dates are harvested in the month of July-August but preferred to eat during winter months, so it becomes necessary to dry and store the fruits at least for 4 to 6 months. The use of an appropriate temperature for drying of dates is quite crucial as a higher temperature may encourage case hardening, caramelization and a higher hygroscopicity; whereas a lower temperature would be insufficient to remove significant moisture leading to a clumpy powder. Farmers generally dry the dates in open sun. This traditional uncontrolled drying method is unhygienic and required more time, also weather dependent, so alternate economical methods are being tested in the region by the scientists and the farmers for drying of dates in the form of Pind. The paper deals with the performance of solar tunnel dryer and electric tray dryer installed at the farmer’s field in Bikaner district of Rajasthan. The results reveal the drying time of Medjool date palm fruits in solar tunnel dryer and electric tray dryer.

Effect of packaging materials on lycopene vitamin C and water activity of dried tomato (Lycopersicon esculentum Mill.) powder during storage.

In this work, a storage study was conducted to find suitable packaging material for tomato powder storage. Experiments were laid out in a single factor completely randomized design (CRD) to study the effect of packaging materials on lycopene, vitamin C moisture content, and water activity of tomato powder; The factor (packaging materials) has three levels (low-density polyethylene bag, polypropylene bottle, wrapped with aluminum foils, and packed in low-density polyethylene bag) and is replicated three times. During the study, a twin layer solar tunnel dried tomato slices of var. Galilea was used. The dried tomato slices were then ground and packed (40 g each) in the packaging materials and stored at room temperature. Samples were drawn from the packages at 2-month interval for quality analysis and SAS (version 9.2) software was used for statistical analysis. From the result, higher retention of lycopene (80.13%) and vitamin C (49.32%) and a nonsignificant increase in moisture content and water activity were observed for tomato powder packed in polypropylene bottles after 6 months of storage. For low-density polyethylene packed samples and samples wrapped with aluminum foil and packed in a low-density polyethylene bag, 57.06% and 60.45% lycopene retention and 42.9% and 49.23% Vitamin C retention were observed, respectively, after 6 months of storage. Considering the results found, it can be concluded that lycopene and vitamin C content of twin layer solar tunnel dried tomato powder can be preserved at ambient temperature storage by packing in a polypropylene bottle with a safe range of moisture content and water activity levels for 6 months.

Comparative Overview of Performance of the Dryers with a Conventional Method of Drying i.e., Open Sun Drying

Since ancient times, conventional techniques of food drying, such as sun drying, have been used. Currently, drying methods have been developed with the latest technology to reduce the damages caused by biochemical changes, which decrease nutritional value during the drying process. Some of the typical drying methods used for food products are sun drying, solar tunnel dryer, cabinet-type solar drying, etc. While this is going on, cutting-edge technology is being created to combine several drying techniques to produce the optimum outcomes. The most recent drying techniques used in food processing technology will be covered in this study.

An Empirical Study on Convective Drying of Ginger Rhizomes Leveraging Environmental Stress Chambers and Linear Heat Conduction Methodology

This comprehensive study provides an in-depth examination of the convective drying process and drying kinetics of ginger rhizomes (Zingiber officinale), precisely honing in on the influence of moisture content variation on the thermal property of thermal conductivity. Our research reveals a direct correlation between decreasing moisture content and thermal conductivity during drying, conducted under meticulously controlled conditions with a drying temperature range of 10 °C to 60 °C and an optimum drying temperature identified at 60 °C with a relative humidity of 35%. We scrutinise the thermal properties, namely, the thermal conductivity, in relation to moisture content, shedding light on the intricate dynamics involved. The study uncovers the distinct advantage of convective drying over traditional methods, shortening the drying time to just 24 h, compared to the nine and eight days required for open sun and solar tunnel drying, respectively. We identified optimal moisture levels for various ginger types: unblanched (6.63%, thermal conductivity 0.0553 W/m·K), blanched (9.04%, thermal conductivity 0.0516 W/m·K), peeled (8.56%, thermal conductivity 0.0483 W/m·K), and unpeeled ginger (5.98%, thermal conductivity 0.0460 W/m·K). As drying progressed, the moisture content fell from 81% to approximately 6–9%, concomitantly lowering the thermal conductivity from roughly 0.0553 W/m·K to around 0.0460–0.0516 W/m·K. These findings offer significant implications for the food industry, proposing improvements in drying processes and strategies for energy conservation when drying ginger rhizomes and similar agricultural produce. Moreover, this study sets a solid foundation for future investigations into potential applications of these insights to other agricultural products and various drying techniques.

Automation and Performance Evaluation of a Solar Tunnel Dryer Using Arduino UNO

The study on automation of an existing solar tunnel dryer was done using the Arduino UNO and DHT11 sensor during 2020–2021 at the Research Farm, Department of Farm Machinery and Power Engineering, Sam Higginbottom University of Agriculture, Science, and Technology, Allahabad, Uttar Pradesh, India. To ensure optimal drying conditions, the Arduino UNO was employed to regulate the operation of an exhaust fan. This control system was activated whenever the humidity level inside the dryer reached a specific threshold. The system was configured to operate at three different humidity levels- 35%, 30% and 25% for three weeks of five working days each. Potatoes weighing 5000 g were sliced and spread inside the dryer daily between 9:30 am to 5:30 pm, ensuring consistent and regular activity within the specified timeframe. It was found that the moisture removal rate and the successive drying time were fastest when the exhaust fan was operated to remove 25% humidity, followed by 30% and 35%. During the third week, the drying time was two hours less than the first week and one hour less than the second. These results demonstrate that removing humidity at lower levels significantly contributed to faster drying. Therefore, it can be inferred that automating the solar tunnel dryer and maintaining a lower humidity threshold can significantly enhance the efficiency of the drying process.

Quality Improvement of Dried Anchovies at Three Solar Drying Methods

Fish drying is one of the traditional methods where the fishermen land their catch on the beaches for drying traditionally under sun for several days. Dried fish provides valuable and economical sources of animal protein. The quality of dried fish is significantly influenced by the presence of microorganisms. Therefore, this study aims to determine the physical quality changes in anchovy under three different solar drying methods which are open sun drying (OSD), solar greenhouse tunnel dryer (GTD), and forced convective solar dryer (FCD) and to verify the chemical and microbial contamination in solar-dried anchovy. About (20 kg) of fresh anchovy were taken for experiments. Quality analyses were conducted in the samples before, during, and after drying. The parameters analyzed included three main analyses which are physical, chemical, and microbial analyses. The drying rate was higher in GTD compared to the two other methods. Moisture content, drying rate, and moisture ratio were significantly affected by drying methods. GTD required less time (6 hr) to dry anchovies compared to other drying methods (9 hr time). The highest reduction in lightness is in GTD dried anchovies followed by FCD and OSD. The drying methods and drying time statistically affect the lightness (L) of dried anchovies ( p ≤ 0.05 ). The water activity of solar-dried anchovies was 0.3. Experimentally dried anchovies were found to have lower microbial count compared to the dried fish quality standards. The total viable count (TVC) in fresh anchovy was 6.44 log CFU/g compared to the greenhouse tunnel dryer 2.90 log CFU/g, open sun dryer 4.16 log CFU/g, and forced convective dryer 4.19 log CFU/g anchovies. Water activity and moisture content did not affect total viable count (TVC) significantly, but it affects total fungal count (TFC) ( p ≤ 0.05 ). There was a significant difference on Krusal Wallis between the samples of three methods of drying and a fresh one on the water activity, ash content, and fat content ( p ≤ 0.05 ).

Edukasi manajemen teknologi produksi untuk menunjang kehalalan produk bagi usaha kecil menengah (Productiom technology management education to support halal products for small scale enterprises)

This community service aimed to educate the small and medium enterprises (SMEs) about management of production technologies in obtaining halal certification. The partners of this program were UKM Meugah Pliek and UKM Wina Mandiri as pliek-u and asam sunti processors in Aceh Besar Regency. The production steps of the products that need technology are drying and pressing process. This program had been conducted through survey, preparation, and education. Results of this program were 2 hours training on production technology management to support halal products, 1 unit Hohenheim Aceh solar tunnel dryer, 1 unit hydraulic press, 4 units digital balance at capacity of 40kg and 1000pc of thin wall plastic containers. The technologies adapted were believed to support the production process in order to warrant the halal products. The results of the program were also published on online media to transfer knowledge and motivation to wider community. The participants showed high enthusiasm to the program as it can increase not only their knowledge but also provide technologies and tools to be used in supporting halal production.

The influence of coconut endosperm composition based on the maturity levels against the quality of pliek-u

Pliek-u is Acehnese’s food heritage that has potential as functional food due to its high protein and lactic acid contents. The study aimed to investigate the effect of coconut endosperm composition based on the maturity levels against the quality of pliek-u. Two levels of Tall Coconut maturities used i.e., over mature (u-riek) and mature (u-pateun). About 2kg of grated coconut endosperm was fermented in a plastic box for 7 days at 3 compositions i.e., 30% over mature and 70% mature (P1), 50% over mature and 50% mature (P2), and 70% over mature and 30% mature (P3). Each treatment had been conducted in 3 replications. Then, the coconut was dried by using solar tunnel dryer type Hohenheim Aceh for 2 days. To produce pliek-u, soon after the drying process, the warm coconut was pressed by using a hydraulic press. The parameters observed to evaluate the quality of pliek-u were moisture, fat, protein, and acidity. The consumer preferences were evaluated from 30 panellists on 4 criteria i.e., aroma, color, texture and taste by using hedonic scale from 1 to 5. Results showed that the composition of coconut endosperm at different maturity levels had influenced the quality of pliek-u significantly. The best moisture was obtained from pliek-u produced by treatment P2, while the lowest fat content, the highest protein content and the most acid taste were identified from pliek-u produced by treatment P3. However, according to consumer’s preferences, the best overall acceptance was pliek-u produced by treatment P1 and P2 at score 4.2 (like). Therefore, this study recommended the best composition of coconut endosperm in pliek-u processing at 50% over mature and 50% mature (P2).

CFD Simulation of Temperature and Air Flow in a Natural Convection Solar Tunnel Dryer with a Bare Flat-Plate Chimney

Computational Fluid Dynamics simulation of a natural convection solar tunnel dryer with a bare flat-plate chimney is presented. The chimney’s function is to create airflow in the dryer through the buoyancy effect by re-heating the air coming from the drying unit and is therefore a major factor in the drying rate. CFD simulation was therefore employed to study the temperature and airflow in the dryer and determine the areas that could be improved upon. The design of the solar tunnel dryer geometry used in this simulation was done in SOLIDWORKS 2016 whereas the simulation of temperature distribution of airflow inside the dryer was performed using SOLIDWORKS 2016 flow simulation program in a steady-state regime. The boundary conditions were set using the obtained experimental data. The simulation results showed that the chimney losses heat, that there is air recirculation in the collector, that the airflow experiences some pressure loss as it moves from the drying chamber to the chimney, and that there is some reduction of the velocity in some parts of the dryer. The simulated and experimental collector efficiencies were found to be 33.09 and 37.63%, respectively, giving a mean relative deviation of collector temperature of 5.1%. To improve the performance of the dryer, insulating and glazing of the chimney is suggested as well as using a curved joint between the chimney and the drying chamber.

Development of Mini Solar Tunnel Dryer and Validation of Thin Layer Drying Models for Pomegranate Seeds

A portable MSTD (mini solar tunnel dryer) was developed and evaluated in terms of drying rate, MR (moisture ratio) and drying efficiency for drying of pomegranate seeds. The drying characteristic curves were also determined for drying in MSTD and OSD (open sun drying). In order to study the drying behaviour of pomegranate seeds in OSD and MSTD, seven different models were fitted. The best prediction model was determined to estimate drying kinetics as criteria for evaluating the goodness-of-fit based on R2, SSE and RMSE. The Approximation of Diffusion model was adequate to describe the drying kinetics of pomegranate seeds in OSD and MSTD with R2 value of 0.99189 and 0.9943, respectively. The MSTD was 7% more efficient in drying of pomegranate seeds compared to OSD without affecting the quality of seeds. The dryer can be used by the farmers as an alternative to sun drying for on field drying of their product without compromising the quality.

Comparison Between Solar Tunnel, Solar-Cum Gas Dryer, and Open Sun Drying Methods for Drying Red Chilies

Comparison Between Solar Tunnel, Solar-Cum Gas Dryer, and Open Sun Drying Methods for Drying Red Chilies

Solar photovoltaic power station system based on composite heat source thermal power technology

In order to solve the shortcomings of single air source heat pump, single solar heat pump and solar air double heat source heat pump, one solar electric heat pump and multi-stage solar heat pump dual source heat pump, a solar integrated heat source heat pump is designed. The heating capacity and COP of the same heat pump and the solar double heat pump under three different operating conditions were simulated, and the simulation results were compared and analyzed. The simulation results were analyzed. The results show that the heat capacity and COP of the solar double heat pump system are higher than those of the heat pump system. With the continuous decrease of outdoor temperature, the advantages of solar wind tunnel hybrid heat pump system are more obvious.

Physicochemical quality evaluation and drying characteristics of nutmeg (Myristica fragrans) dried in a solar tunnel dryer with biomass backup

Experiments on drying of nutmeg was performed in a solar tunnel dryer with biomass back up and in a mechanical dryer under three varying temperatures of 45OC, 5OC and 55OC. Drying of nutmeg in solar tunnel dryer was completed in 147 h, while in a mechanical dryer, drying was completed in 105 h, 102 h and 78 h at drying temperatures of 45OC, 50OC and 55OC, respectively. Solar tunnel dried nutmeg had maximum physical quality retention of bulk density (484.88 kg m-3) and kernel recovery (70.63%) whereas dry recovery of nut (61.88%) and shell recovery (31.55%) were maximum in mechanically dried samples at 55OC and 45OC respectively. Secondary metabolites like essential oil (10.67%) and oleoresin (23.25%) were higher in mechanically dried nutmeg at a drying temperature of 45OC. Volatile oil constituents like β-pinene, safrole, terpineol, γ-terpinene, α-thujene, α-terpinene and myristicin content were highest in solar tunnel dried nutmeg.

Drying of Melons in a Solar Tunnel Dryer: The Effect of Ascorbic Acid Solution on Drying Kinetics and Color Parameters

This study aims to present the performance of the solar tunnel dryer, which is required for the drying of two different types of melon with and without pretreatment. The solar tunnel dryer used in the study was built at Isparta University of Applied Sciences, Department of Agricultural Machinery and Technologies Engineering. The dryer consists of a flat plate solar collector, drying tunnel, solar cell module and a small axial fan. During the drying process, solar radiation, drying air temperature, relative humidity and air velocity were measured continuously in different parts of the dryer. At the same time, the mass loss of the melon slices was measured every two hours during the drying period. On the other hand, colour measurements were made on untreated and pre-treated melon slices, fresh and after drying, before and after the trials. Fresh melon samples were washed with tap water, and cut in half with a knife, the core in the middle was removed and sliced by hand in a half-moon shape without peeling before pre-treatment. 1% ascorbic acid was applied to the fruits as a pretreatment. After the preparations, the solar tunnel drying behaviour of untreated and pretreated sliced melon samples was investigated. Drying characteristic curves were evaluated according to five different mathematical models. In this study, it was determined that the L*, a* and b* values of melon varieties were preserved without pretreatment. The lowest total color change was observed in the bleached samples in both types of melon samples.

Uji Performansi Alat Pengering Tipe Terowongan Hohenheim Aceh Dengan Aplikasi Proportional Integral Derivative Controller Untuk Kipas Outlet

The purpose of this study was to evaluate the performance of Hohenheim Aceh type solar tunnel dryer with the application of proportional integral derivative (PID) controller for outlet fans . The instrumentations used were solar tunnel dryer type Hohenheim Aceh, HTC-meter, anemometer, pyranometer, and other supporting equipment s . The results showed that during the drying process solar irradiation had fluctuat ed , where the average solar irradiation was 649 W/m 2 . The average temperature in the drying chamber is 40.6°C while the average temperature in the environment is 32.9°C. Conditions in the drying chamber were suitable for drying because the temperature inside the dryer was relatively higher than the ambient temperature. The average relative humidity ( RH ) in the drying chamber was 36% and the average RH in the environment was about 40% . T he relationship between temperature and RH value was negative and strong indicated bu r-value of 0.7379 . On the other hand, t he relationship between solar irradiation and temperature was positive and also strong indicating that the energy source for this dryer was from solar irradiation with an R -square of 86.02 % and r-value of 0.92747 . The application of PID controller had improved the performance of Hohenheim Aceh type solar tunnel dryer by preventing the incident of unproper drying temperature. However, the airflow in the drying chamber was too low thus the further engineering design is needed to improve the drying system.

Effects of solar tunnel drying zones and slice thickness on the drying characteristics of taro (Colocasia esculenta (L.) Schott) slice.

This study aims to investigate the effects of slice thicknesses (2, 4, and 6 mm) and solar tunnel drying zones (zone I, zone II, and zone III) on the drying characteristics and thermal properties of taro slices, which were dried using solar tunnel drying (STD). To assess the drying characteristics of taro slices, the data from the drying kinetics were fitted with five different models. The adequacy of fit for the proposed models was evaluated using the reduced chi-square (χ 2), determination of coefficient (R 2), mean relative percent error (P), and root means square error (RMSE). The results showed that, among the five drying models, the drying characteristics of taro are better expressed by the logarithmic model. The thinnest slices dried in zone III had the highest diffusivity (6.57 × 10-09m2/s), lowest specific heat capacity (1.761 kJ/kg °C), and maximum thermal conductivity (0.268 W/m °C). It was also dried within a short period of time (5.5h). The findings of this study provide evidence that STD zones and slice thickness have significant impact on the drying characteristics of dried taro slices.

Fabrication and Performance Evaluation of Solar Tunnel Dryer for Ginger Drying

A series of tests were conducted to investigate the performance of a solar tunnel dryer for drying ginger. To supply hot air to the dryer, two axial flow fans with a power rating of 28 W, a supply voltage of 220 V, and a 50 W photovoltaics (PV) module were employed. By dividing the 8.5-meter-long solar tunnel dryer into four equal portions every thirty minutes, solar radiation, dry air temperature, ambient temperature, relative humidity, and air velocity were measured at five solar tunnel dryer stations. The hot air temperature at the collector output grew from 34°C to 65.5°C for an 8-hour operation in the no-load condition when the solar radiation was changed between 540 and 820 W/m2. At 9:00 a.m., the average maximum temperature was 30°C. During the loading operation, the temperature was 77°C at 1:00 p.m. The moisture content of sliced ginger was reduced from 90.4 to 11.8% on a wet basis using the solar tunnel dryer. With a solar collector area of 6 m2, open sun drying takes 40 hours to achieve the same wet basis condition. A total of eight experiments were carried out, both with and without loads. The dry air temperature at the collector outlet ranged from 34.0 to 65.5 °C. As the drying efficiency, collector area, and time savings improve, the drying time decreases. The ginger is kept in a controlled area, resulting in high-quality dried ginger. The solar tunnel dryer showed a net saving in drying time of 40% over open sun drying.