Development of a Cost-effective Design of a P-V Ventilated Greenhouse Solar Dryer for Commercial Preservation of Tomatoes in a Rural Setting (original) (raw)
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Comparative Analysis of Cabinet Solar Dryer in Natural and Forced Convection Mode for Tomatoes
Two cabinet solar dryers of same dimensions with flat plate solar collector have been developed to test their performance for tomato drying. The experiments were carried out simultaneously in natural and forced convection mode under the same metrological conditions of Chandwad (India).The moisture content of tomato slices were reduced from an initial value of 94% (w.b) to a final value of 10% (w.b) within 9 hrs in forced and 12 hrs in natural convection mode. Also the mass content of 1000 g of tomato slices were reduced to 106 g and 226.6 g in forced and natural convection mode for the same drying period of 9 hrs. During test period, the collector efficiency of cabinet solar dryer in forced and natural convection mode was found to be 32.96% and 17.12 %. For the same period of drying, dryer efficiency in forced convection was higher (11.24%) than natural convection mode (9.94%) of drying. The main aim of this study was to compare the performance of solar cabinet dryer in natural and forced convection mode and it may be useful in setting drying standards for selected agro-commodities.
International Journal of Renewable Energy Technology, 2016
In this paper, a novel scheme of a standalone grid independent solar greenhouse dryer has been proposed. A thermal model for forced convection solar greenhouse drying of Peas has been developed. The model takes hourly values of climate data for the chosen location along with certain other data related to the product and the greenhouse as input and predicts the hourly values of product temperature, greenhouse air temperature, convective heat transfer coefficient and the amount of moisture evaporated from the product. The performance of the dryer has been analysed for a representative day in the month of December for the climatic condition of Kolkata, India (22.32°N, 88.20°E). To make the system grid independent, a photovoltaic-based power system with battery backup has been designed. The performance of the integrated power system has been analysed for all the seasons of a climatic cycle. Finally, an economic analysis has been included to calculate the payback period of the proposed dryer.
Development, design and performance of a PV-ventilated greenhouse dryer
International Energy …, 2007
A PV-ventilated greenhouse solar dryer was developed. The basement of the dryer is a black concrete floor with an area of 5.5× 8.0 m 2. The roof of the dryer was covered with polycarbonate plates and it was designed in the parabolic shape of facilitate the construction. Three fans powered by a solar cell module of 53 W were used to ventilate the dryer. To investigate its performance, the dryer was used to dry 4 batches of chilies during December, 2003 to March, 2004. The air temperature inside the dryer was 60-65°C at the noon of a clear day. High drying air temperature with reasonably low relative humidity inside the dryer during almost whole period of the day demonstrated the potentiality of solar drying inside the greenhouse dryer. The temperatures at three locations (top, middle and bottom) inside the dryer follow the similar pattern. Heat stored in the concrete floor helped to reduce variation of drying air temperature due to the fluctuation of solar radiation. The use of solar cell module helps to regulate indirectly the drying air temperature. The results from the experiments demonstrate that the drying time for drying of 100-150 kg of chilies in the dryer was significantly less than that required for natural sun drying but the drying efficiency increases with loading capacity. The chilies being dried in this PV-ventilated greenhouse dryer was completely protected from insects, animals and rain and good qualities of dried chilies in terms of colour and texture were obtained. The payback period of dryer was estimated to be 3.36 years. To disseminate this type of dryer, two more units of the greenhouse dryer were constructed and used for drying banana and green tea at two locations in Thailand. Users of these dryers were satisfied with the performance of the dryers.
Construction of Solar Dryer for Drying Agricultural Produce: Tomato Slices
-This research dwells on the construction and performance evaluation of mixed-mode solar dryer for Tomato Slices at Kano University of Science and Technology, Wudil. A mixed-mode solar dryer utilizes direct solar radiation from the sun as well as inputs heat from the solar collector inlet which is directly connected to the dryers and at the same time the drying cabinet absorbs solar energy directly through the transparent glass. The results obtained during the test period revealed that the temperature inside all the dryers was much higher than the ambient temperature during most hours of the daylight. However, the temperature risen up inside the drying cabinet was up to 63.1°C with one inlet and also 68.8°C with two inlets occurred within the hour immediately after 12.00 noon. The capacity of the dryer is 0.2kg of products per tray while the inlet temperature is identified to play a crucial role in the solar dryer performance.
Solar Energy, 2009
This paper presents experimental and simulated performance of a PV-ventilated solar greenhouse dryer for drying of peeled longan and banana. The dryer consists of a parabolic roof structure covered with polycarbonate plates on a concrete floor. Three fans powered by a 50-W PV module ventilate the dryer. To investigate the experimental performances of the solar greenhouse dryer for drying of peeled longan and banana, 10 full scale experimental runs were conducted. Of which five experimental runs were conducted for drying of peeled longan and another five experimental runs were conducted for drying of banana. The drying air temperature varied from 31°C to 58°C during drying of peeled longan while it varied from 30°C to 60°C during drying of banana. The drying time of peeled longan in the solar greenhouse dryer was 3 days, whereas 5-6 days are required for natural sun drying under similar conditions. The drying time of banana in the solar greenhouse dryer was 4 days, while it took 5-6 days for natural sun drying under similar conditions. The quality of solar dried products in terms of colour and taste was high-quality dried products. A system of partial differential equations describing heat and moisture transfer during drying of peeled longan and banana in the solar greenhouse dryer was developed and this system of non-linear partial differential equations was solved numerically using the finite difference method. The numerical solution was programmed in Compaq Visual FORTRAN version 6.5. The simulated results reasonably agreed with the experimental data for solar drying of peeled longan and banana. This model can be used to provide the design data and is also essential for optimal design of the dryer.
Semi-industrial drying of vegetables using an array of large solar air collectors
Energy for Sustainable Development, 2017
The design, structure, and evaluation of an indirect solar tunnel dryer are presented. This dryer corresponds to the air forced convection type. Two similar solar dryers were built and tested with vegetables on an industrial scale in Huacalera, northern Argentina, and operated by a cooperative of small agricultural producers. Each dryer consisted of a tunnel chamber of 450 kg load capacity and a bank of 10 solar collectors of 92 m 2. The bank of large solar collectors allowed temperatures in the drying chamber above 50°C for 6 h a day, mixing with ambient air to produce the correct temperature for drying vegetables. A maximum rank of outlet temperatures of 80-90°C and temperature differences of 50-60°C were obtained with minimum air flow of 0.06 kg/s and without load. The dryers were operated with different vegetables, obtaining e.g. dried slicing onion with final moisture content 0.09 in approximately 16 h of sun. The optimum point of the collector efficiency was determined with airflow of 0.4 kg/s, however, lower than 0.23 kg/s airflow is needed to obtain outlet temperatures above 50°C. A financial evaluation of the dryer was also performed as a clean energy project, reflecting that the investment return rate of the device is 13 months. In this scenario NPV improves in a 438% compared with the conventional scenario and SNPV is suitable only in the case of solar dryer. Solar drying at semi-industrial scale is feasible with the proposed technology due to the gusts of wind and the day-night thermal amplitude of Huacalera.
DESIGN, CONSTRUCTION AND TESTING OF A FORCED CONVECTION SOLAR TOMATO DRYER
ABDULHAKEEM ABDULLATEEF ISMAIL, 2021
ABSTRACT The thrust of study was the design and development of a forced convective solar tomato dryer. The solar drying system utilizes solar energy to heat up air and to dry tomatoes loaded, which is not only beneficial in that it reduces wastage of agricultural produce and helps in preservation of agricultural produce. Based on the limitations of the natural sun drying such as exposure to direct sunlight, liability to pests and rodents lack of proper monitoring, and the escalated cost of the mechanical dryers, a solar dryer was therefore developed to cater for these limitations. This project presents the design and construction of a forced convective solar dryer, the dryer is composed of solar collector (air heater) and a solar drying chamber integrated together. The dryer was constructed using square metal pipe to make the frame and four trays rows at 10cm vertical spacing. The frame covered with metal sheet enable heat energy accumulation. The dryer has a volume of 1034061cm3 incorporated with trays each with a load carrying capacity of 3.5kg of tomato. The total capacity of the solar dryer was 12.5kg of tomato. four trays each with 4408cm2 were used for the testing. The amount of moisture expelled from the samples was 2.9kg per tray while the energy used in evaporating the moisture from the tomatoes was averagely 38w. The rate at which moisture was loss was evaluated as 6.5×10-5 kg/s. the total duration for the drying of the product was three days compared to the conventional method of eleven days. Therefore, the system can be used to dry tomatoes during bumper harvest period, which coincide with the dry season for a day or two
Year Round Potential of Greenhouse as a Solar Dryer for Drying Crop Produce
Agricultural Engineering Today, 2017
An experimental investigation was carried out to determine whether sufficiently higher temperatures are available inside the greenhouse for drying crop produce. The greenhouse air temperature was calculated using a steady-state model. Calculated and measured data compared well for different months of the year. The maximum temperature gain of about 25.1°C, 21.4°C and 14.5°C were obtained during May, September and December, 2015 respectively. However, during September the minimum gain was 7.5°C. The maximum temperature inside a bare greenhouse enclosure reached above 64°C. The model can also predict the relative humidity inside the greenhouse enclosure. The inside relative humidity varied from 13.8 to 35.2% in the year 2015 during 10:00 h to 16:00 h Validation of observed and predicted values of greenhouse temperature was carried out with higher R2 values (0.991 to 0.999). The model can also be used to modify the design of the greenhouse according to the optimum temperature required.
Testing of the performance of a fruit and vegetable solar drying system in Iraq
Desalination, 2007
In this work a drying system was constructed, consisting of three parts (solar collector, solar drying cabinent, and air blower). Two identical air solar collectors having V-corrugated absorption plates of two air passes, a single glass cover was used. The total area of the collectors is 2.4 m 2. The dimensions of the drying cabinet are 1 × 0.33 × 2 m (width, depth, and height). The cabinet is divided into six divisions separated by five shelves. The distance between the shelves is 0.3 m except the upper one, which is 0.5 m from the roof. Each shelf is 0.95 × 0.3 m and is made of metallic mesh. The drying chamber walls are made of aluminum plate except the southern side, which was fixed with glass plate having the dimensions 1 × 2 × 0.002 m. Two types of fruit and one type of vegetables were dried during the present work. These were grapes, apricots, and beans. The moisture content of apricot was reduced from 80 to 13% within one day and a half of drying. Moisture content of grapes was reduced from 80 to 18% in two and a half days of drying, while that of beans was reduced from 65 to 18% in one day only. The results show that the most effective factor on the drying rate is the temperature of the air inside the cabinet. The effect variation of speed of air inside the drying cabinet is small and can be neglected. The relative humidity of air exit from the cabinet was small between (25-30%) and therefore there is no need for high velocity air inside the cabinet.
Agricultural Engineering International: The CIGR Journal, 2013
Solar energy is the most promising of the renewable energy sources in view of its apparent limitless potential. A small scale village–level solar dryer for tomato was developed under Yola weather at latitude 9 ° 14 ′ N and longitude 12 ° 26 ′ E using locally available materials and the performance was evaluated. The essence of the dryer was to achieve the effective method of tomato preservation and eliminate the drudgery and product deterioration associated with traditional methods of open sun drying of tomatoes. This is in view of alleviating the weather limitation experienced by farmers in crop drying especially for tomatoes. The solar dryer consists of tray, reflective walls and glass roof, a preheating air absorber plate, inner panels for removal of moisture and chimney through which air stream passes across the dryer. Evaluation of the dryer showed a raised temperature of about 47 ℃ attainable in the drying chamber. The dryer temperature and drying rate was found to be higher t...