Solar Greenhouse Dryer Research Articles

Mango leather (Aam Papad) drying in hybrid greenhouse solar dryer with evacuated tube collector and finned drying tray: drying behavior and economic analysis

ABSTRACT Mango is primarily produced in India, and being a seasonal fruit, its pulp is dried to make mango leather so that it can also be enjoyed in the off-season. Traditionally, it is dried under the open sun, which takes more time to dry, and quality gets compromised due to direct exposure to dirt, direct sunlight, birds, pests, and microbes. Hence, its drying behavior is analyzed in a standalone hybrid greenhouse solar dryer (HGSD) operating in active mode. An evacuated tube collector (ETC) is attached to the dryer for high room air temperature and high drying rate. An aluminum drying tray having fins is fixed over copper tubes of a heat exchanger. The copper tubes get fixed in the finned slots of the drying tray, which increases the heat exchange between tray and tube. Experimentation is performed under three conditions: dryer with a collector, dryer without a collector, and open sun drying (OSD). The drying time in the dryer with the collector is 4 hours, 7 hours less than the dryer without the collector and OSD, respectively. The average convective heat transfer coefficient (CHTC) for the dryer with and without the collector is 0.11 W/m2°C and 0.08 W/m2°C, respectively, while in OSD, it is 0.07 W/m2°C. The economic analysis of the dryer shows that the payback time is 0.25 years only; hence, the large amount invested on the dryer is recovered in very less time and the profit can be enjoyed for the remaining time.

Performance analysis of greenhouse solar dryer using evacuated tubes

Agriculture is India's most popular vocation, and the pace of agricultural product output is increasing every day. Due to a lack of post-harvest and storage facilities, a large quantity of agricultural goods goes to waste. As a result, the agricultural industry need effective agricultural product preservation techniques in order to reduce food losses. Drying/dehydration is a common preservation technique used across the world to extend the self-life of agricultural goods while also reducing spoilage. It is heat and mass transfer process which occurs at same time. Solar drying, combined heat and power drying, geothermal drying, biomass drying, and other technologies for reducing moisture content in agricultural products are all the options. Solar drying is one of these renewable technologies that has been utilized to preserve food and agricultural goods in order to maintain the food balance. The ETSC based greenhouse dryer has been proposed to maintain the food quality. The main objective of the research is to dry the ivy gourd using greenhouse solar dryer with evacuated tubes. The results shows that the maximum temperature obtained in this dryer was found to be 75 °C.The moisture content in the product was reduced from 80% to 9% in active mode whereas passive mode the moisture content was reduced to 12%. The collector and dryer efficiency was found to be 37% and 26% respectively.

EFFECT OF DRYING AREA ON HEAT TRANSFER COEFFICIENT AND DRYING KINETICS OF HIGH-MOISTURE CROP DRIED IN A HYBRID ACTIVE GREENHOUSE SOLAR DRYER

EFFECT OF DRYING AREA ON HEAT TRANSFER COEFFICIENT AND DRYING KINETICS OF HIGH-MOISTURE CROP DRIED IN A HYBRID ACTIVE GREENHOUSE SOLAR DRYER

Experimental Performance Investigation of a Novel Foldable Greenhouse Solar Dryer for Drying of Potato Slices in Arid Climate - in Situ Measurement

Experimental Performance Investigation of a Novel Foldable Greenhouse Solar Dryer for Drying of Potato Slices in Arid Climate - in Situ Measurement

Experimental Performance Investigation of a Novel Foldable Greenhouse Solar Dryer for Drying of Potato Slices in Arid Climate - in Situ Measurement

Experimental Performance Investigation of a Novel Foldable Greenhouse Solar Dryer for Drying of Potato Slices in Arid Climate - in Situ Measurement

Comparison of Warming Efficiency of Greenhouse Solar Dryer with Four Distinct Design Implementations

Drying is a technique for transferring warmth from a source to a product while also removing moisture from the product in a limited space. When using sun drying, the heat required for drying is primarily provided by solar energy. In this paper we have discussed about the fundamentals of different types of green house solar dryer, and to develop new design of solar dryer that would maximize warming efficiency. The main goal of this research is to run a computational fluid dynamics analysis on a previous model to analyze the influence of the highest warming within the greenhouse solar dryer.

Response surface modelling and performance evaluation of solar dryer for drying of grapes

The current study focuses on the performance of Solar Greenhouse Dryer for drying of grapes for raisin making in Solar Dryer and Open sun condition in Western Maharashtra. The Maharashtra state ranks first in the production of grapes, probably Western Maharashtra produces nearly 800 thousand tons of grapes every year. The major wastage of grapes is due to low sugar content, glossy appearance, shrinkage, excess water in berry, scorching and size variation. Therefore, there is a need to preserve the grapes by drying and making raisins for a non-seasonal requirement. The experiment was conducted for drying of grapes in Solar Greenhouse Dryer and Open Sun condition from 1st of April to 4th of April for 48 hours. The initial weight of the grapes to be dried was 500 grams for both Solar Greenhouse Dryer and open sun drying conditions. The experiment was conducted at Bahe, Borgaon, Tal-Walwa, Dist- Sangli, Maharashtra, India located at 17.115o N and 74.33o E. The main aim of using DOE i.e., Response Surface Modelling is to get an optimum region for drying of grapes in Solar Greenhouse Dryer, from the Surface plot; the region of maxima and minima was obtained.

Drying characteristics and prediction of best fitted drying model for coriander leaves

Drying experiments were conducted on coriander leaves as affected by drying methods (solar greenhouse drying and open sun drying), pretreatments (dipping in a solution of magnesium chloride + sodium bicarbonate + potassium metabisulphite, boiled water blanching containing sodium metabisulphite, and untreated), and loading densities (2.0, 2.5 and 3.0 kg/m2). Validity of three commonly used drying models were examined to predict the most suitable drying model for coriander leaves. The increased drying temperature under solar greenhouse dryer (42°C) increases the amount of moisture removal from the coriander leaves and reduces the drying time by increasing the drying rate as compared to open sun drying (29°C), at all the selected levels of pretreatments and loading densities. Chemically treated coriander leaves dehydrated under a solar greenhouse dryer required less drying time than other treated leaves and dried leaves. Nevertheless, drying methods and loading densities had significant effects, while treatment effects were marginal. It was found that reduction of moisture and moisture removal rate per unit time occurred mostly in the falling rate period except some accelerated removal of moisture at the beginning up to 150 minutes. Page's model was found most appropriate for drying coriander leaves among the selected models.

Modeling the optimal condition for drying rumen contents using a solar greenhouse dryer

The ruminal content is a biomass waste obtained from the benefit of cattle. This biomass can be used as a fuel for generating part of the thermal energy that is required in the slaughterhouse processes. For this purpose, the ruminal content must be subjected to several pretreatments to facilitate its use as a fuel. The combustion efficiency of the ruminal content is affected by the particle size and the size distribution, as well as the moisture content. The ruminal content has a high moisture content that must be reduced from around 60% to values below 15% (by mass) within a few days so that the conversion efficiency and heating value are not affected. To dry the rumen content, low-cost natural drying systems can be utilized. A numerical approach for the solar greenhouse dryer performance was analyzed for typical local solar irradiation and natural convection conditions, at the greenhouse site of installation. To analyze the rumen content, at variable drying temperatures ranging from 40 °C to 70 °C, a thin layer model was used. Within the temperature range evaluated, the ruminal content effective diffusivity varied from 1.6 × 10−13 to 5.6 × 10−13 m2/s. The dryer was designed as a semi-cylindrical shape with a loading capacity of about 10 000 kg. A set of ordinary differential equations was formulated for modeling and simulating the heat transfer and drying phenomena inside the greenhouse dryer. The method of finite differences was used for solving the system of equations. The estimated drying time of the ruminal content was around 6 days (d) and the final product moisture was 14.10%.

Experimental performance and economic viability of evacuated tube solar collector assisted greenhouse dryer for sustainable development

A walk-in type solar greenhouse dryer supplemented with solar air heating system has been developed with an objective of sustainable development. One of its novel features is the use of an evacuated tube solar air heating system with the greenhouse dryer to achieve required drying temperature for different products in north India plains. This dryer was tested in laboratory in both batch and semi-continuous mode for turmeric (Curcuma longa). The open sun drying was used as control. The thermal efficiency of the dryer for batch and semi-continuous drying obtained are 18.5% and 22.5% respectively. Drying time in comparison to open sun drying has been found to be 55% approximately. The quality of dried turmeric obtained using this dryer is superior to open sun drying in terms of polishing loss, curcumic content, volatile oil content and colour. Its energy payback period and cost payback period were estimated as 2.95 and 1.10 years, respectively, which is very low as compared to its life of 20 years. In the entire lifetime, the CO2 mitigation was found to be 209.21 tons, which proves its suitability.

The Influence of Meshing Strategies on The Numerical Simulation of Solar Greenhouse Dryer

In the present study, we conduct the numerical simulation for solar greenhouse dryer performance by Ansys Fluent software. The numerical simulations compared the meshing strategies for the dryer and show the effects on both temperature distribution and relative humidity distribution of air inside the dryer. Unstructured meshes were used in the numerical simulation employing hexahedral meshing and tetrahedral meshing for mesh generation. The meshing strategies were evaluated through 2 size of cell i.e., 0.1 m and 0.05m. The results indicated that the size of cell have strong effect than the mesh type on the temperature profile and humidity of air inside the dryer. Thus, the results gave the engineers more options to select the optimum conditions for meshing and simulation the dryer.

Numerical performance assessment of a solar greenhouse dryer for the drying of Olive Mill Wastewater

Numerical performance assessment of a solar greenhouse dryer for the drying of Olive Mill Wastewater

Performance evaluation of evacuated solar collector assisted hybrid greenhouse solar dryer under active and passive mode

The novel hybrid greenhouse solar dryer (HGSD) attached with evacuated tube collector (ETC) is developed for faster drying of high moisture content crops. The slow drying rate of high moisture crops lead to microbial attack on crop surface and have more chance of deterioration. Hence the HGSD is designed and tested for faster drying of crops. The experiments are performed to evaluate the performance of HGSD under active and passive mode. Ginger has been taken as a high moisture crops for the experimentation on two cases. In both the cases the ginger is dried from 79.8% to 9.82% moisture level (wb). In active mode, dryer takes 43.47% less time than the passive mode. The overall efficiency of the dryer in active and passive mode is 4.81% and 3.39% respectively. The lower drying time makes this dryer suitable for rural as well as commercial applications for drying agricultural or non-agro based products.

Numerical simulation and experimental validation of solar greenhouse dryer using finite element analysis for different roof shapes

The word greenhouse dryer is used for a building which is highly glazed with thermal conditioning for desired range and it is used for cultivating crops, plants, vegetables, etc. The actual working of a greenhouse is that the short-wave radiations falling on the greenhouse are absorbed by the outer glazing material thereby heating the interior area of greenhouse and providing ambient heat for plants, vegetables growth respectively. The heated space is retained within the enclosure of greenhouse. This phenomenon is called as greenhouse effect. The important role played during the greenhouse effect phenomenon are atmosphere, insulating roofs, walls, etc. The current study focuses on the numerical and experimental validation of Solar Greenhouse which is utilized for drying phenomenon. The numerical simulation is performed using Finite Element Analysis method. The various roof shapes have been incorporated to have emphasis on maximum solar gain to drying phenomenon.

Experimental and CFD Investigation of a Modified Uneven-Span Greenhouse Solar Dryer in No-Load Conditions under Natural Convection Mode

An uneven-span modified greenhouse dryer was constructed and tested in no-load conditions under natural convection mode under the weather conditions of Marrakech, Morocco, for two distinct days. Moreover, a CFD evaluation of the uneven-span greenhouse dryer was performed as tool to visualize the air temperature distribution inside the dryer. For validating the CFD model, the temperature variations along the hours of the day were compared to the experimental results. A good agreement is obtained between the computed and measured inside air temperature with a difference not exceeding 8.46°C, with a correlation coefficient ( r ) and root mean square percentage deviations ( e ) 0.94 and 8.17, respectively. Furthermore, the maximum inside air temperature was measured to be 56°C and 52°C while the minimum inside relative humidity was measured to be 17% and 12%, for day-1 and day-2, respectively. The benefice of using asphalt as a floor covering material was revealed as an efficient way to heat the inside air at low solar radiations. The performances of the dryer were evaluated by the percentage of net heat gain variation as a way to validate the effectiveness of the dryer. This latter is found to be equal to 46% and 48% for the two days, respectively.

A literature research on the drying quality of agricultural products with using solar drying technologies

Solar energy is a green and renewable clean energy. Using this as main or auxiliary energy to dry agricultural materials could reduce energy consumption and improve product quality. In the drying process of agricultural materials, not only drying technologies but also drying parameters would affect the quality of materials.This paper provides a guided technological tour on solar drying through a literature research. An overview about the drying technologies to evaluate the drying quality, such as traditional sun drying, solar tunnel drying, solar greenhouse drying, solar-assisted drying system, is presented to demonstrate advances and application potential of solar drying. Finally, variable temperature drying is preliminarily proposed and tested to verify its superiority of energy saving and drying quality improvement. The literature research in this paper gives a reference on the effective application of solar drying through specifying the mechanisms of quality transformation.

Heat transfer analysis of hybrid active greenhouse solar dryer attached with evacuated tube solar collector

The objective of the paper is to carry out the heat transfer analysis of novel designed hybrid active greenhouse solar dryer (HAGSD) attached with water-in-tube type evacuated collector. The experimentation is carried out to investigate the performance of dryer with and without evacuated tube collector (ETC) under active mode. Three high moisture seasonal crops namely tomato, ginger and bottle gourd have been dried inside the dryer for the two cases and also in open sun drying. Also the drying kinetic of crops has been fitted with ten drying rate models given by researchers. A new drying rate model is also obtained which gives a very close fit with experimental drying rate. The average values of convective heat transfer coefficients for dryer with ETC are 153%, 3.8% and 305.4% higher than the dryer without ETC for tomato, ginger and bottle gourd respectively. The drying time in case of dryer with ETC for tomato, ginger and bottle gourd is 9, 12 and 6 h respectively less than the dryer without ETC. The overall efficiency of the dryer for the three crops varies between 14.22 and 27.99% for dryer with ETC, while for dryer without ETC, it varies between 9.63 and 24.88%.

Design and Construction of an IoT Solar Dryer for Semi-Dried Jerky

This paper presents the design, construction of an IoT greenhouse solar dryer for semi-dried jerky. In the dryer, the heated air is controlled automatically by an IoT based system, and at the same time, the greenhouse absorbs solar energy directly through the polycarbonate transparent walls and roof. The results showed that the greenhouse solar dryer was a good dryer for semi-dried jerky. The semi-dried jerky after drying into the dryer was ensured for food safety with non-detected of total aerobic organisms, heavy metal, bacteria. The performance of the greenhouse solar dryer was test and temperature and humidity of drying process were collected through an IoT system.

Energy Analysis of Greenhouse Dryer for Ficus Carica L. Leaves

In this study, a greenhouse solar dryer with double-pass multi-hollow collector for leaf drying was design, constructed, and evaluated. From the result, the double pass solar air collector with multi-hollow tube is capable of increasing air temperature by 5.5℃-10.8℃ compared to ambient air temperature. Thermal efficiency of the dryer was evaluated for passive and active modes, where 47.2% and 50% are recorded respectively. The moisture reduction on mass basis in passive and active dryer recorded was 44% and 74%, respectively. The specific moisture extraction rate (SMER) and specific energy consumption (SEC) of passive dryer was determined to be 0.198 kg per kWh and 5.047 kWh per kg, and active dryer at 0.210 kg per kWh and 4.769 kWh per kg, respectively.

Environmental and economic analysis of novel hybrid active greenhouse solar dryer with evacuated tube solar collector

The novel hybrid active greenhouse solar dryer is developed in which a heat exchanger is kept inside the dryer that also acts as a drying bed. The hot water from the evacuated tube solar collectors is supplied to the copper tubes of the heat exchanger that transfers its heat to the room air as well as to the crop surface in contact with it. The experiment is performed on the developed dryer for three crops to test its economic viability and environment suitability. The three high moisture crops selected for the analysis are tomato, bottle gourd and ginger. The maximum temperature inside the dryer is 46.9 °C when the ambient temperature is 31 °C. The developed dryer reduces the drying time of tomato, bottle gourd and ginger by 47.36%, 61.90% and 34.09% respectively as compared to the conventional dryer. The developed dryer with evacuated tube collector mitigates 88.12, 50.49 and 135.04 tonnes of CO2 in its life time while the conventional dryer without collector mitigates 49.58, 26.57 and 41.22 tonnes of CO2 in its lifetime for tomato, ginger and bottle gourd respectively. Energy payback time of tomato, ginger and bottle gourd is 0.69, 1.79 and 2.87 years less than the conventional dryer.