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Solar Drying Technology
Published in Atul Sharma, Amritanshu Shukla, Renu Singh, Low Carbon Energy Supply Technologies and Systems, 2020
Solar energy is available freely and abundantly in most of the areas and is practiced for generations to preserve agri-products, medicinal herbs, and many other products. However, traditionally open sun drying is most prevalent in most of the areas, which has issues of dust accumulation on the products as well as a change in color. A solar dryer consists of an absorber and drying chamber. The energy collected by the absorber is transferred to drying chamber either by natural convection mode or by force convection. The system that works in natural convection is called a passive dryer, and the force convection mode dryer is called an active system [6]. Recently, a few different types of solar dryers were developed around the globe for direct and indirect drying of perishable products. This chapter aims to provide a brief discussion about the market demand of the dried products, benefits of drying of perishable products, principles of drying, and advancements in the solar drying technologies.
Production of Biodiesel from Microalgae
Published in Hyunsoo Joo, Ashok Kumar, World Biodiesel Policies and Production, 2019
Mohammad-Matin Hanifzadeh, Zahra Nabati
Solar drying is the cheapest and the most feasible drying strategy especially in areas with high hours of sunlight (which typically are the most suitable locations for cultivation of microalgae). For valorization of solar energy as the heat source for drying, a thin layer of biomass is exposed to sunlight. Overexposure of biomass to sunlight may lead to degradation of chlorophyll and to undesirable changes in biomass quality (e.g., color) [89]. So, in order to maintain the quality of biomass, it is necessary to optimize the duration of biomass exposure. Application of sun drying to microalgae is limited to the use of algae for animal feeding and biodiesel production because the long-time drying may deteriorate the biomass resulting in undesirable quality of final products for human use [89]. Alternatively, the solar energy can be utilized indirectly through glass plate solar collectors which are usually designed tubular or flat. The application of a solar dryer can control the heat intensity during the process, which results in better quality products than direct sun drying. However, the composition of product can still be altered during a long-time drying process. Another low-cost method for drying microalgae biomass is cross-flow drying, in which drying is performed by blowing hot air to a layer of biomass. The cross-flow drying is faster than sun drying but may lead to the change in biomass composition without proper time management. The cross-flow drying is not dependent on the weather and is more viable than sun drying for the locations where sun radiation is not enough [74].
Polymeric Materials And Their Use In Agriculture
Published in A. K. Haghi, Lionello Pogliani, Devrim Balköse, Omari V. Mukbaniani, Andrew G. Mercader, Applied Chemistry and Chemical Engineering, 2017
K. T. Archvadze, T. I. Megrelidze, l. V. Tabatadze, I. R. Chachava
Because of reduction in drying time, the product is less susceptible to color changes in comparison with the solar air-drying method that makes a product of higher quality. This material is better preserved, determining their nutritional and biological value (sugar, vitamins, and others). Drying in solar dryer also has other economic advantages, since it uses free energy source— the sun—drying time is significantly reduced, increases productivity, and reduces production costs.
Improvement of an open sun drying system for dried banana product using solar tracking system: a case study in Thailand
Published in International Journal of Green Energy, 2022
Chaowanan Jamroen, Preecha Komkum, Punnapit Yoopum, Surachart Pinsakol, Krit Kerdnoan
Solar energy released by the sun is used to remove or reduce moisture content (water activity) in the products, known as the solar drying method. Reducing the moisture content to a safe level can decrease microbiological activities and avoid product spoilage (Eltawil, Azam, and Alghannam 2018). Furthermore, drying can reduce the costs of product storage and maintain the nutritive and flavor benefits of the products (Jain and Tewari 2015). It is also a sustainable and cost-effective application in the agricultural food sector due to its simplicity and environmental friendliness. Solar drying can be classified into two categories (Prakash and Kumar 2017; Udomkun et al. 2020), i.e., open sun drying (OSD) and solar dryers. Traditionally, OSD is the traditional method used for food preservation. It does not require other external sources of energy during drying. Furthermore, the requirement of skilled labor is unnecessary. This drying method is the least expensive and the most suitable for remote rural areas (Lingayat et al. 2020; Vengsungnle et al. 2020). However, it has several limitations and disadvantages, such as that the products can be contaminated by dust and insects. Accordingly, a solar dryer is introduced and can be divided into two types (Djebli et al. 2020): direct and indirect.
Experimental investigation and drying kinetics of mixed type solar dryer with thermal energy storage material for drying of apple slices
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2022
Dheerandra Singh, Sanjay Mishra, Ravi Shankar
A solar dryer becomes more effective when higher amount of moisture is removed from the product to be drying with lower drying time. Figures 7 and 8 show the variation of moisture content and moisture ratio, respectively, in lower tray (tray-1), upper tray (tray-2) and open sun drying with time. The variation of moisture ratio is same as moisture content, since moisture ratio is proportional to moisture content. Approximately 50% of total moisture is removed from apple slices within 1.5 h for all cases, after that the moisture removal is considerably small. The moisture removal for lower tray is higher than that of lower tray and open sun drying, throughout the drying time. At 12:30 PM, final recommended moisture content of 21.7% (w.b.) was obtained for lower tray while at the same time it was 22.6% (w.b.) and 25.6% (w.b.) for upper tray and open sun drying, respectively. This shows that final moisture content is obtained in lesser time for solar drying than for open sun drying.
Energy–exergy analysis and mathematical modeling of cassava starch drying using a hybrid solar dryer
Published in Cogent Engineering, 2020
Suherman Suherman, Evan Eduard Susanto, Asif Widodo Zardani, Nur Haniza Roviqoh Dewi, H. Hadiyanto
Drying technology is aimed to improve the quality of agricultural products tin order to increase the shelf life. In some particular products, the water content should be lowered to deactivate the microbial activity. Solar drying technology is ideally applied in tropical countries, areas that receive excessive sunlight intensity most of the year. In solar drying, solar energy is used as the main source of energy drying. Solar drying technology is very suitable for drying agricultural products, because the drying will not extremely reduce the water contents in the products. With low investment and operating costs, easy operation, solar dryer is the right choice for SME in Indonesia. Solar dryer can be used to dry food and agricultural products such as coffee beans, paddy, cassava starch, corn, onions, etc. In order to anticipate the erratic weather such as clouds and rain, hybrid dryer technology has been developed, which is to add additional energy sources from LPG gas, biomass, etc.