Solar Crop Dryers
A solar crop dryer is used to reduce crop losses during in-season harvesting periods. A solar-dried crop is hygienic and preserves nutritional value. A solar crop dryer reduces drying time with protection from external disturbances such as rain and strong
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Solar Crop Dryers
Abstract A solar crop dryer is used to reduce crop losses during in-season harvesting periods. A solar-dried crop is hygienic and preserves nutritional value. A solar crop dryer reduces drying time with protection from external disturbances such as rain and strong wind.
Keywords Solar drying Open sun drying Cabinet drying Mixed mode dryer Greenhouse dryer PVT-solar dryers
12.1
Importance of Solar-Drying
The primary requirement for survival of human beings is food after air and water. The Food and Agriculture Organization (FAO) estimated that >852 million people worldwide were undernourished in the year 2000–2002 [1]. The projected figure of the world’s population is >7.6 billion up to the year 2020. Hence, agricultural production should be increased to meet the food demand of the fast-growing population across world. In the next 25 years, approximately 50 % more food must be produced, particularly in developing countries. The gap between the supply and demand for food can be challenged (i) by increasing crop/food productivity (ii) by controlling population growth (iii) by reducing food losses, or (iii) a combination of both. In this chapter, we will address the problem of decreasing food losses before/after harvesting using solar drying. Solar drying of agricultural product is one of the important postharvest operations to save grain from postharvest losses. Solar drying is the process of removing moisture from produce to attain optimum moisture content for its long-term storage (Table 12.1). Solar drying of crops helps with the following: (i) facilitating early or preharvest activities, (ii) planning the harvest season, (iii) providing long-term storage, (iv) fetching better returns for farmers, (v) maintaining the viability of seeds, (vi) selling a better-quality product, (vii) the handling, transport, and distribution of crops, and (viii) reduction of the requirement for storage space [2]. © Springer Science+Business Media Singapore 2016 G.N. Tiwari et al., Handbook of Solar Energy, Energy Systems in Electrical Engineering, DOI 10.1007/978-981-10-0807-8_12
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12 Solar Crop Dryers
Table 12.1 Initial and final moisture contents and maximum allowable temperature for drying of some crops [26] Sl. no.
Crop
Initial moisture content (%w.b.)
Final moisture content (%w.b.)
Maximum allowable temperature (°C)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
Apple Apricot Bananas Brinjal Cabbage Carrots Cauliflower Chilies Corn Garlic Grapes Green beans Green peas Guavas Maize Oil seeds Okra Onion Paddy (parboiled) Paddy (raw) Pineapple Potatoes Pulses Rice Sweet potato Tomatoes Wheat
80 85 80 95 80 70 80 80 24 80 80 70 80 80 35 20–25 80 80 30–35 22–24 80 75 20–22 24 75 96 20
24 18 15 6 4 5 6 5 14 4 15–20 5 5 7 15 07–09 20 4 13 11 10 13 09–10 11 7 10 16
70 65 70 60 55 75 65 65 50 55 70 75 65 65 60 40–60 65 55 50 50 65 75 40–60 50 75 60 45
Conventional drying of agricultural products is an energy-intensive operation. For conventional drying proces
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