A New Design for Solar Dryer: Part – 1 | Introduction

Agricultural produce is perishable by nature, In India, nearly 10% of agricultural produce, nearly 15 million tons of food grains per year, is damaged after harvesting. Preserving such agricultural produce by drying reduces wastage and allows storage of food needed. Drying makes produce lighter and smaller with value addition. Drying is the most established and oldest method of improving shelf life [1]. The drying process reduces the moisture content of food to a lower level, which prevents the deterioration of food caused by molds, yeasts, bacteria, and enzymes [2,3].

Agricultural produce is perishable by nature. In India, nearly 10% of agricultural produce, nearly 15 million tons of food grains per year, is damaged after harvesting. Preserving such agricultural produce by drying reduces wastage and allows storage of food needed. Drying makes produce lighter and smaller with value addition. Drying is the most established and oldest method of improving shelf life [1]. The drying process reduces the moisture content of food to a lower level, which prevents the deterioration of food caused by molds, yeasts, bacteria, and enzymes [2,3].

The process also requires a large area of land, takes time, and is highly labour-Intensive, as it is an attentive process [2]. With agricultural and Industrial development, mechanical drying using heat sources from fossil fuels came into practice. However, these mechanical drying systems are highly energy-intensive and expensive, Increasing the production cost [2]. Open sun drying is less costly and straightforward but requires two to three weeks. Due to long-time exposure to solar radiation, its nutritional values decrease [1,2]. Open-air drying has now shifted to solar drying as good options are available due to technological development. The solar drying system utilizes solar energy to heat air and dry agricultural produce.

Solar dryers available in the market are approximately cuboid (Cabinet) in shape with a transparent top face that slopes in a due south direction for installation in the northern hemisphere. Such a design demands proper insulation on five sides except the top. transparent. The cuboid shape prevents the use of solar radiation in the morning and evening. It also exposes the produce, to be dried, to Ultraviolet rays. In this design, the air change differs across the drying area. Air is removed from various spots along the top edge. This action makes it hard to control air exchange, temperature, and humidity. The inside drying area in cuboid dryers is smaller than in hemispherical dryers for the same outside surface area.