Performance study of different solar dryers: A review

Crop drying is essential for preservation in agricultural applications. It is performed either using fossil fuels in an artificial mechanical drying process or by placing the crop under the open sun. The first method is costly and has a negative impact on the environment, while the second method is totally dependent on the weather. By contrast, using a solar dryer is comparatively cheaper and more efficient. Some solar dryers run without electrical grid power or fossil fuels. This paper presents the state of various kinds of solar dryers that are widely used today. The indirect, direct, and mixed mode dryers that have shown potential in drying agricultural products in the tropical and subtropical countries are discussed. Aside from identifying the active and passive mode solar dryers, we also highlight the environmental influence on solar energy (harnessing) that plays a vital role in the solar drying sector. This paper also presents the related technologies that can help improve existing solar dryers. (C) 2014 Elsevier Ltd. All rights reserved.