IJSRSET1734118 | Received : 10 August 2017 | Accepted : 21 August July- 2017 | July-August-2017 [(3)5: 471-479] © 2017 IJSRSET | Volume 3 | Issue 5 | Print ISSN: 2395-1990 | Online ISSN : 2394-4099 Themed Section: Engineering and Technology 471 Experimental Study of Direct and Indirect Solar Biomass Dryer Shafiq Hamid, Eqwan M. R.* Department of Mechanical Engineering, Universiti Tenaga Nasional, Kajang, Selangor, Malaysia ABSTRACT Drying of biomass or agricultural products has been essential in preserving food or conversion into fuel. The traditional method of drying is open drying, which is prone to multiple problems such as contamination, infestations and effect from weather. Solar drying in a closed enclosure can help overcome these issues. This paper discusses the experimental study of direct and indirect solar dryer, in terms of its drying capability, optimal configuration and suitability of usage for different conditions. Four different experiments were conducted, all comparing direct and indirect dryer but with different level of air convection, starting with natural convection, forced convection with one fan, followed by two and three fans. It is found that the level of air flow, the manner of which sunlight is absorbed (direct or indirect) and the position of trays affect the drying rate. Keywords: Solar Dryer, Direct Drying, Indirect Drying, Biomass I. INTRODUCTION Food security has been a concern for humankind for a long period of time, due to seasonal weather conditions and crop production. Post-harvest losses, seasonal scarcity of food and agricultural products, in addition, global warming, has been the driving concern worldwide for the development of environmentally friendly solution for preservation [1]. Drying plant or biomass has long been a process to preserve plants, usually for food products or fuel. One of the common techniques is dehydration [2], which is the removal of moisture to longer the life of the product, such as fruits and vegetables. Traditionally, dehydration is achieved by drying in open air [3], resulting in several issues. The modern method of drying, by burning fossil fuel or other sources of energy, offers stable drying process but at a higher cost. It is estimated that 7 – 15% of energy used in industrialized countries is for foodstuff drying, resulting in high operating cost [4]. This is added by the common inefficient ways of utilizing biomass (especially wood) as a main source of energy [5]. Traditional method of drying, although doesn’t require any significant or high cost, is associated with multiple issues such as fungal attacks, infestation of insects, birds and rodents, crop losses, rain and weather effects, to name a few [6]. These problems, including exposure of food product to solar rays, deterioration of nutritional values and other issues stated above can be solved using a closed system [7]. Solar dryers, a closed system, can be generally classifies into a) direct, b) indirect and c) mixed mode, involving circulation of drying air. A direct dryer utilizes solar radiation by letting it pass through a transparent cover, directly hitting the products to be direct. Indirect dryer utilizes solar radiation by heating a separate collector and then supplied to the drying chamber [2]. One main disadvantage of solar drying is the intermittent availability of solar radiation and its absence at night, resulting in inconsistent drying time and quality of final dried product. This main disadvantage resulted in the development of hybrid dryer, which involves external supply of heat. O. Ekechukwu et al have classified solar dryers into passive and active drying systems [8]. Other classification method classifies based on mode of heating (direct or indirect) [9].