Preface

Energy needs are continuously increasing and the demand for electrical power continues to grow rapidly. The world energy market has to date depended almost entirely on nonrenewable, but low cost, fossil fuels.

Renewable energy is the inevitable choice for sustainable economic growth, for the harmonious coexistence of human and environment as well as for the sustainable development. As we learn how to economically harness the renewable energy sources, they will get cheaper and cheaper while fossil fuels get more and more expensive. A wind, solar or geothermal power plant may be more expensive to build now than a fossil power plant, but the future cost of fuel will be zero. In addition, the effects of the pollution fossil fuels produce become more and more destructive. The cost of controlling these pollutants is growing every day.

> **Arzu Şencan Şahin**  Süleyman Demirel University, Technology Faculty, Energy System Engineering, Isparta, Turkey

**1** 

Feyza Akarslan

*Turkey* 

**Solar-Energy Drying Systems** 

*Süleyman Demirel Univercity, Isparta* 

*Department of Textile Engineering, Engineering and Architectural Faculty,* 

Energy is important for the existence and development of humankind and is a key issue in international politics, the economy, military preparedness, and diplomacy. To reduce the impact of conventional energy sources on the environment, much attention should be paid to the development of new energy and renewable energy resources. Solar energy, which is environment friendly, is renewable and can serve as a sustainable energy source. Hence, it will certainly become an important part of the future energy structure with the increasingly drying up of the terrestrial fossil fuel. However, the lower energy density and seasonal doing with geographical dependence are the major challenges in identifying suitable applications using solar energy as the heat source. Consequently, exploring high efficiency solar energy concentration technology is necessary and realistic (Xie et al.,

Solar energy is free, environmentally clean, and therefore is recognized as one of the most promising alternative energy recourses options. In near future, the large-scale introduction of solar energy systems, directly converting solar radiation into heat, can be looked forward. However, solar energy is intermittent by its nature; there is no sun at night. Its total available value is seasonal and is dependent on the meteorological conditions of the location. Unreliability is the biggest retarding factor for extensive solar energy utilization. Of course, reliability of solar energy can be increased by storing its portion when it is in excess of the load and using the stored energy whenever needed. (Bal

Solar drying is a potential decentralized thermal application of solar energy particularly in developing countries (Sharma et al., 2009). However, so far, there has been very little field penetration of solar drying technology. In the initial phase of dissemination, identification of suitable areas for using solar dryers would be extremely helpful towards their market

Solar drying is often differentiated from "sun drying" by the use of equipment to collect the sun's radiation in order to harness the radiative energy for drying applications. Sun drying is a common farming and agricultural process in many countries, particularly where the outdoor temperature reaches 30 °C or higher. In many parts of South East Asia, spice s and herbs are routinely dried. However, weather conditions often preclude the use of sun drying

**1. Introduction** 

2011).

et al., 2010).

penetration.
