In considering that fossil fuel sources are limited and their use leads to changes in environment, using of renewable sources of energy has been developed and used in recent decades. One of the renewable and clean sources of energy is solar energy. In sight of intermittent nature of solar energy some kind of energy storage, is inevitable. Storing energy as sensible heat in mediums – such as water- is a common way in solar applications. Employing latent heat of Phase Change Material (PCM) in solar dryer is a noble way of conserving heat. The use of phase change materials (PCMs) for thermal energy storage has received a great interest in recent years. PCMs are linked to three energy storage methods: sensible heat, latent heat and chemical energy. Among the various kinds of energy storge, latent heat storage has been proved to be an effective means for thermal management due to its high storage capacity and small tempera ture variation from storage to retrieval. As a kind of latent heat storage PCM, paraffin wax attracts considerable attention since it possesses desirable properties such as high latent heat of fusion, chemically inert, no phase segregation, and commercially available at low cost. However, paraffin waxes exhibit low thermal conductivity, which decreases the overall power of the thermal storage device. Great efforts have been attempted to improve the thermal conductivity of the paraffin wax. Metal foams, additives or fins were used by researchers to enhance the thermal conductivities of paraffin waxes. These enhancers add significant weight and cost to the storage systems and some of them are incompatible with PCMs. Recently, carbon materials are under investigation to enhance the heat transfer in PCMs, since they present high thermal conductivity, low bulk density, and chemical inertness. In any dried fruit production activity, the drying process may be the most important unit of operation. This method of preservation, if done correctly, can preserve and improve the quality and quantity of the end product effectively. Drying for agricultural products are one of the most attractive and cost-effective application of solar energy. Numerous types of solar dryers have been designed and developed in various parts of the world, yielding varying degrees of technical performance. This paper presents a novel type of dryer for experimentally evaluating the drying system. In the developed drying system, it has been particularly included a solar air absorber with phase-change material (PCM) and drying box. A solar air absorber with PCM has been used to perform the drying process even after the sunset. Due to the necessity of drying the grapes within a certain time period, absorber which includes a phase-change material (PCM) based on latent heat storage principle was manufactured in the designed mechanism so as to perform the drying pro cess even after the sunset. Paraffin as PCM was placed in the steel pipes of this absorber. During day hours, solar energy was collected in the PCM with the help of absorber. After the sunset, naturally convected air was passed through the surface where PCM was located, and so the stored energy was utilized. Thereby, even after the sunset, drying process continued using the absorber with PCM. These advantages make the proposed novel system a promising dryer in that lower moisture value and less drying time is achieved. The experiments have been conducted at three different periods. It has been determined that drying time shortens as drying air velocity increases and also drying process shorted in the dryer use PCM. The drying experiments have been carried out under natural condition. Keywords: Solar dryer, Phase Change Material (PCM), Store energy, Moisture ratio.
