Contents lists available at ScienceDirect Solar Energy journal homepage: www.elsevier.com/locate/solener Experimental investigation and energy analysis of a solar-assisted fuidized- bed dryer including solar water heater and solar-powered infrared lamp for paddy grains drying Saeed Mehran a , Mohammad Nikian a, ⁎ , Mehrangiz Ghazi a , Hemad Zareiforoush b , Iraj Bagheri b a Department of Mechanical Engineering, Takestan Branch, Islamic Azad University, Takestan, Iran b Department of Mechanization Engineering, Faculty of Agricultural Sciences, University of Guilan, P.O. Box 41635-1314, Rasht, Iran ARTICLEINFO Keywords: Solar dryer Solar fraction Energy Paddy drying Infrared lamp ABSTRACT During drying process of paddy grains, as one of the major operations of rice milling process, a considerable amount of fossil fuel is consumed. The air pollutants emitted by combustion of fossil fuels are great threat to humanhealthwhichstronglycontributetoenvironmentalproblems.Inthepresentstudy,toreducetheshareof fossil fuels in drying process of paddy grains, a new type solar-assisted fuidized-bed dryer was used with the ability of thermal energy recovery. The drying system mainly consisted of a solar water heater, a solar-powered infraredlamp,agaswaterheater,andadesiccantwheel.Twogeneralconditionswereconsideredforconducting the experiments: Natural gas drying (NGD), and Solar-assisted drying (SAD). The results of evaluations showed thatthehighesttotalenergyconsumptionofthedryerwasequalto1.163kWhwhichwasobtainedinNGDtest mode, while the lowest amount of total energy consumption was obtained in SAD mode which was 0.314kWh. The specifc energy consumption of the drying system in SAD and NGD modes was in the range of 8.30–22.12 and 16.73–32.62kWh/kg water evaporated, respectively. The highest value of solar fraction index was equal to 0.538whichwasobtainedatdryingairtemperatureof45°C,dryingairvelocityof8m/s,whilethelowestsolar fraction value (0.179) was attributed to drying air temperature of 35°C and air velocity of 7m/s. Although applying the infrared lamp caused the solar energy fraction to increase to 0.741, however, the use of infrared lamp in the fuidizing chamber did not have a signifcant efect on the dehydration rate of the product. At two levels of the applied drying temperatures (35°C and 45°C), the required thermal energy during the drying process was completely supplied only by solar energy and without the need for fossil fuel. 1. Introduction Nowadays, the term energy plays a crucial role in the industrial economy, indicating that economy development has been achieved under sufcient and accessible energy condition. Despite of their di- versity, the lifelong of fossil resources is limited and does not exceed a hundred-year cycle (Michaelides, 2012). On the other hand, the use of fossil energy resources has been identifed as the crucial factor for air pollution and undesired weather patterns in the world (Herzog et al., 2001). The increasing health, social and economic problems of en- vironmental pollutants and greenhouse gas emissions from fossil fuels haveledtotheexpansionofdesiretouseofrenewableandcleanenergy sources (Gautam et al., 2017). Among all types of renewable sources, solar energy has the highest potential to apply so that only a small amountofthissourceofenergycanmeetthedemandsofhumanbeings (Yahya et al., 2018). Since solar energy has an intermittent nature, it is not available at all time. Therefore, researchers have attempted to de- velop efective thermal energy storage systems to supply the frequent energy demands of the thermal processes (Agrawal et al., 2018). Low grade thermal energy harvesting is a signifcant method for heat cap- turing and converting it into more usable forms, such as mechanical or electricalenergy(KishoreandPriya,2018).Theenergystoragesystems are of the most important approaches to increase the efciency of thermal processes which can reduce the fraction of CO 2 emissions into theenvironment(Kumaretal.,2019).Oneoftheotherareasofinterest for the researchers has been to enhance the capability of thermal sys- tems by increasing the transfer rate of heat exchangers (Chamoli et al., 2018; Chamoli et al., 2017; Kumar et al., 2016a, 2016b). The packed bed formulated thermal energy storage systems have been used to supplythetemperaturerequirementsofadvancedadiabaticcompressed air energy storage systems (Kunwar et al., 2019). Thermal energy loss in the food industry is an important issue https://doi.org/10.1016/j.solener.2019.08.002 Received 8 March 2019; Received in revised form 14 July 2019; Accepted 1 August 2019 ⁎ Corresponding author. E-mail address: m.nikiyan@tiau.ac.ir (M. Nikian). Solar Energy 190 (2019) 167–184 0038-092X/ © 2019 Published by Elsevier Ltd on behalf of International Solar Energy Society. T