## 1 Introduction  
Drying is a complicated thermodynamic process containing heat and mass transfer between the external constraints and inherent properties, which leads to the decrease of the moisture content of agricultural products or industrial material to a safe storage grade or to a grade appropriate for commercial use [1; 2; 3]. Due to the negative conditions such as the high latent heat of water evaporation and the relatively low efficiency of dryers, drying is a highly energy intensive operation that is an unneglected factor raising environmental concerns [4]. According to [PERSON] [5], drying operations consumed about 10-15% of the total national industrial energy consumed in Canada, France and the USA, and 20-25% in Germany and Denmark. Therefore, like other energy-intensive industries, it is of great significance to search for energy-saving strategies and technologies to achieve the most effective and economic modes for drying industry. Corn drying is a high-energy-consumption process that is very susceptible to the quality of processed corn. In recent years, investigators have conducted many studies of new drying equipment and techniques for the purpose of decreasing the energy consumption of the process and improving quality of product [6; 7; 8; 9; 10]. For example, [PERSON] et al. [11] conducted in-depth explorations into the application of radio frequency-hot air drying technology on corn kernels in 2020 and found that a reduced electrode gap can not only improve seed vigor, but also reduce specific energy consumption. [PERSON] et al. [12] used microwave radiation to assess effects on the physiological quality of the seeds submitted to different drying conditions and indicated that drying with microwaves not only reduced the drying time of corn kernels, but also increased the longevity and the water absorption capacity of the seeds. [PERSON] et al. [13] developed an advanced hot air-drying method for corn kernels by using a pretreatment of low-temperature plasma and results showed that the low-temperature plasma pretreatment had a significant effect on drying kinetics. Although the new methods based on laboratory experiments have been reported as efficient drying methods for quality corn, the study results are still not suitable in industrial drying scale featuring a complex system composed of several parts. Moreover, since energy is an inaccessible factor in the realization of human sustainable development, it is of great significant to reveal the components and quantities of energy loss and exergy destruction in industrial drying system [14]. Traditionally, energy-exergy methodology is a useful tool which reveals where and to what extent more efficient drying systems can be designed by reducing the existing inefficiencies sources [15]. Energy analysis, which applies the first law of thermodynamics, has been commonly adopted in engineering systems performance analysis from the principle of conservation of energy. However, it gives no information about how to distinguish the quality of the energy [1,16]. Exergy refers to the maximum work that can be obtained when the material flow, heat flow or work reaches to equilibrium with the reference environment through a reversible process [17]. Since this is a method to analyze, design and improve energy and other systems by using the principles of conservation of mass and energy and the second law of thermodynamics, it is a more powerful tool for evaluating the effective use of energy. Compared with other energy analysis, the view of this process is more realistic [18]. Hence, based on the second law of thermodynamics and related theories, a large amount of research has been committed to evaluations of energy and exergy in the drying process [19; 20; 21; 22; 23]. For instance, [PERSON] et al. [24] developed a hybrid dryer that utilizes a combination of different energy sources to optimize the drying process, while ensuring high-quality dried products. The result indicated that the efficiency of the equipment was around 60%. [PERSON] et al.