## 2 Materials and Methods
### Principle and Process of Equipment  
Given that corn is a heat-sensitive material, a reasonable drying mode for corn should be able to dry quickly and timely under conditions close to the environment temperature [27]. From the point of view of energy consumption of the structure of the corn drying process [10], the heat energy consumed by the water evaporation process of corn in the drying system must be accompanied by a reduction of its internal energy. The binding energy model constructed by [PERSON] [28] et al. indicates that in grains with low moisture content, the binding energy between the grain and its moisture is significantly affected by the drying temperature, while the water evaporation of grains with high moisture content is hardly limited by the grain itself.  
Infrared radiation (IR) drying is an advisable method due to the fact that corn temperature is not restricted by the wet-bulb temperature of the medium [29]. Moreover, infrared heating has many potential merits over traditional drying, such as fast drying rate, acceptable energy efficiency, uniform product temperature and less dust-generation during drying process [30]. High grain temperatures can be obtained in a short time for quick dehydration, which results in the availability of high-quality grain.  
Based on the above, the present work proposes a combined IRCC corn dryer that adopts a novel drying technology. Figure 2 describes the scene graph of IRCC corn dryer. The system consists of three main parts: heating section, drying chamber and dedusting section. The heating section mainly consists of an economical, durable and efficient combustion chamber using coal as fuel. More details about the self-developed combustion chamber can be found in the patent (CN105757650B) [31]. The tube row of the heat exchanger is a cross-row type, and its main part is a heat exchange pipe, with 11 columns \(\times\) 23 rows and a total of 253. There are two upper and lower diversion layers connected to the heat exchanger pipes. The size of the diversion layer is \(2800\times 1800\times 450\) mm. There are two baffles inside to divide it into three small chambers to conduct heat flow, respectively. This arrangement can ensure that the fluid flows through the tube bundle and increase the disturbance to improve the heat-transfer coefficient. In drying chamber, corn flows through the tempering section (TP), infrared radiation drying section (IRD), counterflow drying chamber (DC) and the discharging section (DCS) from top to bottom and then returns to the TP under the promotion of the hoist, which forms a grain circulation circuit. The IRD is mainly composed of four tubular infrared radiators (RA) which are inserted in the dryer and surrounded by flowing corn. The grain discharging section is composed of a reciprocating grain discharging device [32], which ensuring the self-cleaning of grain and the reduction of damage in the process of discharging. The medium after being heated by heat exchanger (HE) flows into the drying chamber and contacts with the corn to absorb moisture, which forms a medium flow circuit. The partial fuse gas discharged from combustion chamber (CC) passes through the IRD, and the waste heat is used to heat corn. The exhaust gas discharged from DC and the exhaust fuse gas discharged from IRD flow into the dust removal chamber under the promotion of the induced fan (Model 4-68,  
Figure 1: Fresh corn sample for the experiment.  
Tongda, Inc., Linyi, China). The period of a circulation is about 90 min with drying capacity of about 4.2 t/h. The developed IRCC corn dryer has been put into application in Zhencheng Farm at Xinzhou Shanxi Province, China.