## 3 Results and Discussions
### Energy Analysis of Corn Drying with the IRCC Corn Dryer
#### 3.2.3 Heat Loss Characteristics  
Heat loss is the primary cause of high-energy consumption and low efficiency in the grain drying process [53; 54]. Hence, it is necessary to investigate the heat loss characteristics of drying process to propose scientific drying parameters and effective measures for the purpose of high-efficiency and energy savings. In the present work, heat loss characteristics--including heat loss in the outlet air, heat loss in the outlet corn and heat loss to the chamber wall--are depicted in Figure 11. The results indicated that the above three types of heat loss were calculated to be 20,045.23 MJ, 12,547.16 MJ and 5151.52 MJ, accounting for 53.11%, 33.24% and 13.65% of total, respectively, and the average heat-loss rate was learned to be 3145.26 MJ/h. The heat-loss rate in outlet air and outlet corn increased with the drying process and tended to be a constant after reaching the maximum. During the drying process, the grain flow speed and moisture content gradually decrease, which leads to small gaps among particles [55]. As a result, the effective evaporation area coefficient of the drying phase interface was reduced, and the strength of heat and mass transfer between corn and drying medium were weakened. Additionally, the heat in the drying medium is hardly fully utilized, resulting in an increasing heat-loss rate of exhaust gas. Finally, during the period of 500-600 min, the heat-loss rate in outlet air fluctuated slightly, which may result from the impact that ambient on the drying process. During the whole drying process, especially in the later stage, heat-loss rate in outlet air showed an increasing trend. Therefore, it is of great significance to design a recovery device to reuse the waste heat in the outlet air for the motivation of reducing the exhaust heat loss and energy-consumption costs. [PERSON] [56] found a similar result in his research on the characteristic analysis of heat loss in a multistage counterflow paddy dryer and pointed out that a corresponding waste heat recovery device should be designed for the problem of high-exhaust heat loss.  
Figure 10: Variations of wavelength of the far infrared and the energy recovery process.  
At the beginning of drying process, a great deal of heat will be taken out from the DC by the heated grains due to the relatively low ambient temperature, which caused the increase of grain temperature and heat-loss rate in outlet corn. Then, the heat-loss rate of outlet corn was stable as the grain temperature tends to a constant. The water-vapor pressure on the surface of corn with high moisture content is large, and the internal binding energy and resistance to dehydration are relatively small at the early stage. Hence, in order to reduce the heat loss of the outlet corn at this stage, a drying medium with low temperature and low humidity should be utilized. Moreover, in this way, a portion of the moisture in the grains can also be removed with a relatively low energy-consumption cost. At the end of the drying process (after 600 min), the moisture content of grain gradually decreases, which demonstrates that the binding energy of the grain is relatively small. The decrease of binding energy means that under the condition of the same energy input, increasing the internal energy of grains with low moisture content requires more energy. Therefore, the heat loss in outlet corn increased significantly. [PERSON]'s research [57] on the energy efficiency evaluation and experiments on grain counterflow drying systems based on exergy analysis found a similar result.  
Heat loss to the chamber wall mainly occurred at the connection between the heat exchanger and the dryer. At the beginning of drying process, the heat-loss rate of the chamber wall increased with the increasing temperature of the chamber wall--and then tended to be constant. Due to the fact that the temperature of inlet air was relatively stable, the heat-loss rate of the chamber wall varied only slightly (116.58-133.4 kW).