2.1. Materials and Experiment Conditions

The rice used in the experiment was newly harvested Dragon rice 16 from Jilin province in China, which belongs to the sweet rice variety. Samples were harvested from the ground in 2 kg bags, sealed in plastic bags, and kept fresh in refrigerators. Initial moisture was about 27%, which was measured using a PM-8188 grain moisture meter produced by KETT Japan. During the test, samples were taken out and placed in the environment for about 10 min. Then, 340 g of the sample was weighed for the drying test. The weight and moisture of the samples were measured before and at the end of the test.

As low-temperature drying is conducive to maintaining the quality of rice [25,28], six temperature levels, namely 30, 35, 40, 45, 50, and 55 °C, were selected to analyze the exergy characteristics of the drying chamber during the rice-drying test. For the variable air temperature experiment, the air velocity across the grain layer was 0.5 m/s; for the variable air velocity experiment, the temperature was 40 °C.