Abstract: Abstract: Ventilating and cooling are popular measures to achieve high quality storage for cereals. In large diameter squat silos with high-moisture cereal, the heat gain conducted through the building envelope would accumulate in the cereal bulk if only conventional ventilation was applied. Normal ventilating modes, such as slots under the floor or ducts on the ground, could not provide an airflow organization meeting the temperature and moisture distribution demand in the large diameter squat silo, because the size and shape of the new-style was different from that of the exited. In this paper a ringed ducts experiment system was set up to study the ventilating and cooling effect for large diameter squat silos. Considering the different seasons for storage in practice, experiments were carried out in 2 different climate conditions: hot season mode and warm season mode, corresponding to spring/autumn and summer, respectively. The experiment included 3 parts: 1) bulk preheating- the cereal and the ambient temperatures were brought to a set initial value;2) constant thermal environment - the radiator was turned on, so that the top of the silo was heated by uniform radiation, and the ambient temperature around the silo was constant in a preset range by feeding warm air; 3) cooling- the cold air was supplied into the silo at a temperature lower than that of the cereal until the average bulk temperature was stable. During the experiment process, the air velocity at the supply outlet in the vertical main pipe was 2.01-2.05 m/s, that was, an air supply volume of 6.58-6.67 m3/h. The ambient temperature and relative humidity was at the range of 25.59-28.48 ℃ and 46.3%-48.7% for warm season mode, and the range of 29.32-31.05 ℃ and 37.5%-39.2% for hot season mode. The initial temperature was approximately 27 ℃ in both modes. The effective temperature difference was 5 and 7 ℃ in warm season mode and hot season mode, respectively, considering 2 different dew-point temperatures. The results showed that external thermal environment had an influential effect on time spending for cereal cooling. The temperature drops in an hour were 0.43 and 0.16 ℃ for warm and hot season mode, respectively. At the ending of cooling, the average temperature of the bulk was 17.24 and 22.76 ℃ for the 2 modes, meeting the targets of quasi-low temperature and normal temperature storage (20 and 25 ℃, respectively). As to the temperature field after cooling, an expected uniformity was achieved in both warm season mode and hot season mode, along both the vertical and horizontal directions. The temperature difference between vertical cereal layers was 0.5 ℃ in warm season mode and 1.6 ℃ in hot season mode. With a supply temperature higher than dew point, the relative humidity in the cereal bulk fluctuated within a range of 5% during the cooling process. That was, no significant dehydration was found in the cereal bulk under both modes through the quick cooling processes from the experimental results. Furthermore, the configuration of ringed ducts was optimized by CFD method. The results were confirmed with experiment data, the maximum error between the experiment and the simulation was 1.89 ℃ and the average relative error was 6.43%. The simulation results indicated that a shorter time for cooling and better temperature distribution could be expected by moving the ringed ducts up to near the cereal bulk surface, which was consistent with the experiment results. With elevated ducts, a cold shielding effect was observed in a 5-cm range above the cereal surface and this prevented the heat flow from the top of the silo.