Two-Dimensional Simulation of Temperature in Paddy Bulk Storage with Closed-Loop Oscillating Heat Pipes

doi: 10.14456/mijet.2016.5

Abstract

The temperature distribution characteristic of 250 kg paddy was computational studied. The paddy was kept in the cylindrical bin with 0.7 m diameter and 1.0 m height and cooled by an array of closed-loop oscillating heat pipes (CLOHPs). The moisture content of paddy was 14% wet basis. CLOHPs were made of copper capillary tubes with 0.0014 m inside diameter and 0.0022 m outside diameter and filled with R134a at 50% of the total internal tube volume. The evaporator and condenser lengths of CLOHP were 1.0 m and 0.5 m respectively. CLOHPs were arranged in a circular form within the bin. The evaporator section was buried in the storage bin and the condenser section was exposed to the ambient air in order to remove heat from the respiration of paddy. The temperature distribution inside paddy bulk was numerical analyzed as the two-dimensional transient heat transfer in cylindrical coordinates (r, z, t) and the temperature of paddy in circumferential direction was supposed to be uniform. The temperature distribution within paddy bulk with CLOHP was investigated through 60 h and compared to the temperature distribution of system without cooling unit. The temperature difference of paddy inside the storage bin with and without CLOHPS was found in the range of 0.99- 2.55%. The array of CLOHPs within paddy bin can remove the heat from grain during storage and reduce the bed temperature although there are a few temperature differences of paddy and ambient air. The thermal efficiency of simulated CLOHPs cooling system was about 45.2%