Avaliação de sistemas de aeração convencional e com ar artificialmente resfriado para grãos de milho

Abstract

The aeration system is used to preserve the qualities of the stored grains, with the objective of cooling the mass of the grains to preserve the quality of the grains. Despite being the most widespread system for preserving stored grains, aeration has limitations such as dependence on local climatic conditions. For this reason, the cooling system can be an alternative technology to replace conventional aeration. This work aimed to design, build and evaluate an artificially cooled aeration system. Two prototype silos were built with dimensions (0.9 m in diameter and 3 m in height with a perforated bottom and adapted for an aeration system. For the artificially cooled aeration system, the vortex tube was used, which was attached to the side of the plenum, to blow cold air in. In order to record temperature and humidity data of the grain mass and the environment, SHT 75 sensors were used, which were placed in the center of the prototype silo. The conventional and artificially cooled aeration systems were activated at the the same time every day at 7 pm and shut down at 8 am For statistical analysis, the Student's “t” test with a 5% significance level was used to compare the temperature averages of conventional and artificially cooled processes. evaluation period of the systems the air temperature did not suffer great variations, oscillating from 20.97 to 26.56 ºC, in contrast the relative humidity of the air suffered great oscillations of 81.13 to 34.78%. The evaluation time was 26 days and the average temperature recorded at the end of the experiment was 24.41 ºC in the silo with conventional aeration system and in the silo with artificially cooled aeration 24.02 ºC. The results of the analysis using the Student's “t” test indicated that there was no significant variation at 5% probability of error. The artificially cooled aeration system worked correctly, decreasing the temperature of the aeration air, but only with a compressor it has a low efficiency.