Simultaneous monitoring of stored grain with relative humidity, temperature, and carbon dioxide sensors

Haidee B. Gonzales, Paul R. Armstrong, Ronaldo G. Maghirang

Research output: Contribution to journalArticlepeer-review


Grain moisture content (MC) and temperature (T) are the primary factors affecting grain deterioration in storage. If these factors are not properly monitored and controlled, grain quality can deteriorate quickly due to mold growth and insect infestation. This research examined use of relative humidity (RH), T, and carbon dioxide (CO2) sensors for their suitability to determine adverse storage conditions of wheat. A mock-up storage system was constructed and used to simulate a wheat storage bin 6.86 m high. Sensors for T, RH, and CO2 measurement were placed at various depths in the storage. High-moisture grain, comprising about 11% of the grain volume, was placed in the top section of the bin. Wheat was aerated with the high-moisture grain conditioned to nominal MCs of 14%, 16%, and 18% wet basis (MCwb) and the remaining grain at approximately 11% MCwb. Sensors monitored air conditions during the entire storage period. Aeration was provided over 3-h periods at rates of 0.083 m3/min/tonne (eight experiments) and 0.166 m3/min/tonne (one experiment). Airflow was from top to bottom of the bin. CO2 sensors were effective in indirectly detecting moist grain conditions due to the large amount of CO2 generated from the wet grain. CO2 measurement was less effective as grain temperature was reduced as a result of aeration. CO2 levels monitored at the exhaust of the aeration duct were generally adequate in determining adverse storage conditions. The equilibrium moisture content (EMC) of wheat, determined from RH and T, gave reasonably accurate measurements of grain MC. EMC measurements were also effective in determining moisture changes in the grain due to the moisture front movement from the high-moisture grain.

Original languageEnglish (US)
Pages (from-to)595-604
Number of pages10
JournalApplied Engineering in Agriculture
Issue number4
StatePublished - Oct 29 2009
Externally publishedYes


  • Carbon dioxide
  • Equilibrium moisture content
  • Grain storage monitoring
  • Sensors

ASJC Scopus subject areas

  • General Engineering


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