What is Heat of Compression in pressure or push (up-flow) aeration?
Heat of Compression is a mechanical air compression process which adds heat to the ambient air as the pressure fan compresses the air to overcome the static pressure resistance to airflow of all the grain storage system down-stream of the fan. In addition to overcoming the flow resistance of the grain, part of the static pressure is needed to force the air through the transfer duct, then along the perforated duct, then finally through the perforated duct surface into the grain, as well as from the headspace through the roof vent. Example #1: Identical 7.5 HP high speed (3500 rpm) centrifugal fans were mounted in a pressure aeration mode on four 40 ft. diameter by 140 ft high concrete silos at a country elevator in western OK. Silo #1 was empty. Silo #2 had 70 feet of wheat. Silo #3 and Silo #4 each had 130 feet of wheat. A small hole was drilled in the metal transition duct between the fan outlet and the silo wall. A digital thermocouple temperature readout was used to monitor ambient
