Masters Theses

Date of Award


Degree Type


Degree Name

Master of Science


Biosystems Engineering Technology

Major Professor

B.L. Bledsoe

Committee Members

L.R. Wilhelm, John Reynolds


A multi-use, modular, solar hay-drying facility was constructed at the Middle Tennessee Experiment Station at Spring Hill, Tennessee. Tests were conducted to evaluate the daytime hay drying collector system and to determine the effect of bale density on drying rate.

A drying building, one of three main structural units of the facility, was constructed with the south wall and south facing portion of the roof serving as the daytime solar collector. The drying building, which doubled as a space-heated shop during the winter months, had the capacity to dry simultaneously 32 large round bales of high moisture hay. A collector/storage unit was constructed to supply heat, stored in a rock bed, for nighttime drying. A 5000 bushel grain bin was constructed for drying grain during the fall months using solar heated air.

Instrumentation recorded dry-bulb and wet-bulb temperatures, relative humidity, air pressure, and solar radiation. These variables were used to calculate collector efficiency. Periodic hay moisture content determinations were made to record the progress of moisture removal from the hay.

Calculated collector efficiencies were found to be in excess of the 100 percent, thus indicating some definite error in data acquisition. Various problems with respect to sensor location and lack of suitable air moisture sensors resulted in errors in determining psychorometric conditions.

Problems encountered during the baling and bale treatment preparation resulted in the elimination of one of the four hay package treatments. The initial moisture content of the hay ranged from 34 to 51 percent. No significant difference was found in the drying rate of any of the density treatments. Lack of control of the dry matter density was the primary reason for no difference in drying rates. Because of inclement weather, the drying cycle extended to 4-5 days instead of the projected 2-3 days.

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