Rectangular bales of hay measuring 35 x 46 x 84 cm baled to a density ranging from 145 to 172,4 kg/m$ sp3$ were dried on a dryer which can contain 4 300 bales for a total weight of approximately 130 tons. A 1,2 meter fan activated by a 60 kw L.P. Gaz engine insured an air flow of 840 m$ sp3$/min at 625 Pa of static pressure. This research has clearly demonstrated that approximately 50% of the drying air flowed between the bales placed on the dryer. By increasing the flow of air, the drying rate of the bales of hay was also increased. The results obtained prove of the effect of both temperature and relative humidity of the air on drying capacity. Finally, the dryer was more efficient when ten (10) rows of bales were dried at one time rather than 5. It would be desirable to develop a mathematical model to produce a computer simulation of drying applied to bales of hay. Efficient strategies to improve drying procedures of densely baled hay could thus be developed.

No description available.

The curing or hay on the farm to retain its maximum feeding value, including minerals and vitamins, is of recognized importance. For several years, agricultural workers have realized that a limiting factor in the production of high quality hay in the Southeastern United States is the difficulty of proper curing. The climatic conditions found in the southern states are among the nations most favorable for the production of hay, but these same conditions make it almost impossible to cure high quality hay in the field. The average total rainfall for any one month during the hay curing season is not excessive, but numerous light showers at short intervals make the field curing of hay very difficult. In 1942 a survey of hay losses was made on 215 farms in nine Southwest Virginia counties. The results of the survey showed that 25% of the crop had been lost or damaged. Virginia's annual production of tame hay is about 1,500,000 tons. If the same ratio of loss was applied to the total crop of the state, it would mean that 375,000 tons of the annual hay crop were lost or damaged. Hay and grain drying by forced ventilation has been practiced successfully by farmers in the Southeast for the past decade. At the close of the 1948 hay drying season, there were 500 driers in operation on Virginia farms. Available data on the analysis of a number of barn and field dried samples indicate a decided advantage in favor of the barn dried hay, when considering the amount of leaves, green color, carotene, and protein retained. The design and testing of the drying equipment and forced ventilation systems have become an important part of the research work of the Agricultural Engineering Department, Virginia Agricultural Experiment Station, in cooperation with the U.S. Department of Agriculture. With the increased use of supplemental heat in forced ventilation drying, a definite need has arisen for data showing the effect of the temperature and relative humidity or the air supply on the drying rate and equilibrium moisture content of hay. The equilibrium moisture content is that moisture content at which no further moisture will be removed from the hay by a particular combination of temperature and relative humidity. The elementary laws of thermodynamics and heat transfer show that the condition of the drying media has a definite effect on the rate at which a substance may be dried. A thorough investigation showed that the literature on this particular phase of hay drying is very limited; however, a number of articles have been published on closely related subjects, such as the humidity equilibrium of wheat, flour, flaxseed and various other common substances. Of the literature available the most applicable reports were those by Mr. Davis¹, "Supplemental Heat in Mow Drying of Hay - Part Two", and Dexter, Sheldon and Waldron², "Equilibrium Moisture Content of Alfalfa Bay". In Mr. Davis I report the drying rate factor for the 68°F. dew point only was given, and the study by Dexter, Sheldon and Waldron was limited to a constant temperature condition throughout the humidity range. Since practically all hay drying installations operate with varying dry bulb temperatures and varying relative humidities, this investigation was proposed for the purpose of providing data that would constitute an important contribution to the further study and design of hay drying systems. 1. Davis, R. B. Jr., "Supplemental Heat in Mow Drying of Hay - Part Two", U.S.D.A., V.P.I., Agr. Engr. Journal, June 1948. 2. Dexter, S. T., Sheldon, W. H., and Waldron, Dorothy I., Michigan State College. "Equilibrium Moisture Content of Alfalfa Hay". Agr. Engr. Journal, July 1947. / M.S.

Hay is one of Virginia's important agricultural crops. It ranks third in dollar value, being exceeded in value only by corn and tobacco. The 1948 hay crop was valued at $46,486,000 according to the Virginia Crop Reporting Service (16), and 1,414,000 acres of land were used to produce approximately 1,823,000 tons of hay. As shown by this report, more acres of Virginia's crop land were used to produce hay in 1948 than any other single crop. By using better agronomic practices the hay yield per acre of land used to produce hay has been gradually increased. The climatic conditions found in the southeastern states are among the nation's most favorable for the production of hay, but these same conditions make it almost impossible to cure high quality hay in the field. The average total rainfall for any one month during the hay curing season is not excessive, but the numerous light showers at short intervals make the field curing of hay very difficult. In many instances, hay crops are almost sufficiently field dried for safe storage in the barn when a light shower falls and causes additional hay losses to occur. In 1942 a survey (1) of hay losses was made on 215 farms in nine Southwest Virginia Counties, with the farmers reporting 25% of their crops lost or damaged because of unfavorable weather. In 1948 a survey was made of the hay losses due to weather hazards in all counties of Virginia. The county agents estimated that 31.6% of Virginia's total hay crop was damaged 25%, 15% was damaged 50%, and 4% was a total loss. This report shows that 50.6% of all hay produced in Virginia was damaged 25% or more. Reports from Virginia hay inspectors indicated that only a very small amount of the field cured hay met the requirements for U.S. No. 1 hay. This means that the annual hay losses in Virginia due to weather hazards have been tremendous when it was cured in the field. Agricultural Engineers in cooperation with many organizations have developed barn hay driers as a means of reducing these hay losses. Farmers have been furnished detailed plans and specifications for installing and operating these driers. At the close of the 1948 hay drying season, there were 487 hay driers in operation on Virginia farms. Eighty-three of these systems were installed in 1948. The same survey shows that 456 units were used to dry long hay, 22 baled hay, and 19 chopped hay. Available data (1) shows that barn dried hay will grade from one to two grades better than field dried hay which is harvested from the same field, the only difference being in the method used in curing. The barn dried hay shows a decided advantage over field dried hay when considering the amount of leaves, green color, carotene and protein content retained. The success farmers have obtained by using the forced ventilation method of curing hay has made hay driers very popular. Hay dryers can 7 be used advantageously on many farms that produce hay. This is particularly true when the hay is stored in mows where electric service is available to operate motors. With this system, each mow is considered separately and the air distribution system must be “tailor-made“ to fit the mow. On some farms, the relative location of buildings and fields, availability of electric service, or methods of storing and feeding hay, are such that the typical barn hay dryer is not adaptable. / Master of Science