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Cooling and drying of high moisture shelled corn in deep beds
| Content Provider | Semantic Scholar |
|---|---|
| Author | Huzayyin, A. S. |
| Copyright Year | 1969 |
| Abstract | The purposes of the study were (1) to determine drying and cooling rates at any depth of a deep bed of high moisture corn during simultaneous cooling and drying with refrigerated air; (2) to design and build an apparatus for measuring the various parameters involved in the process; and (3) to analyze data and explain the process involved during simultaneous cooling and drying. The main factors affecting the process are: (1) initial air conditions, (2) air flow rates, (3) initial moisture content of the corn, (4) initial grain temperature, and (5) drying and cooling rate characteristics. Number 5 above, is generally governed by the other four for a specific grain. A bin with a cross-sectional area of four square feet capable of holding a bed of corn six feet deep was built. The bin, insulated from outside environmental conditions, contained 24 test trays, each 3" deep and one foot by one foot in plan. Each tray was suspended from a cantilever beam fitted with strain gauges for weighing of the corn. The weight changes were recorded as a function of time to evaluate the drying rate of the corn. Tne test trays were surrounded by guard trays filled with corn to minimize outside effects. Refrigerated air was passed vertically through beds of high moisture corn. Temperatures of the air were recorded at selected time and. location intervals in order to know the air temperature history throughout the bed of corn. Copper-constantan thermocouples and a recording potentiometer were used for recording the temperatures. Three tests were carried out in this investigation. The air rate of flow in each experiment was 1.3 + 5% ft /ft -4 "minute. Average inlet air temperature was 3 7.5 + 0.5°F. The average initial moisture contents of the grain for the three tests were 23, 38.4 and 44% (dry basis), respectively. Naturally moist corn was used in the first test and remoistened corn was used in the other two. Results from tests with initial corn temperature of 70°F. showed that during the simultaneous drying and cooling period the air state does not follow an adiabatic saturation line on the psychrometric chart, since both latent and sensible heat were added to the air. After the cooling period ended, the air temperature reached the wet bulb temperature of the incoming air and a pure drying front moved slowly through the grain. Moisture sensing instrumentation failed to measure moisture changes accurately, but results were adequate to describe qualitatively the mechanism of moisture change with time. For the third test, an average moisture loss of about 2% of the initial weight occurred throughout the entire bed. Some moisture addition to grain at layers above 1 foot deep was noted during the early parts of the test. These layers started to dry again as the drying front moved across them. Generally the moisture loss during cooling increases with higher initial moisture content or initial grain temperature. The rate of cooling of corn was found to increase with increasing initial moisture content and, or, initial temperature. The time for initiating the falling rate of temperature decrease was found to increase with bin depth. The falling rate of temperature decrease increases to a maximum then decreases until the temperature asymtotically reaches the wet bulb temperature of the inlet air conditions. The maximum rate of temperature decrease at each location in the corn bed was found to be a linear function with time. Further study varying initial corn temperature, initial moisture content, air flow rates and initial air properties are suggested for better understanding the mechanism of cooling associated with drying. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://krex.k-state.edu/dspace/bitstream/handle/2097/26683/LD2668T41969H887.pdf?isAllowed=y&sequence=1 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
