Development of procedure for partial drying of palay using the Los Baños multi-crop dryer

Date

1995

Abstract

The study aimed to evaluate the performance of the Los Banos Multicrop Dryer and develop operating procedures for partial drying of palay. The variables considered were the effects of grain layer thickness, mixing interval and drying temperature on drying capacity, moisture reduction rate or evaporation rate and on the milling quality of the palay. The drying experiments were laid in split-plot in randomized complete block design where the four grain layer thickness (2, 3, 4, and 5 cm) were the main plots and four mixing interval periods (30, 60, 90 mins and no mixing at all) were the subplots. The results indicated that the grain layer thickness (GLT) has significantly influenced the drying rates as measured by the moisture content reduction and evaporation rates. The moisture content reduction and evaporation rates were significantly high at GLT of 2 to 3 cm than at GLT of 4 to 5 cm. In combination with the frequency of mixing during the drying process, the drying rates were not significantly affected at GLT f 2 to 3 cm. however, at 4 to 5 cm, drying rates were highly dependent on the mixing frequency wherein moisture reduction rate was linearly increasing at increasing mixing frequency. The drying time for the GLT of 2 or 3 cm ranged from 1.51 to 2.05 hours which was significantly higher than 3.45 to 4.95 hours for GLT of 4 to 5 cm. Another factor which significantly influenced drying rate air temperature at the plenum. The drying rate was linearly increasing at increasing drying air temperature. At an average drying air temperature of 71.85°C, the moisture content reduction was 1.04 percent (w.b.) per hour lower than 1.58 percent (w.b.) per hour at temperature of 82.40°C. The fuel used was the LPG which had a uniforms burning rate. Samples from the partially dried paddies with 18 percent MC were further sundried to 14 percent at 0, 10,20 and 30 days interval to determine the effect of length of storage on milling yield. Milling recovery was not significantly different among the means of the storage intervals. However, the percentage brokens were significantly high (20.12%) at zero day storage than 14.70%, 15.47% and 14.22% at 10, 20 and 30 day intervals respectively. Another experiment was conducted where the partially dried grains were air dried, sun dried, and dried in the LB dryer down to 14 percent MC. Using the total sundrying as the control, the result showed that the milling recovery of the air dried grains was significantly higher while the other methods showed no significantly difference with the control. Using the best combination of GLT and mixing frequency, the 6 ft x 12 ft twin bed LB multicrop dryer can dry about 0.50 ton of wet palay per day of operation having 100 kg per load per two hours drying time.

Document Type

Master Thesis

Degree

Master of Science in in Agricultural Engineering

Language

English

LC Subject

Rice, Multicrop-dyer -- Los Baños, Laguna (Philippines), Agricultural Engineering Institute of Agricultural Engineering

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 995 1995 A2 R53

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