Convertible Multipurpose Dryer


This study aims to develop a multipurpose mechanical dryer that uses rice hull and solar energy as power source. The mechanical dryer has two main parts: (1) the furnace/drying bin made of concrete that measures 1.0 meter (m) by 0.75 m by 0.6 m; and, (2) the extended dryer-measuring 1.0 m X 0.75 m X 1.0 m-is made of angle bars, GI sheets, and four layers of perforated screen for drying other crops. The furnace directly under the bin provides the heat when the relative humidity of the air is high.

Tests were done to check the effectiveness of the dryer in terms of capacity and drying performance (moisture content reduction rate, drying air temperature). The drying process was also compared to direct sun-drying practices.

Several trials indicated that palay, at an initial moisture content (MC) of 19 percent, can be dried to 13.3 percent and 9.3 percent in four hours, or at moisture reduction rates of 1.43 percent per hour and 2.25 percent per hour for the convertible multipurpose dryer (CMPD)-solar and CMPD-furnace, respectively. The mechanically dried samples were also comparable with the sun-dried samples in terms of milling recovery, and even had a head rice recovery.


Moisture content of grains and different crops are commonly lowered by sun-drying. Sun-drying is still predominant, even if mechanical dryers are available, mainly because it is cheaper. Furthermore, the milling quality of sun-dried palay is believed to be better, and mechanical dryers do not have the capacity for large-scale drying (Gagelonia, et al., 1996). With the double-cropping system prevalent in most rice-producing regions and the single-harvest season coinciding with the rainy period in other areas, sun-drying becomes inappropriate, necessitating the use of mechanical dryers in order to maximize the value of wet-season harvest.

Mechanical dryers commonly used by millers and traders are of medium to large sizes. These are of the recirculating type, with capacities ranging from 6 to10 tons per batch. Most farmers cannot afford to own or operate these dryers. A small-capacity (1 ton to 2 tons per batch) flatbed dryer with a kerosene burner as heat source is already available but not widely used because of high drying costs (Gagelonia, 1996). Farmers who have small farm holdings (1 hectare or less) usually dry their harvest on pavements or mats, causing harvest deterioration. Hence, this study’s dryer uses rice hull and solar energy as power sources, making it more accessible to small multicrop farmers.

Materials & Equipment

Selected References:

Agriculture, Multi-crop Solar Dryer. R. Andres, ILARRDEC, October 2000. Principles and Practices of Rice Production. Surajit K. De Datta, copyright 1981., p. 520-523. The Philippines Recommendation for Rice Reproduction Operations (Handout) The Philippine Recommendations for Grain-Legume Postproduction Operation Series No.73 (Handout).

Further clarification of the procedures and results should be directed to the researchers and adviser.

Rizza Margareth P. Arma
Arvin C. Sarte
Cornelio Santiano

Mrs. Racquel C. Diaz
Talavera National High School