Md. Ahiduzzaman
Senior Scientific Officer
Farm Machinery and Postharvest Technology Division
Bangladesh Rice Research Institute
Gazipur-1701
Md. Golam Kibria Bhuiyan
Farm Machinery and Postharvest Technology Division
Bangladesh Rice Research Institute
Gazipur-1701
Dr. SM Mahfuzur Rahman
Farm Machinery and Postharvest Technology Division
Bangladesh Rice Research Institute
Gazipur-1701
Dr. Md Syedul Islam
Farm Machinery and Postharvest Technology Division
Bangladesh Rice Research Institute
Gazipur-1701
Physical dimensions including length, breadth and thickness of 50 randomly selected rice grains were measured accurately. The maximum geometric mean diameter was found 3.34 mm in BRRI dhan38 and maximum percent of sphericity was observed in BR5. The dimension of volume was found to be 12.23, 10.92, 15.71 and 19.59 mm3 for BR5, BRRI dhan34, BRRI dhan37 and BRRI dhan38, respectively. Maximum bulk density was found 593 Kg/m3 in BR5. Highest value of angle of repose was observed in BRRI dhan37.
Sphericity, Angle of repose, Void ratio, Porosity, Paddy, Size and Shape
Farm Mechanization
Farm machineries
• To investigate physical and engineering properties of BR 5, BRRI dhan34 and BRRI dhan37 and BRRI dhan38
varieties
Paddy BR11, BR22 and BR23 were collected from BRRI store to determine the physical and engineering properties. To determine the average size of the grain, 50 grains from each variety was selected. Moisture content of grain was determined by moisture meter (Rice Ter D, Kett).Thousand grain mass (TGM) was determined by counting 100 grains from each variety and weight with a precision digital balance and then multiplied by 10. Each sample was replicated three times. The geometric mean diameter, Dgm of the grain was calculated using the following relationship: Dgm = (LBT) 1/3
Where L, B, T are the length, breadth and width (mm) of the grain.
Mohsenien (1986), expressed degree of sphericity as follows: Ф = (LBT) 1/3 /L
The surface area (S) and volume (V) of paddy grains were calculated following the semiempirical relation proposed by Murthy et al. (1986), as
Surface area, S = − L (B+T)
Volume, V = Π/6 LBT
Where L is length of grain, B is breadth of grain and T is the thickness of grain.
The bulk density σb of paddy grains was obtained by dividing the weight of sample to the volume of sample. The kernel density σk was determined by the water displacement method as proposed by Mohesenin (1970).
The porosity was calculated by η = (1 - σb/σk)X 100
The void ratio was calculated by ℮ = η/ (1 – η)
The slanting surface was formed by raising slowly a hollow cylindrical mould of diameter 100 mm and height 150 mm filled with paddy grains and the angle of repose was calculated by
Angle of repose, φ = tan -1(H/D)
Where D is the diameter of grain heap and H is the height of the intersecting point of the tangent to the slant surface with the vertical plane.
BRRI Annual Research Review 2006-07
An inverse relationship was observed between geometric mean diameter and percent sphericity. Bulk density was observed 593, 580, 537 and 485 kg/m3 for BR5, BRRI dhan34, BRRI dhan37 and BRRI dhan38 respectively. Maximum porosity percentage was observed in BRRI dhan38 and lowest in BR5.Angle of repose was found 34.2°, 31.10°, 34.4° and 32° for BR5, BRRI dhan34, BRRI dhan37 and BRRI dhan38, respectively.
Report/Proceedings