Moisture dependent mechanical and thermal properties of Locust bean (Parkia biglobosa)

Olajide Ayodele Sadiku, Isaac Bamgboye

Abstract


 

The mechanical and thermal properties of African locust bean (Parkia biglobosa) seeds were investigated as a function of moisture content in the range of 5.9%–28.2% dry basis (d.b.).  These properties are required for the engineering design of equipment for handling and processing locust bean.  Universal Testing Machine was used to determine the mechanical properties at 5 mm/min load rating transversely.  Normal and shear stresses were determined for 200–500 g loads at 100 g interval.  Specific heat and thermal conductivity were determined using the method of mixtures and steady-state heat flow method respectively.  Linear decreases in rupture force (214.42–129.86 N) and rupture energy (109.17–73.46 N mm) were recorded, while deformation of the seed samples increased (0.98-1.13 mm).  Linear increase in normal stress at 200, 300, 400 and 500 g loads were 8.38–8.69, 9.39–9.70, 10.40–10.71 and 11.41–11.72 g/cm2 respectively, while shear stress ranged from 0.589 to 0.845, 0.688 to 0.998, 0.638–1.213 and 0.688–1.359 g/cm2 at 200, 300, 400 and 500 g with increasing seed moisture content.  The specific heat and thermal conductivity of locust bean increased from 2.74 to 4.38 kJ kg-1 oC-1 and 0.052 to 0.118 W m-1 oC-1 respectively.  Seed moisture content effect was statistically significant (p<0.05) on all properties investigated except rupture force, rupture energy and thermal diffusivity while baseline data were generated for the development of necessary handling and processing equipment.

 

Keywords: bulk density; deformation; rupture force, shear stress, moisture content, thermal conductivity

 


Keywords


Bulk density; Deformation; Rupture force; Shear stress; Moisture content; Thermal conductivity.

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