A dimensionless parameter b0 is defined as the ratio of the total
flow area to the cross sectional area of the pipe (Ghayal et al., 2013).
The relationship between b0 and conversion for 15 min operation
time at an inlet pressure of 2 bar is illustrated in Fig. 7. The b0
parameter of the orifice plates in the present study varied from 0.09
to 0.20. It was observed that the conversion increased with
decrease in b0 value, i.e. the rate of reaction was higher at smaller b0
value. Plates 1 and 2 which had the same value of b0 value of 0.09
were compared. The plate with a smaller hole size, plate 2 resulted
in better conversion compared to plate 1 with a single large hole
size due to the high turbulence frequency and cavitation intensity.
A larger number of smaller holes in the plate and high shear zones
which were evenly distributed across the cross section of the pipe,
resulted in a larger probability for the cavity to experience the shear
zone and collapse violently (Ghayal et al., 2013). Besides that, the
smaller holes in plate 2 provided maximum turbulence and larger
shear layer area, which was attributed to the greater collapse
pressure, subsequently eliminating mass transfer resistance and
achieved better conversion in a shorter reaction time. Similar results
were reported by Sivakumar and Pandit (2002).