A dimensionless geometrical parameter b is defined as the ratio
of a hole diameter to a pipe diameter (Ghayal et al., 2013). The
relationship between b and the conversion of FAME within 15 min
reaction time at inlet pressure of 2 bar is presented in Fig. 6. The b
value of the orifice plates were plate 1 e 0.31, plate 2 e 0.07, plate 3
e 0.13 and plate 4 e 0.20. It was observed that the conversion
increased with decreasing b value, i.e. the plate 2 with the lowest b
value resulted in the highest conversion of 98%. A similar result was
reported by Senthil Kumar et al. (2000). This is due to the fact that
the smaller hole diameter in the orifice plate generates a larger
number of small bubbles, resulting in a higher number of the
cavitational events and better emulsification which in turn leads to
a higher mass transfer. Vichare et al. (2000) reported that the intensity
of turbulence increased with the decrease in b value. The
increase in turbulence makes the collapse of cavities more violent
and generates large magnitude pressure pulses.