Similarly, high initial velocity has resulted in a much higher
diameter gradient which indicates a higher evaporation rate. This
is due to the higher mass transfer rate from the droplet surface to
the surrounding. Although it has a much higher evaporation rate,
but high-velocity droplet penetrates much longer before it stops.
Their primary influences appear in the inertial forces. However,
droplet particles at high velocity also appear to have a lesser
amount of time to stop. The drag forces substantially play a dominant
role as the velocity increases. Variations of different initial
velocity are illustrated in Figs. 7 and 8 for evaporation and penetration
processes. Therefore, it concluded that higher droplet velocities
have shown faster evaporation rate and longer penetration length.
Evaporation and penetration process of different alternative
fuels are compared and illustrated in Figs. 9–12. Firstly, we shall see the effects of high initial temperature towards both processes.
Each fuel is heated to 500 K and modelled in a transient condition.
The behaviour of these fuels is almost similar to the one obtained in Figs. 1 and 2. However, it should be highlighted again that higher
initial temperature reduced the time for the droplet to stop and
enhanced the evaporation rate as the gradient is much larger.
However, only MTH fuel is almost completely vapourized when
the droplet particle stopped. Meanwhile, other fuels showed that
the diameter of the droplets is reduced more than 50%. Among
all the biofuels, JA fuel has much more diameter reduction. The difference
is that all fuels appear to have greater diameter reduction
in a much shorter time at high initial temperature.