What are implication of high Prandtl number, thermal diffusivity and thermal conductivity of a particular fuel in a diesel engine or IC engine?
Let me try to give some thoughts. Starting from the definition of the Prandtl number,
Pr = Cp*mu/k = nu/a
When it comes to a fuel for an IC engine, high Pr number could mean one or more of the following:
(1) The fuel viscosity is high, so it's more difficult to atomize, or requires high injector pressure to achieve the same droplet size.
(2) It could mean the heat capacity of the fuel is larger than other fuels, which increases the time to heat up to evaporation temperature.
(3) It could mean the thermal conductivity of the fuel is small, resulting in a larger Biot number. Thus, it's more likely to develop a temperature gradient within the droplet.
High thermal diffusivity, on the contrary, makes thermal relaxation faster, so there'll be less temperature gradient within the droplets. High thermal conductivity has a similar effect as high thermal conductivity.
Therefore, I'd say that a liquid fuel with high Prandtl number is undesirable for an IC engine. It could delay ignition, result in poor combustion efficiency and compromise engine operability.
Xuantian Li, Thank for your explanation. Kindly support your explanation with published material/ journal or references, please. Looking forward to hear from you. Best Regards,
Sam O.D ([email protected]
Dr. Kharseh,
The material is gratefully received. But I will appreciate it if you kindly send me those that support the statements made by Xuantian L.
I need the material urgently.
Samuel O.D
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