Learning Forum

[RajasekarK123]

Is it possible to have negative spalding heat and mass transfer number during DPM droplet evaporationn

[Surya Deb]

Hello, nSpalding Mass Transfer Number is (Yf_infinity - Yf_surface)/(Yf_surface -1). Where Yf_infinity is the mass fraction of the fuel (considering a fuel droplet) far away from the droplet surface and Yf_surface is the fuel mass fraction on the droplet surface. nEssentially is can be less than zero or negative if Yf_infinity becomes larger than Yf_surface, because the denominator is always negative (Yf_surface<1).nThat essentially means the surrounding is saturated with fuel and the concentration gradient is sort of reversed. nCan you please check the mass fractions in your case?nRegards,nSuryan