Symbol Alternative Symbol Quantity or parameter Units

A surface area m2 aw water activity - B nucleation rate kg-1m-1s-1 b breakage function m-3 C constant or coefficient - c specific heat capacity J/kgK D equipment diameter m D Γ, δ diffusion coefficient m²/s D transport tensor m²/s d diameter or size of solids m E energy J F mass flux function - f relative (normalized) drying rate - f multi-dimensional number density - G shear function or modulus Pa G growth rate kg/s g acceleration due to gravity m/s2 H height m H enthalpy J H Heaviside step function - h specific enthalpy (dry basis) J/kg h~ hN molar enthalpy J/mol

vh∆ specific enthalpy of evaporation J/kg I total number of intervals - J numerical flux function - K constant - K dilatation function or bulk modulus L length m M m mass kg M~ M, MN molecular mass kg/kmol M& W mass flow rate kg/s m& J mass flux, drying rate kg/m²s N number - N molar amount mol N& WN molar flow rate mol/s n molar density, molar concentration mol/m³ n number density m-3 n outward normal unit vector n& JN molar flux mol/m²s P power W P total pressure kg m/s2 p partial pressure / vapour pressure of component kg m/s2 Q& Q heat flow rate W q& q heat flux W/m2 R equipment radius m R individual gas constant J/kgK R~ RN universal gas constant J/kmolK r radial coordinate m

r pore (throat) radius m S saturation - S selection function 1/s s boundary layer thickness m T temperature K, °C t time s u velocity in z-direction m/s u displacement m V volume m3 V& F volumetric flow rate m³/s v specific volume m3/kg v velocity in x-direction m/s v general velocity vector ms-1 W weight force N w velocity in y-direction m/s X solids moisture content (dry basis) - x mass fraction in liquid phase - x particle volume in population balances m³ x lateral coordinate m x general eulerian coordinate m x0 general lagrangian coordinate m x~ xN molar fraction in liquid phase - Y gas moisture content (dry basis) - y lateral coordinate m y mass fraction in gas phase - y~ yN molar fraction in gas phase - z axial coordinate m Special symbols ∇ gradient operator ∇⋅ divergence operator ∆ difference operator - Greek letters α h heat transfer coefficient W/m²K β k mass transfer coefficient m/s β aggregation kernel 1/s δ Dirac-delta distribution ε voidage - ε emissivity - ε strain η efficiency - θ angle, angular coordinate rad κ thermal diffusivity m²/s λ thermal conductivity W/mK µ dynamic viscosity kg/ms µ moment of the particle size distribution ν kinematic viscosity m2/s π circular constant -

ρ density, mass concentration kg/m3 Σ summation operator - σ surface tension N/m σ Stefan-Boltzmann constant for radiative heat transfer W/m2K4 σ standard deviation (of pore size distribution) m σ stress Pa τ dimensionless time - Φ characteristic moisture content - ϕ relative humidity - ω angular velocity rad Subscripts a at ambient conditions as at adiabatic saturation conditions bed bed c cross section c capillary cr at critical moisture content D drag dry dry dp at dewpoint eff effective eq equilibrium (moisture content) f friction g gas (dry) H wet (humid) gas i inner i,1,2,… component index, particle index i,j,k coordinate index, i,j,k = 1 to 3 in inlet value l liquid (alternative: as a superscript) m mean value max maximum mf at minimum fluidisation min minimum N molar quantity o outer out outlet value P at constant pressure p particle pbe population balance equation ph at the interface r radiation rel relative velocity s solid (compact solid phase), alternative: as a superscript S at saturation conditions surf surface V based on volume v vapour, evaporation w water w wall

wb at wet bulb conditions wet wet ∞ at large distance from interface

Superscripts

average, phase average α intrinsic phase average

v volumetric strain * rheological strain * at saturation conditions

Multiple subscripts should be separated by a colon, e.g.: dry,pρ : density of dry particle. Bold symbols denote vector or tensor quantities