FORMULA SHEET. General formulas:

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Leonard Todd
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1 FORMULA SHEET You may use this formula sheet during the Advanced Transport Phenomena course and it should contain all formulas you need during this course. Note that the weeks are numbered from 1.1 to 2.7. Part 1.1 to 1.7 contain all the formulas that were needed in the basic course The basics of Transport Phenomena and part 2.1 to 2.7 contain new formulas used in Advanced Transport Phenomena. General formulas: Newton s 2 nd law of motion. Kinetic energy. Gravitational energy. Angular velocity of circular motion, where T is the period of the motion. Ideal gas law. R is the Gas constant. Density in mass per unit volume. Specific heat: Heat needed to heat an object by 1 degree Celsius. Units are The conversion of going from Celsius to Kelvin. It is important to note that negative temperatures do not exist on the Kelvin scale, while they do for the Celsius scale, so when calculating with absolute temperatures, use Kelvin. In relative calculations where you take a temperature difference, it doesn t matter since Kelvin and Celsius are the same scale, except they are shifted. F = m a E k = 1 2 mv2 E g = m g h ω = 2π T pv = nrt ρ = m V J. C = Q kg K mδt T K = T C + 273,15 The radius of a circle, where r is the radius (half the diameter) of the circle. s = 2πr The area of a circle. A = πr 2 The volume of a sphere. V = 4 3 πr3

2 Constants N = molecules R = J mol K σ = W m 2 K 4 The number of molecules in a mole, called Avogadro s Constant. The gas constant The Stefan-Boltzmann constant Quantities &Units Mass m kg Time t s Volume V m 3 Velocity v m/s Density ρ Kg/m 3 Diameter D or d m Force F N Temperature T K Pressure p or P Pa Mass flow φ Kg/s Diffusion coefficient D m 2 /s Internal energy U J Heat Q J Work W Nm Total energy E J Area A m 2 Heat transfer coefficient h W/(m 2 K) Thermal conductivity λ W/(m K) Specific heat C p J/(kg K) Drag coefficient C D - Thermal diffusivity a m 2 /s Viscosity η Pa s Mass transfer coefficient k m/s Specific energy dissipation e J/kg Shear stress τ Pa Wavelength λ m AIR AT 20 ⁰C: WATER AT 20 ⁰C: DENSITY: KG/M 3 DENSITY: KG/M 3 HEAT CAPACITY: KJ/(KG K) HEAT CAPACITY: KJ/(KG K) PRANDTL: PRANDTL: 7.01 THERMAL DIFFUSIVITY: * 10-5 M 2 /S THERMAL DIFFUSIVITY: * 10-6 M 2 /S VISCOSITY: 1.82 * 10-5 PA S VISCOSITY: * 10-3 PA S

3 WEEK 1.1: The general balance equation. d = in out + production dt WEEK 1.2: Total energy balance First law of Thermodynamics, where ΔWis the net work done on the system. The thermal energy balance in a steady state without energy change. The mechanical energy balance. Bernoulli s equation: Neglects all friction and heat production. h is height. Bernoulli s Principle: The energy per unit volume before is the same as the energy per unit volume after. de dt = φ m,in {U + p ρ v2 + gh}in ΔU = ΔQ + ΔW 0 = φ m (u in u out ) + φ q + φ m e fr 2 ) φ m,out {U + p ρ v2 + gh} out 0 = φ m ( (v in 2 v out + g(h 2 in h out ) + (p in p out ) + φ ρ w φ m E fr ) p ρ + v2 + gh = constant 2 P ρv ρgh 1 = P ρv ρgh 2 WEEK 1.3: Reynolds number, where ρ f is the density of the fluid, v r is the relative velocity, D is the diameter and μ is the viscosity of the fluid The drag force. C D is the drag coefficient, A is the frontal area, v is the relative velocity. Stokes law: The drag force on a sphere with a low Reynolds number (Re < 1). Re = ρ fv r D μ F D = C D A 1 2 ρ fv r 2 F D = 3πDμv r

4 WEEK 1.4: Fourier s law, the transfer of heat. λ is the material conductivity, Δx is the thickness, A is the area, ΔT is the difference in temperature. Fick s law of diffusion, analogous to Fourier s law. D is the diffusion coefficient, A is the area and dc a is the change in concentration over x. dx φ q = λa ΔT Δx φ m = D A ( dc A dx ) WEEK 1.5: Newton s law of cooling. h is the heat transfer coefficient. Nusselt number. Used to make h dimensionless. Mass transfer coefficient, where Sh is the Sherwood number, analogous to Nusselt number. Δx is the size of the object, also called D sometimes. φ q = h A ΔT Nu = D h λ k = Sh D Δx WEEK 1.6: Thermal diffusivity. λ is thermal conductivity, ρ is material density, C p is specific heat. a = λ ρ C p Penetration depth. Only valid while penetration theory still holds, for πat < D, where D is the size of the sheet 2 being penetrated by heat. Fourier number. Nusselt number for penetration theory. x p = πat Fo = at D 2 Nu = 1 πfo WEEK 1.7: No new formulas this week!

5 WEEK 2.1: The general microbalance equation. Where β is the dependent variable of interest dβ dt = φ β x φ β x+dx + P β WEEK 2.2: Momentum balance d dt (m v x) = φ m,in v x,in φ m,out v x,out + F x Fanning pressure drop equation Δp = 4f L 1 ρ < v >2 D 2 Hydraulic diameter, S is the wetted perimeter. D h = 4A S The fanning friction factor for the laminar regime: Re < f = 64 Re The fanning friction factor for the turbulent regime (formula of Blasius): 4000 < Re < f = Re 1/4 The specific energy dissipation is modelled as the sum of e diss = (e fr ) i + (e L ) j dissipation in pipelines parts and appendage parts Specific energy dissipation in appendages for turbulent flow i e L = K L 1 < v >2 2 j GATE VALVE open 3/4 1/2 1/4 K L KINK α K L

6 WEEK 2.3: DIMENSIONLESS NUMBERS: Greatz number: Fraction of conductive over convective heat transfer Grashof number: Fraction of buoyancy forces over viscous forces Lewis number: Fraction of thickness of thermal boundary layer over mass transfer boundary layer Peclet (heat) number: Fraction convective heat transfer over conductive heat transfer Peclet (mas) number: Fraction convective mass transfer over diffusive mass transfer Prandtl number: Fraction of hydrodynamic boundary layer thickness over thermal boundary layer thickness Schmidt number: Fraction of hydrodynamic boundary layer over mass transfer boundary layer Gz = al d 2 v Gr = d3 g γ ΔT v 2 Le = a D Pe = vd a Pe = vd D Pr = ν a Sc = ν D (D is the mass diffusion constant) (D is the mass diffusion constant) (ν is the kinematic viscosity) (ν is the kinematic viscosity, D is the mass diffusion constant) DIMENSIONLESS CORRELATIONS FOR HEAT TRANSFER: Laminar flow in tubes: Gz < 0.05 Laminar flow in tubes: Gz > 0.1 Turbulent flow in tubes: Re > 10 4 and Pr 0.7 Flat plate parallel to flow: Re < Long cylinders perpendicular to the flow: 10 < Re < 10 4 and Pr > 0.7 and Pe >> 1 Long cylinders perpendicular to the flow: Re > 10 4 and Pr > 0.7 Flow around spheres: 10 < Re < 10 4 and Pr > 0.7 and Pe >> 1 Nu = 1.08 Gz 1/3 and < Nu > = 1.62 Gz 1/3 Nu = < Nu > = 3.66 < Nu > = Re 0.8 Pr 0.33 Nu = Re 1/2 Pr 1/3 < Nu > = 0.57 Re 1/2 Pr 1/3 < Nu > = Re 0.8 Pr 0.33 < Nu > = Re 1/2 Pr 1/3

7 DIMENSIONLESS CORRELATIONS FOR MASS TRANSFER: Laminar flow in tubes: Gz < 0.05 Laminar flow in tubes: Gz > 0.1 Turbulent flow in tubes: Re > 10 4 and Sc 0.7 Flat plate parallel to flow: Re < Long cylinders perpendicular to the flow: 1 < Re < 10 4 and Sc > 0.7 and Pe >> 1 Flow around spheres: 10 < Re < 10 4 and Sc > 0.7 and Pe >> 1 Sh = 1.08 Gz 1/3 and < Sh > = 1.62 Gz 1/3 Sh = < Sh > = 3.66 < Sh > = Re 0.8 Sc 0.33 Sh = Re 1/2 Sc < Sh > = 0.42 Sc 1/ Re 1/2 Sc 1/3 < Sh > = Re 1/2 Sc 1/3 OTHER FORMULAS: Sieder and Tate correction, this equation is used in Nu = Re 0.8 Pr 0.33 ( µ ) 0.14 situations with a viscosity gradient in turbulent pipe flow µ s The Chilton and Colburn relations combines heat and h mass flow coefficients k = Le 2/3 ρ C p WEEK 2.4: The partition coefficient, in which you may assign phases to superscript 1 and 2 Henry s Law: with p the partial pressure, H the henry s coefficient and y the fraction dissolved in the liquid m = C1 C 2 p A = H A y A

8 WEEK 2.5: Shear stress in Newtonian fluids τ yx = µ dv x dy Shear stress for liquids that follow the power law (Ostwald De Waele model) τ yx = K v x dy n 1 dv x dy Shear stress for Bingham liquids Shear stress for visco-elastic fluids, where λ is a elasticity parameter Hagen-Poiseuille law is used to calculate flow rates from velocity profiles in tubes τ yx τ 0 = µ dv x dy for τ yx τ 0 dv x dy for τ yx < τ 0 τ yx + λ dτ yx dt = µ dv x dy R φ v = v x (r) 2π r dr 0 WEEK 2.6: Stefan-Boltzman Law for grey radiators. Note if e = 1 the object is a black radiator φ q " = e σ T 4 Wiens Law that relates the temperature of a radiator to its maximum in radiation wavelength λ max T = m K Heat radiation with the help of visibility factors φ net,1 2 = F 1 2 A 1 σt F 2 1 A 2 σt 2

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10 GRAPHS:

12 FOR A SPHERE

Convective Mass Transfer

Convective Mass Transfer Definition of convective mass transfer: The transport of material between a boundary surface and a moving fluid or between two immiscible moving fluids separated by a mobile interface