What is Mass transfer: Definition and 40 Discussions

Mass transfer is the net movement of mass from one location, usually meaning stream, phase, fraction or component, to another. Mass transfer occurs in many processes, such as absorption, evaporation, drying, precipitation, membrane filtration, and distillation. Mass transfer is used by different scientific disciplines for different processes and mechanisms. The phrase is commonly used in engineering for physical processes that involve diffusive and convective transport of chemical species within physical systems.
Some common examples of mass transfer processes are the evaporation of water from a pond to the atmosphere, the purification of blood in the kidneys and liver, and the distillation of alcohol. In industrial processes, mass transfer operations include separation of chemical components in distillation columns, absorbers such as scrubbers or stripping, adsorbers such as activated carbon beds, and liquid-liquid extraction. Mass transfer is often coupled to additional transport processes, for instance in industrial cooling towers. These towers couple heat transfer to mass transfer by allowing hot water to flow in contact with air. The water is cooled by expelling some of its content in the form of water vapour.

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  1. A

    B Mass transfer between neutron stars in a binary pair

    When we read about the mass transfer between neutron star pairs in a binary system, how is it that the one receiving the matter can increase its spin rate. Adding mass to a spinning object ought to slow due to conservation of momentum. Where does the energy come from?
  2. R

    Engineering Mass Transfer in a wetted-wall column

    Please can someone assist me as this particular question seems to have me completely confounded?
  3. maistral

    Boundary conditions for convective heat and mass transfer + wall Temperature

    I am operating via finite differences. Say for example, I have this pipe that contains a fluid. I have the boundary condition at x = x1: k is the effective thermal conductivity of the fluid, T is the temperature of the fluid at any point x, hw is the wall heat transfer coefficient, and Tw is...
  4. K

    Mass Transfer in a Binary Star System

    Homework Statement: A binary star system consists of M1 and M2 separated by a distance D. M1 and M2 are revolving with an angular velocity w in circular orbits about their common center of mass. Mass is continuously being transferred from one star to the other. This transfer of mass causes...
  5. B

    Mass transfer coefficient from a numerical model

    Dear all, For an assignment, I am trying to find the relationship between the Sherwood number and the Reynolds number in a channel for different laminar velocity profiles, where there is a concentration of a species at both the top and bottom wall which is transported to the fluid. For this, I...
  6. Rahulx084

    Mass Transfer: are both convective mass transfer and eddy diffusion the same?

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  7. Rahulx084

    What Is the Concept Behind Finding Mole Fraction in Gas Absorption Problems?

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  8. Rahulx084

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  9. Rahulx084

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  10. jdawg

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  11. jdawg

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  12. jdawg

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  13. T

    A Questions about Taylor dispersion in laminar pipeflow

    In the equation characterizing the mass transfer in laminar flow, the radial variation of velocity and concentration can be lumped into the axial dispersion term as below: After reading the original paper about Taylor dispersion, I know how to derive this equation. But I am still not able to...
  14. D

    Heat and Mass Transfer Problem

    Homework Statement A plastic pipe (k=0.092 W/m.K) of inner and outer radius of 1 and 1.25 cm, respectively. If the inner and outer surfaces are at 60 °C and 30 °C, respectively. The rate of heat transfer per unit length is close to: a) 98 W/m b) 89 W/m c) 78 W/m d) 168 W/m e) 112 W/m...
  15. M

    Shell balances in cylindrical coordinates

    I have a question regarding writing a shell balance for a cylindrical system with transport in one direction (in any area of transport phenomena). When we set up the conservation equation(say steady state), we multiply the flux and the area at the surfaces of our control volume and plug them...
  16. Ravi Singh choudhary

    I What will be the flow direction?

    I guess there would be no flow in case 2; case 3 seems easy to me applying fluid mechanics principle; flow will be 1 to 2. But I doubt case 1; it is not in thermal equilibrium ? Pls help
  17. M

    Heat and mass transfer analogy to find average Nusselt no.

    I am trying to find an expression for the average Nusselt number corresponding to heat transfer from an isothermal disk. Given: ShD≡hm(r)D/DAB=Sho[1 + a (r/ro)n] (1) Sho=hm(r=0)D/DAB=0.814ReD1/2Sc0.36 (2) Relevant equations: Average nusselt number is defined as Nuav=havD/k where k...
  18. T

    Derivation of the Overall Mass Transfer Coefficient

    Homework Statement The problem requires me to find the overall mass transfer coefficient or Kg. Homework Equations $$N_{1}=\frac{1}{\frac{1}{k_{p}+\frac{H}{k_{x}}}}(p_{1}-Hx_{1}), (1)$$ $$N_{1}=k_{p}(p_{1}-p_{1i}), (2)$$ $$N_{1}=k_{x}(x_{1i}-x_{1}), (3)$$The Attempt at a Solution So, I...
  19. MexChemE

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  20. MexChemE

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  21. MexChemE

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  22. MexChemE

    Difference between Thiele modulus and Damköhler number

    Hi, PF! In the study of mass transfer involving chemical reactions, I have seen the use of two different non-dimensional parameters which apparently quantify the same ratio. These are the second Damköhler number and the Thiele modulus, which are defined as \textrm{Da}^{\textrm{II}} =...
  23. MexChemE

    How do I model mass transfer in a tubular reactor?

    Good evening, PF! I am supposed to model the following system. I will be using the same notation as in BSL. Fluid A enters the reaction zone at z = 0 at a concentration CA0. A reacts to form B in the first order reaction A → B at a rate of R_A = k_1''' C_A. We assume the whole mixture to be...
  24. MexChemE

    Heat and mass transfer -- Boundary conditions & balance terms

    Hello, PF! Recently, while reading chapter 10 (microscopic energy balances) of the second edition of BSL, I found a minor discrepancy which is confusing me, especially when considering the mathematical analogies of heat and mass transfer. In section 10.1, the authors introduce Newton's law of...
  25. Soumalya

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  26. S

    Question on Mass transfer coefficient (Sc Number)

    Homework Statement What is the mass transfer coefficient for natural convection from rock salt (assume flow is over a horizontal cylinder (salt crystal) of length 2cm, diameter 0.5cm). Given: Temperature = 24degrees Density of salt 2165kg/m^3 Density of mixture when salt...
  27. S

    Calculating Average Oxygen Flux in Wetted-Wall Column

    Dear all, I am currently doing a lab question. I do not know how to solve a calculation question. Question: Calculate the average flux of the oxygen through the gas-liquid interface in the wetted-wall column. Remember that a more accurate value of the average flux can be calculated by...
  28. Avi Nandi

    Rotation: mass transfer and angular momentum conservation

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  29. D

    Mass Transfer - Boundary Conditions

    Homework Statement An airborne spherical cellular organism, 0.015 cm in diameter, utilizes 4.5 gmol O2/(hour kg of cell mass). Assume Sh = 4 for external convective resistance to O2 transfer to the cell. (Sh = kd/D is based on diffusivity in the gas phase). Assume zero-order kinetics for...
  30. D

    Mass Transfer - Need help on setting it up

    Homework Statement Not looking for solutions, just confused with the problem set up. Need help with the boundary conditions. Here it is: A porous ceramic sphere of radius R1 is kept saturated with a pure component liquid A. The vapor pressure of A is 50 torr. This sphere is surrounded by a...
  31. Greg Bernhardt

    Fundamentals of Heat and Mass Transfer by Bergman, Lavine, Incropera & DeWitt

    Author: Theodore L. Bergman (Author), Adrienne S. Lavine (Author), Frank P. Incropera (Author), David P. DeWitt (Author) Title: Fundamentals of Heat and Mass Transfer Amazon Link: https://www.amazon.com/dp/0470501979/?tag=pfamazon01-20 Prerequisities: Contents:
  32. steves1080

    Mass transfer with with a pressure regulator

    Hi all, I am trying to determine what approach to use to solve the following scenario: I have a pressure vessel with pressure P1 and volume V1. I have another vessel of pressure P2 and volume V2. Vessel #1 is supposed to be a high-pressure storage vessel and vessel #2 is supposed to be...
  33. J

    Mass Transfer Problem question

    Consider a chemical species A, which is soluble in water. The equilibrium of this system with A in air is described by the following question: C(air) = HC(water) where C(air) is mass concentration of the species in air C(water) is the mass concentration in water, and the Henrys Law constant...
  34. R

    Evaporation of Water Mass Transfer

    Hi I had a question regarding an example about mass transfer. I already have the solutions to this but there is one thing I am confused about. The problem just asks the rate of evaporation from the water-air surface to the atmosphere at a given temperature, pressure, and relative...
  35. Y

    Heat and Mass Transfer Problem

    Hi everyone I've got a problem about the convective heat loss from a spa any help or pointers would be greatly appreciated A person installed a circular outdoor spa bath in the open area. In a typical operating condition, when the spa water is maintained at 37°C, and when the ambient air...
  36. P

    Momentum problem with mass transfer

    Homework Statement (Kleppner & Kolenkow - Introduction to Mechanics - 3.12) A sand-spraying locomotive sprays sand horizontally into a freight car situated ahead of it. The locomotive and freight car are not attached. The engineer in the locomotive maintains his speed so that the distance to...
  37. D

    Mass Transfer - GAS ABSORPTION help

    Homework Statement A Mixture of air and acetone is being vented from a solvent recovery plant. The air has to be scrubbed and this is done by absorbing the acetone into water in an absorption column. The acetone is present in small amounts and its concentration never rises above 4 mol % of the...
  38. B

    Heat and Mass Transfer - finding surface temp

    Homework Statement A wire is conducting electricity, given values of : R' = .4 ohms/m D = .002 m Tinf=300k Tsur=300k k=380W/m*C emissivity = 1 h=10W/m^2*C Ts = Find this sigma=Stefan boltzmann Plot the Temperature of the wire...
  39. B

    Heat and mass transfer empirical equations

    I guess this question applies to deriving empirical equations from any data set but in my engineering studies I've wondered this when working with heat and mass transfer. When you do an experiment and want to identify the governing equation for the process, is it simply a case of bringing...
  40. S

    Mass transfer between black holes

    Hypothetical scenario: A small black hole passes by a much larger black hole at a velocity large enough to avoid capture. Is there any chance that the tidal forces generated by the gravitational field of the larger black hole could cause part of the smaller black hole's mass-energy to...
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