Questions tagged [mass-transfer]
18 questions
4
votes
1 answer
Modelling gas desorption from a still solution (e.g. a beer)
The common way to model or estimate gas (e.g. CO2) desorption rate from a liquid solution is by using an equation similar to this one
$J_{CO_2} = -k_L a(H·C^G_{CO_2} - C^L_{CO_2})$
where $J_{CO_2}$ is the molar (or mass) flowrate, $k_L$ is the mass…
Toulousain
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2
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0 answers
When teaching separation processes, which one should be introduced first? Distillation or absorption?
I am preparing a basic course on Separation Processes (5th semester, BSc Chemical Engineering). I can see that many well-known textbooks (e.g. Seader & Henley, Wankat) start by teaching in detail distillation and only then, the chapters on…
Toulousain
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- 11
2
votes
2 answers
Does a tank of liquid nitrogen increase in total internal energy after emptying?
Suppose there's a 10 liter perfectly-insulated sealed tank of saturated liquid nitrogen at 4 bar. Therefore the fluid has properties,
$\rho=740 \,\frac{\text{kg}}{\text{m}^3}$,
$m=7.4 \,\text{kg}$,
$\hat{u}=-93\,\frac{\text{kJ}}{\text{kg}}$,
and…
Victor
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1
vote
4 answers
How is the relationship between Entrance Length and Reynold’s number proven?
For laminar flow in a pipe or annulus of diameter $D$, there is a region from the circle of entry where velocity profile slowly develops until it is fully developed and no longer changes with the axial direction of the pipe.
The length from the…
TheTenthBox
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1
vote
1 answer
Under what conditions is grinding unnecessary for liquid-solid leaching in mineral processing?
I am a chemical engineering student and I am having trouble understanding a passage in a separation process textbook I am reading. The passage is about the preparing solids for leaching, such as grinding and crushing ores. At the end of the…
wlsa
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1
vote
1 answer
How to create a mechanical equivalent to dropping object onto steel floor
(I was informed on the Physics board that this is an Engineering question, therefore they closed it there, and I moved it here)
First, I have next to zero formal physics training... I opted for all math & electronics electives back in my 1970s high…
RTC
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- 3
1
vote
2 answers
How to calculate heat and mass transfer rates from an enclosed box?
I'd like to know if it's possible to calculate the heat and mass transfer rates from a small volume to the environment.
Let's assume there is a box with a small opening at the top. The air inside the box is hot and humid (65 °C and 100% relative…
Sergio
- 19
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1
vote
0 answers
Slow integration of system ODE under specific conditions in adsorption problem
I am trying to solve the system of ODEs below. I am applying the finite differences to z, so I get a system of ODE that I can solve with a solver like ode45.
The problem is that under the conditions that interest me integration is too slow (time…
Synergix
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1
vote
0 answers
Adsorption - what models are used for dry scrubbing?
For scrubbing with activated carbon, air is generally brought through a dry adsorption media, where the contaminant is adsorbed onto the media.
I would like to know what mathematical model is used for this process. I presume the rate of adsorption…
Mark
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Determining the no. of ideal stages in leaching
2000 kg/h of soybean meal containing
45% by weight edible oil is to be treated in
a multiple stage counter current leaching
equipment using 3000 kg/h of n-hexane
containing 3% oil by weight. The insoluble
solids retain 1 kg solution per kg of…
0
votes
0 answers
Free convection between parallel walls
Problem: Consider two walls separated by distance $2B$ with a fluid of density $\rho$ and viscosity $\mu$ located between the vertical walls. The left wall (at $y=-B$) is at temperature $T_2$ and the right wall (at $y=B$) is at $T_1$. Additionally…
Sam
- 101
0
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0 answers
How do I derive the governing equations for gas transport in porous media?
The governing equation for a Diffusion-Reaction equation is given by:
\begin{equation}
\frac{\partial C_i}{\partial t} + \nabla \cdot N_i = R_i,
\end{equation}
where:
$C_i$ is the concentration of species (i) (in moles per unit volume),
$N_i$ is…
Mechanician
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- 3
0
votes
0 answers
Innovative Adjustable Dumbbell Concept: Seeking Expert Advice
I'm a student with an innovative idea for gym equipment, specifically adjustable dumbbells. My concept aims to solve space, hygiene, and progression issues in gyms:
Instead of multiple sets of fixed-weight dumbbells, there would be a few adjustable…
0
votes
0 answers
Mass balance in a vacuum system
I’m working on simulating a system where a rough vacuum is used to evaporate water. To do this, I need to perform a mass and species balance on the vacuum side of the system, but I’ve been having some trouble.
The system consists of a water…
Priscillian26
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0
votes
2 answers
what is effect of temperature on dew point?
I read that relative humidity changes with change in temperature though there can be constant humidity. So, if RH is changing then dew point should get increase with increase in temperature?
https://en.wikipedia.org/wiki/Dew_point
Rohit
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