Questions tagged [chemical-engineering]

Use this tag for questions within the problem domain of chemical engineering.

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2answers
141 views

Heat balance in a pipe flow network

I have 2 pipe lines, both water . that combine to heat up water. Assuming at steady state , Heat gained by cold water = heat lost by hot water Let's say , according to formula , I calculated the ...
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1answer
79 views

What is an unstructured mathematical model?

I want to model a chemical process. I was searching in the literature to find similar works. In some of papers they say that "we proposed an unstructured model". What does it mean? What is the ...
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1answer
504 views

Are brass and copper utensils safe for humans to eat from? [closed]

In my research over the internet everyone is telling that brass is not safe but still there are solenoid valves, joints, and piping made of brass used in everything like coffee machines, water ...
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2answers
91 views

is it possible to achieve 1000C temperature in a cabin?

is it possible that if i have a cabin which is insulated from outside but is built with some sort of material like copper and there is a heating element of sort which is providing 100C constantly but ...
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2answers
104 views

Nylon brittleness as function of moisture content

Can someone explain the how/why Nylons brittleness is to some degree a function of it's moisture content. I don't understand HOW the water content changes the elongation at break of the material. ...
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2answers
191 views

Chemical engineering calculations - basis

You have a gas of the following compositions : 40% N2, 30% CO2, 30%,CH4 in a tank . What is the Average Molecular Weight of the gas if your compositions is based on molar ? I found that the AMR with ...
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0answers
428 views

How to use VBA on Aspen Hysys? [closed]

I am trying to write a program on Aspen Hysys. Hysys has a script manager to write scripts using Visual Basics for Applications syntax. Having no background in VBA, I'd like some help to: Import the ...
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2answers
230 views

Valve first,then heat exchanger OR heat exchanger first then valve

In my exam, I was given 2 options to design a process. Assuming a saturated liquid coming out from the separator, A) should the stream pass through a valve to reduce pressure, then to heat exchanger ...
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2answers
53 views

Optical methods for reaction engineering

What optical methods can be used to measure the concentration of reacting gases in a packed bed reactor during an exothermic and fast reaction? I need to monitor and measure the local concentration of ...
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1answer
1k views

A rule of thumb when assuming ideal gas

When to assume ideal gas law without incurring too intolerable error. I have the idea that it must be at high temperature and low pressure. Is there any specific values, and are there any other things ...
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1answer
373 views

How to do a pressure drop or saltation velocity calculation on pneumatically conveyed solids in slug flow?

If I am pneumatically conveying solids in slug flow, is there a method that works in a general case to determine the pressure drop or saltation velocity? By a general case method, I mean one that is ...
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3answers
117 views

Chemical engineering thermodynamics

Which thermodynamic property does the PdV for a free expansion define if work is zero? Considering there is a finite change in PdV.
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2answers
114 views

DOE to optimize a chemical reaction with impurity forming in series

This question contains chemistry, but the main focus is DOE design--hence posting on the engineering stack exchange. The problem is a chemical reaction: A + B -> Product Product + B -> Impurity The ...
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1answer
93 views

Calculating water content of a tank given humidity?

I have a 4700 gallon tank and am looking to create a table of the water content by mass in the tank given relative humidity %. The tank is held at 70 degC and 18 psig, and the only thing inside the ...
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1answer
32 views

Health Hazard from leaching?

I recently got dental braces and have been using foam earplugs to protect the inside of my lips from the braces. I place them between the lips and the braces and they work quiet well. However I am ...
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1answer
451 views

I need to determine the RPM of a rotating cylinder over which a silk thread is wound and is moving along in the fashion of a screw.

Recently I visited a sericulture facility in India and I saw that people there 'degummed' (https://www.youtube.com/watch?v=h13fctiTylI) silk in a batch process. As a Chemical Engineer, I thought of ...
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2answers
123 views

What is a good non-combustible oil to be used in air compression regenerative braking/energy storage system for cars, buses, and trucks?

An important energy storage method that is being given very little consideration is gas compression. The kinetic energy of the vehicle can drive an air pump or compressor that would compress air into ...
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1answer
84 views

Flow rate into a reactor from feed

I have a fresh feed (stream 1) entering a reactor . This fresh feed consists 225kg/h of iso-butane , 225kg/h of butylenes and 50kg/h of n-butane . In the stream table I need to add in a flowrate ...
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1answer
234 views

Interpreting roots of a cubic EOS with 3 phases (VLLE)

I would like to know how to interpret the roots of the Peng Robinson equation of state for vapor-liquid-liquid equilibrium. I know that if two phases are present, the largest root is taken as the ...
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2answers
321 views

Why not use Sodium Hydroxide mist to precipitate carbon dioxide from hydrocarbon combustion exhaust

Much of the currently used techniques of scrubbing the carbon dioxide from power plant exhaust uses sophisticated amine and other organic compounds. These compounds are then forced to release the CO2 ...
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1answer
4k views

2 Parameter Margules derivation

I'm trying to find online the derivation for the 2 parameter margules equation but cant find it anywhere. basically need to prove $$ \frac{d}{dn1} (x_{1}x_{2}(A_{21}x_{1} + A_{12}x_{2})) = x_2^2(A_{...
3
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1answer
71 views

Which coating best exploits “darker when wet” phenomena

This "practice calligraphy" paper has a special coating that amplifies the contrast between light/dark when a wet brush is applied. The physics behind this effect has been explained: Why do wet ...
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1answer
307 views

Derivation: Entropy of Vaporisation using Redlich-Kwong EoS

The part I'm stuck on is the last part. Basically, the question is to obtain the following equation for the entropy of vaporisation using the Redlich-Kwong equation: $$ \Delta S = R\Bigg[ \ln \frac{...
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1answer
286 views

Calculation of Activity Coefficient Model parameters

Here is the question, I am stuck on part B: Basically, this is my thought process so far, as $x_a \rightarrow 0$, the Henry's law line becomes tangential to the actual partial pressure curve. Henry'...
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2answers
57 views

Diffusion in one dimension

I was wondering where the negative sign comes from in the following simplification for diffusion in 1 dimension. The initial equation is given as follows: $$\frac{\partial C_i}{\partial t} A \Delta ...
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1answer
110 views

Boiling Point, Pressure and Distillation

I have a line in my text that states the following: "For systems with low boiling points (e.g. Ethane-Ethylene, propane-propylene etc.), high pressures are used so the vapour leaving the column at ...
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1answer
138 views

How to determine heat exchanger equation?

What is the equation to determine the inside surface temperature along the length of the counter flow heat exchanger?
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0answers
37 views

using a coil for an electrochemical reaction

I wish to calculate the amount of energy required for electrolysis through induction, instead of electrodes. If there is a crucible metal core with solution inside and the coil wrapped around it. Can ...
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1answer
57 views

Electrical Resistance of molten aluminium oxide [closed]

I would like to calculate or find the electrical resistance (in ohms) of aluminium oxide at or past its melting point, for the purposes of using it as an electrolyte in a molten state. My apologies ...
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2answers
79 views

Need help with interpreting units of kinetics data in a scientific paper

I need help with interpreting the kinetics of a scientific paper: https://www.researchgate.net/publication/...
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1answer
436 views

Can pressure drops in a heat exchanger shell side be super low?

i'm a chemical eng. student from Italy and i'm "sizing" ("setting"?) a heat exchanger to cool some octane with toluene. Is it possible that pressure drops shell side in a 1,2 pull-through floating ...
4
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1answer
48 views

silicone injection molding - making a flexible ring

I am working with silicone injection molding as a hobby and I am wanting to make a ring. I have tried with 100% silicone and the results are a clear ring that is not quite the consistency I want. I ...
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0answers
32 views

permeation properties of concrete under surface treatment

I wonder which permeation properties are critical in concrete with and without surface treatment (e.g sodium silicates-based solution) , is it air permeability,water permeability or absorption. If u ...
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2answers
263 views

Why do we still scuba dive with bottled air? [closed]

Breaking down water into H2 and O2 through electrolysis takes 241.8 Kj/mol. According to howstuffworks.com, the average person uses 550L of pure oxygen per day, which equates to about 24.6 moles of ...
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2answers
3k views

Diesel or Gasoline? Which one is more dangerous to our health?

I have an overall question that's been bothering me for years. Which is more dangerous for our health, a diesel car or a gasoline car? This is quite a cliche question and I can find a lot of ...
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5answers
444 views

Why is “regular” gasoline standard instead of something more knock-resistant?

The standard light petroleum distillate for vehicle engines, "regular gasoline," is (or is equivalent to) some mix of heptane (C7) and octane (C8). Higher proportions of C8 are more knock-resistant, ...
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1answer
232 views

Chemical Engineering Process Analysis - Process Flow Calculations using linear matrices

I am doing a process flow question and trying to calculate the grams of $\text{C}_{10}\text{H}_{14}$, $\text{C}_4\text{H}_6\text{O}_3$, and $\text{C}_{12}\text{H}_{16}\text{O}$ produced during a ...
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1answer
122 views

Dimensionless Thickness

I have encounter this notion: "Dimensionless Thickness". Does anyone have any idea how to interpret this? One can find such a term here. My interpretation is that the name comes from the fact that ...
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1answer
453 views

Molecular diffusion into sphere

The gas $(A)$ is diffusing into the solid sphere $(B)$, The sphere phase is assumed to be stagnant so we have no bulk movement, $(A)$ is being consumed in the sphere by a rate of $KC_A$ which $K$ is a ...
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1answer
76 views

Managing precipitation in cooling process

Are there standardized ways of dealing with precipitation in chemical engineering continuous flow processes? I have an application in which I need to cool a fluid via a heat exchanger and the fluid ...
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1answer
188 views

How to model a humidity control system inside a box?

I am a computer engineering student and currently having my undergraduate thesis. My thesis is about a chicken egg incubator and i need to control the humidity inside the incubator. Right now, i dont ...
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2answers
495 views

Can I control latent/sensible heat changes in a counter-flow, induced draft cooling tower using climate?

Some extensive background information to start I'm attempting to reduce water consumption at 25+ production facilities, and I've identified that the largest consumption of water (60+%) comes from ...
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1answer
725 views

What is the gain and time constant of a system with a constant output?

For example, if your transfer function is defined as : $$\frac{H(s)}{Q(s)} = \frac{1}{5s}$$ What would the gain and time constant be in this case (since it's usually in the form of $\dfrac{k}{Ts+1}$ ...
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1answer
441 views

Fluid dynamics of non interacting tanks in series

I have a system like this: and I have to estimate the height of the lower tank. First of all, I'm considering that I have a non-viscous, incompressible fluid in steady flow. Base apertures The ...
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1answer
88 views

Centrifugal pumps working

Why is it not recommend to have pump shut off head lower than its operating head? Is the answer related to dropping curve by any chance? Also why is the discharge valve closed when starting the pump ...
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1answer
56 views

Define inlet temperature in multi-stage adiabatic reactor

While solving some exercises for an exam, I faced a problem with a two-stage adiabatic reactor, producing methanol (exothermal reaction), with intermediate cooling. Both stages achieve equilibrium. ...
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1answer
135 views

Thermal efficiency of a furnace reactor?

I'm doing plant design and one of the reactors is a furnace that uses methane to burn. I want to calculate the amount of methane that is required. I have the energy needed and the calorific value of ...
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1answer
38 views

Disposal of dung, related products, and cleaning products, prioritized and case by case [closed]

This question is a chemical engineering question related to ecology. What is the list of possible threats of human feces to the environment? What about toilet paper? How do engineers deal with this ...
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1answer
193 views

How to hermetically seal a circuit in a visual & bluetooth transparent solid cube ~2-3"?

I want to encase a circuit in a ~2-3" cube of some kind of visually and Bluetooth transparent material. What material will do this? Something like: 1. half fill a cube shaped mold with liquid or ...
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0answers
84 views

What is the actual natural gas and electricity consumption of a Haber Bosch plant?

Plants running the Haber Bosch process provide the vast majority of nitrogen used in fertilizers. Collectivly, they consume about 3–5% of the world's natural gas production [...] (around 1–2% of the ...