Use this tag for questions within the problem domain of chemical engineering.
Questions tagged [chemical-engineering]
340 questions
87
votes
9 answers
Why do glass windows still exist? (Why haven't they been replaced by plastics?)
Glass is fragile and impractical to transport, install and repair. Even worse, glass kills and hurts people when it breaks. Falling to the streets like guillotines during earthquakes and bomb raids. During wars people put tape on their windows to…
LocalFluff
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14
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1 answer
What are some cost-effective metal substances that can wet glass?
A highly desirable property of metals like gallium and indium is that they are able to wet glass.
Normally, as metals, they wouldn't be able to form an airtight seal when in contact with glass. But they are able to do so, and they can be used in…
APerson
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13
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1 answer
What causes rechargeable batteries to age? What can be done to extend life of these batteries?
These days most of modern electronics use rechargeable batteries as a power source. Also, these days most modern rechargeable batteries are Lithium Ion or Lithium Polymer based. Like any other devices, over time these rechargeable batteries lose the…
Mahendra Gunawardena
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12
votes
3 answers
Exploiting fluid dynamics for the optimal design for gas mixing in a furnace
Background
This is the standard design for a thermal furnace used in the Clauss process, which converts H2S to SO2. The main problem with the furnace is that gas mixing is rather poor and results in only a 60% conversion rate. This in turn…
22134484
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10
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1 answer
How do I choose operating parameters for input air to a methane reformer?
I'm interested in controlled oxidation of nickel in a methane reformer with diameter ~3 m and height ~1.5 m. In this reactor, CH4 is converted into H2 and CO, and CO into H2 and CO2 but for this problem, we assume that the methane and water stopped…
Corvinus
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10
votes
2 answers
External diffusion: calculation of surface concentration
I am struggling a bit with an external diffusion problem. I am trying to calculate the concentration at the surface (as well as surface reaction rate) and would like some help or guidance.
Here is what I have thus far.
The reaction taking place,…
Mierzen
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10
votes
1 answer
Steam sterilization of whey in a bioreactor
I'm trying to design a bioreactor to produce citric acid with whey and Aspergillus Niger.
The first step in the process would be to put whey into the reactor with some dextrose (approx. 10%). Then, this solution should be sterilized, and I was…
Pepe Mandioca
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10
votes
1 answer
What liquid crystals are used most frequently in displays?
Is there a specific chemical that is used frequently in the production of liquid crystal displays? During my internet research so far, it seems as if the specific chemical composition of the liquid crystal does not matter very much. This website…
dk2ax
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9
votes
5 answers
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, which allow for higher compression ratios and…
feetwet
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8
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2 answers
What does "a" mean at the end of a refrigerant's designation (R-134a)?
I was studying the designation of names to refrigerants.
The following is the basic formula:
R - (m - 1) ( n + 1) ( o )
where:
m = number of carbon atoms in the refrigerant
n = number of hydrogen atoms in the refrigerant
o = number of fluorine…
Fennekin
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8
votes
2 answers
Why can we neglect the inertial (but not viscous) term in Navier-Stokes at low flow and high viscosity?
Why can we neglect the inertial (but not viscous) term in Navier-Stokes at low flow and high viscosity?
Complete Navier-Stokes: $\rho \frac{D\vec{v}}{Dt}=\rho g - \nabla P+ \mu \nabla ^2 \vec{v}$
Inertial…
Raoul
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8
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1 answer
Estimating Darcy Friction Factors for Critical Flow
The Darcy-Weisbach equation is used to calculate the frictional pressure losses in pipes transporting incompressible fluids. This equation uses a dimensionless Darcy friction factor, also known as the Moody factor, to account for the relative…
Jim Hargreaves
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8
votes
1 answer
Degassing silicone solution with negative pressure
I am planning to use polydimethylsiloxane (PDMS) to create a phantom for mimicking tissue for imaging. For this, I plan on using SYLGARD® 184, which is a viscous liquid. When adding other components to it, air bubbles will be introduced.
I have…
Nazar
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7
votes
2 answers
What are the advantages of chemical oxygen generation over compressed tank storage?
Chemical oxygen generation (COG) is used in commercial airliners to supply emergency oxygen to passengers and crew if the plane is depressurized. Weight for weight it produces far more oxygen than compressed oxygen tanks.
I read the original paper…
Leavenotrace
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6
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2 answers
Cleaning anodised aluminium
We have some metal parts in our machines, which are anodised aluminium. Those machines are due to be shipped to the customer in the near future, but I have noticed some pitting or slight rust developing on some of the anodised aluminium surfaces. I…
am304
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