Questions tagged [chemical-engineering]

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

Filter by
Sorted by
Tagged with
-1
votes
1answer
31 views

How can I transfer a multivariate model between spectrometers without the use of standard samples?

Our lab has created several multivariate models to predict sample properties from infrared spectra. However, different spectrometers often give different responses, and often the model created on one ...
0
votes
1answer
61 views

What is the plastic blister chemical compound that stores plastic toys?

I have observed that plastic toys that are stored in the plastic blisters, which is transparent, tends to stay the same over a long time. There are no chemical reaction taking place even after decades ...
0
votes
1answer
898 views

Why isn't air added to the primary reformer in ammonia production?

Is there an energy related reason why, in the production of ammonia, air is not introduced in the primary reformer? In this case we don't need the second reformer. I could think of a few reasons like ...
3
votes
0answers
38 views

Parameter effects on kinetics of esterification for bio-diesel production

I want to discuss the effect of parameters on the kinetics of esterification for bio-diesel production. In esterification process, temperature effect and molar ration are two important parameters. ...
3
votes
3answers
749 views

foam earplugs: what’s the composition of the (non washable) substance that slow down their expansion?

What’s the composition of the (slighlty sticky) substance we find on foam earplugs that allow them to be easily moldable? This substance slows down the expansion of the foam, so it makes the foam a ...
1
vote
1answer
1k views

What is the common filler used in plastic injection moulding?

What are the common filler materials used in PP, PE, LDPE, HDPE, and PVC-moulded materials? To give a background - I own a limestone quarry and selling calcium carbonate in powder form. I want to ...
5
votes
1answer
276 views

Thermodynamics of gas exchange between gas cylinders

A synthesis gas mixture ($\text{H}_2:\text{CO}$ with molar proportion 2:1) is needed for methanol synthesis. The final mixture must be available in a gas cylinder of 50 L, say cylinder $M$, which ...
4
votes
2answers
4k views

How does one calculate degrees of freedom in a reactor with parallel reactions?

Some time ago, I was going through some exercises and I came across a odd question, for which my atomic species degrees of freedom did not match my degrees of freedom using molecular species. I showed ...
1
vote
2answers
2k views

Derivation of Overall Mass Transfer Coefficient

The flux in the gas can be written as: $$N_{1}=k_{p}(p_{1}-p_{1i})$$ And the flux in the liquid can be written as: $$N_{1}=k_{x}(x_{1i}-x_{1})$$ And we know that $$x^*_{1}=\frac{p_{1}}{H}$$ How ...
1
vote
2answers
159 views

Second Order Transfer Function Question regarding Overshoot Formula

If I have a closed loop second order transfer function such as: $$T(s) = \frac{10-s}{0.3s^2+3.1s+(1+24K_{c})}$$ Can I still use this formula for overshoot (when a step input is applied) ?: $$\frac{A}...
4
votes
3answers
974 views

Calculating the minimum reflux ratio for separation of Acetone and Chloroform

Acetone must be recovered from a waste process stream, which also contains chloroform , so that it can be reused in the chemical process. The chemical process requires however that before the ...
2
votes
1answer
515 views

Fluid allocation for shell and tube heat exchanger

I'm designing a shell and tube heat exchanger with a hydrocarbon stream (31.6% propane and 60.4% propylene) entering at 135F and 321psi, and leaving at 100F being cooled by water at 85F and 74.7 psi. ...
0
votes
1answer
689 views

Finding mass flow rate and exit temperature in heat exchanger stream

I'm working on a heat exchanger design project and I'm stuck at one of the first steps - energy and rate balance. In the problem, we have a hydrocarbon stream getting cooled by a water stream. We are ...
5
votes
2answers
2k views

Normalization and Non-Dimensionalization of a mass balance equation

I would like to ask what is the difference (if any) between normalization and non-dimensionalization. I will try to explain what I have done until now with an equation that I would like to work with ...
2
votes
1answer
467 views

Convective heat transfer coefficient in finite difference method boundary conditions

Suppose there is a cubic material with an internal heat source ($\Delta q / \Delta t =$ Constant), and is immersed in a sufficiently large amount of water. Now I would like to use finite difference ...
5
votes
1answer
147 views

Working Out Shaft Torque in a Stirred Tank with a Cylindrical Cavern Formation (using a non Newtonian fluid)

Here is some background to the problem (in a stirred tank): "With yield stress non-Newtonian (viscoplastic) fluids, it is possible to generate an agitated volume around the impeller, defined as a ...
1
vote
2answers
221 views

Heat Exchanger Design - finding necessary variables

I'm working on a project to design a shell and tube heat exchanger. There's a mixture of 68.4% C,3H6 and 31.4% C3H8 being cooled from 135 $^\circ$F and 321 psia to 100 $^\circ$F and 285 psig. The ...
0
votes
1answer
165 views

Mass Transfer from an Oxygen Bubble

I think there is an error in this questions solution and I want someone to check: Example 8.1-4:Mass transfer from an oxygen bubble A bubble of oxygen originally 0.1 cm in diameter is injected ...
3
votes
1answer
692 views

How do temperature and pressure influence the rate of evaporation of water in a closed vessel?

I am trying to solve a fairly simple question but I'm kind of stuck on the technicalities: Imagine that water is evaporating into initially dry air in the closed vessel shown schematically in Fig....
4
votes
1answer
213 views

How to determine if mass transfer convection is natural or forced?

I know that forced convection requires some external bulk flow, but is there an equation to determine which form of Convection is dominant? I looked around and found the Richardson number $\mathrm{Ri}=...
3
votes
1answer
514 views

Will ammonia vapor corrode 304SS?

Will 25% ammonia vapor balance water vapor between 350°C - 550°C corrode 304 SS? If you know the answer how did you find it what was your source or equation or book? Will it cause pitting or stress ...
2
votes
2answers
1k views

How to estimate power consumption for an oven given volume?

Is there a good way to estimate the power consumption of an oven/heating device given the volume of the oven? I'm trying to do really, really dirty/quick math - I know that the average oven uses ...
2
votes
1answer
579 views

Polyurethane coating on fabric

I want to use a mix of polyurethane and acetone to coat some polyester fabric. I have the choice between using a PU glue or a PU foam but because polyurethane isn't a single material with a fixed ...
0
votes
1answer
23 views

Solubility Data

I am trying to obtain solubility data for a polymer in sc-CO2 and the data is reported at each T and P as $$w \ \ \times \ 10^6$$ Does anyone know what this means?
79
votes
9answers
35k views

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. ...
3
votes
0answers
85 views

Purification of wet-process phosphoric acid

I'm doing my senior design class and I have design a chemical plant that produces phosphoric acid by reacting phosphate rock with sulfuric acid. The phosphate rock has a lot of impurities, some of ...
8
votes
2answers
14k views

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 ...
0
votes
1answer
230 views

Mass Transfer Question

Predict the diffusion coefficient for nitrogen through a mixture containing 50% hydrogen, 30% ammonia, 15% nitrogen, and 5% water at 25°C and 1 atm. This was my thought process on which equation to ...
5
votes
2answers
668 views

Dynamic mass balance in plug flow reactor

So I would like to ask you about a problem I encountered. The case study goes like this: I want to study species distribution inside a packed bed reactor, at first at steady state but eventually what ...
5
votes
1answer
1k views

How does Alloy 20 compare with Ti 6-4, C-276 and 316 stainless for corrosive service?

While I've designed tons of plastics for corrosive service, the fasteners to hold the plastics together are inevitably metallic. There have been a lot of ways to protect them from rusting (due to ...
2
votes
1answer
202 views

Problem with process controls/simulink?

I have an issue with simulink, basically it's to do with a second order system, well two first order systems in series. As I understand it as you increase the damping factor (above 1), the system ...
10
votes
1answer
155 views

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 ...
8
votes
2answers
5k views

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: $\rho \frac{D\vec{v}}{Dt}=\rho g - \nabla P+ \mu \nabla ^2 \vec{v}$ ...
3
votes
2answers
1k views

Saturation Temperature of Binary Mixture

I have a binary mixture of water and methane. The system is at 2000kPa and I am trying to find the saturation temperature of the water in the mixture. I know Tsat is a function of partial pressure, ...
3
votes
1answer
2k views

How to do gold plating on Anodized aluminum and stainless steel?

I have done some research and asked in a few forums for gold plating on anodized aluminum and stainless steel but haven't yet found the answer to my questions. What are the chemicals for pre-...
2
votes
1answer
60 views

How can I remove Ozone from a sealed enclosure

One of the processes in a current product design catalyzes the conversion of atmospheric oxygen into ozone: $$ 3\text{O}_2+\text{energy}\rightarrow 2\text{O}_3 $$ Ozone is highly reactive and, over ...
1
vote
1answer
671 views

“Transport Phenomena” (Bird, Stewart, Lightfoot) difference between edition 1 and 2 [closed]

What is the difference between Transport Phenomena first edition (1979) and second edition (2002)? Which one do you recommend to be bought, taking into account that I am a student and that the first ...
10
votes
2answers
598 views

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 ...
6
votes
2answers
915 views

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 ...
2
votes
0answers
78 views

What is the retention time distribution in an STRcascade when the reactors are of uneven side and we have some recircultion?

Consider 2 or 3 stirred tank reactors as a cascade. The sizes are different. A part of the throughput is recirculated from the last to the first. The mean hydraulic retention of course is ...
3
votes
2answers
3k views

How can I calculate pressure change due to reaction?

I'm studying a reactor, that can be imagined simply as a pipe in which a reaction advances. In this reactor, the inlet and outlet flow are constant as is the temperature. If that reaction is equi-...
1
vote
0answers
43 views

Verify parameters variation in local sensitivity coefficients for microkinetic model

I’m performing a sensitivity analysis for a model of a set of elementary chemical reactions. I’m considering the variation in species concentration ($c_{k}$) with respect to the forward reaction rate ...
2
votes
1answer
617 views

How to get the maximum power point from I-V curve for Organic Photovoltaics (OPV)?

I am taking organic solar cell course on Coursera, and I have a question about I-V curve for a certain solar cell. The question asks for the solar cell characteristics such $V_{oc}$, $P_{max}$ and $FF$...
2
votes
1answer
973 views

ASTM grain size: diffusion of nickel in copper

Question: All other factors being equal, the diffusion rate of nickel is the highest in copper with ASTM grain size number of: A. 4 B. 6 C. 8 Honestly, the question does not appear to be very ...
4
votes
4answers
2k views

Discrepancy of calculated critical compressibility factor in Peng Robinson EoS

The Peng Robinson Equation of State gives a better approximation of the critical compressibility factor $Z_c$, where experimental data ranges between $0.24$ and $0.28$ (Source). Since the calculated ...
8
votes
1answer
924 views

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 ...
4
votes
1answer
402 views

How does conductivity $\sigma$ of salt-water depend on salinity?

In what way does the electrical conductivity $\sigma$ (or conversely, resistivity $\rho = 1/\sigma$) depend on the salinity $S$ of the saline- (or sea-) water? I know they must be in some way ...
6
votes
2answers
960 views

Can the Sabatier reaction power a vehicle?

The Sabatier reaction converts CO2 to methane. Can a vehicle that burns methane recover it (at least some part) from the exhaust gases via the Sabatier reaction? I am interested to know how this would ...
6
votes
1answer
148 views

Removing water and nitrogen from reactor effluent

I wish to remove water and nitrogen from my reactor effluent in order to decrease downstream equipment sizes and subsequently capital costs. Stream composition: ${H_2S}$.................5.6% ${SO_2}...
1
vote
0answers
35 views

Corrosion of a galvanic couple made with silver and gold

If a bangle is made out of gold and silver, connected with each-other would there be a corrosion happening? If so can it be explained using the galvanic series? Also do those metals undergo oxidation ...