Questions tagged [chemical-engineering]

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

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21 views

Nozzle inlet and outlet diameter for a shell and tube heat exchanger

Hi I have designed a shell and tube heat exchanger to cool octane and water. I have all the dimensions but I was unsure which equation to use to calculate the diameter for the inlet and outlet nozzles....
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12 views

Plug Flow Reactor Concentration UDF Debugging

I'm new to CFD and I'm trying to write a UDF that calculates the concentration at any position as a function of its x-coordinate (for example, Ca = .5C - .1x, or dCa/dx = -kCa). This is my first time ...
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1answer
191 views

How to calculate initial concentration of first-order reaction in CSTR?

(This question comes from a Chemical Engineering background, but basic Math and Programming knowledge is also required. I hope it still falls in the scope of engineering.stackexchange.com If not, ...
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2answers
192 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}...
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29 views

Thermal conductivity and the second law

I am having trouble figuring out the solution for part d. Can anyone give me a hint?
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1answer
77 views

What is the effect of different ways to adding liquid materials into a mixing tank?

I am working with body wash products and there is a problem happening with the mixing process. I use a 5000-liter tank to mix all the liquid materials including water, surfactant and preservatives. ...
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1answer
58 views

CO2 production from sugar [closed]

Greenhouses often use burners for CO2 enrichment, which requires a source of liquid propane or natural gas. The yeast fermentation process can also be used to create CO2 for a greenhouse by supplying ...
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0answers
23 views

Question regarding evaluating 1D heat transfer PDE

My question regards cooling of an object using 1D-heat transfer with fixed surface temperatures. First I need to find the solution to this PDE: Based on the conditions, I worked out that the ...
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1answer
71 views

How to calculate a gas burner dimensions?

I am trying to calculate the dimesnions of a natural gas burner for a hospital. The burner will be heating water. I have calculated the thermal duty that needs to be produced and the water mass flow, ...
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2answers
67 views

Advantages of hydrogen gas turbine over fuel cell

In the setting of large-scale electricity generation, I was wondering why one would want to burn hydrogen in a gas turbine instead of using it to power a fuel cell. Aren't fuel cells more efficient ...
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1answer
46 views

the volume in hydraulic retention time is of reactor/container or liquid

I have a tiny reactor, and the volume I need is 425ml. If there is no/few other reactants, then the volume in hydraulic retention time is clear: reactor/container's ...
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1answer
48 views

More temperature after boil the water can cook more faster the food?

My Question was not well received in physics.stackexchange.com and I get a simple answer when I want to know the theory inside this question. I want to cook more efficient wasting less ( gas or ...
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1answer
303 views

Custom User Models in Aspen Plus

I'm trying to simulate a purifier in Aspen Plus in a cryogenic system. This purifier is just meant to change the pressure of the outlet stream based on the inlet flow and pressure (we are using the ...
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3answers
76 views

How do you imagine momentum?

If you want to explain it to a layman (who belongs to the science stream ofc!!) how do you explain it? Also, what is momentum transfer when it comes to fluid mechanics?
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1answer
495 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
47 views

How can the air pressures exiting from a blower be adjusted?

During this covid-19, I was thinking about designing a low cost simple ventilator using a blower. There is a limit of the inspiratory and expiratory pressures, the inspiratory pressure being higher. ...
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1answer
56 views

How to identify the time delay of manipulated variables which are important to the final quality of polymer product

In a polymer production process, there are a lot of manipulated variables(MV) such as temperature ,pressure , or level of reactor that affect the quality of my polymer product. However, it usually ...
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51 views

Method of separating oxygen from a mixture of oxygen + carbon monoxide

I have a 99,9% oxygen, with 0,1% is CO. Is it possible to separate the CO from oxygen in this mixture? The closer the percentage to 0 for CO, the better. I've read about separation of oxygen from air, ...
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51 views

Calculating gas volume in a gas-liquid system/pressurized vessel

There is water in a tank and the tank is connected to a piece of piping that has a volume of 2.5L. The headspace above the water is pressurised by using air, to a pressure of 3 bar (a). What happens ...
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1answer
48 views

Elution from an Ion Exchange Column

I am using concentrated NaCl(10%) to elute Cobalt (II) ions from a cationic exchange column. How would I determine the volumetric flowrate of regenerant needed to completely elute the cobalt ions from ...
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2answers
110 views

Aluminum or Copper, which one is better to control and maintain the temperature?

Friends, I am an EE/SW/Controls eng. Please, pardon me of perhaps incorrect terminologies. I am working on a R&D project: A chemical lab equipment has a 2" long metal pipe enclosed in ...
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26 views

How to model a condenser (heat exchanger) where both streams are two fluid mixtures?

As mentioned I would like to model a heat exchanger (using Python). In this case, the condenser/hx streams are both a mixture of O2 and N2 These are known for both streams: Inlet temperature Inlet ...
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1answer
905 views

Entropy change in a throttling process

In an adiabatic throttling process of ideal gas: I understand that mathematically lost work is given by Tsurr * entropy generated. But intuitively I can't understand if there is not heat exchange ...
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1answer
167 views

Calculate the specific surface area of a mesoporous sample

I'm a nanoengineering student who's been stuck on the following problem for a few days. I've gone back over my professors slides, watched podcasts from an old professor, etc. etc., but don't ...
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1answer
50 views

Doubt regarding meta-stable and labile region of a supersaturated solution

I have read in a paper that the for formation of new crystals in a solution the energy released due to formation of solid from solution should be more than the energy needed to overcome solid-liquid ...
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2answers
59 views

Why are there no propane refrigerator air-conditioning units that run on solar heat?

I was thinking about how hot it was outside, when a thought came to me. There are propane refrigerators, so why not replace the propane as the heat source with solar heat and then change it from a ...
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3answers
137 views

Is there a maximum life for things made out of stainless steel or cast iron?

Do steel objects have a maximum lifespan? I read that "316 stainless steel is estimated to last for 1200 years in a “rule“ environment before heavy pitting. In the marine environment this is ...
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1answer
48 views

How to compute velocity distribution in the developing boundary layer on the cylinder

Air flows perpendicular to the axis of a cylinder $a=1$ cm in diameter. Air speed upstream of the cylinder is $U=6.72$ mm/s and its kinematic viscosity is $2.1×10^{-5}$ at 350 K. I want to obtain the ...
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17 views

Book recommendation for hydrodynamics of bubbles, drops, and particles

I am wondering if someone could please recommend to me some references on the topic of hydrodynamics of bubbles, drops, and particles, preferably in the context of complex and bio fluids. I am ...
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1answer
25 views

Distillation modelling McCable Thiele, Chemical Engineering

I am using an extractive distillation column to seperate ethanol and ethylene glycol. I am trying to find Rmin however its proving difficult as the the top operating line, q-line and bottom operating ...
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1answer
70 views

Industrial recycling of mirrors

I learned recently that mirror is mostly manufactured by pouring thin metal coating (i.e alumunium) on top of a substrate surface (i.e glass), Due to the nature of this composition it cannot be easily ...
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2answers
16k 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 ...
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42 views

What is the energy and capital cost of NH3 from Haber Bosch plant that takes in pure H2 and N2?

A question that becomes particularly relevant for "the hydrogen economy" or in the event that IGCC coal baseload electric generation seeks off-peak markets for hydrogen. I can't seem to ...
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21 views

Side entry mixer sizing

I'm involved in purchasing a set of mixers for a crude oil storage tank. The tank volume is around 98,500 cubic meters. The main purpose of the mixers is base sediment & water control (cleaning). ...
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34 views

Calculating estimated Overall Heat Transfer Coefficient

I have problem where I'm trying to determine the Overall Heat Transfer coefficient of a heat exchanger that uses the latent heat of vaporization of water in the process. I know the Q value I'm trying ...
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16 views

Determining length of interstage cooling coils for removal of heat

I'm currently trying to determine the length of cooling tube required to remove a specific amount of heat from my exothermic reactor in stages. I'm aware I need to use the equation $Q = UA \theta_{...
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1answer
45 views

How can I calculate the density of air?

I major in chemical engineering, and I'm solving a example of unit operations. The textbook is Warren L. McCabe, Unit Operations of Chemical Engineering 7th ed. Here is example 24.1. And this is its ...
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2answers
96 views

Eulerian description of fluid flow

In Eulerian description of fluid flow, we observe how the properties of the fluid are changing at a point. Since a point has zero dimension hence a zero area, how can we make sense of the 'finite ...
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9answers
37k 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. ...
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1answer
104 views

Is it possible to use direct air capture technology for CO2 on a non-commercial level?

CO2 is used as fertilizer in aquariums where it's brought into the water with diffusors from compressed form in cylinders. Direct Air Capture machines for CO2 have been presented for experimental geo-...
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1answer
43 views

How can I confirm nL Volume Measurement for Pump and Sensor Calibration

I'm dispensing around 1uL of volume with 1% accuracy. Although I'm confident in my pump, I'd like to be able to routinely confirm that I'm getting the exact volume I'm requesting every time. How can ...
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31 views

P&ID questions on reports, connection, etc

Good day to all of you. I got some questions in my mind regarding on P&ID: In electrical, symbol will have their own default reference name for example "Motor" will use "M" , ...
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2answers
82 views

chemical reaction engineeing

What is the definition of rate $(−ra)=−\frac{dCa}{dt}$ or $(−ra)=−1/V\frac{dNa}{dt}$ ? I think the general one is the second one and first one is for constant volume reaction system. Is the above ...
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70 views

Navier-Stokes with non-newtonian fluids

So I've got a problem here in fluids. It's driving me insane but I know I'm missing something simple. Up until now we've worked with Newtonian fluids resulting in the "normal" NS equations ...
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1answer
66 views

Recommended books for process engineering? [closed]

I made a career change from machine design to CNG processing. What I’m looking for are some good books/handbooks that cover the following topics. Something similar to Machinery’s Handbook. Piping, ...
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1answer
70 views

How to derive phase equillibrium criteria for more than 2 phases mathematically?

I know the derivation of phase equilibrium criteria derivation for 2 phases. I am not getting how to extend the derivation to more than 2 phases. Please help me out on that. Thank you
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1answer
72 views

Theoretical maximum pressure from combusting LPG

I am curious how to find or estimate the theoretical maximum pressure that the combustion of a LP gas, such as propane, can produce inside of a constant volume, such as in a cylinder. I know what the ...
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1answer
33 views

Is molecular dynamics relevant for an undergraduate Mechanical Engineering degree? [closed]

I am completing my final year undergraduate study in Mechanical Engineering. I've had to have a scope change because my last project was not going to work with the pandemic. I've been given a project ...
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1answer
43 views

Gaps in derivation of thermodynamic property equations

If $h=h(T, P)$. Does $ dh = c_pdT + \left[v - T\left(\frac{\partial v}{\partial T}\right)_P \right]dP \Rightarrow h_2 - h_1 = \int_{T_1}^{T_2} c_pdT + \int_{P_1}^{P_2}\left[v - T\left(\frac{\partial v}...

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