ChEng

Mass Spectroscopy

2010-09-09T01:06:00.012+05:30

Last month, I've presented a seminar on Mass Spectroscopy at my college and it was not bad or either good. Time was limited and didn't allow me to pare down the vast amount of information available in cyberspace at a single shot. Well, it was one hell of a sleepless night that I had managed to cope up with power-cuts and internet failures(got no books to read). I wish if I could soon install a Wi-fi in my computer.And I wanted to share at least a few titbits of spectroscopy here, as I've found the concept intriguing and really helpful for chemical engineers.Although, I have got only the basic stuff, I hope that I would update this post soon with further more interesting information.

At first, let us take a radical approach to spectroscopy. It is simply used to identify an unknown chemical species and determine its structure, properties and molecular composition. This could be achieved by generating a spectrum with the help of special instruments like spectrophotometer or interferometer. A spectrum is simply a plot between energy variable of a radiation and wavelength, or the frequency of that particular radiation. It gives us useful information about an unknown chemical species; it's derivatives, molecular weight, etc. Initially, it was referred as the dispersion of white light into seven different colors of radiation with the help of a prism. But, the concept has been developed greatly later. Depending upon the nature of interaction between radiation and the sample, types of sources used and based on several other factors, there are different kinds of methods, which are in use today in different areas. Some examples are Absorption Spectroscopy, Emission Spectroscopy, Raman Spectroscopy(scattering technique),NMR(Nuclear Magnetic Resonance), X-ray, Astronomical, Fourier Transform, Gamma-ray, etc.

Coming to the mass spectrometry, it's concerned with the separation of matter according to atomic and molecular mass, and often used in the analysis of organic compounds of molecular mass up to as high as 200,000 Daltons. First, a sample is introduced into a mass spectrometer and it is bombarded by an electron beam, or simply converted into ionic phase by fragmenting the sample into its constituents. This is done by ionizers. Then, the ions pass through a mass-analyzer, which is the electromagnetic field. Here the mass-to-charge ratio of the ions are calculated and the constituents are sorted into different groups. The analyzer passes the ions to a detector where the abundance of each ionic constituent is calculated and a mass spectrum is constructed finally. The mass spectrum is a graph between mass-to-charge ratio of an ion taken on X-axis versus the relative intensity, or abundance of that kind of ionic constituent on a vertical axis. It shows us peaks of differing heights, among which the largest one has a relative intensity of 100 and is called as the base peak. The heights of other peaks are considered relative to it. These peaks give us the molecular weights of the constituents present in the sample. We can also compare the mass spectrum of an analyte with that of an authentic sample. If they are identical, then they both resemble a single species. If you want to know more about the details of mass spectroscopy, then click here.
And here are other useful resources:
i-mass.com
http://www.chemguide.co.uk/analysis/masspec/howitworks.html
http://en.wikipedia.org/wiki/Mass_spectrometryhttp://chemistry.about.com/od/spectroscopy/Spectroscopy_Spectrometry.htm
http://chemistry.about.com/gi/o.htm?zi=1/XJ/Ya&zTi=1&sdn=chemistry&cdn=education&tm=17&f=00&tt=14&bt=0&bts=1&zu=http%3A//masspec.scripps.edu/hist.html

Softwares & links

2010-07-04T06:33:00.003+05:30

Here is a list of open source softwares:http://opensource.cheme.info/index.php?topic=4.0.And here you go with some chemical engineering link collection.

Matlab Vs Scilab

2010-07-01T13:22:00.011+05:30

There are quite a few differences between MATLAB and Scilab.As the syntax of Scilab is similar to MATLAB, Scilab includes a source code translator for assisting the conversion of code from MATLAB to Scilab. Scilab is available free of cost under an open source license. Due to the open source nature of the software, some user contributions have been integrated into the main program.However, MATLAB is payware. So for people who don't have MATLAB installed in their computers, Scilab could be used as an alternative.For downloading Scilab click here.

Note:To obtain this logo for displaying on your blog or website, you should make a request by email at: communication@scilab.org

Chemical Engineering Division Wikiversity and Blogroll updates

2010-07-01T12:31:00.002+05:30

Kudos for all the active participants of chemical engineering division (Wikiversity), who have been trying to build a brand new environment of chemical engineering .Click here to enter. The core areas like chemical process principles, fluid mechanics, instrumentation and control systems, heat transfer, chemical process technology, chemical engineering thermodynamics,process equipment design, unit operations,mass transfer,reaction engineering,particle mechanics,transport phenomena,process dynamics and control, chemical plant economics and management need to be treated further more.Besides, there are databases, journals, textbooks, research projects, magazines, softwares and other resources available online.

I've added a few websites under the category ''chemical engineering communities'' on the sidebar of this blog.I request my blog readers to create an account in Wikiversity and contribute to the development of any of your concerned areas.To create an account click here.Although, you can edit the content without an account, where all your edits are publicly associated with your IP address at the time of that edit.In fact, there are more advantages in editing as a user which lets you build trust and respect through a history of good edits. It is also easier to communicate and collaborate with veteran editors if you're a registered user (at least, who you are on Wikiversity).

Green Home

2010-07-01T08:35:00.001+05:30

Do you want to build a smarter planet with green ideas, then here is the ideal site which can help you.Green products for all kinds of daily requirements are available for sale.

Engineering Ethics

2010-06-30T23:17:00.006+05:30

Well, it's been a long time since I'd posted on this blog. Actually, I finished my second academic year of chemical engineering.I have had a bad face at the time of exams last month. The standard of the questions asked were very high and brainstorming.I would share a few of them later.A while ago, just gone through an article on ethics from the chemical engineering magazine( IChemE) and felt like sharing it here-Andrew Haslett asks what professional ethics mean for chemical engineers.

Computer and Software Applications in Chemical Engineering

2010-04-26T23:05:00.003+05:30

Any problem requiring lengthy calculations or calculations which are repetitive in nature, or the storage and retrieval of a large volume of data can be solved efficiently by computers. Moreover, a computer's ability to perform logical operations makes it suitable for the solution of complex problems. It is possible to write a program so that the calculations may be carried along one direction or branched out along another, depending on the situation, after an intermediate result has been calculated. A master program may have many such decision making points. Frequently repeated calculations may be written as separate sub-programs or sub-routines, which may be recalled many times by the master program or main program by a single statement. A program may also be made to find the probable cause, or causes of some effects(or vice versa) from a set of cause-and-effect relations known as rules of logical analysis.

At first, I really wondered why we had to learn C & DS and OOPS(Object-Oriented Structured Programming Language).And in the coming semesters we have C++, Unix & Shell programming and Data Base Management Systems.Well, they are important for chemical engineers to solve many engineering problems.For instance, numerical methods such as LU decomposition, Newton-Raphson, fourth-order Runge-Kutta, and orthogonal collocation modeled as Java classes are applied to a variety of chemical reactor problems.
Here is a link to research articles related to computer applications in chemical engineering.

And below is the summary of a company's requirement of a desired chemical engineering professional. It's been clearly mentioned that the desired candidate should have the experience of working in Object Oriented Programming Language like c++.Take a look at it:

Summary

Experience: 3 - 8 Years

Location:

Hyderabad / Secunderabad

Education: UG - B.Tech/B.E. - Chemical PG - Any PG Course - Any Specialization,Post Graduation Not Required

Industry Type: Oil and Gas/ Power/Infrastructure/Energy

Role: Software Developer

Functional Area: IT-Other

Posted Date: 15 Apr

Desired Candidate Profile

Should have 3+ years of experience in chemical process engineering industry.
Should have strong background in Dynamic Simulation or Mathematical Modeling.
Should have experience of working on commercial process simulation packages (like Aspen, Hysys, Dynsim etc.)
Should have experience of working in Object Oriented Programming Language like C++.

Must Possess Good communication and interpersonal skills. Should be a good team player and self motivated.
Should also be able to work independently on well defined tasks.

Must be ready to relocate to Hyderabad.

Job Description

Should have 3+ years of experience in chemical process engineering industry.
Should have strong background in Dynamic Simulation or Mathematical Modeling.
Should have experience of working on commercial process simulation packages (like Aspen, Hysys, Dynsim etc.)
Should have experience of working in Object Oriented Programming Language like C++.

Interview questions based on some chemical engineering facets

2010-04-01T02:27:00.003+05:30

I've downloaded a PDF file containing open ended questions from IIT Madras site.The questions might increase the activity of your grey cells.Here they are-
1. On a cold wintery morning, I made the mistake of driving to office from my residence on a scooter without adequate warm clothing. Should I drive fast or slow in order to minimize the total heat loss from my body?
2. It is generally stated that for every 100m you go up the atmosphere, the temperature drops by 1 deg C. Explain how you can get verify this statement?
3. The manual for the 5L Prestige pressure cooker mentions that you should fill the cooker with 200gms of water when you cook food in a vessel placed inside it. What do you think will happen if you don't follow this instruction? The nozzle on the cooker has a diameter of 4mm and the weight placed to cover the nozzle has a mass of 250 gms. For what pressure should the cooker be designed to withstand? What is the typical cooking temperature in the vessel and how can you estimate it?
4. In the Bhopal disaster that occurred in 1984, a storage vessel containing 45 tons of methyl iso-cyanate (MIC) stored in a closed vessel exploded releasing the contents. About 2500 people died and several thousand severely affected. The investigation into the disaster concluded that water entered the vessel and there was a runaway reaction. The refrigeration system designed to keep the vessel cold, was not functioning. As a chemical engineer explain what do you think happened.
When the gas was released, it was night time. MIC also has a density more than that of air. This resulted in a greater tragedy and more deaths. Do you believe that if the accident had occurred during the daytime, the damage would have been much less, even if no additional precautions were taken?
5. Most pipeline designers for liquid transport use a thumb rule that the pipe diameter should be chosen such that the velocity in the pipe is between 1-3 m/s. How do you verify whether this is a good choice or not?
6. It is required to heat a cold stream from 25 deg C to 80 deg C. We have two hot streams, H1 and H2, one at 100 deg C and the other at 90 deg C. The flow rates of all three streams are the same, while the specific heat capacities of the hot streams are the same and equal to half that of the cold stream. The cold stream can first pick up heat from hot stream H1 followed by hot stream H2, or from H2 first followed by H1. Does the order matter and why?
7. You are participating in a competition to guess the hidden treasure which is behind one of three closed chests. Amitabh Bachchan is hosting the competition and asks you to choose one of the chests which you believe contains the treasure. After you have made the choice, he opens one of the chests (not chosen by you) and shows that it does not contain the treasure. Now he again asks you to choose one of the remaining two closed chests. Will you stick to the original choice or will you change in order to improve your chances of finding the treasure. Explain.

The first class of Polymerization

2010-03-17T23:55:00.011+05:30

Organic chemistry is one of the fascinating subjects, I've in this semester. Today we started-off Polymerization and firstly discussed about polythene bags.They come under the category of thermoplastics, and are a result of additional polymerization,i.e,when all the small monomer units combine to form the polymer without the elimination of any water/ammonia/hydrochloric acid.In case of polythene or polyethylene, ethylene(C2H4) is the monomer unit and it forms polyethylene in the presence of light/heat/pressure/catalysts.It's important to note that the summation of molecular weights of all the small monomer units is equal to the molecular weight of the polymer.Another example can be PVC(poly vinyl chloride).

Coming to condensation polymerization, the monomers with different functional groups may combine to form polymers and resulting in the elimination of water/NH3/HCl in general.The polymers formed by condensation polymerization come under thermosetting category.Examples:Bakelite(commonly used in making switches), consists of two monomeric units having formaldehyde and phenol as their respective functional groups.
Nylon 6,6 also belongs to this category. Its two monomeric units are hexa-methylene diamine and adipic acid. These two monomers form the polymer by the elimination of water.
nHOOC-(CH2)4-COOH(adipic acid)+n H2N-(CH2)6-NH2(hexa-methylene diamine)---->[-OC-( CH2)4-CO-NH-(CH2)6-NH-] n(repeating unit)+2nH2O(water).

And there are a lot of differences between thermoplastics and thermosetting polymers.The polymers of the former are less brittle,become soft on heating,can be recycled,soluble in organic solvents,possess long linear chain and are formed as a result of additional polymerization. While the latter are a result of conditional polymerization as discussed above, where the overall molecular weight of the polymer would not be the same as the summation of the individual molecular weights of the monomers.They cannot be recycled, have cross-links and are more brittle and strong.They are insoluble in all the organic solvents and the monomers combine under heat and pressure, whereas in the former case, only one parameter may be sufficient.And, molding is easy for thermoplastics.

Save our Environment

2010-03-16T18:33:00.011+05:30

While going to my college I face a lot of pollution and it arises a feeling of disgust in me. It takes about two hours for me to reach my college and by that time I get exhausted. Traveling is not at all a problem, but facing pollution while we travel possess a serious threat to our health.For all the nations, it is important to reduce the emissions and switch to the sustainable development completely, meet wider economic growth,good health etc by 2020.But I think before reaching 2020, I might become sick, lose patience and also worried that I might get many health problems. And I can feel that the environmental conditions are worsening day by day. It's a sin if I blame others ,as I have got to blame myself first when it comes to pollution. I've contributed to the environmental degradation in some way or the other like wasting water, electricity, throwing polythene bags wherever I wish etc.However, I've taken an initiative to protect our environment.

Some ways to save our environment for every responsible global citizen are as follows(free advices, though you might be aware of):
1.Avoid using vehicles that work on fossils and try switch to alternative sources of energy like biodiesel, electric batteries, CNG(compressed natural gas) etc.And you can use public transport system instead of your vehicles to reach nearby places.

2.RRR-Reduce, reuse and recycle. This is the formula for managing plastics. Avoid throwing polythene bags in public or private places and always use bins. Always carry a paper or a cloth bag along with you when you go for shopping. And also request the shopkeepers to charge some extra money, if people ask them a polythene bag.Secondly, avoid use-and-throw pens.

3.Coming to water, implement a rain water harvesting plan for your house. And use water according to your necessity, without wasting it.

4.Electricity for life. Switch off all the fans and lights when you are not using them.

5.Plant many trees.Well, actually if anything bad happens, their are many ways through which we can overcome it, but we are losing the other ways too and in turn getting lost. Global warming, when it first started to happen, people might have thought that it's time to grow many trees.But trees were cut down. Opportunity declined. Now the only opportunity is to switch to renewable sources of energy.

6.Though all are aware of the common points above, but here is the cardinal problem-POPULATION. It depends upon you.

7.Paper which is made of bagasse, not trees is another good opportunity for us to save our trees.Bagasse comes from sugarcane. After the cane has been crushed to make sugar, the leftover pulp is turned into paper and eco-buddy books are manufactured. Think about it, every time you buy an eco-buddy book which uses bagasse made paper of fine quality, you make our planet a little greener. It's up to you. Go ahead and create a revolution. Some companies, which offer eco-friendly type of books in India are Navneet, Classmate etc.

8. Do not burn the dry leaves that accumulate in your yards and streets, as they release more co2 and other gases into the atmosphere.Just inform your municipal officials to collect them. Encourage curbside pickup of leaves and other yard waste, which can be turned into compost for park maintenance or for sale commercially.

9. Don't switch on the geyser for a long time as a lot of electricity and gas gets wasted.

10. In case of air quality worsens in your area, inform the concerned government authorities to check the air quality index and also to take measures in order to reduce the pollution in your area to a threshold limit.

11.Don't be hesitant to complaint about any sewage leakages or any garbage problems in your area.

12. Try to stick to traffic rules, which can help to control noise pollution.

13.Most importantly, avoid using bulbs and install compact fluorescent lights instead.

There are many other ways you can follow and save your environment. And as a responsible human being, I've been following the above principles and requesting you to have concern on protecting your mother earth(I worship you if you are already an environmentalist).And below are some environment widgets.Come on, share these widget on your site.Make people aware of what is happening and what could be done to protect our environment.Spread the word.
1. Shows co2 levels in the atmosphere.

2. CO2 calculator:

3.Sustainable housing design:

Sodium and Potassium in Nuclear Reactors

2010-02-24T10:01:00.019+05:30

I didn't post for quite a while as I was busy. The 2-1 results have been announced and everything is going well. In the meantime, I wanted to share this topic on why sodium and potassium are used in the nuclear reactors . Last week, we arrived at this point while discussing Prandtl no.

Prandtl number

Pr

is a dimensionless number approximating the ratio of momentum diffusivity (kinematic viscosity) and thermal diffusivity, named after the German physicist Ludwig Prandtl.
Pr =v/

α

=Viscous diffusion rate/Thermal Diffusivity
=

μ

c p/

k

$μ$ : dynamic viscosity, (SI units : Pa s)
$ρ$ : density, (SI units : kg/m³ ).
$ν$ : kinematic viscosity, $ν = μ / ρ$ , (SI units : m²/s)
$c p$ : specific heat, (SI units : J/(kg K) )
$α$ : thermal diffusivity, $α = k / (ρ c p)$ , (SI units : m²/s)
$k$ : thermal conductivity, (SI units : W/(m K) )

In heat transfer problems, Prandtl no. controls the relative thickness of the momentum and thermal boundary layers. When Pr is small, it means that the heat diffuses very quickly compared to the velocity (momentum). This implies that for liquid metals the thickness of the thermal boundary layer is much bigger than the velocity boundary layer.For Na and K, Pr< 1.Prandtl number is dependent only on the fluid and the fluid state. So when either of it is used as a coolent, it can easily remove the heat released from the reactor core.
Typical values for

Pr

are as follows:

0.015 for mercury
7 for water (At 20 degrees Celsius)
100- 40,000 for engine oil
0.16-0.7 for mixtures of noble gases or noble gases with hydrogen
0.7-0.8 for air and many other gases,
1 × 10²⁵ for Earth's mantle
4 - 5 for R-12 refrigerant

Measuring Devices(Series)

2010-02-12T18:59:00.003+05:30

This post is on psychrometers and hygrometers, which are used to measure the relative humidity.Relative humidity refers to the ratio of the quantity of water vapor in a particular sample of air to the quantity there would be in an equal volume of saturated air at the same temperature and pressure. It is expressed in terms of percentage.

When a gas or a gaseous mixture remains in contact with a liquid surface, it will acquire vapor from the liquid until the partial pressure of the vapor in the gas mixture equals the vapor pressure of the liquid at its existing temperature. When the vapor concentration reaches this equilibrium value the gas is said to be saturated with the vapor. If a gas contains a vapor in such proportions that its partial pressure is less than the vapor pressure of the liquid at the existing temperature, the mixture is but partially saturated. The relative saturation of such a mixture may be defined as the percentage ratio of partial pressure of the vapor to the vapor pressure of the liquid at the existing temperature.The relative saturation is therefore a function of both the composition of the mixture and its temperature as well as of the nature of the vapor.

Because of the widespread occurrence of water vapor in gases of all kinds, special attention has been given to humidity case and a special terminology has been developed. The humidity H of a gas is defined as the weight of water per unit weight of moisture per mole of moisture-free gas.Whereas, the molal humidity is the number of moles of water per mole of moisture-free gas.And when the vapor under consideration is water, the relative saturation becomes the relative humidity.

Back to the devices, here they are:
Psychrometer-It measures the readings on two thermometers, one with its bulb directly exposed to the atmosphere and the outer with its bulb covered by a wick kept continuously wet with water. This is a drop in the temperature of the second bulb(the wet bulb) due to the evaporation of water. This drop varies directly with the rate of evaporation, and this, in turn, is inversely proportional to the amount of water vapor in the air. The wick must be kept at about 5 m/s. The wet bulb measures the temperature at the thermodynamic equilibrium reached between the cooling due to the evaporation of water and the heating due to convection from air. Psychrometric charts give the relative humidity or humidity corresponding to the readings on the dry and wet bulb thermometers.

Wet- and Dry-Bulb Thermometry
When a liquid evaporates into a large volume of an unsaturated gas which is initially at the same temperature as the liquid, if no heat is supplied from an external source, the liquid will spontaneously cool to supply part of the energy required for vaporization. If the body of liquid has a large surface area in proportion to its mass, its temperature will quickly drop to an equilibrium value. This equilibrium temperature attained is determined by a dynamic balance established between the rate of transfer of heat to the liquid from the warmer ambient gas and the rate of transfer of vapor from the liquid to the ambient gas with absorption by the liquid of the corresponding heat of vaporization. The equilibrium temperature attained by a liquid which is vaporizing into a gas is termed as the wet-bulb temperature and is always less than the actual dry-bulb temperature of the gas into which evaporation is taking place.
A Sling psychrometer consists of two mercury-in-glass thermometers mounted on a suitable frame and arranged with a swivel-mounted handle at one end so that it can be swung rapidly to give the proper air velocity. One bulb is covered with clean cotton wick wetted with water.It is used in meteorology, and in the HVAC industry for proper refrigerant charging of residential and commercial air conditioning systems.

Hygrometers-They depend on the expansion o contraction of certain hygroscopic substances, such as human hair, with a change in the relative humidity of the surrounding atmosphere. The materials commonly used are wood, paper, silk, animal membranes and hair. Below is the image of a digital hygrometer.

In the hair hygrometer, human hair mounted on a suitable structure is used to actuate an indicating pointer, or a recording pen. Hair absorbs moisture from the ambient atmosphere and lengthens as its water content increases. The amount of water absorbed is dependent on the temperature of the hair and the partial pressure of water vapor in the surrounding atmosphere. The change in the length of the hair is approximately a direct function of the relative humidity.

In the membrane hygrometer, animal membranes are used as the sensitive element. Under changes in atmospheric humidity, such membranes also take up or give off moisture, changing in length with changes in the relative humidity of the ambient air, in the same manner as human hair. The changes in the length of such membranes are greater than the corresponding changes in the length of human hair by a factor of 2.3:1. But membranes show a greater tendency to shift calibration in service.

Changes in the humidity of the atmosphere cause changes in the concentration of a salt solution exposed to it. Changes in the concentration and temperature of such a solution cause changes in its electrical conductivity. This effect is put to practical use in salt-conductivity hygrometers.

Applications: Greenhouses and industrial spaces, saunas, humidors, museums, residential settings, humidity control (too low humidity damages human skin and body, while too high humidity favours growth of mildew and dust mite).

Top online engineering degree online

2010-02-08T16:05:00.009+05:30

Well, some time back I received a mail sent by Betty Jones. He had newly posted an article(100 Eye-Opening Lectures on Future of Engineering) on his site. The article is on 100 engineering topics by different professionals, and each one followed by its respective excerpt. Among those, this one impressed me:

Aubrey de Grey says we can avoid aging

Inventions that slow or entirely halt the aging process have the potential to also cure humans of the many medical problems that settle in as one grows older.

The article is worth reading especially for all the engineering students.Here is the link:http://toponlineengineeringdegree.com/?page_id=103

Professionls have answered my questions, still I'm in a dilemma

2010-02-08T15:22:00.007+05:30

me: Hi, your blog has always been interesting and cute. I’m a chemical engineering student.Could you please give me some advices for manipulating my engineering studies efficiently.Secondly, I’m interested in Alchemy.Could you please guide me regarding the same.

Gaussling said...
Hi Vinith, can’t help much with alchemy given that it faded out centuries ago. As a chemist, I’m reluctant to advise in regard to chemical engineering. But in regard to the chemical processing industry (CPI), you should decide where you would like the arc of your career to take you.

If you are business oriented, then you need to be sharp in the area of process economics and finance. If you want to be on the technical end, then you have to try to guess what part of the CPI you’ll end up in. Pharmaceuticals requires different skills than petroleum refining. Biotechnical engineering favors those with some knowledge of cell biology and microbiology. If you show good mechanical aptitude, you might end up being a plant engineer maintaining and installing equipment. You should have a good look in the mirror and decide on what really excites you about engineering – do you like to be out on the plant floor supervising or indoors planning? Perhaps you want to be a consulting engineer who flys in to solve specific problems. Before anyone can help you plan your studies, you need to look inward and decide what drew you to engineering and what do you love to do.

me:I'm a chemical engineering student and interested in rheology. Could you please give me any suggestions.

John said... I'd say you are off to a good start being in chemical engineering. (That's my background as well, only I ended up here without any planning.) Despite its importance across so many fields, you can't get a degree in rheology. It's the same way with thermodynamics - so useful across so many fields, but you can't get a degree in it. There aren't job postings for "Rheologists" but for people (engineers, mostly) with experience in rheology. And it's mostly engineers because fluid mechanics is an engineering subject that few "scientists" ever study. Studying polymers is a good entry point, as is food processing. Lastly, take as much math as you can handle. The mathematics behind much of rheology is the same mathematics used in Relativity Theory - tensor analysis. Taking the derivative of a vector is trivial; taking the derivative of a tensor is a nightmare.

I'm not able to decide which area of chemical engineering more interests me. Our choices design our fortune and I hope, I would make a good choice. On the whole, many areas like I'd mentioned in my profile-rheology, nanotechnology, microbiology etc. have influenced me.And yesterday, I read some chemical engineering matter on the net. Then I decided to become a freelancer.However, I'm in a dilemma whether to procure a job and go for working in an industrial sector directly after b.tech, or opt for higher studies and go for R & D in my interested area(s). Have some time to decide. Before that I should just complete doing my engineering.Lastly, I would like to thank all the chemical engineering and other professionals who were supportive and did care my presence(blog) on the net and responded to my queries.Some have even included my blog on their sites. I want to list them up: Chemical Professionals, Chemical Engineering, It's a micro world, The Chem Blog, Coronene Chemistry Blog, Smart Process Design .I'm also a big fan of Zaki, Profmaster and Dilantha.

Overall Heat Transfer Coefficient

2010-02-05T19:06:00.014+05:30

The heat transfer coefficient is used in calculating the heat transfer by convection or phase change between a fluid and a solid.

------->(1)

ΔQ = heat input or heat lost, J

h = heat transfer coefficient, W/(m²K)

A = heat transfer surface area, m²

Δ T

= difference in temperature between the solid surface and surrounding fluid area, K

Δ t

= time period, s

The overall heat transfer coefficient

U

is a measure of the overall ability of a series of conductive and convective barriers to transfer heat applied to heat exchangers.

Q = U A Δ T L M

----->(2) where

Q

= heat transfer rate (W)

U

= overall heat transfer coefficient (W/(m²·K))

A

= heat transfer surface area (m²)

Δ T L M

= log mean temperature difference (K)

Today process heat transfer class has been very interesting. HOD has discussed about heat exchangers. As you can see, the above formula( equation 2), could be used for calculating the overall heat transfer coefficient U. Actually, I got to know that there are even two other heat transfer coefficients, i.e, U subscript d and U subscript c. The former represents the heat transfer coefficients of fouling tubes and the latter that of clean tubes. Always coefficient of clean tubes is greater than the coefficient of fouling, as in case of the latter, scale formation takes place and heat loss occurs. A high jet stream is required to remove the dirt or scale-up in such kind of tubes.

Coming to the heat transfer rate in the above expression, it is determined by comparing the rates of heat transfer of two substances. For instance, if a substance is converted to another at a particular temperature, then the respective heat transfer rates of the two be Q1 & Q2. And
Q = m C dT ------>(3) where

m = mass

C = specific heat capacity

dT = infinitesimal or small change in temperature

So when we equate Q1 & Q2, then with the help already known values, one could easily find out Q.
Back to the overall heat transfer coefficient, it takes into account the individual heat transfer coefficients of each stream and the resistance of the pipe material.It is calculate as follows:

R = Resistance(s) to heat flow in pipe wall (K/W)

But more complex relationships exist, for example when heat transfer takes place by different routes in parallel.And the thermal resistance due to the pipe wall is calculated as follows-

x = the wall thickness (m)

k = the thermal conductivity of the material (W/(m·K))

A = the total area of the heat exchanger (m²)

The following relationship is often used: =
where

U e x p

= overall heat transfer coefficient based on experimental data for the heat exchanger in the "fouled" state,

U p r e

= overall heat transfer coefficient based on calculated or measured ("clean heat exchanger") data,

R f

= thermal resistance due to fouling,

In general, the heat transfer coefficients, h inner and h outer are also taken in consideration for heat exchanger tubes. And it's very important for a chemical engineer to calculate the surface area of heat transfer.

Here is a recommended book on extended heat transfer by D.O.Kern and A.D.Kraus.

And the widely used books, softwares or standards in industries, while dealing with heat exchangers is TEMA which is an acronym for Tubular Exchanger Manufacturers Association on shell and tube heat exchanger mechanical design...

Note: If I had made any mistake, then please inform me. Whatever info I've provided here is based on my today's class, and some internet surfing.

Measuring Devices

2010-02-04T21:52:00.005+05:30

I've an interest to construct a rheometer. But, only have an inkling on it. I got this idea when I heard about a fest that is going to take place soon, in one of the top-most engineering colleges at my place. However, I can't make it, as there's no time.Actually, another interesting idea crossed my fickle mind, however, I'd finally resolved to do the former-rheometer.And I felt that it's worth including some posts in my blog based on some measuring instruments.

Firstly, a measuring instrument has three functional elements, namely:

a primary element to detect changes in the magnitude of the variable,and
a transmitting means for connecting the detecting element to
measuring element

Most industrial products are manufactured to meet certain specified physical and chemical properties. And, I'm herewith different measuring devices that are employed for different process variables.I would post them in series.In this post, I'm going to discuss hydrostatic balance, specific gravity bottle, or pycnometer and hydrometer, which are used to detect the specific gravities of solids and liquids. Note: I could even modify/append/delete any content in my posts whenever I feel it as necessary.

1.Let us start with hydrostatic balance- It is a balance adapted for weighing a body in air and in a liquid. To determine the specific gravity of an insoluble solid heavier than water, the sample is first weighed in air, and then in water. Let mass of the sample in air = m1 and
mass of sample in water = m2
Then, (m1-m2) is the mass of an equal volume of water. The specific gravity of the sample is, then,
s = m1/(m1-m2) at the temperature of the experiment, t degree C.
True specific gravity = s* (sp.gr. of water at t deg. C)
To determine the specific gravity of a solid which is soluble in water but heavier, the sample is first weighed in air and then in a liquid in which it doesn't dissolve.
Let mass of sample in air = m1
mass of sample in the liquid = m2
Specific gravity of the liquid relative to water = s'
The specific gravity of the solid relative to water is s = [m1/(m1-m2)] s'
To determine the specific gravity of an insoluble solid, which is lighter than water, the sample is first weighed in air. The sample is tied to a sinker and the sample is weighed in air with the sinker dipped in water and then, the weight of the sample and sinker both in water is determined.
Let mass of the sample in air = m1
Mass of the sample in air and sinker in water = m2
Mass of the sample and sinker in water = m3
The specific gravity of the sample is s = m1/(m2-m3)

2. Pycnometer or Specific Gravity Bottle- It is a flat bottomed bulb-like glass bottle with a long, tapering neck. A well-ground solid glass stopper with a narrow bore fits the neck. If the bulb is filled with a liquid and the stopper dropped in place, some liquid comes out through the bore and the bottle contains a fixed volume of the liquid.

To determine the specific gravity of a liquid, clean, dry, empty bottle with stopper in place is weighed. The bottle is then filled with liquid and weighed. It is then washed clean, filled with water, and weighed. Let mass of the empty bottle be m1.
Mass of bottle filled with the liquid = m2
Mass of the bottle filled with water = m3
The specific gravity of the liquid is s = (m2-m1)/(m3-m1)
To determine the specific gravity of a granular solid, which is insoluble in water, the empty bottle is first weighed. About one-third of the bottle is then filled with the granular solid and weighed. The rest of he bottle is filled with water, taking care that no air bubble is entrapped, and the bottle is weighed again. Finally, the bottle is washed clean, filled with water and weighed. Let the mass of dry, empty bottle be m1.
Mass of bottle partly filled with granuled = m2
Mass of bottle + granules + water = m3
Mass of bottle filled with water = m4
The specific gravity of the granular solid is calculated as follows: s= m2-m1/(m4-m1)-(m3-m2)
To determine the specific gravity of a granular solid, which is soluble in water, select a liquid of known specific gravity s', in which the solid is insoluble. Repeat the step as mentioned above with the liquid insted of water. The specific gravity of the granules relative to the liquid is s1 = m2-m1/(m4-m1)-(m3-m2)
and that relative to water : s=s1 * s'

3.Hydrometer: This consists of a weighed float with a stem of small diameter proportioned so that the height of the scale submerged in the liquid in which it is floated varies according to the density or specific gravity of the liquid. Since the weight of the hydrometer is constant, it measures directly the volume of the liquid which is equal to the weight of the hydrometer. It is calibrated in terms of density or specific gravity.

I may take some time to post on rheometer. And for your kind information, I may refer some books, or gather sufficient information from library, and even inquire as many professionals as possible before posting here on certain topics.

Special Chemical

2010-01-22T22:12:00.009+05:30

I'm glad that my cousin returned to India from USA on leave.I met him today after one long year.He gave me a daily moisturizing lotion- Aveeno- which is fragrance free with natural colloidal oatmeal and also non-greasy.Its label showing dimethicone( ingredient), caught my eyes on it. Actually, dimethicone is nothing but polydimethylsiloxane (PDMS), belongs to a group of polymeric organo-silicon compounds which are commonly referred to as silicones.

PDMS is viscoelastic, meaning that at long flow times (or high temperatures), it acts like a viscous liquid, similar to honey...

I eagerly waited to apply this lotion on my hands and when I did, I found it better than any other lotions I used till date. But I wonder why it is made fragrance-free. Maybe for quick absorption( random thought). Anyway it is a good product and I liked it very much.

Design:Key for Engineering

2010-01-09T01:35:00.007+05:30

Well, I watched a T.V show-Doing Da Vinci-on Discovery, telecasted in India today. It was good.Actually it was about the construction of a catapult which has been designed by none other than Leonardo Da Vinci. A Leonardo man organized the whole group of a builder,carpenter et al to construct it. Here are the related videos.And I like The Vitruvian Man ,which is one of the finest works by Da Vinci based on the correlation of human proportions with geometry by the ancient Roman architect Vitruvius in Book III of his treatise De Architectura. It is a symbol of symmetry of human body. Anyway ,let me come to the main point-Engineering. According to me, Leonardo Da Vinci is the epitome of the engineer/artist.

Engineering is nothing but designing and inventing new technology with the help of scientific knowledge.And here are a few design areas in chemical engineering:
Chemical Plant Design
Chemical Process Modeling
Process Design
Process Simulation
Coming to chemical processing, you need some process simulators to simulate the material and energy balances. And here is the useful list of chemical process simulators,dynamic process simulators, design data, information and advice and Design Projects.
Related books:

Caution: Chemicals are hazardous

2010-01-08T12:38:00.004+05:30

Industrial Safety and Hazard Management is an important subject in chemical engineering. I attended a seminar last year on the same, and below are a few presentations. I read a post at my favorite blog Lamentations on Chemistry- The pitfalls of process intensification. I wanted to make you aware of the same. Occupational safety training is a basic requirement of standards, regulation and legislation. It cannot be overlooked and it cannot be short cut.You can purchase a special Health and Safety toolkit online. And here are some safety videos by the U.S chemical safety board. They may be useful to you.
Presentations:
1. Occupational Hazard and Safety Management
2. Fires & Explosions

The Golden Jubilee

2010-01-07T14:26:00.007+05:30

I read an article at The Hindu Sci Tech by Pradeep (IIT Madras), about Nanotechnology.I felt interesting and wanted to share some nanotech snippets here.

Well, let me start with Richard P.Feynman .He suggested that lifeless machines could move around in our body through the blood vessels and do surgeries, and the entire Encyclopaedia Britannica could be written on the tip of a needle. His celebrated talk, ‘There’s plenty of room at the bottom’ delivered fifty years ago (on December 29, 1959, at the annual meeting of the American Physical Society at the California Institute of Technology)envisaged the era of nanotechnology – the technology of nanometer scale objects.

Nanotechnology heralds a new revolution. Many people have become conversant with this fact. In many educational institutions, separate courses and subjects on nanotechnology have been introduced, as it has so much demand.Nanotechnology can be defined as the design,characterization,production and application of structures, devices and systems by controlling shape and size at the nanometer scale.A nanometer is one billionth of a meter.The prefix “nano-” comes from the Greek word nanos, meaning dwarf. We are now able to manipulate atoms easily through a technique which has been found dating back to 1991-The scanning tunneling microscope(STM). In 1985, a buckyball(round molecule consisting of 60 carbon atoms and also known as Buckminster fullerence), has been discovered.And since 1991, we started creating nanostructures(carbon nanotube).

TEM images of prepared mesoporous silica nanoparticles with mean outer diameter

Nanomaterials
They could be defined as those materials which have structured components with size less than 100 nm at least in one dimension.Two principle factors cause the properties of nanomaterials to differ significantly from other materials-increased relative surface area and quantum effects. They can be synthesized in many methods-Plasma arcing,chemical vapor deposition,sol-gels, electro deposition and ball milling.And they have applications in fields like:
Materials Technology-Harder metals, flexible/dense ceramics and insulators(super plastic), filters in replacement of body parts and metal-car types,unusual color paints, smart magnetic fluids, film precursors, magneto resistance spin valves, sunscreens, lipsticks, wear and scratch resistant hard coatings and lubricants.
Materials science is practiced by many companies and is intellectual offspring of conventional chemical engineering and our new nanoscale powers.
Information Technology-Quantum electronic devices, photonic crystals, efficient display devices, electron spin operated computer ships and information storage-high density data storage.

Biomedicals-Tagging of DNA and DNA chips with bio-sensitive nanoparticles, controlled drug delivery and bio-implant materials.

Energy storage-Hydrogen storage devices, improved fuel efficiency, fabrication of fuel efficiency, fabrication of ionic batteries and magnetic refrigeration.

Molecular manufacturing
Kim Eric Drexler first got this idea. He thought of using DNA to make computers. And soon expressed his ideas through his book Engines of Creation.Molecular nanotechnology describes engineered nanosystems (nanoscale machines) operating on the molecular scale.It is especially associated with the molecular assembler, a machine that can produce a desired structure or device atom-by-atom using the principles of mechanosynthesis.
more...

But we have to wait for some serious breakthrough's to take place.Robert Freitas who is a senior researcher at the nonprofit foundation Institute for Molecular Manufacturing in Palo Alto, California told one interviewer that the kind of nanomedicine he envisions is “at least 10 to 20 years away”; in a different interview he put the number at 40 years. Another nanotech expert says molecular manufacturing is 20 or 30 years away.So in the coming years, there could be many discoveries and inventions.Let us wait and see.

The History of Nanotechnology from Ken Hama on Vimeo.
More videos...
Here are a few nanotechnology blogs...

2010: The International Year of Biodiversity

2010-01-06T10:25:00.000+05:30

UN Secretary General Welcome Message for the 2010 International Year of Biodiversity from CBD on Vimeo.

The United Nations has designated 2010 the International Year of Biodiversity and International Year of Youth.

Green Technology Electric Cars

2010-01-05T22:20:00.004+05:30

A brand new car is at our doorstep. But we have to wait, and it will be out on the roads by 2011.The Twizy Z.E(Zero Emissions) concept, a new electric car from Renault has been unveiled in New Delhi recently.The blue and white two-seater works on the green technology principle.They are aimed at minimizing the impact on the environment from design stage to the point of recycling.And these vehicles are going to carry ''Renault eCO2'' label.They can easily reduce the effects of global warming, air pollution and noise pollution.Moreover, they are beautiful, and a single charge is sufficient to fill up with electricity at home or at a charging station. As you can see, below are 4 models, which are going to be available in the market from 2011 and 2012. More than 15 countries of the Renault-Nissan have already offered their support.

Eco-friendly cars have been launched in India like Reva before, and many other attempts are making their way. But, still there usage is comparably less than other emission cars, which are gaining significant growth these days. And if the green technology cars don't dominate fast, then there could be a serious threat to our environment. But, the problem with electric cars is that they require serious battery power for large distances.
Anyway, by using them, we can bring about some good change in our environment.
Here is the PDF on role of chemical engineers in green engineering.

The Software Buzz

2009-12-29T23:57:00.016+05:30

1. COCO(CAPE-OPEN to CAPE-OPEN)-It's components are:COFE - the CAPE-OPEN Flowsheet Environment,TEA- Thermodynamics for Engineering Applications,COUSCOUS - the CAPE-OPEN Unit-operations,CORN - the CAPE-OPEN Reaction Numerics package.
2. ChemSep-It's download section has the following softwares:
a.[lite.exe]-ChemSep-LITE, limited to 150 stages and 10 components with the equilibrium flash/column simulator and 194 component library.
b.[uc.exe]-Windows Units Conversion utility with dimension analysis (public domain).
3.G & P Engineering Software- Specializes in delivering high quality chemical engineering software for chemical professionals.

Molecular Modeling softwares-

For other softwares, please visit the following sites:

ChEngineer Folderland
ChemeSoft
ENGCEN

Title: Blog Header

2009-12-28T23:01:00.008+05:30

The only idea(as far as I'm concerned), what most of the non-chemical engineers have on chemical engineering is that it is only linked up with chemistry.This is a total misconception. Whomever(my friends) I met till now,except a few, after all the hi-what-where-which... they let out chemistry shrieks for my reply(Chemical Engineering). Hey you people, common sense matters so much.
Actually Chemical Engineers work in conversion of raw materials to definite products, using our physical sciences and life sciences along with the principles of mathematics.

Now, let me explain it in my own way on an industrial scale:
1. I'll start with an example- For manufacturing chemicals, RAW MATERIALS are required. This is Chemistry(it's all about elements and compounds, atoms and molecules...).
2. In order to transport the raw materials from one place to another in industries, you need some equipments like pipes, pumps, valves etc. And many Unit Operations must be conducted. Principles like Heat Transfer, Thermodynamics, fluid dynamics etc could be applicable. So this is Physics.
3.For the purpose of calculations, Mathematics is an inevitable resource:)

4.Lastly, very important products get manufactured.