First Law of Thermodynamics

The first law of thermodynamics states that total energy of the universe is conserved i.e. energy can neither be created nor destroyed. 

For a closed system    ΔU=Q+W

for surrounding           ΔU=-Q-W

For universe               ΔU=ΔU(system) +  ΔU(surrounding) = 0

The total energy of universe is constant. It seems to be simple, but it strikes out so many impossibilities. Like the one I had in my childhood, I had a dream to build a device that will produce continuous power by rotating a wheel, which will drive a dynamo to produce electricity, part of which will be utilized to drive wheel and rest can be used for other purposes. but after studying this law I got to know, it is not possible to make such a system.  

We can't produce energy without giving it some equivalent amount of energy in another form.

Education: Base of Society

In India, competition is increasing day by day, though the development is not in that ratio. The students are working harder to get into jobs, the level of the entrance has been increased a lot, though the output is same. Like to get into PSUs or high paying companies, the candidates are preparing much harder as compared to 5-10 years ago, but the improvement in technology or innovations are not according to the efforts.
The reason behind this may be in my views:
1. The candidates do very hard work till they get the job and after getting the job their hard work slows down.
2. The students passing out from IITs and other good institutes, dont prefer to go in their core sectors. The government is expanding so much money on their education and they are earning money for other countries.
3. In India, many teachers are not interested in teaching and the students also are not interested in studying their core courses.
Many of the great technologies are taken from other countries. The students should know their interest and then get into that field.
If one gets into IAS, thats a very big achievement, but if he is a doctor or engineer, he has wasted one slot for the one who could have done great in that field.
In engineering curriculum, there should be video lectures about current technologies, quizzes to tackle the problems which occur in industries, videos about the manufacturing of products.
To choose a field, one should not think what is having more scope in society, he should think what kind of interest he has.The guidance should be available at high school to choose a suitable field. When a student chooses a field, his thoughts should revolve around his field. 

Projects in Chemical Engineering for UG

The projects which can be done using analytical methods or computer simulation/coding
1. Design of a distillation column using FUG method and rigorous calculation
2. Dynamic response and tuning of controllers for absorption column
3. Heat integration in a plant using heat exchanger network
4. Generation of electricity from falling rain water in tall buildings.
5. Design of fire fighting system for any building.

Chemical Engineering in India

Mr. Modi has a vision of Make in India. In this a Chemical engineer can play a very vital role. There are so many chemical products we use in daily life. If the products have to be made in India, there is a need of skilled chemical engineers. The power requirement is increasing day by day. To compete with energy needs, chemical engineering can provide the solution. Mr. Modi has done a great deal of nuclear fuel, and nuclear power has the potential to replace hydrocarbon fuel. So, in coming days chemical engineering can be a good option in India for those who love engineering. Where other branches have so many seats in India, chemical engineering is in only government institutes and some private institutes. So, it can be a great career option with almost every PSUs and many big companies.

Thermodynamics/Process Calculation: Partial Pressure and deviation

There are three law’s which are used to calculate pressure of a component in a mixture.

Raoult’s Law: gives the partial pressure of a component from its vapor pressure (function of temperature) by multiplying it with its mole fraction in liquid phase: p_A=x_APAv

Henry Law: gives the partial pressure of a component from its mole fraction in liquid phase multiplied by a constant (H: Henry constant) which depends on temperature and the presence of other component: p_A=x_AH_A

Dalton law: gives the partial pressure of a component from its vapor phase mole fraction multiplied by total pressure: p_A=y_AP_T

The question arises where to apply Raoult’s Law and where Henry Law. 

The difference between the two is Raoult’s law is applicable to the pure component i.e. xi close to 1, while the Henry law is applied to a very dilute component i.e. xi is close to 0.

At any concentration other than the limiting values of 0 and 1, the partial pressure of solute A will be different from the Henry Law and it shows a deviation. The positive deviation shows that the component A has more tendency to go in vapor phase. While the negative deviation shows that the component A has more tendency of being in the liquid phase.

 

Practical Problems in Chemical Engineering

1. How to find the direction of fluid flow in a very long metal pipe without disturbing its flow?
Ans: By heating its one section and check the temperature at same distance from heated point. the fluid will be flowing in higher temperature side.

2. How can we demonstrate the molecular flux, convective flux and total flux with perfume?
Ans: When the molecules of perfume diffuses by its concentration difference, then it is called molecular flux. if, a person spray it on the body and start walking, then the molecules will travel by both (total) concentration difference (molecular) and the velocity of person (convective).

3. How the hot streams like steam can be transported in pipe to long distances with consideration of thermal expansion?
Ans: The pipe should have some provisions for expansion and contraction. The pipe should have bends that can be expended or contracted.

4. Design an equipment to separate potatoes according to their size.
Ans: To separate potatoes, we can use a device with increasing width and potatoes will fall down according to their size in a collecting pan.

5. How the concrete material can be transported to a building in a pipe?
Ans: The concrete material from a mixer can be transported in a pipe with the hydraulic pressure acting upon by a piston/plunger.

6. How would you clean a pipe which is used to carry concrete material?
Ans: It is important to clean the pipe, which is used to carry concrete material otherwise the concrete material will solidify inside the pipe. to clean the pipe a ball of size fitted to pipe can be made to pass through a pipe by hydraulic force.

7. How would you construct a tunnel through a river having mud at bottom?
Ans: We can decrease the temperature of mud leads to freeze and solidify it and can construct the tunnel.

8. How the diameter of a pipe is decided for a specified flow?
Ans: For a larger diameter pipe, velocity will be less and hence the friction losses, but it will have high cost of material. On the other side, small diameter pipe will have less material cost but will offer high resistance to flow. therefore, economy will be considered for the selection of diameter of pipe.

9. How the water in a bottle (plastic) can be cooled naturally?
Ans: The water can be kept cooled by the evaporative cooling process. A cloth can be wrapped on the bottle and make it wet. as the water will evaporate, the temperature of bottle will decrease.

10. Can the air be cooled by evaporative cooling if the air and water both are at same temperature?
Ans: the air will be cooled depending on its humidity. If the humidity is less than saturation humidity, it will get cooled.

Mass Transfer: Distillation

Distillation is a very important mass transfer operation which is used to separate components based on the difference in boiling points. it is used in refineries to distill crude oil into useful petroleum products. There are two phases liquid and gases. As in distillation all the components are volatile, so all components will be there in liquid and vapour phase, but the more volatile component has lesser boiling point, so has more tendency to be in vapour phase at any temperature, compared to less volatile components. The temperature increases down the column.

At any temperature,  a component has a vapor pressure which makes it to go in vapor phase. When vapour and liquid streams at different temperatures (not in equilibrium) are brought in contact, more volatile in the liquid phase will vaporise and less volatile from the vapour phase will condense. So, vapour phase will be enriched with more volatile and liquid phase will be enriched with less volatile components.

Distillation column has two sections: extraction and enriching or stripping and rectifying. Extraction or stripping (bottom section) refers to more volatile component which gets extracted or stripped from less volatile component and get rectified or enriched (top section) at the top. 

In distillation of binary mixture let say benzene (x in liquid, yin vapor) and toluene ;
Let at any plate x = 0.3 and y = 0.6; then can benzene be transferred from the liquid to vapour phase, that means low concentration (0.3) to high concentration (0.6). the answer is difference in pressure of benzene in liquid and vapor phases.
the pressure in the liquid phase is calculated through Raoult’s law (p_A = x_AP_v) and vapor phase pressure is calculated by Dalton’s law (p_A = y_AP_T); if the pressure in liquid phase is higher, then the component will go in vapor phase increases till the pressure in vapor phase becomes equal to liquid phase pressure.