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The First Law of Thermodynamics

Happy New Week.

The week's topics: UPDATED!!
First Law of Thermodynamics:
- the first law as it relates to the universe;
- revision of heat, work, the thermodynamic potentials (U, H, A, G); and
- the 1st Law and its application to Open Systems


"Thermodynamics is a branch of physics which deals with the energy and work of a system.
Thermodynamics deals only with the large scale response of a system which we can observe and measure in experiments. Small scale gas interactions are described by the kinetic theory of gases.
There are three principal laws of thermodynamics which lead to the definition of thermodynamic properties which help us to understand and predict the operation of a physical system." (NASA).

“The first law of thermodynamics is the application of the conservation of energy principle to heat and thermodynamic processes.” (All energy in the universe is accounted for). “The laws of thermodynamics are special laws upon which the other [natural] laws depend” (Physica…

Thermo Solved Questions

QUESTION 1- Constant Volume Heat Addition
(from www.msubbu.com)
A 28 liter rigid enclosure contains air at 140 kPa and 20oC. Heat is added to the container until the pressure reaches 345 kPa. Calculate the heat added.

SOLUTION:
Given: V = 28L= 0.028m (1L = 1dm3; 10dm = 1m so (10dm)3 = (1m)3)
P1 = 140 KPa
T1 = 20oC = 293K
P2 = 345KPa
∆Q = ?

From the 1st Law of Thermodynamics,
∆Q = ∆U + W

Introducing the reversible work terms,
∆Q = ∆U + P∆V

But at constant volume, P∆V = 0
So ∆Q = ∆U
And ∆Q = ∆U = mCp∆T

But what is m? Cp?

-m can be gotten from the formula PV = nRT, where n = m/M (mass/molecular mass)
m = nM, and n = PV/RT = (140 x 0.028)/(8.314 x 293)
n = 1.609 x 10^-3, and M air = 29, so m = 1.609 x 10^-3 x 29 = 0.0467kg

Good. Now,
-Cv is used, not Cp, because we are dealing wit constant volume here.
Cv air at 20C = 0.718KJ/KgC
Also, at constant V, P ∞ T

So P1/T1 = P2/T2 and T2 = 722K
and ∆Q = ∆U…

Undstanding Thermodynamics

Knowledge of today’s Thermodynamic principles came little by little to our ancestors . As time went on, they made educated guesses based on experiments; sometimes they were spot-on, other times they were wrong. According to MIT, “...Our predecessors faced problems and situations that they couldn't explain with existing principles in Physics and Mathematics. Consequently, they proceeded to create new theories and 'laws' verifying their hypotheses with experiments...”
The Historical Progression of Classical Thermodynamics:
The Preclassical Era (1600 - 1840)
People like Galileo, Black and Count Rumford developed Physics mainly, focusing on experiments. Towards the ending of this era, however, Joule and Carnot proposed the Work and Heat Concepts , leading to the next era---
The Classical Era (1840 – 1900)
Scientists like Maxwell, Clausius, Lord Kelvin and Boltzmann studied and further developed Physics, Mathematics and Mechanical Engineering, focusing on laws and postulates.
Gibbs…

1st Law of Thermo

SOME DEFINITIONS

SYSTEM: Region being considered, usually enclosed in a boundary

SURROUNDING: Region that is not under consideration

BOUNDARY: Demarcation between system and surrounding

MATTER: Anything at all, that has weight and occupies space

ENERGY: The ability to do work. Heat energy is usually implied in Chem. Eng

WORK: Product of the force applied and resulting distance moved

State of a System: The state of a system can be identified by property values (eg. pressure, temperature) required to reproduce the system.

Path of a System: Refers to the steps taken to reach certain property values

Simple Systems: Are devoid of any internal adiabatic, rigid, impermeable boundaries; no external force fields or internal forces. A simple system can be single or multi-phase.

Composite Systems: Are two or more simple systems

Open Systems: Allow matter, energy …

An Innovation 360 Experience-- 1st Hand Info

The Innovation 360° competition has come and gone, and speaking as one who had the privilege of participating in the competition, I say it was wonderful.
In case you were living under a rock during the entire duration of the British Council –sponsored competition, I have said a little bit about it in an earlier post—just click the link at the right or better yet, scroll down.
Okay, so I have neglected this blog for quite some time, so in the spirit of revival, I will quickly highlight a few things that I gained during the competition:

>>> Congratulations to the British Council on its 75th Anniversary—people celebrate birthdays all the time, with food, drink and general merry-making, but I see that it is even more admirable to give back to society while you are at it. The BC sponsored the six winners with UK Masters’ scholarships worth N3.5Million, as well as Virgin Atlantic plane tickets to and fro and monthly upkeep allowances… lucky fellas and chica menn! Well they all deserve…

British Council's INNOVATION 360 Graduate Programme

The competition, Innovation 360 degrees, is targeted at young Nigerians who are university graduates. The process will be online and the final five winners get a full master's degree scholarship to a university in the United Kingdom.

"The competition is designed for exceptional people," said Omotola Oyebanjo, Communications Team Leader of the Council. "We are looking for young Nigerians who can take advantage of their intelligence and win scholarships to the UK. Every two weeks, we will put a task online and in the newspapers, and ask young Nigerians to solve them." Starting from September 14, and running through November 21, the programme will list out specific tasks for contestants to solve. Any candidate, who succeeds in solving a task, at any time during the programme, is deemed to qualify for the final draw which entails an interview with a panel of judges. The competition is open to anyone who holds a university degree.

Tomi Soyinka, the Business Partnershi…

PTDF selection process

The selection for the MSc PTDF OSS is an annual process. The whole process from application through to selection is administered and managed by the PTDF, so please check the PTDF website for information on application form availability.

How the Application is Advertised
The PTDF places an advert in the national press in Nigeria announcing the next round of applications for the Overseas Scholarship Scheme. This is for both MSc and PhD programmes. Please check the website and at www.ptdf.gov.ng for information regarding the release of the application forms. The advert will inform you of all relevant details of where, in each Nigerian state, application forms can be obtained.

The Selection Process
This is the first step in the application procedure. From the applications received a selected number will be invited to sit an exam. On the basis of the results of the exam the final selection will be made. The list of successful candidates for the scholarship will be published on the PTDF websi…

2003/2004 PTDF QUESTIONS

These were the questions asked in the 2003/2004 year and we will be working on finding some more questions (source: nairasource.com). )3/04 seems to be the only year in circulation though :-

DVT:2003/2004
PART 1
ANSWER ALL QUESTIONS
TIME 25 MINUTES

1. WHICH OF THE FOLLOWING IS LEAST AFFECTED BY THE BUSINESS CYCLE?
A. AUTOMOBILE MANUFACTURE
B. FOOD PRPCESSING
C. OIL AND GAS INDUSTRY
D. SHIP BUILDING
E. IRON AND STEEL INDUSTRY

2. GROSS NATIONAL PRODUCT IS DEFINED AS:
A. TOTAL GOODS PRODUCED
B. TOTAL GOODS AND SERVICES PRODUCED
C. TOTAL GOODS AND SERVICES PRODUCED LESS TAXES
D. NET NATIONAL PRODUCT LESS DIVIDENDS
E. NET NATIONAL PRODUCT LESS INVESTMENTS

3. DURING DEFLATIONARY TIMES NIGERIAN NAIRA BUYS,
A. MORE
B. LESS
C. AN AMOUNT OF GOODS LESS TO THAT OF THE PREVIOUS YEAR
D. MORE GOODS BUT FEWER SERVICES
E. FEWER GOODS BUT MORE SERVICES

4. INSURANCE IS USED FOR ALL THE FOLLOWING EXCEPT
A. PROTECTION AGAINST LOSS
B. SAVINGS
C. PROTECT THE FAMILY IN CASE OF DEATH OF THE BREADWINNER
D. INCOME TAX REDUCTION

Experience-Based Rules of Chemical Engineering

A Chererources Article
You are about to read an award winning article which won the 2000 Beychok-Montemayor Award at The Chemical Engineers' Resource Page.

Experience is typically what turns a good engineer into a great engineer. An engineer that can look at a pipe and a flowmeter and guess the pressure drop within 5%. Someone who can at least estimate the size of a vessel without doing any calculations. When I think of such rules, two authors come to my mind, Walas and Branan. Dr. Walas' book, Chemical Process Equipment: Selection and Design has been widely used in the process industry and in chemical engineering education for years. Mr. Branan has either helped write or edit numerous books concerning this topic. Perhaps his most popular is Rules of Thumb for Chemical Engineers. Here, I'll share some of these rules with you along with some of my own. Now, be aware that these rules are for estimation and are not necessarily meant to replace rigorous calculations when such ca…