ENGR 102 · Ch 15. Energy (Lectures 10-16) • Vocabulary and concepts See vocabulary list Ideas related to vocabulary list • Gas law question See Assignment 24, Question 3 •

ENGR 102PROBLEM SOLVING FOR ENGINEERS

Lec

ture

# 2

5

May 5, 2020

I N T O / C S U P A R T N E R S H I P

REVIEW FOR EXAM 4

VOCABULARY, ENERGY, AND THERMODYNAMICS

www.youtube.com/watch?v=MGHZ0Ww1Rfs

Source of images: Amazon.com

10,000 HOUR RULE

2

Source: zintro.com

3So

urc

e:

zin

tro

.co

m

44

NEXT WEEK(All times are in Colorado. Qatar/Kuwait +9 hours. Korea +15 hours)

Sunday Monday Tuesday Wednesday Thursday Friday

May 5Assignment

23 noonVideo class

3:30 pm

May 6 May 7Assignment

24 noonVideo class

3:30 pm

May 8

May 10Recitation 3:30 pm

May 11Exam 4

9:40 -11:40am

55

Exam 4 – Monday, May 11

Ch 16. Thermo(Lectures 10-16)

Ch 15. Energy(Lectures 10-16)

• Vocabulary and concepts See vocabulary list Ideas related to vocabulary list

• Gas law question See Assignment 24, Question 3

• Energy conversion calculation See assignment 23, Question 3

• Thermodynamics Use 7-step process See Assignment 23, Question 4 See Assignment 24, Questions 4 & 5

Ch 7. Units and

dimensions(Lecture 9)

66

ASSIGNMENT 23 & NOTES

77

ASSIGNMENT 24 & NOTES

88

ASSIGNMENT 23(Due before noon on Tuesday, May 5)

1. Number of students in this class = __6__

2. Students with homework on time = __6__

3. Number of students with full credit = __6__

4. Students with all questions correct = __0__

99

Exam 4 – Monday, May 11

Ch 16. Thermo(Lectures 10-16)

Ch 15. Energy(Lectures 10-16)

• Vocabulary and concepts See vocabulary list Ideas related to vocabulary list

• Gas law question See Assignment 24, Question 3

• Energy conversion calculation See assignment 23, Question 3

• Thermodynamics Use 7-step process See Assignment 23, Question 4 See Assignment 24, Questions 4 & 5

Ch 7. Units and

dimensions(Lecture 9)

1010

Vocabulary on Exam 4

Words will be in questions to test your understanding, such as:

Explain when to use Carnot efficiency and when to use refrigeration efficiency when making a thermodynamicscalculation.

Give an example of a closed system that converts mechanical work to electricity.

Give an example of a process in which entropy is not produced.

When would you need to calculate using moles in this class?

Write the equation for the first law of thermodynamics.

1111

Vocabulary on Exam 4(Example of logical groupings)

Units and dimensions: Basic energy terms:

Energy, society & environment:

Forms of stored energy:

Gas law problems:

Energy conversion devices:

Solving energy equations:

Can be written as equations:

Base unitDerived unitDimensionUnit

1212

Units and dimensions:Base unitDerived unitDimensionUnit

Gas law problems:MoleAbsolute temperature

1313

Units and dimensions:Base unitDerived unitDimensionUnit

Gas law problems:MoleAbsolute temperature

1414





Gas law problems:





MoleAbsolute temperature

Alternative energyConsumptionFossil fuelGreenhouse gasHuman development indexLife expectancyRenewable energyStandard of living

1515

Energy, society & environment:Alternative energyConsumptionFossil fuelGreenhouse gas

Human development indexLife expectancyRenewable energyStandard of living

1616





Gas law problems:





EnergyEntropyMechanical workPowerThermodynamics



17

Basic energy terminology: EnergyEntropyMechanical workPowerThermodynamics

1818





Gas law problems:







Chemical energyInternal energy / HeatKinetic energyNuclear energyPotential energy


19

Forms of stored energy: Chemical energyInternal energy / HeatKinetic energyNuclear energyPotential energy

Chapter 16Assignment 9Lecture 10

2020





Gas law problems:



Can be written as equations:Conservation of energyCarnot efficiencyEfficiencyFirst law of thermodynamicsGas lawRefrigeration efficiencySecond law of thermodynamics




Chemical energyInternal energy / HeatKinetic energyNuclear energyPotential energy


Combustion engineElectric generatorElectric motorFrictionHeat pump

Absolute temperatureAccumulateClosed systemOpen system

21

Can be written as equations:Conservation of energyCarnot efficiencyEfficiencyFirst law of thermodynamicsGas lawRefrigeration efficiencySecond law of thermodynamics

Energy conversion devices:Combustion engineElectric generatorElectric motorFrictionHeat pump

Solving energy equations:Absolute temperatureAccumulateClosed systemOpen system

Chapter 16Assignment 10

Lecture 11

Chapter 16Assignments 11, 12 & 14Lectures 12-14 and 16

Videos in Assignment 23

Example:

22

Gas law: pv=nrt

First law of thermodynamics:Conservation of energy:

Σ(energy inputs) = Σ(energy outputs)

Efficiency = (useful output)/(total inputs)

Second law of thermodynamics: EntropyT2 >= EntropyT1

Carnot efficiency = 1 - TL/TH

Refrigeration efficiency = 1/(TH/TL -1)

CAN BE WRITTEN AS EQUATIONS

2323

Vocabulary on Exam 4

Words will be in questions to test your understanding, such as:

Why is absolute temperature important for thermodynamics?

Can potential energy in the world ever increase? Explain why or why not?

What base units are needed to define a kilowatt?

Explain whether the world is an open system or a closed system based on how those terms were defined in this class.

Friction converts _________________ to _________________.

What can you do to increase the Human Development Index?

24

ASSIGNMENT 23, Question 2a

25

ASSIGNMENT 23, Question 2b

Life expectancy+ Education+ Standard of living= Human development index

Having higher life expectancy doesn’t require consuming more energy.

Greater education doesn’t require consuming more energy.

In many cases, it can be possible to have a higher standard of living without consuming more energy because a lot of energy is wasted.

26

ASSIGNMENT 23, Question 2c

27

ASSIGNMENT 23, Question 2d

By the coronavirus epidemic, people are trying to stay in the home. As a result, they don't use their own cars and other transportation like bus, metro, and airplanes. So, greenhouse gas emission are getting less than normal condition.

Factories in china has shut down, there are less planes, less cars etc., all of these have a positive impact among the environment.

Because of coronavirus epidemic, people are trying not to go out as a result, they don’t use their cars and also other transportations, so greenhouse gas emissions are less than normal.

The covid-19 decreased the pollution because most of the workers stayed at home and most of the factories and industries for the countries reduced or stopped working. Which affected positively on the greenhouse gas emissions.

I think the coronavirus reduce greenhouse gas because it reduces the frequency of people go outside and using car.

Definitely we can say the air pollution. Because of the coronavirus epidemic, people are being quarantine and a lot of cars are not going on the road so the air pollution are decreasing and could be good effects to everything including greenhouse gas emissions.

28

What is meant by “greenhouse gas?”

1. What is a greenhouse?

2. What does a greenhouse gas do?

3. Which are the most important greenhouse gases?

_____ Carbon dioxide

_____ Water vapor

_____ Nitrogen

_____ Carbon

_____ Methane

1

2

3

Not a gas

N2 not problem. N2O is greenhouse gas

CSU is #1 in the USA for atmospheric science

29

kinetic energy = (0.5)(mass)(velocity)2

mass = (2)(kinetic energy)/(velocity)2

mass = (2)(625,000 kg m2/sec2)/((95,000/3,600)m/sec)2

mass = (1,250,000 kg m2/sec2)/((950/36)m/sec)2

mass = (12,500 kg)/(95/36)2

mass = 1795 kg

mass = 1800 kg (2 significant digits)

30

Diesel

engine5.4 liters

@38 MJ/liter

Work

(42%)

Qheat1

(58%)

Qin Electric

generator

Qheat2

(25%)

Electricity

(75%)

Building

Electricity = (75%)(42%)(5.4 liters)(38 MJ/liter) = 64 MJ

Heat = [(58%)+(42%)(25%)](5.4 liters)(38 MJ/liter) = 141 MJ

Note: you didn’t need the answer, only the equations.

31

7-STEP PROCESS

General process (Chapter 4.4):Problems other than material balance

1. Problem statementWhat to calculate?

2. DiagramInclude all variables and values

3. TheoryAll equations

4. AssumptionsInformation to simplify calculation

5. Calculation stepsDetail so others can follow and to ensure that there are no errors

6. ResultsRight units and significant digits

7. Discussions/conclusionWhat did we learn?How can we use this?What are next steps?

3232

NEXT WEEK(All times are in Colorado. Qatar/Kuwait +9 hours. Korea +15 hours)

Sunday Monday Tuesday Wednesday Thursday Friday

May 5Assignment

23 noonVideo class

3:30 pm

May 6 May 7Assignment

24 noonVideo class

3:30 pm

May 8

May 10Recitation 3:30 pm

May 11Exam 4

9:40 -11:40am

33

Documents

ENGR 102 · Ch 15. Energy (Lectures 10-16) • Vocabulary and concepts See vocabulary list Ideas related to vocabulary list • Gas law question See Assignment 24, Question 3 •