TEST BANK FOR Energy Management 5th Edition International Version By Klaus Dieter E. Pawlik

Solutions Manual
for
Guide to Energy Management,
Fifth Edition
Klaus-Dieter E. Pawlik
v
Table of Contents
Chapter 1: Introduction to Energy Management .................................. 1
Chapter 2: The Energy Audit Process: An Overview ........................ 15
Chapter 3: Understanding Energy Bill .................................................. 21
Chapter 4: Economic Analysis and Life Cycle Costing ..................... 37
Chapter 5: Lighting ................................................................................... 53
Chapter 6: Heating, Ventilating, and Air Conditioning .................... 69
Chapter 7: Combustion Processes and the
Use of Industrial Wastes ...................................................... 83
Chapter 8: Steam Generation and Distribution ................................. 103
Chapter 9: Control Systems and Computers ......................................111
Chapter 10: Maintenance ......................................................................... 119
Chapter 11: Insulation .............................................................................. 127
Chapter 12: Process Energy Management ............................................ 141
Chapter 13: Renewable Energy Sources and Water ........................... 149
Management Supplemental ......................................................................... 159
Introduction to Energy Management 1
1
Chapter 1
Introduction to Energy Management
Problem: For your university or organization, list some energy management
projects that might be good “fi rst ones,” or early
selections.
Solution: Early projects should have a rapid payback, a high probability
of success, and few negative consequences (increasing/
decreasing the air-conditioning/heat, or reducing
lighting levels).
Examples:
Switching to a more effi cient light source (especially
in conditioned areas where one not only saves with
the reduced power consumption of the lamps but also
from reduced refrigeration or air-conditioning load).
Repairing steam leaks. Small steam leaks become large
leaks over time.
Insulating hot fl uid pipes and tanks.
Install high effi ciency motors.
And many more
2 Solutions Manual for Guide to Energy Management
Problem: Again for your university or organization, assume you are
starting a program and are defi ning goals. What are some
potential fi rst-year goals?
Solution: Goals should be tough but achievable, measurable, and
specifi c.
Examples:
Total energy per unit of production will drop by 10
percent for the fi rst and an additional 5 percent the
second.
Within 2 years all energy consumers of 5 million British
thermal units per hour (Btuh) or larger will be separately
metered for monitoring purposes.
Each plant in the division will have an active energy
management program by the end of the fi rst year.
All plants will have contingency plans for gas curtailments
of varying duration by the end of the fi rst
year.
All boilers of 50,000 lbm/hour or larger will be examined
for waste heat recovery potential the fi rst year.
Introduction to Energy Management 3
Problem: Perform the following energy conversions and calculations:
a) A spherical balloon with a diameter of ten feet is fi lled
with natural gas. How much energy is contained in
that quantity of natural gas?
b) How many Btu are in 200 therms of natural gas? How
many Btu in 500 gallons of 92 fuel oil?
c) An oil tanker is carrying 20,000 barrels of #2 fuel oil.
If each gallon of fuel oil will generate 550 kWh of
electric energy in a power plant, how many kWh can
be generated from the oil in the tanker?
d) How much coal is required at a power plant with a
heat rate of 10,000 Btu/kWh to run a 6 kW electric
resistance heater constantly for 1 week (16 8 hours)?
e) A large city has a population which is served by a
single electric utility which burns coal to generate
electrical energy. If there are 500,000 utility customers
using an average of 12,000 kWh per year, how many
tons of coal must be burned in the power plants if the
heat rate is 10,500 Btu/kWh?
f) Consider an electric heater with a 4,500 watt heating
element. Assuming that the water heater is 98% effi -
cient, how long will it take to heat 50 gallons of water
from 70 degree F to 140 degree F?
4 Solutions Manual for Guide to Energy Management
Solution:
a) V = 4/3 (PI) P
= 4/3 × 3.14 × 53
523.33 ft3
E = V × 1,000 Btu/cubic foot of natural gas
= 523.33 ft3 X 1,000 Btu/ft3
= 523,333 Btu
b) E = 200 therms × 100, 000 Btu/therm of natural gas
= 20,000,000 Btu
E = 500 gallons × 140,000 Btu/gallon of #2 fuel oil
70,000,000 Btu
c) E = 20,000 barrels × 42 gal./barrel × 550 kWh/gal.
4.6E+08 kWh
d) V = 10,000 Btu/kWh × 6 kW × 168 h/25,000,000
Btu/ton coal
= 0.40 tons of coal
e) V = 500,000 cus. × 12,000 kWh/cus. × 10,500
Btu/kWh × I ton/25,000,000 Btu
= 2,520,000 tons of coal
f) E = 50 gal. × 8.34 lbm/gal. × (140F - 70F) ×
1 Btu/F/lbm
= 29,190 Btu
= 29,190 Btu/3,412 Btu/kWh
= 8.56 kWh
= 8.56 kWh/4.5 kW/0.98
= 1.94 h
Introduction to Energy Management 5
Problem: If you were a member of the upper level management in
charge of implementing an energy management program
at your university or organization, what actions would you
take to reward participating individuals and to reinforce
commitment to energy management?
Solution: The following actions should be taken to reward individuals
and reinforce commitment to energy management:
Develop goals and a way of tracking their progress.
Develop an energy accounting system with a performance
measure such as Btu/sq. ft or Btu/unit.
Assign energy costs to a cost center, profi t center, an
investment center or some other department that has
an individual responsibility for cost or profi t.
Reward (with a monetary bonus) all employees who
control cost or profi t relative to the level of cost or
profi t. At the risk of being repetitive, note that the level
of cost or profi t should include energy costs.
6 Solutions Manual for Guide to Energy Management
Problem: A person takes a shower for ten minutes. The water fl ow
rate is three gallons per minute, the temperature of the
shower water is 110 degrees E Assuming that cold water
is at 65 degrees F, and that hot water from a 70% effi cient
gas water heater is at 140 degrees F, how many cubic feet
of natural gas does it take to provide the hot water for the
shower?
Solution: E = 10 min × 3 gal./min × 8.34 lbm/gal ×
(110 F - 65 F) × 1 Btu/lbm/F
= 11,259 Btu
V = 11,259 Btu × 1 cubic foot/1,000 Btu/0.70
= 16.08 cubic feet of natural gas
Introduction to Energy Management 7
Problem: An offi ce building uses 1 Million kWh of electric energy
and 3,000 gallons of #2 fuel oil per year. The building has
45,000 square feet of conditioned space. Determine the
Energy Use Index (EUI) and compare it to the average EUI
of an offi ce building.
Solution: E(elect.) = 1,000,000 kWh/yr. × 3,412 Btu/kWh
= 3,412,000,000 Btu/yr.
E(#2 fuel) = 3,000 gal./yr. × 140,000 Btu/gal.
= 420,000,000 Btu/yr.
E = 3,832,000,000 Btu/yr.
EUI = 3,832,000,000 Btu/yr./45,000 sq. ft
= 85,156 Btu/sq. ft/yr. which is
less than the average offi ce building
8 Solutions Manual for Guide to Energy Management
Problem: The offi ce building in Problem 1.6 pays $65,000 a year for
electric energy and $3,300 a year for fuel oil. Determine the
Energy Cost Index (ECI) for the building and compare it
to the ECI for an average building.
Solution: ECI = ($65,000 + $3,300)/45,000 sq. ft
= $1.52/sq. ft/yr.
which is greater than the average building
Introduction to Energy Management 9
Problem: As a new energy manager, you have been asked to predict
the energy consumption for electricity for next month
(February). Assuming consumption is dependent on units
produced, that 1,000 units will be produced in February,
and that the following data are representative, determine
your estimate for February.
—————————————————————
Units Consumption Average
Given: Month produced (kWh) (kWh/unit)
—————————————————————
January 600 600 1.00
February 1,500 1,200 0.80
March 1,000 800 0.80
April 800 1,000 1.25
May 2,000 1,100 0.55
June 100 700 7.00 Vacation month
July 1,300 1,000 0.77
August 1,700 1,100 0.65
September 300 800 2.67
October 1,400 900 0.64
November 1,100 900 0.82
December 200 650 3.25 1-week shutdown
January 1,900 1,200 0.63
Solution: First, since June and December have special circumstances,
we ignore these months. We then run a regression to fi nd
the slope and intercept of the process model. We assume
that with the exception of the vacation and the shutdown
that nothing other then the number of units produced
affects the energy used. Another method of solving this
problem may assume that the weather and temperature
changes also affects the energy use.
10 Solutions Manual for Guide to Energy Management
—————————————————————————
Units Consumption Average
Month produced (kWh) (kWh/unit)
—————————————————————————
January 600 600 1.00
February 1,500 1,200 0.80
March 1,000 800 0.80
April 800 1,000 1.25
May 2,000 1,100 0.55
July 1,300 1,000 0.77
August 1,700 1,100 0.65
September 300 800 2.67
October 1,400 900 0.64
November 1,100 900 0.82
January 1,900 1,200 0.63
From the ANOVA table, we see that if this process is modeled
linearly the equation describing this is as follows:
kWh (1,000 units) = 623 + 0.28 × kWh/unit produced
= 899 kWh
2,500
2,000
1,500
1,000
500
January
Febuary
March
April
May
June
July
August
September
October
November
December
Units produced
Comsumption (kWh)
Introduction to Energy Management 11
——————————————————————————————————
Coeffi cients Standard Error t Stat P-value Lower 95% Upper 95% Lower 95. 0% Upper 95.0%
——————————————————————————————————
Intercept 623.1884058 93.46296795 6.667759 9.19E-05 411.7603222 834.616489 411.760322 834.6164893
X Variable 1 0,275362319 0.06993977 3.942772 0.003392 0,117373664 0.43335097 0.11737366 0.433350974
——————————————————————————————————
SUMMARY OUTPUT
————————————
Regression Statistics
————————————
Multiple R 0.795822426
R Square 0.633333333
Adjusted R Square 0.592592593
Standard Effort 118.6342028
Observations 11
————————————
ANOVA
——————————————————————————
df SS MS F Signifi cance F
——————————————————————————
Regression 1 218787.9788 218787.9 15.54545 0.00339167
Residual 9 126666.6667 14074.07
Total 10 345454.5455
——————————————————————————
500 1,000 1,500 2,000 2,500
•
•
•
•
•
•
•
•
•
•
•
1,400
1,200
1,000
800
600
400
200
Units produced
Energy Used (kWh)
12 Solutions Manual for Guide to Energy Management
Problem: For the same data as given in Problem 1.8, what is the
fi xed energy consumption (at zero production, how much
energy is consumed and for what is that energy used)?
Solution: By looking at the regression run for problem 1.8 (see
ANOVA table), we can see the intercept for the process in
question. This intercept is probably the best estimate of the
fi xed energy consumption:
623 kWh.
This energy is probably used for space conditioning and
security lights.
Introduction to Energy Management 13
Problem: Determine the cost of fuel switching, assuming there were
2,000 cooling degree days (CDD) and 1,000 units produced
in each year.
Given: At the Gator Products Company, fuel switching caused
an
increase in electric consumption as follows:
——————————————————————————
Actual energy
Expected consumption
energy after
consumption switching fuel
——————————————————————————
Electric/CDD 75 million Btu 80 million Btu
——————————————————————————
Electric/units of
production 100 million Btu 115 million Btu
——————————————————————————
The base year cost of electricity is $15 per million Btu,
while this year’s cost is $18 per million Btu.
Solution: Cost variance = $18/million Btu - $15/million Btu
= $3/million Btu
Increase cost due to cost variance
= Cost variance × Total Actual Energy Use
= ($3/million Btu) × ((80 million Btu/CDD) ×
(2,000 CDDs) + (115 million Btu/unit) × (1,000
units))
= $825,000
CDD electric variance
= 2,000 CDD × (80 - 75) million Btu/CDD
= 10,000 million Btu
Units electric variance
= 1,000 units × (115 - 100) million Btu/unit
= 15,000 million Btu
14 Solutions Manual for Guide to Energy Management
Increase in energy use
= CDD electric variance + Units electric variance
= 10,000 million Btu + 15,000 million Btu
= 25,000 million Btu
Increase cost due to increased energy use
= (Increase in energy use) × (Base cost of electricity)
= 25,000 billion Btu × $15/million Btu
= $375,000
Total cost of fuel switching
= Increase cost due to increased energy use
+ Increased cost due to cost variance
= $375,000 + $825,000
= $1,200,000
The Energy Audit Process: An Overview 15
15
Chapter 2
The Energy Audit Process:
An Overview
Problem: Compute the number of heating degree days (HDD) associated
with the following weather data.
Tempera- 65F -Temture
Number perature Hours
Given: Time Period (degrees F) of hours (degrees F) × dT
Midnight - 4:00 AM 20 4 45 180
4:00 AM - 7:00 AM 15 3 50 150
7:00 AM - 10:00 AM 18 3 47 141
10:00 AM - Noon 22 2 43 86
Noon - 5:00 PM 30 5 35 175
5:00 PM - 8:00 PM 25 3 40 120
8:00 PM - Midnight 21 4 44 176
———
1,028
Solution: From the added columns in the given table, we see that the
number of hours times the temperature difference from 65
degrees F is 1,028 F-hours. Therefore, the number of HDD
can be calculated as follows:
HDD = 1,028 F-hours/24 h/day
= 42.83 degree-days
16 Solutions Manual for Guide to Energy Management
Problem: Select a specifi c type of manufacturing plant and describe
the kinds of equipment that would likely be found in such a
plant.
List the audit data that would need to be collected for each
piece of equipment.
What particular safety aspects should be considered when
touring the plant?
Would any special safety equipment or protection be required?
Solution: The following equipment could be found in a wide variety
of manufacturing facilities:
Equipment Audit data
Heaters Power rating
Use characteristics (annual use, used in conjunction
with what other equipment, how is the equipment
used?)
Boilers Power rating
Use characteristics
Fuel used
Air-to-fuel ratio
Percent excess air
Air-conditioners Power rating
Chillers Effi ciency
Refrigeration Cooling capacity
Use characteristics
Motors Power rating
Effi ciency
Use characteristics
Lighting Power rating
Use characteristics
Air-compressors Power rating
Use characteristics
Effi ciency
Various air pressures
An assessment of leaks