Assignment 3
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School
University of Toronto *
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Course
1241
Subject
Aerospace Engineering
Date
Dec 6, 2023
Type
Pages
2
Uploaded by CorporalMoosePerson987
Energy management
Assignment 3
Due date: November 10
Q1-
The prices of petrol and electricity in some European countries are shown in the figure
below:
a)
Which one(s) of these countries are economically suited for electric vehicles? Justify
your choice(s).
b)
What other economic factors (except electricity and petrol price) should be considered to
choose a suitable market for electric vehicles?
c)
Name three important technologies that could help flourishment of electric vehicles in
near future.
d)
Mention two reasons why using electric vehicles in some countries could lead to higher
GHG emission.
Q2-
The economizer shown in figure below is designed to maintain temperature in a room. One
of economizer inlets (return air inlet) returns the air from the room, in which the temperature is
maintained
at 23 C. Another
inlet (fresh air inlet) takes the 5 C air from the outdoor. Air streams
have total flow rates of 1.2
𝑚
3/
𝑠
and 4.8
𝑚
3/
𝑠
at fresh air and return air inlets, respectively. The
mixed air finally exits from the supply air outlet at a temperature of 35
C
. As shown in the figure
below, an electric resistance heating system is used for heating up the inlet airs.
a)
Determine the amount of heat needs to be produced by the electrical heater.
b)
Assuming an Energy Efficiency Ratio of 8 BTU/Wh, determine the heater energy input
c)
Calculate the Coefficient of Performance (COP).
d)
Assuming a total pressure drop of 15 kPa in the economizer and the ductwork, calculate
the required fan power for supplying the air into the room (Fan efficiency: 80%).
e)
Explain briefly the advantage of air recovery from the room over using 100% fresh air?
Note: air density= 1.2 kg/m
3
air C
p
= 1 kJ/kg.C
Energy management
Assignment 3
Due date: November 10
Q3-
Assume the heat needed for heating up the inlet air in question 3 is provided using a hot
water line (heat exchanger) fed by a boiler instead of the electrical heater. The heat exchanger
inlet and outlet temperature difference is 12 C and the efficiency of the heat transfer from the
water to the air is 90%. Calculate the hot water flowrate.
Note: Water density= 1000 kg/m
3
Water C
p
= 4.2 kJ/kg.C
Q4-
The image below shows the plan view of a round metal ductwork supplying air from a fan
coil unit to 4 air terminals. The flowrate for each section is shown in the image. Assuming a
friction rate of 0.1inch water/100 ft ductwork, determine the duct size for each section.
Hint: for ducting the size you can use
https://www.oceanhvac.com/ductulator/
website (in the
case you are using this website, consider a TEL of 100 ft) , or any other online ductulator website
or software. You just need to enter the friction rate and the CFM to find the appropriate round
duct size.
Supply Air
Return Air
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