Energy input to the unit for 1 h of operation 2400 Wh 2.4 kWh.
The cost to run the unit for a month for a period of 10 hours a day is calculated in the fol-
lowing manner:The coefficient of performance (COP) is calculated from Equation (13.21):
Note the relationship between the EER and COP:
13.6 Energy Sources, Generation, Consumption
As we have been emphasizing throughout this book, there are certain concepts that every engi-
neer regardless of his or her area of specialization should know. In this chapter, we discussed the
importance of energy and power in engineering analysis and in our everyday life. We stressed the
fact that we need energy to build structures, make goods, move or lift things, cultivate and pro-
cess food, and heat or cool buildings. So whether you are planning to be a civil engineer, mechan-
ical engineer, or electrical engineer, you need to have a firm grasp of how we quantify the amount
of energy we need to address our needs. It is also equally important for every engineer to know
about energy sources, generation, and consumptions rates. This is especially true during this
period in our history where the world’s growing demand for energy is among one of the most
difficult challenges that we face. As future engineers, you are faced with two problems, energy
sources and emissions; the solutions to these problems require innovative approaches. The energy
use per capita in the world has been increasing steadily as the economies of the world grow. Add
to these concerns, the expected rise in the population of the world from the current 6.5 billion
to about 9 billion people by mid-century. We are counting on you to address these concernsCOP
EER
3.412
10
3.412
2.9
COP
heat removal from the evaporator
energy input to the compressor
24,000 Btu
1 2400 Wh2a
3.412 Btu
1 Wh
b
2.9
cost to operate the unita
2.4 kWh
1 h
ba
10 h
day
ba
$0.12
kWh
b130 days 2 $86.40
10
24,000 1 Btu 2
energy input to the compressor 1 Wh 2
EER
heat removal from the evaporator 1 Btu 2
energy input to the compressor 1 Wh 2
13.6 Energy Sources, Generation, Consumption 393
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