Chapter 4
Energy Analysis of Closed
systems
:
First of of
Energy
conservation
Thermodynamics
Law -
AKE
heat → Qin -
Q out
DPE
+ win Wont =
work → -
A -0
→ + Ein -
E out
energy EW
crossing changing over
boundaries time
Notation : Q inte system is ④
W done ④
work done →
by system going± is
system
on - we
E info system is ④
In closed No mass in / out but still
a
system
-
going
heat and work
One of work done is
type
-
boundary work
↳ When the
boundary moves
eg Expansion
. → work out +
Compression → work in -
, Volume
←
Wb =
fpdv
it in
boundary
work
pressure
p
• ① Expansion
④~•②
^ ^
←
•.②
④ >
v
←
sv
contraction
→
Wb -
This is
expansion
( workout)
for a
cycle :
WneE=WbouE - Wbin
Constant volume :
p
^ ①
@
" " "
rigid
"
tank isometric
②
>
✓ Wb=0
Constant pressure
:p
^
① ② " " "
"
• .
isobaric
weighted piston
"
"
piston not attached to shaft
>
v
Vi U2
Expansion -
workout
Wb= PDV
workin
compression -
Energy Analysis of Closed
systems
:
First of of
Energy
conservation
Thermodynamics
Law -
AKE
heat → Qin -
Q out
DPE
+ win Wont =
work → -
A -0
→ + Ein -
E out
energy EW
crossing changing over
boundaries time
Notation : Q inte system is ④
W done ④
work done →
by system going± is
system
on - we
E info system is ④
In closed No mass in / out but still
a
system
-
going
heat and work
One of work done is
type
-
boundary work
↳ When the
boundary moves
eg Expansion
. → work out +
Compression → work in -
, Volume
←
Wb =
fpdv
it in
boundary
work
pressure
p
• ① Expansion
④~•②
^ ^
←
•.②
④ >
v
←
sv
contraction
→
Wb -
This is
expansion
( workout)
for a
cycle :
WneE=WbouE - Wbin
Constant volume :
p
^ ①
@
" " "
rigid
"
tank isometric
②
>
✓ Wb=0
Constant pressure
:p
^
① ② " " "
"
• .
isobaric
weighted piston
"
"
piston not attached to shaft
>
v
Vi U2
Expansion -
workout
Wb= PDV
workin
compression -
