Chapter Oz -
Gas Power Cycles
. I intro to
2
gas power cycles
gas cycles use a
gaseous working fluid throughout the entire cycle . They a re
often called and the
thermodynamic cycles they operate
engines ,
are on
called power cycles.
liquid fuel is added
,
however we assume that only gaseous working
fluid exists in the engine cycle
in open
thermodynamic cycles ,
the
working fluid is renewed at the end of
each cycle instead of
being recirculated .
the
cylinder is open system during
intake and exhaust , but the
·
an
thermodynamic cycle is an open cycle
in closed thermodynamic cycles ,
the working fluid is returned to the initial
state at the end of the and is recirculated .
cycle
internal combustion (ICE) burn fuel within the system boudaries
engines .
external combustion heat supplied to the
working fluid from
engines use an
external source .
. 2
2 -
Basic Considerations
ideal all internal
an
simplified model created by removing
cycle is a
irreversibilities and complexeties . It closely resembles the actual
cycle ,
but consists entirely of
internally reversible processes .
Pe Yactual <Mideal (Mcarnot
real
⑫ &
· if Th increases
will increase
,
,
along
or Th decreases
with Mideal and Real
, Year not
, ideal
cycle assumptions :
I no friction or viscous effects and
resulting pressure drop
.
z
quasi-equilibrium expansion and compression (spatially uniform (
3. well insulated components with negligible heat transfer
The fluid which circulates
working is air in a closed loop and behaves as
ideal with constant specific heat
an
gas .
air is 179 % Ne Cp & C
Tang <, 20
.
Mair
Mfuel
The combustion is replaced by a heat addition process from a n external
The exhaust a heat the
source . replaced by is
rejection
process so working
fluid returns to initial state .
clearance volume
TDC TDC TDC
2
Stroke
B
C
13DC 13DC
bore
displacement
.
I I
volume
T DC - top dead center
BDC - bottom dead center
r = Vmax =
VBD = Vaisplacement + V clearance compression
Amin VTDC ratio
Vclearance
Whet = MEP (Apiston Stroke)
*
= MEP
displace
P
3
mean effective
pressure (MEP) = Whet
Vmax-Vmin
= Wnet
Umax-Umin
ii
nep-1/////
Urin & max
Gas Power Cycles
. I intro to
2
gas power cycles
gas cycles use a
gaseous working fluid throughout the entire cycle . They a re
often called and the
thermodynamic cycles they operate
engines ,
are on
called power cycles.
liquid fuel is added
,
however we assume that only gaseous working
fluid exists in the engine cycle
in open
thermodynamic cycles ,
the
working fluid is renewed at the end of
each cycle instead of
being recirculated .
the
cylinder is open system during
intake and exhaust , but the
·
an
thermodynamic cycle is an open cycle
in closed thermodynamic cycles ,
the working fluid is returned to the initial
state at the end of the and is recirculated .
cycle
internal combustion (ICE) burn fuel within the system boudaries
engines .
external combustion heat supplied to the
working fluid from
engines use an
external source .
. 2
2 -
Basic Considerations
ideal all internal
an
simplified model created by removing
cycle is a
irreversibilities and complexeties . It closely resembles the actual
cycle ,
but consists entirely of
internally reversible processes .
Pe Yactual <Mideal (Mcarnot
real
⑫ &
· if Th increases
will increase
,
,
along
or Th decreases
with Mideal and Real
, Year not
, ideal
cycle assumptions :
I no friction or viscous effects and
resulting pressure drop
.
z
quasi-equilibrium expansion and compression (spatially uniform (
3. well insulated components with negligible heat transfer
The fluid which circulates
working is air in a closed loop and behaves as
ideal with constant specific heat
an
gas .
air is 179 % Ne Cp & C
Tang <, 20
.
Mair
Mfuel
The combustion is replaced by a heat addition process from a n external
The exhaust a heat the
source . replaced by is
rejection
process so working
fluid returns to initial state .
clearance volume
TDC TDC TDC
2
Stroke
B
C
13DC 13DC
bore
displacement
.
I I
volume
T DC - top dead center
BDC - bottom dead center
r = Vmax =
VBD = Vaisplacement + V clearance compression
Amin VTDC ratio
Vclearance
Whet = MEP (Apiston Stroke)
*
= MEP
displace
P
3
mean effective
pressure (MEP) = Whet
Vmax-Vmin
= Wnet
Umax-Umin
ii
nep-1/////
Urin & max
