OCTOBER 19-20, 2012 - YMCA University of Science & Technology

Proceedings of the National Conference on
Trends and Advances in Mechanical Engineering,
YMCA University of Science & Technology, Faridabad, Haryana, Oct 19-20, 2012
∆ m )
w
= (
1
− ω1′
m a
ω (12)
where ω
1
is the humidity ratio of air after cooling, The partial pressure of water vapour can be found from the
respective relative humidity (φ ) by:
P
= φ
(13)
v
P sat
where P and
sat
P are the saturation pressures of water for the corresponding temperature. Pressure loss in the
sat
adiabatic mixing is neglected.
The enthalpy, entropy, and exergy can be determined at each state point using mass and energy balances. The
performance parameters required for the thermodynamic analysis of retrofitted systems are given below:
Thermal Efficiency (η Th ): Thermal efficiency of a thermal system is defined as the ratio of net work output
W & ) to the total heat input ( Q & ) of the fuel.
f
W&
net
=
Th
Q&
(
net
η (14)
f
Generation Efficiency (η Gen ): Generation efficiency of a thermal system is defined as the ratio of electrical
power output (W el ) to the total heat input of the fuel(Q f ).
W
el
η =
(15)
Gen
Q
f
Heat-Rate (HR in kJ/s/kW): Heat rate is defined as the ratio of heat produced by the fuel (
W &
Q&
W&
power output (
HR
el
el
) of the thermal system.
Q & ) to the electrical
f
= (16)
Specific Fuel-Consumption (SFC): Specific fuel–consumption of a thermal system is defined as the ratio of
mass of fuel to the net work output. It is reciprocal of specific net work (W spec ).
SFC
m&
W&
f
= (17)
net
First–Law Efficiency (
): The ratio of all the useful energy extracted from the system (electricity and process
heat) to the energy of fuel input is known as first-law efficiency. First-law efficiency is also known as fuel
utilization efficiency or utilization factor or energetic efficiency. By definition,
where
( W& + Q&
)
el Pr o
η =
(18)
I
Q&
f
is process heat rate.
Second–Law Efficiency (
): Since exergy is more valuable than energy according to the second law of
thermodynamics, it is useful to consider both output and input in terms of exergy. The amount of exergy supplied
in the product to the amount of exergy associated with the fuel is a more accurate measure of thermodynamic
performance of a system, which is called second-law efficiency. It is also called exergetic efficiency
(effectiveness or rational efficiency). By definition,
( W& + E&
)
el pro
η =
(19)
II
E&
f
where is the exergy content of process heat and is the exergy content of fuel input.
E &
Exergy-Destruction Rate (
DR
)-The component exergy destruction rate can be compared to the total exergy
destruction rate within the system.
E&
E&
D
E& = (20)
DR
D, tot
Results and Discussion
In the present study following configurations with retrofitting have been studied in comparison to simple gas
turbine cycle:
(i) Simple gas turbine cycle with inlet air cooling (IAC)
f
199