THERMODYNAMIC ANALYSIS OFALTERNATIVE MARINE FUELS FOR MARINE GAS TURINE POWER PLANTS

2. COMMONLY USED MARINE
FUELS
 Marine Diesel Oil (MDO)
 Residual Fuel Oil (heavy fuel oil)
 Intermediate Fuel Oil (MDO + HFO)
 Low Sulphur Marine Gas Oil (MDO+low
sulfur diesel )

3. EMISSION
REGULATIONS
 MARPOL Convention treaty
 Maximum sulfur content in fuel used on
onboard ships – 3.5% as of january
2012
 By 2020 sulfur content should not
exceed 0.5%

4. WHY ALTERNATIVE MARINE
FUELS
 High Cost of installation,operation and
maintenance of NOx and SOx reduction
treatment device
 High Cost of low sulfur fuels
 Need of dual fossil fuel systems

5. ALTERNATIVE MARINE
FUELS
 Natural Gas
 Propane
 Hydrogen

6. Fuel Symbol Calorific value
/(kJ·kg−1)
Stoichiometric air
fuel ratio
Max. excess air
factor
Diesel C12H26 42 800 15.14 3.11
Natural gas CH4 50 000 17.39 3.13
Hydrogen H2 120 000 34.78 4.03
PROPERTIES OF DIESEL, NATURAL GAS,
AND HYDROGEN FUELS

7. MARINE GAS TURBINE
ENGINES

8. COMPARISON OF GAS TURBINE
PERFORMANCE PARAMETERS USING
ALTERNATIVE FUELS
 Comparison of gas turbine performance
using diesel, natural gas, and hydrogen
fuels was made assuming constant
power output.
 Comparison is based on LM2500
MARINE GAS TURBINE MODEL

9. CYCLE EFFICIENCY
 The gas turbine performance is limited
by the predominating ambient
temperature of inlet air
 Power output is inversely proportional to
the ambient temperature of inlet air
 Study determined that both gaseous
fuels provide a lower efficiency than the
original case of diesel for the same
power output

10. CYCLE EFFICIENCY OF
DIFFERENT FUELS

11. SPECIFIC FUEL
CONSUMPTION
 The higher calorific value of both natural
gas and hydrogen compared to that of
diesel reduces the quantity of fuel
required to give the same heat output
 Specific fuel consumption for natural gas
and hydrogen is lower than that of diesel
 Advantage could not be realised
because of the lower density of these
two fuels compared to diesel

12. Specific fuel consumption
comparison as a function of inlet
air temperature for different fuels

13. SPECIFIC FUEL CONSUMPTION
COMPARISON AS A FUNCTION OF
COMPRESSION RATIO FOR
DIFFERENT FUELS

14.  Specific fuel consumption of the three
fuels increases with an increase in the
inlet air temperature
 The fuel consumption rates decrease
with an increase in the compression
ratio.

15. PEAK TEMPERATURE
 Hydrogen and natural gas were
controlled to avoid obtaining higher
combustion temperatures than diesel to
avoid increase in turbine blade cooling
 Peak temperatures obtained for the
natural gas and hydrogen are lower than
that obtained for diesel

16. Comparison of maximum
cycle temperatures for
various fuels at different inlet
air temperatures

17. Comparison of maximum
cycle temperatures for
various fuels at different
compression ratios

18. EXHAUST TEMPERATURE
 main parameters affecting gas turbine
exhaust temperatures are inlet air
temperature and the compression ratio
 The temperature of exhaust gases
increases with an increase in the inlet air
temperature
 the exhaust gas temperature decreases
as the compression ratio increases in
relation to increased rates of inlet air
mass flow

19. Exhaust temperatures as a function of
inlet air temperature: comparison of
different fuels

20. Exhaust temperatures as a
function of compression ratio:
comparison of different fuels

21. WORK RATIO
 The work ratio is the ratio between the
useful work developed inside the engine
and the total work developed
 Due to the lower efficiency of gaseous
fuels, the work ratio of the fuels also
appears inferior to that of diesel
 The work ratio decreases in line with an
increase in the compression ratio for the
three fuels

22. Work ratio as a function of
inlet air temperature:
comparison of different fuels

23. Work ratio as a function of
compression ratio:
comparison of different fuels

24.  The compressor inlet temperature and
the intake air density dictate the
mechanical work required by the
compression process
 The quantity of fuel used in obtaining the
necessary temperature at the gas
turbine inlet

25. AIR MASS FLOW RATE
 The gas turbine output power is directly
proportional and limited by the air mass
flow rate
 The mass flow rate of air is dependent on
the temperature and relative humidity of
the ambient air
 The air flow rates for natural gas and
hydrogen fuels are higher than that of
diesel, because of the higher stoichiometric
air to fuel ratio for gaseous fuels than that
of diesel fuel

26.  In gaseous fuel engines a greater
amount of air is used to keep the
temperature in a reasonable range, and
thus part of the heat generated by fuel
combustion is lost to enable a decrease
in maximum temperature.

27. Air flow rates versus inlet air
temperature for different
fuels

28. Exhaust mass flow rate
 For natural gas and hydrogen, the
exhaust mass flow rate is also
increased, although by a smaller
percentage compared to the diesel
 This smaller increase is due to the lower
fuel flow rates for both the gaseous fuels

29. Exhaust flow rates versus
inlet air temperature for
different fuels

30. EXHAUST FLOW RATES VERSUS
COMPRESSION RATIO FOR
DIFFERENT FUELS

31.  This study shown that gaseous fuels
deliver a good performance compared to
diesel fuel, and that natural gas is the
currently the best choice of hydrocarbon
to replace diesel fuel as it can be
supplied at a relatively low price and is
highly availabile

32. why alternative is better
 liquid fuels, which are currently used with
marine gas turbines, are associated with a
number of environmental and economic
issues
 natural gas and hydrogen fuels can
overcoming the difficulties associated with
current marine liquid fuels.
 the thermodynamic performance of natural
gas is found to be close to that of diesel oil,
and its maximum cycle temperature is
1474 K, which is close to that of diesel fuel
(1485 K).

33.  gas turbine thermal efficiency was found
to be 1% less in the case of hydrogen
compared to diesel, with a maximum
cycle temperature of 1445 k
 gaseous fuels deliver good
performances compared to diesel fuel,
but to achieve such performances the
engine compressor and turbines need to
be modified to accommodate differing
flow rates

34.  fossil fuel reserves will ultimately be
exhausted, particularly with the increasing
global energy demand
 hydrogen could eventually be introduced to
replace fossil fuels once the problems
associated with its application are solved, such
as the cost of its production and its storage
onboard vessels.
 hydrogen fuel could be considered as an
alternative new fuel for marine gas turbines in
the long term, but in the short term natural gas
represents a positive solution for marine
applications.

35. REFERENCE
 Aviation GE, 2015. LM2500 datasheet.
General Electric.
 Brown D, Holtbecker R, 2007. New ferry
concepts reduce costs and emissions.
Wartsila¨ Tech
 Canova A, Chicco G, Genon G, Mancarella
P, 2008. Emission characterization and
evaluation of natural gas fuelled
cogeneration microturbines and internal
combustion engines