Advanced LNG cryogenic energy recovery in a modern cruise ship
Ukkonen, Anniina (2018)
Ukkonen, Anniina
2018
Ympäristö- ja energiatekniikka
Teknis-luonnontieteellinen tiedekunta - Faculty of Natural Sciences
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Hyväksymispäivämäärä
2018-06-06
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201805221791
https://urn.fi/URN:NBN:fi:tty-201805221791
Tiivistelmä
Nowadays marine industry is encountering increasing demand to decrease emissions and create more energy efficient systems. Liquefied natural gas (LNG) is rather new fuel on the market replacing the old liquid bunker fuels and meeting the new emission requirements.
LNG is stored in cryogenic circumstances. It is necessary to evaporate the LNG fuel before burning it at engines. One option for the evaporation process is to transfer the external heat load from cold energy users of the ship to the LNG. The cold energy users are walk-in freezers, walk-in refrigerators, ice-rink and air conditioning cooling. The cold energy users have commonly vapor-compression cooling systems, where the cooling demand is covered by producing cooling energy from compressor systems with electricity.
In this research the target is to improve the energy efficiency of LNG cryogenic energy recovery. The energy efficiency improvement can be achieved by optimizing the system to the setup, where the electricity consumption is the least.
The research methods in this research are theoretical existing data analysis and simulation model comparison. In existing data analysis the theoretical heat transfer rates for different connection setups are analyzed. Creating simulation model of the research system enables a chance to compare the dynamic heat transfer rates in different connection setups.
The result of the simulations indicated that the most optimal setup is to deliver cooling energy from LNG firstly to the freezer and refrigerator system and thereafter to AC cooling system. The simulation model returned a result that yearly cold energy users’ energy consumption savings are 10.2 % and payback time for the system is 3 years. More research is necessary to be conducted to ensure the functional reliability of the system.
LNG is stored in cryogenic circumstances. It is necessary to evaporate the LNG fuel before burning it at engines. One option for the evaporation process is to transfer the external heat load from cold energy users of the ship to the LNG. The cold energy users are walk-in freezers, walk-in refrigerators, ice-rink and air conditioning cooling. The cold energy users have commonly vapor-compression cooling systems, where the cooling demand is covered by producing cooling energy from compressor systems with electricity.
In this research the target is to improve the energy efficiency of LNG cryogenic energy recovery. The energy efficiency improvement can be achieved by optimizing the system to the setup, where the electricity consumption is the least.
The research methods in this research are theoretical existing data analysis and simulation model comparison. In existing data analysis the theoretical heat transfer rates for different connection setups are analyzed. Creating simulation model of the research system enables a chance to compare the dynamic heat transfer rates in different connection setups.
The result of the simulations indicated that the most optimal setup is to deliver cooling energy from LNG firstly to the freezer and refrigerator system and thereafter to AC cooling system. The simulation model returned a result that yearly cold energy users’ energy consumption savings are 10.2 % and payback time for the system is 3 years. More research is necessary to be conducted to ensure the functional reliability of the system.