Abstract
As dominant synthetic refrigerants are increasingly regulated, natural refrigerants have been resurrected as
working fluids. Like all other sectors, the cruise industry must adapt to reduce GHG emissions. More emphasis
has been given to natural working fluids, such as water, ammonia, hydrocarbons, and carbon dioxide, than new
synthetic refrigerants. Among the natural refrigerants, CO2 refrigerant is the only non-toxic and non-flammable
and offers compact units suited for cruise ships. Cruise ships utilise refrigeration systems for air-conditioning
and to preserve provision. The performance of two CO2 refrigeration systems employed for air conditioning
and provision chilling and freezing aboard a medium-sized cruise ship is simulated. Furthermore, how cold
thermal energy storage (CTES) can be utilised to supply the cooling demand of a two-hour port stay has been
investigated. Three reference cases with different boundary conditions are defined and referred to as warm-,
medium, and cold cases. Respectively for the cases, it has been found that the maximum cooling COP of an
AC system is about 2.89, 4.19, and 5.99. Furthermore, for the provision system, it is 2.33, 2.98, and 3.54,
respectively. Lastly, the CTES must contain 21163 kg of water as phase change material and a total volume of
38.0 m3
Keywords: Refrigeration, Carbon Dioxide, Transcritical, cruise ships, Thermal Energy Storage, Ejectors,
Energy Efficiency.
working fluids. Like all other sectors, the cruise industry must adapt to reduce GHG emissions. More emphasis
has been given to natural working fluids, such as water, ammonia, hydrocarbons, and carbon dioxide, than new
synthetic refrigerants. Among the natural refrigerants, CO2 refrigerant is the only non-toxic and non-flammable
and offers compact units suited for cruise ships. Cruise ships utilise refrigeration systems for air-conditioning
and to preserve provision. The performance of two CO2 refrigeration systems employed for air conditioning
and provision chilling and freezing aboard a medium-sized cruise ship is simulated. Furthermore, how cold
thermal energy storage (CTES) can be utilised to supply the cooling demand of a two-hour port stay has been
investigated. Three reference cases with different boundary conditions are defined and referred to as warm-,
medium, and cold cases. Respectively for the cases, it has been found that the maximum cooling COP of an
AC system is about 2.89, 4.19, and 5.99. Furthermore, for the provision system, it is 2.33, 2.98, and 3.54,
respectively. Lastly, the CTES must contain 21163 kg of water as phase change material and a total volume of
38.0 m3
Keywords: Refrigeration, Carbon Dioxide, Transcritical, cruise ships, Thermal Energy Storage, Ejectors,
Energy Efficiency.