Analysis of energy saving with variable frequency control for sea water cooling pumps on ships

Electricity consumption in ships mainly focuses on motors, particularly in the cooling water pumps of the central cooling system. The seawater cooling system in ships is normally designed to maintain the temperature of in-take seawater at 32°C when the pumps operate at full speed to reach the required flow rate nowadays. However, the seawater temperature is normally less than 32°C as a ship sails through different areas. Thus, the actual in-take seawater flow can be reduced to avoid waste of energy. Due to the trend in energy saving and carbon reduction from the shipping industry, this paper investigates the feasibility of energy-saving control for the central cooling system in ships and proposes a strategy of energy saving control. A ship central cooling system is implemented and simulated using Matlab/Simulink in this paper in order to adjust the in-take seawater flow as the seawater temperature is less than 32°C with the same cooling ability. Thus, the power consumption on seawater pumps can be reduced to reach the goal of energy saving.