Assessment of Energy Savings in the Seawater Cooling Pumps Using Variable Frequency Drives Control

• Main Authors: Zhi-WeiLiu, 劉志偉
• Other Authors: Chien-Hsing Lee
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/80822595441510847226

碩士 === 國立成功大學 === 系統及船舶機電工程學系碩博士班 === 101 === This thesis assesses potential energy savings in the cooling water circuit of a ship with the use of variable frequency drives (VFDs) for sea water pumping system control. Since a ship's cooling system typically requires roughly one third of the electrical energy on board, ship-owners are seriously looking for ways to reduce fuel consumption in order to remain profitable. The cooling water systems onboard most ships are normally designed to deal with the full workload of the main and auxiliary machines, assuming a sea water temperature of 32°C to keep a constant temperature of 36°C downstream of the central cooler. However, depending on the heat load from the engines and the temperature of sea water, some of the cooling water flow may bypass the cooler. Thus, the sea water volume can be reduced, resulting in a significant reduction of the required amount of electrical energy. This thesis examines the feasibility of adding VFDs to control the sea water pumps based on a small-scale cooling water system and to identify the potential of energy savings. In addition, the control strategies of pumps have been undertaken to decide which approach is suitable for the proposed system. Finally, the calculation of the payback period from VFDs installation on an existing 8000 TEU container ship based on the operational scenario of a representative journey is presented.