本論文針對船舶冷卻水系統之海水冷卻泵採用變頻控制進行節能效益的評估。由於船舶冷卻水系統的耗電量一般來說約佔整艘船舶的三分之一，因而為了維持獲利，船東們無不積極尋找降低燃油消耗的方法。傳統上，船舶冷卻水系統的設計條件為主輔機皆為全載情況下，且海水進水溫度以32°C為基準，以使中央冷卻器淡水出水溫度能維持在36°C。因此，當主機熱負載改變或是海水溫度產生變化時，部分冷卻淡水於流入冷卻器之前就會流經旁通。是故，藉由降低海水流量將可大幅降低船舶冷卻水系統所需的耗電量。本文擬建構一小型船舶冷卻水系統以檢視海水冷卻泵投入變頻器之可行性並確認其節能效益。此外，文中也將探討海水冷卻泵的控制策略以找出適合本文所提小型船舶冷卻水系統之海水泵控制的方法。最後，本文將根據某艘8000 TEU貨櫃船之營運模式與航行路線來評估裝設變頻器至該船冷卻水系統之投資回收年限。

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.

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