What problem can cause fluctuations in water pressure within a closed cooling water system?

Air entrained in the cooling water can significantly affect the water pressure within a closed cooling water system. When air enters the system, it creates pockets of air that can compress and expand, leading to variations in pressure readings. Additionally, these air pockets can obstruct the flow of water, disrupting the system's intended function and causing fluctuations in pressure. This inconsistency in pressure can impact the overall efficiency of heat exchange processes, which are crucial in cooling operations.

In essence, having air in the system compromises the fluid dynamics, thereby causing varying water pressure levels that might lead to operational issues.