These are systems that provide indirect cooling or heating using heat exchangers.
These are systems that are completely sealed off from the atmosphere, operate under pressure, have an internal water circulation system, and lose very little water.
In closed-loop heating and cooling systems, water is most commonly used as the heat transfer fluid.
Carbon steel, stainless steel, copper and its alloys, aluminum and its alloys, and cast materials are used to manufacture components for mechanical systems.
The advantages of closed-loop systems over open-loop systems include minimal use of makeup water, low operating costs, controllable corrosion, reduced consumption of protective chemicals, and high heating and cooling efficiency.