Intersecting V-shaped channels are closed by plugs to thereby define a continuous cooling channel inside the body.

Cooling systems: Once-through cooling systems with cooling towers use large quantities of water and can be replaced by closed circuit cooling systems.

The heat dissipating lighting system includes a closed-loop coolant path with a warmed fluid channel and a cooled fluid channel.

The open water column is closed; this is comparable to a sealed heating or cooling system.

The problem solved by the invention is how to operate a closed circuit refrigeration or cooling system without using mechanical compressors for the fluid refrigerant.

Cooling systems in closed or semi-open circuit are becoming the rule, thus limiting the potential sources of water pollution.