The principle of OTEC
Figure 2 shows the principle of OTEC using the closed cycle, which is one method for OTEC. The concept presented in the figure can be explained as follows.
  1. A working fluid sends a fluid consisting of liquid ammonia to an evaporator.
  2. Inside the evaporator there are many pipes or thin plates called the heating surface. Warm seawater is drawn by a warm water pump through the interior of the pipes. Ammonia fluid around the exterior of the pipes is heated and boils.
  3. The evaporated ammonia vapor enters an ammonia turbine, where the thermal energy of the ammonia vapor is converted into mechanical energy, and the ammonia turbine is rotated as the vapor flows out. At that time electrical energy is generated by a power generator linked to the turbine.
  4. Meanwhile the ammonia vapor passing through the turbine enters a condenser where it is cooled by cold seawater drawn by the cold seawater pump from a layer about 700 m deep, and becomes liquid ammonia.
  5. This liquid ammonia is again sent to the evaporator by the working fluid pump. By repeating this cycle, power can be generated without using oil, coal or uranium.
Fig. 2
The Principle of OTEC (closed cycle)

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