With a neat sketch, explain closed cycle and hybrid cycle in OTEC cycle

Closed-Cycle Ocean Thermal Energy Conversion (OTEC) System

A Closed-cycle OTEC system utilizes the temperature difference between warm surface seawater and cold deep seawater to generate electricity. The process involves a working fluid with a low boiling point, such as ammonia, which is cycled through the system to convert thermal energy into mechanical energy and then into electrical energy.

Components and Working:

1. Warm Water Intake: Surface seawater, warmed by the sun, is pumped into the heat exchanger (evaporator).
2. Heat Exchanger (Evaporator): The warm seawater heats the working fluid (e.g., ammonia) in the evaporator. The working fluid boils and turns into high-pressure vapor.
3. Turbine: The high-pressure vapor drives a turbine connected to a generator. The turbine converts the thermal energy of the vapor into mechanical energy.
4. Generator: The mechanical energy from the turbine is converted into electrical energy by the generator.
5. Condenser: Cold deep seawater is pumped into the condenser. The vaporized working fluid is condensed back into a liquid by transferring its heat to the cold seawater.
6. Pump: The liquid working fluid is pumped back to the evaporator to repeat the cycle.

Working Steps:

1. Heat Absorption: Warm surface seawater is pumped into the evaporator, where it heats and vaporizes the working fluid.
2. Energy Conversion: The vaporized working fluid expands and drives the turbine, which converts the thermal energy into mechanical energy.
3. Electricity Generation: The turbine is connected to a generator, which converts the mechanical energy into electrical energy.
4. Heat Rejection: Cold deep seawater is pumped into the condenser, where it cools and condenses the vaporized working fluid back into a liquid.
5. Cycle Continuation: The liquid working fluid is pumped back to the evaporator to continue the cycle.

OTEC Hybrid Cycle

The Hybrid OTEC cycle combines elements of both closed and open cycles to enhance energy production.

Process:

1. Vacuum Chamber: Warm sea water is pumped into a vacuum chamber where it is flashed to produce steam.
2. Heat Transfer: The steam evaporates a working fluid in a separate closed-loop cycle, causing it to vaporize.
3. Electricity Generation: The vaporized working fluid drives a turbine connected to an electrical generator, producing electricity.