23-05-2012, 04:36 PM
OCEAN THERMAL ENERGY CONVERSION
ocean thermal.ppt (Size: 396.5 KB / Downloads: 80)
WHAT IS OCEAN THERMAL ENERGY CONVERSION
OTEC USES THE DIFFERENCE BETWEEN COOLER DEEP AND WARMER
SHALLOW OR SURFACE OCEAN WATERS TO RUN A HEAT ENGINE
AND PRODUCE USEFUL WORK, USUALLY IN THE
FORM OF ELECTRICITY.
THE TEMPERATURE DIFFERENCE BETWEEN THE SURFACE AND
DEEP WATER IS AROUND 20 – 25 DEGREES
CLOSED CYCLE
USES FLUID WITH LOW BOILING POINT, SUCH AS AMMONIA.
WARM SURFACE SEAWATER IS PUMPED THROUGH THE HEAT
EXCHANGER TO VAPOURISE THE FLUID.
THE EXPANDING VAPOUR TURNS THE TURBO GENERATOR.
COLD WATER PUMPED THROUGH A SECOND HEAT EXCHANGER,
CONDENSES THE VAPOUR THROUGH THE LIQUID WHICH IS RECYCLED
THROUGH THE SYSTEM.
HYBRID CYCLE
COMBINES THE FEATURES OF BOTH CLOSED AND OPEN CYCLE
SYSTEM.
WARM SEAWATER ENTERS VACUUM CHAMBER AND IS FLASH
EVAPORATED, SIMILAR TO THE OPEN CYCLE EVAPORATION
PROCESS.
STEAM VAPOURISES AMMONIA OF THE CLOSED LOOP CYCLE ON THE
OTHER SIDE OF THE AMMONIA VAPOURIZER.
VAPOURISED FLUID THEN DRIVES THE TURBINE TO PRODUCE
ELECTRICITY.
TECHNICAL DIFFICULTIES
DISSOLVED GAS: AS COLD WATER RISES UP THE PIPE, IT REACHES A POINT WHERE GAS BEGINS TO EVOLVE FORMING A GAS TRAP
BEFORE THE DIRECT CONTACT OF HEAT EXCHANGERS.
MICROBIAL FOULING: HEAT TRASFER IMPAIRMENT OCCURS AS A
RESULT OF THIN WATER LAYER TRAPPED BY THE MICROBIAL
GROWTH ON THE SURFACE OF THE HEAT EXCHANGER.
SEALING: THE SYSTEM MUST BE CAREFULLY SEALED TO PREVENT INLEAKAGE OF ATMOSPHERIC AIR THAT CAN DEGRADE OR SHUT DOWN
OPERATION
ocean thermal.ppt (Size: 396.5 KB / Downloads: 80)
WHAT IS OCEAN THERMAL ENERGY CONVERSION
OTEC USES THE DIFFERENCE BETWEEN COOLER DEEP AND WARMER
SHALLOW OR SURFACE OCEAN WATERS TO RUN A HEAT ENGINE
AND PRODUCE USEFUL WORK, USUALLY IN THE
FORM OF ELECTRICITY.
THE TEMPERATURE DIFFERENCE BETWEEN THE SURFACE AND
DEEP WATER IS AROUND 20 – 25 DEGREES
CLOSED CYCLE
USES FLUID WITH LOW BOILING POINT, SUCH AS AMMONIA.
WARM SURFACE SEAWATER IS PUMPED THROUGH THE HEAT
EXCHANGER TO VAPOURISE THE FLUID.
THE EXPANDING VAPOUR TURNS THE TURBO GENERATOR.
COLD WATER PUMPED THROUGH A SECOND HEAT EXCHANGER,
CONDENSES THE VAPOUR THROUGH THE LIQUID WHICH IS RECYCLED
THROUGH THE SYSTEM.
HYBRID CYCLE
COMBINES THE FEATURES OF BOTH CLOSED AND OPEN CYCLE
SYSTEM.
WARM SEAWATER ENTERS VACUUM CHAMBER AND IS FLASH
EVAPORATED, SIMILAR TO THE OPEN CYCLE EVAPORATION
PROCESS.
STEAM VAPOURISES AMMONIA OF THE CLOSED LOOP CYCLE ON THE
OTHER SIDE OF THE AMMONIA VAPOURIZER.
VAPOURISED FLUID THEN DRIVES THE TURBINE TO PRODUCE
ELECTRICITY.
TECHNICAL DIFFICULTIES
DISSOLVED GAS: AS COLD WATER RISES UP THE PIPE, IT REACHES A POINT WHERE GAS BEGINS TO EVOLVE FORMING A GAS TRAP
BEFORE THE DIRECT CONTACT OF HEAT EXCHANGERS.
MICROBIAL FOULING: HEAT TRASFER IMPAIRMENT OCCURS AS A
RESULT OF THIN WATER LAYER TRAPPED BY THE MICROBIAL
GROWTH ON THE SURFACE OF THE HEAT EXCHANGER.
SEALING: THE SYSTEM MUST BE CAREFULLY SEALED TO PREVENT INLEAKAGE OF ATMOSPHERIC AIR THAT CAN DEGRADE OR SHUT DOWN
OPERATION