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Oceanic Thermal Energy Conversions

Amal MandalRoll No-08101007015

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Background Information

OTEC system is basedon the Rankine Cycle

Uses the verticaltemperature gradient

in the ocean as a heatsink/source

Mainly used inequatorial waterswhere temperaturegradient is greatest

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Closed Rankine Cycle Overview

1-2 Power in topressurize liquid tohigher pressure

2-3 Heat addition toevaporate ammonia

3-4 Work producedfrom expansionthrough turbine

4-1 Heat extractionto condense theammonia beforepump

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ClosedRankine Cycle Calculations

wpump h2 h1 P2 P1

carnot 1

TL

TH

qevaporator h3 h2

w

turbine

h

3

h

4

rankine 1

qout

qin

qcondenser h4 h1

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Pros of OTEC

Extremely benign impact on environment

No dependency on oil

Minimal maintenance costs compared to conventional

power production plants Government cannot tax OTEC plants that are off-shore.

Provide air conditioning to buildings within the OTECplant

Open cycle OTEC systems can produce desalinatedwater which is very important in third-world countries

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Cons of OTEC

Low thermal efficiency due to small temperaturegradient between heat sink and source

Available only in equatorial waters

Only moderate power outputs are available Currently this technology is not as monetarily

feasible as conventional power production plants

The manufacturing and installation of theextremely long cold water pipes is extremelytime consuming and costly.

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Problem Statement

To create and design an operating OceanicThermal Energy Conversion model that employsa closed Rankine Cycle that utilizes ammonia asthe working fluid to illustrate the viability.

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Specifications

Produce 100 Watts of power Be smaller than 8 ft. wide, 6 ft. tall, and 2 ft.

deep. Final product must be easily portable.

OTEC model must be aesthetically pleasing andallow viewers to easily understand and view theinner-workings of the Rankine Cycle utilized byOTEC systems.

Must start and stop operation using simplemechanical or electrical devices

Must not endanger the operator or anyoneviewing the OTEC presentation

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Heat Pump Conversion

One possible design idea is to convert a heatpump into a power producing Rankine Cycle

Many moderately sized Geothermal energycycles use large commercially available AC units.

Objective is to make the compressor function asa turbine/generator

Add an auxiliary pump to circulate the working

fluid throughout the cycle Very little modification is necessary to convert

heat pumps and AC units into power producingunits

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Future Design Plans

Research Heat PumpConversion

Find pump that fits mass

flow rate and pressurespecifications

Determine whether shelland tube or plate andframe heat exchanger will

be more efficient Select piping sizes based

on calculations

Find optimal size of heatexchangers for effectiveheat transfer between the

ammonia and the heatsink/sources

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Conclusion

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