Oceanic Thermal Energy Conversions

1
Oceanic Thermal Energy Conversions

• Group Members
• Brooks Collins
• Kirby Little
• Chris Petys
• Craig Testa

2
Background Information

• OTEC system is based on the Rankine Cycle
• Uses the vertical temperature gradient in the
  ocean as a heat sink/source
• Mainly used in equatorial waters where
  temperature gradient is greatest

3
Closed Rankine Cycle Overview

• 1-2 Power in to pressurize liquid to higher
  pressure
• 2-3 Heat addition to evaporate ammonia
• 3-4 Work produced from expansion through turbine
• 4-1 Heat extraction to condense the ammonia
  before pump

4
ClosedRankine Cycle Calculations
5
Pros of OTEC

• Extremely benign impact on environment
• No dependency on oil
• Minimal maintenance costs compared to
  conventional power production plants
• Open cycle OTEC systems can produce desalinated
  water which is very important in third-world
  countries

6
Cons of OTEC

• Low thermal efficiency due to small temperature
  gradient between heat sink and source
• OTEC technology is only ideally suitable 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 the
  extremely long cold water pipes is extremely time
  consuming and costly.

7
Problem Statement

• To create and design an operating Oceanic
  Thermal Energy Conversion model that employs a
  closed Rankine Cycle that utilizes ammonia as the
  working fluid to illustrate the viability of OTEC
  power production.

8
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 and
  allow viewers to easily understand and view the
  inner-workings of the Rankine Cycle utilized by
  OTEC systems.
• Must start and stop operation using simple
  mechanical or electrical devices
• Must not endanger the operator or anyone viewing
  the OTEC presentation

9
Heat Pump Conversion

• One possible design idea is to convert a heat
  pump into a power producing Rankine Cycle
• Many moderately sized Geothermal energy cycles
  use large commercially available AC units.
• Objective is to make the compressor function as a
  turbine/generator
• Add an auxiliary pump to circulate and pressurize
  the working fluid throughout the cycle
• Very little modification is necessary to convert
  heat pumps and AC units into power producing units

10
Future Calendar
11
Future Design Plans

• Research Heat Pump Conversion
• Find pump that fits mass flow rate and pressure
  specifications
• Determine whether shell and tube or plate and
  frame heat exchanger will be more efficient
• Select piping sizes based on calculations

• Find optimal size of heat exchangers for
  effective heat transfer between the ammonia and
  the heat sink/sources