scholarly journals Thermoelectric Ocean Thermal Energy Conversion

1980 ◽  
Vol 102 (2) ◽  
pp. 119-127 ◽  
Author(s):  
M. S. Bohn ◽  
D. K. Benson ◽  
T. S. Jayadev
Keyword(s):  
Solid State ◽  
Heat Exchangers ◽  
System Performance ◽  
Working Fluid ◽  
Thermoelectric Generators ◽  
Closed Cycle ◽  
Thermal Energy Conversion ◽  
Power Modules ◽  
Ocean Thermal Energy ◽  
High Level

A novel thermoelectric OTEC concept is proposed and compared with the ammonia closed-cycle designs. The thermoelectric OTEC uses no working fluid and therefore requires no pressure vessel, working fluid pumps, or turbogenerator. These components are replaced by power modules which are heat exchangers integrated with thermoelectric generators. The thermoelectric OTEC concept offers several potential advantages including: higher reliability system performance through the use of a high level of redundancy and long-lived, solid-state thermoelectric generators with no moving parts, greater safety for crew and environment by elimination of the pressurized working fluid, and the possibility of comparable system costs, i.e., costs near $2000/kWe (net) in 1980 dollars.

Optimization of a Closed-Cycle OTEC System

1990 ◽  
Vol 112 (4) ◽  
pp. 247-256 ◽  
Author(s):  
Haruo Uehara ◽  
Yasuyuki Ikegami
Keyword(s):  
Heat Exchangers ◽  
Sea Water ◽  
Working Fluid ◽  
Turbine Efficiency ◽  
Thermal Energy Conversion ◽  
Calculation Results ◽  
Change Temperature ◽  
Ocean Thermal Energy ◽  
Powell Method ◽  
Method Of Steepest Descent

Optimization of an Ocean Thermal Energy Conversion (OTEC) system is carried out by the Powell Method (the method of steepest descent). The parameters in the objective function consist of the velocities of cold sea water and warm sea water passing through the heat exchangers, the phase change temperature, and turbine configuration (specific speed, specific diameter, ratio of blade to diameter). Numerical results are shown for a 100-MW OTEC plant with plate-type heat exchangers using ammonia as working fluid, and are compared with calculation results for the case when the turbine efficiency is fixed.

Preliminary Design of a 1-MWe OTEC Test Plant

1982 ◽  
Vol 104 (1) ◽  
pp. 3-8 ◽  
Author(s):  
T. Kajikawa
Keyword(s):  
Cold Water ◽  
Working Fluid ◽  
Test Plant ◽  
Mooring System ◽  
Preliminary Design ◽  
Closed Cycle ◽  
Water Pipe ◽  
Thermal Energy Conversion ◽  
Design Value ◽  
Ocean Thermal Energy

An ocean-based, 1-MWe (gross) test plant has been planned to establish the feasibility of OTEC (ocean thermal energy conversion) power generation in the revised Sunshine Project. The preliminary design of the proposed test plant employs a closed-cycle power system using ammonia as the working fluid on a barge-type platform with a rigid-arm-type, detachable, single-buoy mooring system. Two types each of titanium evaporators and condensers are to be included. The steel, cold-water pipe is suspended from the buoy. The design value of the ocean temperature difference is 20 K. The paper presents an overview of the preliminary design of the test plant and the tests to be conducted.

Mini-OTEC Operational Results

1981 ◽  
Vol 103 (3) ◽  
pp. 233-240 ◽  
Author(s):  
W. L. Owens ◽  
L. C. Trimble
Keyword(s):  
Single Point ◽  
Seawater Temperature ◽  
Electrical Power ◽  
Working Fluid ◽  
Mooring System ◽  
Closed Cycle ◽  
Pumping Power ◽  
Thermal Energy Conversion ◽  
Formed Part ◽  
Ocean Thermal Energy

The first at-sea ocean thermal energy conversion (OTEC) power was produced by Mini-OTEC on Aug. 2, 1979. The powerplant was mounted on a barge located approximately 2.2 km off Keahole Point on the Kona Coast of Hawaii. Ammonia was employed as the working fluid in a closed-cycle (Rankine) powerplant, which produced approximately 50 kW of gross electrical power at an average seawater temperature difference of 21°C. Parasitic pumping power requirements for seawater and ammonia resulted in a net electrical power of approximately 15 kW. Cold seawater was drawn from a depth of approximately 670 m through a 0.61 m dia polyethylene pipe, which formed part of a single-point tension leg mooring system. The longest period of continuous operation was 10 days, terminated by the conclusion of the program on Nov. 18, 1979.

Shell-and-Plate-Type Heat Exchangers for OTEC Plants

1984 ◽  
Vol 106 (3) ◽  
pp. 286-290 ◽  
Author(s):  
H. Uehara ◽  
H. Kusuda ◽  
M. Monde ◽  
T. Nakaoka ◽  
H. Sumitomo
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchangers ◽  
Porous Plate ◽  
Working Fluid ◽  
Performance Tests ◽  
Overall Heat Transfer Coefficient ◽  
Thermal Energy Conversion ◽  
Ocean Thermal Energy ◽  
Plate Type

New titanium, shell-and-plate type heat exchangers for ocean-thermal-energy-conversion (OTEC) plants have been developed which include three different plate types (fluted, impinging, and porous-surface) for the evaporator and two kinds of plates (No. 1 and No. 2) for the condenser. Performance tests with fresh water show that the overall heat transfer coefficient U of the evaporator using the porous plate is the highest among the three plates; it can reach 4000–4500 W/m2K using ammonia as the working fluid and 3500–4000 W/m2K for a Freon, R-22. The U of the condenser using the No. 2 plate is higher than that using the No. 1 plate; it can reach 3800–4500 W/m2K for ammonia and 2000–3500 W/m2K for R-22.

Performance Analysis of 15 kW Closed Cycle Ocean Thermal Energy Conversion System With Different Working Fluids

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
Jianying Gong ◽  
Tieyu Gao ◽  
Guojun Li
Keyword(s):  
Energy Conversion ◽  
Thermal Energy ◽  
Sea Water ◽  
Working Fluid ◽  
Closed Cycle ◽  
Working Fluids ◽  
Ocean Thermal Energy Conversion ◽  
Thermal Energy Conversion ◽  
Stable Operating ◽  
Ocean Thermal Energy

Closed cycle ocean thermal energy conversion (CC-OTEC) is a way to generate electricity by the sea water temperature difference from the upper surface to the different depth. This paper presents the performance of a 15 kW micropower CC-OTEC system under different working fluids. The results show that both butane and isobutane are not proper working fluids for the CC-OTEC system because the inlet stable operating turbine pressure is in a very narrow range. R125, R143a, and R32, especially R125, are suggested to be the transitional working fluids for CC-OTEC system for their better comprehensive system performance. Moreover, it is recommended that propane should be a candidate for the working fluid because of its excellent comprehensive properties and environmental friendliness. However, propane has inflammable and explosive characteristics. As for the natural working fluid ammonia, almost all performance properties are not satisfactory except the higher net output per unit sea water mass flow rate. But ammonia has relative broader range of the stable operating turbine inlet pressure, which has benefits for the practical plant operation.

Biofouling Monitors for Noncylindrical OTEC Heat Exchanger Tubes

1982 ◽  
Vol 104 (3) ◽  
pp. 257-261
Author(s):  
T. M. Kuzay ◽  
C. B. Panchal ◽  
A. P. Gavin
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Steel Tube ◽  
Stainless Steel Tube ◽  
Thermal Energy Conversion ◽  
Shell And Tube ◽  
Ocean Thermal Energy ◽  
Analytical Approaches

Heat-transfer monitors (HTMs) have been used since 1976 to measure the reduction in the seawater heat-transfer coefficient due to buildup of biofouling and corrosion products inside circular tubes of shell-and-tube heat exchangers being developed for ocean thermal energy conversion (OTEC) plants. For OTEC heat exchangers (HXs) with other tube geometries, special, modified HTMs, which we call STMs, are being sought. The analytical approaches and calibration results to date are summarized for STMs of two types: (i) an STM simulating a rectangular seawater passage in a compact, aluminum, plate-fin HX, and (ii) an STM for a helical stainless-steel tube. The development of type 1 has been successful. A software change is needed for type 2.

The Ocean Thermal Gradient Hydraulic Power Plant and Its Scope

2003 ◽  
Author(s):  
Earl J. Beck
Keyword(s):  
Power Plant ◽  
Thermal Gradient ◽  
Cold Water ◽  
Working Fluid ◽  
Hydraulic Power ◽  
Tropical Oceans ◽  
Thermal Energy Conversion ◽  
Near Shore ◽  
Power Outputs ◽  
Ocean Thermal Energy

Heretofore, the concept of developing power from the tropical oceans, (Ocean Thermal Energy Conversion, or OTEC) has assumed the mooring of large platforms holding the plants in deep water to secure the coldest possible condensing water. As the Ocean Thermal Gradient Hydraulic Power Plant (OTGHPP) does not depend, on the expansion of a working fluid, other than forming a foam of steam bubbles. It does not need extremely cold water as would be dictated by Carnot’s concept of efficiency and the 2nd Law of Thermodynamics. Plants may be based on or near-shore on selected tropical islands, where cool but not extremely cold water may be available at moderate depths. This paper discusses the above possibilities and two possible plant locations, as well as projected power outputs. The location and utilization of large of amounts of power on isolated islands, where cabling of power to major population centers would not be feasible are discussed. Two that come to mind are the reduction of bauxite to produce aluminum and the of current interest is the electrolyzing of water to produce gaseous hydrogen fuel to be used in fuel cells, with oxygen as a by-product.

scholarly journals Determine the best location for Ocean Thermal Energy Conversion (OTEC) in Iranian Seas

2016 ◽  
Vol 10 (5) ◽  
pp. 32 ◽  
Author(s):  
Ashrafoalsadat Shekarbaghani
Keyword(s):  
Energy Conversion ◽  
Thermal Energy ◽  
Caspian Sea ◽  
Power Plants ◽  
Sea Water ◽  
Working Fluid ◽  
The South ◽  
Ocean Thermal Energy Conversion ◽  
Thermal Energy Conversion ◽  
Ocean Thermal Energy

Two-thirds of the earth's surface is covered by oceans. These bodies of water are vast reservoirs of renewable energy.<strong> </strong>Ocean Thermal Energy Conversion technology, known as OTEC, uses the ocean’s natural thermal gradient to generate power. In geographical areas with warm surface water and cold deep water, the temperature difference can be leveraged to drive a steam cycle that turns a turbine and produces power. Warm surface sea water passes through a heat exchanger, vaporizing a low boiling point working fluid to drive a turbine generator, producing electricity. OTEC power plants exploit the difference in temperature between warm surface waters heated by the sun and colder waters found at ocean depths to generate electricity. This process can serve as a base load power generation system that produces a significant amount of renewable, non-polluting power, available 24 hours a day, seven days a week. In this paper investigated the potential of capturing electricity from water thermal energy in Iranian seas (Caspian Sea, Persian Gulf and Oman Sea). According to the investigated parameters of OTEC in case study areas, the most suitable point in Caspian Sea for capturing the heat energy of water is the south part of it which is in the neighborhood of Iran and the most suitable point in the south water of Iran, is the Chahbahar port.

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