Ocean thermal energy conversion plants: experimental and analytical study of mixing and recirculation

Technical Report · Thu Sep 01 04:00:00 EDT 1977

DOI:https://doi.org/10.2172/5963964· OSTI ID:5963964

Jirka, G. H.; Fry, D. J.; Johnson, R. P.; Harleman, D. R.F.

Experimental and analytical studies have been carried out to determine the characteristics of the temperature and velocity fields induced in the surrounding ocean by the operation of an OTEC plant. The condition of recirculation, i.e. the re-entering of mixed discharge water back into the plant intake, was of particular interest because of its adverse effect on plant efficiency. The studies were directed at the mixed discharge concept, in which the evaporator and condenser water flows are exhausted jointly at the approximate level of the ambient ocean thermocline. The OTEC plant was of the symmetric spar-buoy type with radial or separate discharge configurations. A distinctly stratified ocean with uniform, ambient current velocity was assumed. The following conclusions are obtained: the recirculation potential of an OTEC plant in a stagnant ocean is determined by the interaction of the jet discharge zone and a double sink return flow (one sink being the evaporator intake, the other the jet entrainment). This process occurs in the near-field of an OTEC plant up to a distance of about three times the ocean mixed layer depth. The stratified internal flow beyond this zone has little effect on recirculation, as have small ocean current velocities (up to 0.10 m/s prototype). Conditions which are conducive to recirculation are characterized by high discharge velocities and large plant flow rates. A design formula is proposed which determines whether recirculation would occur or not as a function of plant design and ocean conditions. On the basis of these results, it can be concluded that a 100 MW OTEC plant with the mixed discharge mode can operate at a typical candidate ocean site without incurring any discharge recirculation.

• Research Organization: Massachusetts Inst. of Tech., Cambridge (USA). Energy Lab.
• OSTI ID: 5963964
• Report Number(s): MIT-EL-77-011
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140800* -- Solar Energy-- Ocean Energy Systems
CIRCULATING SYSTEMS
COMPUTERIZED SIMULATION
CONVERSION
CURRENTS
DATA
DATA FORMS
ENERGY CONVERSION
EXPERIMENTAL DATA
FLOW RATE
FLUID MECHANICS
GRAPHS
HYDRODYNAMICS
HYDROGEN COMPOUNDS
INFORMATION
INTAKE STRUCTURES
ISOLATED VALUES
JETS
MATHEMATICAL MODELS
MEASURING METHODS
MECHANICAL STRUCTURES
MECHANICS
MIXING
NUMERICAL DATA
OCEAN THERMAL ENERGY CONVERSION
OCEAN THERMAL POWER PLANTS
OXYGEN COMPOUNDS
POWER PLANTS
SEAWATER
SIMULATION
SOLAR ENERGY CONVERSION
SOLAR POWER PLANTS
STAGNATION
STRATIFICATION
TEMPERATURE DISTRIBUTION
TEMPERATURE GRADIENTS
TEMPERATURE MEASUREMENT
VELOCITY
WATER
WATER CURRENTS