Results of Scoping Tests for Open-Cycle OTEC Components Operating With Seawater

The most recent research effort in the Ocean Energy Technology program of the U.S. Department of Energy has been to scale up the experimental apparatus for open-cycle ocean thermal energy conversion (OC-OTEC) research to a thermal capacity of more than 1 MW using seawater as the process fluid. This apparatus, the Heat- and Mass-Transfer Scoping Test Apparatus (HMTSTA), was designed and built todetermine the performance of key open-cycle OTEC components operating in seawater. This research builds on extensive data bases and analytical capabilities developed over the last decade in open-cycle technology. Seawater tests in the HMTSTA have confirmed the excellent heat- and mass-transfer performance of spout evaporators and direct-contact condensers using structured packings, which wasobserved in freshwater experiments and predicted by analytical models. Data on the performance of surface condensers, seawater deaeration, and carbon dioxide emissions were also obtained in HMTSTA experiments. These results provide the required technical basis for confident engineering design of a facility to produce net power for the first time using open-cycle OTEC technology.