Uehara Cycle
The Uehara Cycle is a system devised by Haruo Uehara and Yasuyuki Ikegami of Saga University, Japan.

In ocean thermal energy conversion (OTEC) plants, the open cycle using water as the working fluid, or the closed Rankine cycle using ammonia have been examined. In 1987, Kalina invented the Kalina cycle using ammonia-water mixture as the working fluid and showed that the efficiency of the Kalina cycle was about twice as large as one of the Rankine closed cycle and open cycle. In 1993, Uehara and Ikegami conducted the parametric performance analysis of OTEC using the Kalina cycle and found that efficiency of the Kalina cycle became 5% when the inlet warm seawater temperature was 28 and the inlet cold seawater temperature was 4. If they used the ammonia-water mixture as the working fluid of the Kalina cycle for OTEC, the performance of evaporator and condenser in the Kalina cycle was smaller than that of the conventional Rankine cycle using pure fluid. Especially, the performance of condenser became considerably lower in value, and a large amount of deep cold seawater and the surface area of condenser were required. In order to correct the defect of the Kalina cycle, Uehara and his colleague developed a new system in 1994, that is, the Uehara Cycle, with absorption and extraction process for power plants by developing the plate type. The Kalina Cycle has added a separator, a regenerator, and an absorber to improve its efficiency. The Uehara Cycle has added a second turbine, a heater, and an after-condenser to improve its efficiency much more.


Uehara Cycle

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