Performance simulation of solar-boosted ocean thermal energy conversion plant

Performance Evaluation of Integrated Energy Systems

“…The energy efficiency of the Rankine cycle in an OTEC plant is usually limited to around 5 % due to the small temperature differences between surface water and deep water of the ocean. Thus, in order to improve the efficiency of OTEC, other thermodynamic cycles such as the Kalina cycle and the Uehara cycle that use an ammonia-water mixture as the working fluid are being considered [88]; they are reported to have better energy efficiencies than a Rankine cycle at the same temperature difference [88]. Increasing in the temperature difference between the hot heat source and the cold heat sink can improve the efficiency of OTEC plants, as can the integration of OTEC with other energy technologies.…”

“…Increasing in the temperature difference between the hot heat source and the cold heat sink can improve the efficiency of OTEC plants, as can the integration of OTEC with other energy technologies. Saitoh and Yamada [88] proposed a conceptual design of a multiple Rankinecycle system using both solar thermal energy and ocean thermal energy in order to improve the cycle efficiency. Figure 6.8 shows a schematic diagram of an integrated OTEC system equipped with a flat plate and PV/T solar collector, a reverse osmosis (RO) desalination unit, a single effect absorption chiller and PEM electrolyzer.…”

“…Physical exergy is defined as the maximum useful work obtainable as a system interacts with an equilibrium state. Chemical exergy is associated with the departure of the chemical composition of a system from its chemical equilibrium and is considered important in processes involving combustion and other chemical changes [88][89][90]. Through the second law of thermodynamics, the following exergy rate balance is written as (6.1) where subscripts i and e denote the control volume inlet and outlet flow, respectively, Ex D is the exergy destruction rate and other terms are given as follows: Here, Ex Q is the exergy rate of heat transfer crossing the boundary of the control volume at absolute temperature T, the subscript 0 refers to the reference environment conditions and Ex W is the exergy rate associated with shaft work.…”

Energy and Exergy Analysis of a Cogeneration Cycle, Driven by Ocean Thermal Energy Conversion (OTEC)

“…Their study also pointed out that both the thermal efficiency and the power output of the system increased by increasing the temperature difference between warm and cold seawater. One way of increasing this temperature difference is by increasing the temperature of the heat by using solar heat energy [4,5] and the waste heat from the condenser of existing thermal power plants. Another technique that is effective in improving cycle efficiency involves the integration of other components such as a regenerator to the cycle to maximize the utilization of the available heat resource.…”

Characteristics of Small ORC System for Low Temperature Waste Heat Recovery

“…Almost all past researches and developments have been carried out for power outputs over 10 kW. For example, turbine powers of the ORC developed by Ebara Co., Ltd., and Freepower Co., Ltd., are up to 50 kW and 120 kW, respectively; those of OTEC systems and geothermal plants are usually over 30 kW (5), (6) . Accordingly, an ORC with an output of less than 1 kW has not yet been extensively studied and developed.…”