Bubble Nucleation and Growth in Open-Cycle OTEC Subsystems

Bubble nucleation and growth in the evaporator, condenser, upcomers, and feedwater distribution systems of open-cycle ocean thermal energy conversion (OTEC) power plants are examined. The phenomenon that will probably have the most impact on system design is cavitation in the warm water feed near the entrance of the evaporator. The critical bubble size for cavitation is about 105 μm. Sources of bubbles in the warm water feed are those entering from the ocean, those nucleating on suspended particles, and those nucleating on the upcomer wall. Analyses of bubble growth induced by changes in hydrostatic pressure, mass transfer, and coalescence are presented. Using available information for bubble size distribution in seawater at California locations, it is shown that cavitation will probably have a significant impact on evaporator performance unless a debubbler is provided upstream of the evaporator entrance.

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Ocean Thermal Energy Conversion (OTEC): Choosing a Working Fluid

ASME 2009 Power Conference ◽

10.1115/power2009-81211 ◽

2009 ◽

Cited By ~ 1

Author(s):

James H. Anderson

Keyword(s):

Thermal Energy ◽

Power Plants ◽

Thermal Power ◽

Deep Ocean ◽

Working Fluid ◽

Closed Cycle ◽

Working Fluids ◽

Advantages And Disadvantages ◽

Open Cycle ◽

Ocean Thermal Energy

Ocean thermal energy plants are thermal power plants that use warm ocean surface water as a source of heat and cold seawater from the deep ocean as a heat sink. A historical perspective along with the development of the technology will be presented. A short description describing the subtle differences between OTEC and fossil and nuclear plants will be presented. Open cycle OTEC and closed cycle OTEC will be described with a focus on the influence of choice of working fluid on the design of a plant. Various working fluids could be selected for use in closed cycle OTEC plants. A review and comparison of potential working fluids will address the advantages and disadvantages of the individual fluids. Their characteristics along with a comparison to water as a working fluid in open cycle OTEC will be explained.

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Turbulent Falling Film Evaporators and Condensers for Open Cycle Ocean Thermal Energy Conversion

Proceeding of Advanced Course in Heat Exchangers: Theory and Practice. ICHMT Symposium. ◽

10.1615/ichmt.1981.advcourseheatexch.70 ◽

1981 ◽

Cited By ~ 1

Author(s):

A. T. Wassel ◽

Anthony F. Mills

Keyword(s):

Energy Conversion ◽

Thermal Energy ◽

Falling Film ◽

Ocean Thermal Energy Conversion ◽

Thermal Energy Conversion ◽

Open Cycle ◽

Ocean Thermal Energy

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Dynamic observations of vesiculation reveal the role of silicate crystals in bubble nucleation and growth in andesitic magmas

Lithos ◽

10.1016/j.lithos.2017.11.024 ◽

2018 ◽

Vol 296-299 ◽

pp. 532-546 ◽

Cited By ~ 14

Author(s):

P. Pleše ◽

M.D. Higgins ◽

L. Mancini ◽

G. Lanzafame ◽

F. Brun ◽

...

Keyword(s):

Nucleation And Growth ◽

Bubble Nucleation

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Formulation of a Mathematical Process Model for the Foaming of a Mesophase Carbon Precursor

MRS Proceedings ◽

10.1557/proc-270-35 ◽

1992 ◽

Vol 270 ◽

Cited By ~ 3

Author(s):

S. S. Sandhu ◽

J. W. Hager

Keyword(s):

Process Model ◽

Analytical Description ◽

Nucleation And Growth ◽

Bubble Surface ◽

Bubble Nucleation ◽

Mesophase Pitch ◽

Experimental Production ◽

Mathematical Equations ◽

Experimental Effort ◽

Mathematical Process

ABSTRACTMathematical equations have been formulated to guide an experimental effort to produce an open-celled mesophase pitch foam. The formulation provides an analytical description of homogeneous bubble nucleation and growth, diffusion of the blowing gas through the liquid to the bubble surface, and the average material thickness between bubbles. Implications of the formulation for the experimental production of mesophase pitch foam are discussed.

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A Review of Research Works on Supervised Learning Algorithms for SCADA Intrusion Detection and Classification

Sustainability ◽

10.3390/su13179597 ◽

2021 ◽

Vol 13 (17) ◽

pp. 9597

Author(s):

Oyeniyi Akeem Alimi ◽

Khmaies Ouahada ◽

Adnan M. Abu-Mahfouz ◽

Suvendi Rimer ◽

Kuburat Oyeranti Adefemi Alimi

Keyword(s):

Intrusion Detection ◽

Supervised Learning ◽

Power Plants ◽

Distribution Systems ◽

Remote Access ◽

Future Research ◽

Monitoring And Control ◽

Efficient Detection ◽

Learning Techniques ◽

Scada Systems

Supervisory Control and Data Acquisition (SCADA) systems play a significant role in providing remote access, monitoring and control of critical infrastructures (CIs) which includes electrical power systems, water distribution systems, nuclear power plants, etc. The growing interconnectivity, standardization of communication protocols and remote accessibility of modern SCADA systems have contributed massively to the exposure of SCADA systems and CIs to various forms of security challenges. Any form of intrusive action on the SCADA modules and communication networks can create devastating consequences on nations due to their strategic importance to CIs’ operations. Therefore, the prompt and efficient detection and classification of SCADA systems intrusions hold great importance for national CIs operational stability. Due to their well-recognized and documented efficiencies, several literature works have proposed numerous supervised learning techniques for SCADA intrusion detection and classification (IDC). This paper presents a critical review of recent studies whereby supervised learning techniques were modelled for SCADA intrusion solutions. The paper aims to contribute to the state-of-the-art, recognize critical open issues and offer ideas for future studies. The intention is to provide a research-based resource for researchers working on industrial control systems security. The analysis and comparison of different supervised learning techniques for SCADA IDC systems were critically reviewed, in terms of the methodologies, datasets and testbeds used, feature engineering and optimization mechanisms and classification procedures. Finally, we briefly summarized some suggestions and recommendations for future research works.

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Sea Wave Energy. A Review of the Current Technologies and Perspectives

Energies ◽

10.3390/en14206604 ◽

2021 ◽

Vol 14 (20) ◽

pp. 6604

Author(s):

Domenico Curto ◽

Vincenzo Franzitta ◽

Andrea Guercio

Keyword(s):

Wave Energy ◽

Power Plants ◽

New Technologies ◽

Morphological Characteristics ◽

Electrical Energy ◽

Wave Energy Converter ◽

Tidal Range ◽

Ocean Current ◽

Energy Converter ◽

Ocean Thermal Energy

The proposal of new technologies capable of producing electrical energy from renewable sources has driven research into seas and oceans. Research finds this field very promising in the future of renewable energies, especially in areas where there are specific climatic and morphological characteristics to exploit large amounts of energy from the sea. In general, this kind of energy is referred to as six energy resources: waves, tidal range, tidal current, ocean current, ocean thermal energy conversion, and saline gradient. This review has the aim to list several wave-energy converter power plants and to analyze their years of operation. In this way, a focus is created to understand how many wave-energy converter plants work on average and whether it is indeed an established technology.

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Design and Optimization of Steam Distribution Systems for Steam Power Plants

Industrial & Engineering Chemistry Research ◽

10.1021/ie102059n ◽

2011 ◽

Vol 50 (13) ◽

pp. 8097-8109 ◽

Cited By ~ 9

Author(s):

Cheng-Liang Chen ◽

Chih-Yao Lin

Keyword(s):

Power Plants ◽

Distribution Systems ◽

Steam Power ◽

Design And Optimization ◽

Steam Power Plants

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OTEC Maximum Net Power Output Using Carnot Cycle and Application to Simplify Heat Exchanger Selection

Entropy ◽

10.3390/e21121143 ◽

2019 ◽

Vol 21 (12) ◽

pp. 1143 ◽

Cited By ~ 10

Author(s):

Kevin Fontaine ◽

Takeshi Yasunaga ◽

Yasuyuki Ikegami

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Pressure Drop ◽

Power Output ◽

Heat Exchangers ◽

Power Plants ◽

Seawater Temperature ◽

Carnot Cycle ◽

Ocean Thermal Energy ◽

Net Power Output

Ocean thermal energy conversion (OTEC) uses the natural thermal gradient in the sea. It has been investigated to make it competitive with conventional power plants, as it has huge potential and can produce energy steadily throughout the year. This has been done mostly by focusing on improving cycle performances or central elements of OTEC, such as heat exchangers. It is difficult to choose a suitable heat exchanger for OTEC with the separate evaluations of the heat transfer coefficient and pressure drop that are usually found in the literature. Accordingly, this paper presents a method to evaluate heat exchangers for OTEC. On the basis of finite-time thermodynamics, the maximum net power output for different heat exchangers using both heat transfer performance and pressure drop was assessed and compared. This method was successfully applied to three heat exchangers. The most suitable heat exchanger was found to lead to a maximum net power output 158% higher than the output of the least suitable heat exchanger. For a difference of 3.7% in the net power output, a difference of 22% in the Reynolds numbers was found. Therefore, those numbers also play a significant role in the choice of heat exchangers as they affect the pumping power required for seawater flowing. A sensitivity analysis showed that seawater temperature does not affect the choice of heat exchangers, even though the net power output was found to decrease by up to 10% with every temperature difference drop of 1 °C.

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