Design Optimization of Floating Structure for a 100 MW-Net Ocean Thermal Energy Conversion (OTEC) Power Plant

2018 ◽  
Author(s):  
Ristiyanto Adiputra ◽  
Tomoaki Utsunomiya
Keyword(s):  
Power Plant ◽  
Power Output ◽  
Design Procedure ◽  
Iteration Process ◽  
Floating Structure ◽  
Independent Variables ◽  
Ocean Thermal Energy ◽  
Net Power Output ◽  
Oil Tanker ◽  
Seawater Transport

This paper presents a design procedure based on optimization to contrive a floating structure for a commercial scale of OTEC power plant. In the aim to get a safe yet economical floating structure, a commercial oil tanker ship was converted as the plantship. The process was started by defining independent variables, constraints and fix parameters. The independent variables included the velocity of seawater transport and type of oil tanker ship. The next step was breaking down the fix parameters which were kept constant during the iteration process. These parameters were about the general requirements and the necessary equipment to produce 100 MW-net power output. Some constraints were also introduced as permissible borders to determine whether the particular case was acceptable or not. The constraints included the constraint due to provided space, allowed weight, net power output and fluid phenomena on the riser. During the iteration process, a spiral model was developed as analysis guideline. Based on the result of the optimization, it could be concluded that the typical Suez-max oil tanker ship was the best option and the most optimum seawater transport velocity was 3 m/s. Finally, the general arrangements and the base layout design were also conceptualized in this paper.

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

Entropy ◽  
2019 ◽  
Vol 21 (12) ◽  
pp. 1143 ◽  
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.

Retrofitting a Geothermal Power Plant to Optimize Performance: A Case Study

1999 ◽  
Vol 121 (4) ◽  
pp. 295-301 ◽  
Author(s):  
M. Kanog˘lu ◽  
Y. A. C¸engel
Keyword(s):  
Power Plant ◽  
Power Output ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Geothermal Power Plant ◽  
Northern Nevada ◽  
Single Flash ◽  
Geothermal Power ◽  
Net Power Output ◽  
Double Flash

Performance evaluation of a 12.8-MW single-flash design geothermal power plant in Northern Nevada is conducted using actual plant operating data, and potential improvement sites are identified. The unused geothermal brine reinjected back to the ground is determined to represent about 50 percent of the energy and 40 percent of the exergy available in the reservoir. The first and second-law efficiencies of the plant are determined to be 6 percent and 22 percent, respectively. Optimizing the existing single-flash system is shown to increase the net power output by up to 4 percent. Some well-known geothermal power generation technologies including double-flash, binary, and combined flash/binary designs as alternative to the existing system are evaluated and their optimum operating conditions are determined. It is found that a double-flash design, a binary design, and a combined flash/binary design can increase the net power output by up to 31 percent, 35 percent, and 54 percent, respectively, at optimum operating conditions. An economic comparison of these designs appears to favor the combined flash/binary design, followed by the double-flash design.

Performance Simulation of Solar-Ocean Thermal Energy Conversion

2018 ◽  
Author(s):  
Yue Juan ◽  
Li Dashu ◽  
Li Zhichuan ◽  
Xiao Gang ◽  
Zhang Li ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Thermal Energy ◽  
Power Output ◽  
Thermal Efficiency ◽  
Performance Simulation ◽  
Comprehensive Utilization ◽  
Ocean Thermal Energy Conversion ◽  
Thermal Energy Conversion ◽  
Ocean Thermal Energy ◽  
Net Power Output

Compared to the restriction of intermittency of solar power generation, ocean thermal energy conversion (OTEC) is not only 24/7 base-load, but also comprehensive utilization of fresh water production, air-conditioning, mariculture etc. However, limited temperature difference between warm surface seawater and the cold deep seawater is a crucial factor that restricts the thermal efficiency of OTEC. But today, with the appliance of solar collector in OTEC net power output and the net thermal efficiency have been significantly improved. In this study theoretical analysis and performance simulation of 1MW solar-ocean thermal energy conversion (SOTEC) in South China Sea area is conducted. Net power output and net thermal efficiency of SOTEC with solar-boosted temperature of 20K and OTEC under the condition of weather conditions in South China Sea are compared and analyzed. The results show that the net power output and net thermal efficiency of SOTEC have been significantly improved by combining the solar collector. This study is practical for autonomous supply of islands and coastal areas, and instructive for the comprehensive utilization of renewable energy.

Efficiency Improvement in Precombustion CO2 Removal Units With a Waste–Heat Recovery ORC Power Plant

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Carsten Trapp ◽  
Piero Colonna
Keyword(s):  
Heat Exchanger ◽  
Power Plant ◽  
Thermal Energy ◽  
Co2 Capture ◽  
Power Output ◽  
Heat Recovery ◽  
Total Power ◽  
Working Fluid ◽  
Water Mixture ◽  
Net Power Output

This paper presents an analysis about recovering low-grade thermal energy from a precombustion CO2 capture process as part of an integrated gasification combined cycle (IGCC) power plant by means of organic rankine cycle (ORC) turbogenerators. The distinguishing feature of this system is the thermal energy source that is a syngas-water mixture, which is cooled from a temperature of approximately 140 °C, and partly condenses due to the heat transfer to the ORC primary heat exchanger. This study explores various types of ORC power systems for this application. The performance of commercially available ORC units is used as a benchmark and compared to the performance of two types of tailor-designed ORC power plants. The working fluid has a major influence on system performance and other technical and economic factors. The effect of selecting a fluid from the hydrocarbon and refrigerant families are therefore investigated, targeting the maximum net power output. In addition to pure fluids, two-component mixtures are also considered. The use of mixtures as working fluids in subcritical heat-recovery ORC systems allows for a better match of the temperature profiles in the primary heat exchanger and the condenser due to the temperature glide associated with phase-transition, leading to lower irreversibilities within the heat exchanging equipment. In order to further improve the thermal coupling between the cooling heat source and the heating of the working fluid, the supercritical cycle configuration is also studied. The performance of the three categories of systems, depending on working fluid and cycle configuration, i.e., systems based on (i) commercially available units, (ii) tailor-designed subcritical cycle, (iii) tailor-designed supercritical cycle, are analyzed in terms of net power output, second law efficiency, and component-based exergy efficiencies. The analysis shows that an improvement of 38.0% in terms of net power output compared to the benchmark system can be achieved by an optimized supercritical ORC power plant using an R134a/R236fa mixture as the working fluid. It is estimated that the total power consumption of the considered exemplary CO2 capture plant can be reduced by approximately 10% with the optimal ORC system. In this study, particular attention is focused on the semi-empirical optimization approach, in order to avoid unnecessary computations, and general guidelines are provided.

scholarly journals Modeling and simulation of the effect of moisture content and ambient temperature on gas turbine power plant performance in Ughelli, Nigeria

2020 ◽  
Vol 39 (1) ◽  
pp. 182-188
Author(s):  
F. Onoroh ◽  
M. Ogbonnaya ◽  
U.P. Onochie
Keyword(s):  
Power Plant ◽  
Moisture Content ◽  
Ambient Temperature ◽  
Gas Turbine ◽  
Fuel Consumption ◽  
Power Output ◽  
Power Efficiency ◽  
Specific Fuel Consumption ◽  
Plant Performance ◽  
Net Power Output

The influence of ambient temperature and moisture content on the performance of Transcorp Power Plant, Ughelli, Delta State, Nigeria was investigated with the aid of a digital psychrometer. The simulation was done using codes developed on MATLAB R2017a and the results show that compressor power consumption increased by 1.65% for 0.7% rise in temperature, and 0.50% for 71.4% rise in moisture content. The specific fuel consumption also increased with increase in temperature where a 1.71% rise in ambient temperature resulted in a 0.15% rise in specific fuel consumption but it decreased by 0.49% for a 41.7% rise in moisture content. A 1.62% rise in temperature led to a 0.13% drop in net power output and a 29.4% rise in moisture content resulted in a 0.48% drop in net power output. Thus gas turbine plant operates optimally in areas with low ambient temperatures and high moisture content. Keywords: Work ratio, net power, efficiency, moisture content, specific fuel consumption, heat rate.

Optimal Design of a Pilot OTEC Power Plant in Taiwan

1991 ◽  
Vol 113 (4) ◽  
pp. 294-299 ◽  
Author(s):  
C. H. Tseng ◽  
K. Y. Kao ◽  
J. C. Yang
Keyword(s):  
Power Plant ◽  
Optimal Design ◽  
Optimization Model ◽  
Large Scale ◽  
Design Procedure ◽  
Optimization Method ◽  
Optimization Techniques ◽  
Thermal Energy Conversion ◽  
Design Variables ◽  
Ocean Thermal Energy

In this paper, an optimal design concept has been utilized to find the best designs for a complex and large-scale ocean thermal energy conversion (OTEC) plant. The OTEC power plant under this study is divided into three major subsystems consisting of power subsystem, seawater pipe subsystem, and containment subsystem. The design optimization model for the entire OTEC plant is integrated from these subsystems under the considerations of their own various design criteria and constraints. The mathematical formulations of this optimization model for the entire OTEC plant are described. The design variables, objective function, and constraints for a pilot plant under the constraints of the feasible technologies at this stage in Taiwan have been carefully examined and selected. The numerical optimization method called Sequential Quadratic Programming (SQP) is selected to obtain the optimum results. The main purpose of this paper is to demonstrate the design procedure with the optimization techniques for engineering and economics in the OTEC plant so that anyone else can build upon their models according to their needs.

scholarly journals Alterations in flight muscle ultrastructure and function in Drosophila tropomyosin mutants.

1996 ◽  
Vol 135 (3) ◽  
pp. 673-687 ◽  
Author(s):  
A J Kreuz ◽  
A Simcox ◽  
D Maughan
Keyword(s):  
Amino Acid ◽  
Power Output ◽  
Flight Muscle ◽  
Structure And Function ◽  
Wild Type ◽  
Muscle Tropomyosin ◽  
Ultrastructure And Function ◽  
And Function ◽  
Net Power Output ◽  
Current Report

Drosophila indirect flight muscle (IFM) contains two different types of tropomyosin: a standard 284-amino acid muscle tropomyosin, Ifm-TmI, encoded by the TmI gene, and two > 400 amino acid tropomyosins, TnH-33 and TnH-34, encoded by TmII. The two IFM-specific TnH isoforms are unique tropomyosins with a COOH-terminal extension of approximately 200 residues which is hydrophobic and rich in prolines. Previous analysis of a hypomorphic TmI mutant, Ifm(3)3, demonstrated that Ifm-TmI is necessary for proper myofibrillar assembly, but no null TmI mutant or TmII mutant which affects the TnH isoforms have been reported. In the current report, we show that four flightless mutants (Warmke et al., 1989) are alleles of TmI, and characterize a deficiency which deletes both TmI and TmII. We find that haploidy of TmI causes myofibrillar disruptions and flightless behavior, but that haploidy of TmII causes neither. Single fiber mechanics demonstrates that power output is much lower in the TmI haploid line (32% of wild-type) than in the TmII haploid line (73% of wild-type). In myofibers nearly depleted of Ifm-TmI, net power output is virtually abolished (< 1% of wild-type) despite the presence of an organized fibrillar core (approximately 20% of wild-type). The results suggest Ifm-TmI (the standard tropomyosin) plays a key role in fiber structure, power production, and flight, with reduced Ifm-TmI expression producing corresponding changes of IFM structure and function. In contrast, reduced expression of the TnH isoforms has an unexpectedly mild effect on IFM structure and function.

Hybrid Solar-Geothermal Power Generation to Increase the Energy Production From a Binary Geothermal Plant

2011 ◽  
Author(s):  
Giovanni Manente ◽  
Randall Field ◽  
Ronald DiPippo ◽  
Jefferson W. Tester ◽  
Marco Paci ◽  
...  
Keyword(s):  
Power Plant ◽  
Power Output ◽  
Energy Production ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Solar Thermal Energy ◽  
Geothermal Fluid ◽  
Industrial Grade ◽  
Design Values

This article examines how hybridization using solar thermal energy can increase the power output of a geothermal binary power plant that is operating on geothermal fluid conditions that fall short of design values in temperature and flow rate. The power cycle consists of a subcritical organic Rankine cycle using industrial grade isobutane as the working fluid. Each of the power plant units includes two expanders, a vaporizer, a preheater and air-cooled condensers. Aspen Plus was used to model the plant; the model was validated and adjusted by comparing its predictions to data collected during the first year of operation. The model was then run to determine the best strategy for distributing the available geothermal fluid between the two units to optimize the plant for the existing degraded geofluid conditions. Two solar-geothermal hybrid designs were evaluated to assess their ability to increase the power output and the annual energy production relative to the geothermal-only case.

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