scholarly journals Research on Optimization and Verification of the Number of Stator Blades of kW Ammonia Working Medium Radial Flow Turbine in Ocean Thermal Energy Conversion

2021 ◽  
Vol 9 (8) ◽  
pp. 901
Author(s):  
Yun Chen ◽  
Yanjun Liu ◽  
Wei Yang ◽  
Yiming Wang ◽  
Li Zhang ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Thermal Energy ◽  
Simulation Analysis ◽  
Reverse Flow ◽  
Internal Flow ◽  
Field Performance ◽  
Working Fluid ◽  
Ocean Thermal Energy Conversion ◽  
Thermal Energy Conversion ◽  
Ocean Thermal Energy

Ocean Thermal Energy Conversion (OTEC) is one of the emerging industries of ocean energy and an important link in carbon neutrality. Turbine is a key component of ocean thermal energy conversion, which has an important impact on the performance and energy conversion efficiency of the system. This paper fully considers the application characteristics of ocean thermal energy conversion and the state conversion characteristics of ammonia working fluid. Taking the 100 kW radial inflow turbine in the OTEC application system as an example, based on the design, the turbine is optimized for the key parameters of the turbine stator and the influence of different geometric parameters is analyzed. Subsequently, the optimization results are verified by CFD numerical simulation analysis under different conditions. The results show that the number of stator blades has an important influence on the performance of the turbine. Further optimization studies have shown that through optimization, when the number of stator blades is 33, the internal flow field performance is the best, and the working conditions of the inlet and outlet working fluids are in accordance with the design points without obvious shock wave and reverse flow phenomenon, the efficiency is 89.46%, 3.94% higher than the design value.

scholarly journals Determine the best location for Ocean Thermal Energy Conversion (OTEC) in Iranian Seas

2016 ◽  
Vol 10 (5) ◽  
pp. 32 ◽  
Author(s):  
Ashrafoalsadat Shekarbaghani
Keyword(s):  
Energy Conversion ◽  
Thermal Energy ◽  
Caspian Sea ◽  
Power Plants ◽  
Sea Water ◽  
Working Fluid ◽  
The South ◽  
Ocean Thermal Energy Conversion ◽  
Thermal Energy Conversion ◽  
Ocean Thermal Energy

Two-thirds of the earth's surface is covered by oceans. These bodies of water are vast reservoirs of renewable energy.<strong> </strong>Ocean Thermal Energy Conversion technology, known as OTEC, uses the ocean’s natural thermal gradient to generate power. In geographical areas with warm surface water and cold deep water, the temperature difference can be leveraged to drive a steam cycle that turns a turbine and produces power. Warm surface sea water passes through a heat exchanger, vaporizing a low boiling point working fluid to drive a turbine generator, producing electricity. OTEC power plants exploit the difference in temperature between warm surface waters heated by the sun and colder waters found at ocean depths to generate electricity. This process can serve as a base load power generation system that produces a significant amount of renewable, non-polluting power, available 24 hours a day, seven days a week. In this paper investigated the potential of capturing electricity from water thermal energy in Iranian seas (Caspian Sea, Persian Gulf and Oman Sea). According to the investigated parameters of OTEC in case study areas, the most suitable point in Caspian Sea for capturing the heat energy of water is the south part of it which is in the neighborhood of Iran and the most suitable point in the south water of Iran, is the Chahbahar port.

Effect of Entrainment Ratio and Subcooling Degree on Dual System of Cooling-Thermal Energy Conversion Applying Ejector

2017 ◽  
Vol 379 ◽  
pp. 140-148
Author(s):  
Jung In Yoon ◽  
Ho Saeng Lee ◽  
Chang Hyo Son ◽  
Sung Hoon Seol ◽  
Kwang Seok Lee ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Thermal Energy ◽  
Simulation Analysis ◽  
Cooling Capacity ◽  
Dual System ◽  
Working Fluid ◽  
Generation System ◽  
Entrainment Ratio ◽  
Thermal Energy Conversion ◽  
Ocean Thermal Energy

This study proposes a system called 'dual system of cooling-thermal energy conversion applying ejector', which practically applies an ejector to an ocean thermal energy conversion (OTEC) system. The proposed system presents higher system efficiency, owing to the application of an ejector, and reduced initial and operating costs. The main results, obtained from simulation analysis, are as follows: the cooling capacity tended to decrease as the entrainment ratio increased, and the system using R134a generally presented the highest cooling capacity and COP. In terms of generation system, the highest turbine gross power was obtained when the R134a working fluid was applied. The efficiency of the system decreased as the entrainment ratio increased. Finally, the application of the ejector enhanced the efficiency of the generation system, using R134a, by approximately 50%, from 4.73% to 7.10% at the entrainment ratio of 0.1.

scholarly journals Analysis of Ocean Thermal Energy Conversion Power Plant using Isobutane as the Working Fluid

2018 ◽  
Vol 7 (1) ◽  
Keyword(s):  
Heat Exchanger ◽  
Energy Conversion ◽  
Thermal Energy ◽  
Working Fluid ◽  
Ocean Thermal Energy Conversion ◽  
Thermal Energy Conversion ◽  
Useful Power ◽  
Design Characteristics ◽  
Process Energy ◽  
Ocean Thermal Energy

The use of organic isobutane will be investigated for a closed-cycle Ocean Thermal Energy Conversion (OTEC) onshore plant that delivers 110 MW electric powers. This paper will cover concept, process, energy calculations, cost factoids and environmental aspects. In isobutane cycle, hot ocean surface water is used to vaporize and to superheat isobutane in a heat exchanger. Isobutane vapor then expands through a turbine to generate useful power. The exhaust vapor is condensed afterwards, using the cold deeper ocean water, and pumped to a heat exchanger to complete a cycle. Results show the major design characteristics and equipment's of the OTEC plant along with cycle efficiency and cycle improvement techniques.

Ocean Thermal Energy Conversion Primer

2002 ◽  
Vol 36 (4) ◽  
pp. 25-35 ◽  
Author(s):  
L. A. Vega
Keyword(s):  
Energy Conversion ◽  
Thermal Energy ◽  
Heat Engine ◽  
Bottom Layer ◽  
Working Fluid ◽  
Turbine Generator ◽  
Ocean Thermal Energy Conversion ◽  
Thermal Energy Conversion ◽  
Open Cycle ◽  
Ocean Thermal Energy

The vertical temperature distribution in the open ocean can be simplistically described as consisting of two layers separated by an interface. The upper layer is warmed by the sun and mixed to depths of about 100 m by wave motion. The bottom layer consists of colder water formed at high latitudes. The interface or thermocline is sometimes marked by an abrupt change in temperature but more often the change is gradual. The temperature difference between the upper (warm) and bottom (cold) layers ranges from 10°C to 25°C, with the higher values found in equatorial waters. This implies that there are two enormous reservoirs providing the heat source and the heat sink required for a heat engine. A practical application is found in a system (heat engine) designed to transform the thermal energy into electricity. This is referred to as OTEC for Ocean Thermal Energy Conversion. Several techniques have been proposed to use this ocean thermal resource; however, at present it appears that only the closed cycle (CC-OTEC) and the open cycle (OC-OTEC) schemes have a solid foundation of theoretical as well as experimental work. In the CC-OTEC system, warm surface seawater and cold seawater are used to vaporize and condense a working fluid, such as anhydrous ammonia, which drives a turbine-generator in a closed loop producing electricity. In the OC-OTEC system, seawater is flash-evaporated in a vacuum chamber. The resulting low-pressure steam is used to drive a turbine-generator. Gold seawater is used to condense the steam after it has passed through the turbine. The open-cycle can, therefore, be configured to produce desalinated water as well as electricity.

Performance Analysis of 15 kW Closed Cycle Ocean Thermal Energy Conversion System With Different Working Fluids

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
Jianying Gong ◽  
Tieyu Gao ◽  
Guojun Li
Keyword(s):  
Energy Conversion ◽  
Thermal Energy ◽  
Sea Water ◽  
Working Fluid ◽  
Closed Cycle ◽  
Working Fluids ◽  
Ocean Thermal Energy Conversion ◽  
Thermal Energy Conversion ◽  
Stable Operating ◽  
Ocean Thermal Energy

Closed cycle ocean thermal energy conversion (CC-OTEC) is a way to generate electricity by the sea water temperature difference from the upper surface to the different depth. This paper presents the performance of a 15 kW micropower CC-OTEC system under different working fluids. The results show that both butane and isobutane are not proper working fluids for the CC-OTEC system because the inlet stable operating turbine pressure is in a very narrow range. R125, R143a, and R32, especially R125, are suggested to be the transitional working fluids for CC-OTEC system for their better comprehensive system performance. Moreover, it is recommended that propane should be a candidate for the working fluid because of its excellent comprehensive properties and environmental friendliness. However, propane has inflammable and explosive characteristics. As for the natural working fluid ammonia, almost all performance properties are not satisfactory except the higher net output per unit sea water mass flow rate. But ammonia has relative broader range of the stable operating turbine inlet pressure, which has benefits for the practical plant operation.

Thermodynamic Analysis of Ocean Thermal Energy Conversion System With Different Working Fluids

2017 ◽  
Author(s):  
Dashu Li ◽  
Li Zhang ◽  
Xili Duan ◽  
Xiaosuai Tian
Keyword(s):  
Energy Conversion ◽  
Thermal Energy ◽  
Thermal Efficiency ◽  
Sea Water ◽  
Working Fluid ◽  
Ocean Temperature ◽  
Water Pump ◽  
Ocean Thermal Energy Conversion ◽  
Thermal Energy Conversion ◽  
Ocean Thermal Energy

A thermodynamic model is developed for ocean thermal energy conversion (OTEC) systems. Considering the narrow temperature range in the evaporator, different refrigerants including R717, R134a and R600 were analyzed and compared under sub-critical state with practical ocean thermal conditions. The results show that larger ocean temperature differences will lead to higher evaporation pressures, and less pumping power requirements for all pumps, i.e., warm sea water pump, cold sea water pump and pumps for the working fluid. The thermal efficiency of different systems and the net power output were found to be closely related to ocean temperature difference, with a positive linear relationship. It was also found that R717 provides the highest thermal efficiency with the least pump power requirement. This working fluid could potentially be used for OTEC system development. This study provides useful insights to the design and equipment selection of OTEC systems.

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