Supercritical Carbon Dioxide Fluid and Its Application to Rankine Cycle

2021 ◽  
pp. 533-565
Author(s):  
Hiroshi Yamaguchi
Keyword(s):  
Heat Transfer ◽  
Supercritical Co2 ◽  
Rankine Cycle ◽  
Heat Energy ◽  
Working Fluid ◽  
Supercritical State ◽  
Power Cycle ◽  
Cycle System ◽  
Main Components ◽  
Cycle Efficiency

Supercritical CO2 has been given much attention to be a working fluid in a power cycle due to its unique properties. The supercritical CO2 solar Rankine cycle system was designed and developed by using the benefit of supercritical state of CO2 to generate electric power and supply heat energy in environmentally friendly manner. The development of main components in the system are introduced and discussed particularly by focusing on the properties of CO2 for obtaining higher performance. The properties of CO2 in near critical region are also discussed in this chapter. Operating the power cycle in the supercritical region of CO2 enhances the heat transfer in energy exchanging process and improves the cycle efficiency.

Supercritical Carbon Dioxide and Its Application to Rankine Cycle

2017 ◽  
pp. 335-368 ◽  
Author(s):  
Hiroshi Yamaguchi
Keyword(s):  
Heat Transfer ◽  
Supercritical Co2 ◽  
Rankine Cycle ◽  
Heat Energy ◽  
Working Fluid ◽  
Supercritical State ◽  
Power Cycle ◽  
Cycle System ◽  
Main Components ◽  
Cycle Efficiency

Supercritical CO2 has been given much attention to be a working fluid in a power cycle due to its unique properties. The supercritical CO2 solar Rankine cycle system was designed and developed by using the benefit of supercritical state of CO2 to generate electric power and supply heat energy in environmentally friendly manner. The development of main components in the system are introduced and discussed particularly by focusing on the properties of CO2 for obtaining higher performance. The properties of CO2 in near critical region are also discussed in this chapter. Operating the power cycle in the supercritical region of CO2 enhances the heat transfer in energy exchanging process and improves the cycle efficiency.

scholarly journals Energy and exergy analysis of a combined refrigeration and waste heat driven organic Rankine cycle system

2017 ◽  
Vol 21 (6 Part A) ◽  
pp. 2621-2631 ◽  
Author(s):  
Ertugrul Cihan ◽  
Barıs Kavasogullari
Keyword(s):  
Exergy Analysis ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Power Cycle ◽  
Cycle System ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis ◽  
Organic Fluids

Energy and exergy analysis of a combined refrigeration and waste heat driven organic Rankine cycle system were studied theoretically in this paper. In order to complete refrigeration process, the obtained kinetic energy was supplied to the compressor of the refrigeration cycle. Turbine, in power cycle, was driven by organic working fluid that exits boiler with high temperature and pressure. Theoretical performances of proposed system were evaluated employing five different organic fluids which are R123, R600, R245fa, R141b, and R600a. Moreover, the change of thermal and exergy efficiencies were examined by changing the boiling, condensing, and evaporating temperatures. As a result of energy and exergy analysis of the proposed system, most appropriate organic working fluid was determined as R141b.

scholarly journals Research on Performance Test Characteristics of Solar Energy ORC Generator Set

2018 ◽  
Vol 232 ◽  
pp. 04007
Author(s):  
Yongkang Zhang ◽  
Jinghui Song ◽  
Yunfeng Xia
Keyword(s):  
Heat Transfer ◽  
Power Generation ◽  
Heat Source ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Source Condition ◽  
Power Cycle ◽  
Solar Powered ◽  
Regenerative Cycle

In order to study the performance of low-temperature solar-powered ORC generator sets, a solar-powered ORC power generation test bench was designed and built. In the experiment, R-123 was used as the organic Rankine cycle working fluid, and the solar ORC power generation system was experimentally studied. The research results show that when the direct solar radiation intensity is about 400W, the temperature of the heat transfer oil at the outlet of the collector can reach 140 °C. When the temperature of the heat transfer oil at the outlet of the collector is around 110°C, the collector efficiency of the collector can reach about 60%. Under the heat source condition, when the power cycle part is switched from the basic cycle to the regenerative cycle mode, the collector heat collection efficiency can reach about 60%. Under the heat source condition, when the power cycle part is switched from the basic cycle mode to the regenerative cycle mode, the measured efficiency is increased from 9.3% to 10.8%, and the measured cycle efficiency is increased from 1.57% to 1.67%, which is an increase of 6.07%. The measured cycle system efficiency is about 10%, and the heat recovery mode is slightly higher than the basic cycle mode. The organic Rankine cycle performance under different working fluid flows was also investigated in the experiment. The maximum measured average power was 386.27 W when the working fluid flow was 6.88 kg·s. At a certain heat source temperature, as the flow rate of the working fluid increases, the inlet pressure of the expander increases, and the circulating output work also increases. Under a certain working fluid flow rate, as the temperature of the heat source increases, the temperature of the inlet of the expander increases, and the inlet pressure increases. the cycle output work also increased.

scholarly journals Effect of Two Different Heat Transfer Fluids on the Performance of Solar Tower CSP by Comparing Recompression Supercritical CO2 and Rankine Power Cycles, China

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3426
Author(s):  
Ephraim Bonah Agyekum ◽  
Tomiwa Sunday Adebayo ◽  
Festus Victor Bekun ◽  
Nallapaneni Manoj Kumar ◽  
Manoj Kumar Panjwani
Keyword(s):  
Heat Transfer ◽  
Supercritical Co2 ◽  
Rankine Cycle ◽  
First Year ◽  
Concentrated Solar Power ◽  
Power Cycles ◽  
Power Cycle ◽  
Pollution Levels ◽  
Heat Transfer Fluids ◽  
Cost Of Energy

China intends to develop its renewable energy sector in order to cut down on its pollution levels. Concentrated solar power (CSP) technologies are expected to play a key role in this agenda. This study evaluated the technical and economic performance of a 100 MW solar tower CSP in Tibet, China, under different heat transfer fluids (HTF), i.e., Salt (60% NaNO3 40% KNO3) or HTF A, and Salt (46.5% LiF 11.5% NaF 42% KF) or HTF B under two different power cycles, namely supercritical CO2 and Rankine. Results from the study suggest that the Rankine power cycle with HTF A and B recorded capacity factors (CF) of 39% and 40.3%, respectively. The sCO2 power cycle also recorded CFs of 41% and 39.4% for HTF A and HTF B, respectively. A total of 359 GWh of energy was generated by the sCO2 system with HTF B, whereas the sCO2 system with HTF A generated a total of 345 GWh in the first year. The Rankine system with HTF A generated a total of 341 GWh, while the system with B as its HTF produced a total of 353 GWh of electricity in year one. Electricity to grid mainly occurred between 10:00 a.m. to 8:00 p.m. throughout the year. According to the results, the highest levelized cost of energy (LCOE) (real) of 0.1668 USD/kWh was recorded under the Rankine cycle with HTF A. The lowest LCOE (real) of 0.1586 USD/kWh was obtained under the sCO2 cycle with HTF B. In general, all scenarios were economically viable at the study area; however, the sCO2 proved to be more economically feasible according to the simulated results.

Study of Buoyancy Effects on Supercritical CO2 Heat Transfer in Circular Pipes

2020 ◽  
Author(s):  
Akshay Khadse ◽  
Ladislav Vesely ◽  
James Sherwood ◽  
Andres Curbelo ◽  
Vipul Goyal ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Cross Sections ◽  
Supercritical Co2 ◽  
High Pressures ◽  
Cooling System ◽  
Reduction Process ◽  
Density Variation ◽  
Working Fluid ◽  
Power Cycle

Abstract Supercritical CO2 (sCO2) can be utilized as a working fluid in various systems including high scale power cycle, portable power production unit, centralized cooling system and standalone cooling device. Lack of accurate predication tools such as heat transfer coefficient correlations and insufficient knowledge behind fundamental heat transfer processes can hinder its practical realization in key energy and cooling systems. The overall objective of the proposed study is to extend fundamental knowledge about heat transfer and fluid flow processes in conduits pertinent to sCO2 power cycle with an emphasis on buoyancy effects. Operational requirement of high pressures and temperatures for intended applications put a significant amount of constraints on measurement strategy and instrumentation. For this paper, experiments were conducted with uniform volumetric heat generation within pipe wall, for a single Reynolds number of 16,600 at test section inlet. The designed test apparatus and data reduction process are validated with high pressure air experiments, complemented by companion computations. Nusselt number was found to be within 10% of conventional correlations. For the test parameters and pipe size selected, factors of 2 to 4 variations in circumferential Nusselt number distributions are observed in sCO2 flow. Richardson number and other similar parameters to indicate importance of buoyancy-driven flow phenomena suggest that buoyancy forces caused by large density variation of sCO2 in flow cross-sections may cause the observed circumferential variations in Nusselt number.

Selection of Working Fluids for Low-Temperature Power Generation Organic Rankine Cycles System

2012 ◽  
Vol 557-559 ◽  
pp. 1509-1513 ◽  
Author(s):  
Zhong He Han ◽  
Yi Da Yu
Keyword(s):  
Low Temperature ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Heat Sources ◽  
Working Fluids ◽  
Cycle System ◽  
Organic Rankine Cycles ◽  
Organic Fluids ◽  
Cycle Efficiency

A Rankine cycle using organic fluids as working fluids, called organic Rankine cycle (ORC), is potentially feasible in recovering low enthalpy containing heat sources. The choices of fluids should meet the requirement of environment, safety, critical pressure and critical temperature etc. Under the proposed working conditions, R600a, R245fa, R236fa, R236ea, R227ea are chosen as the working fluids of the low-temperature Rankine cycle system, then those fluids are investigated and compared from cycle efficiency, work ratio, exergy efficiency, irreversible loss. The results show that R245fa is an available and effective working fluid for low-temperature Rankine cycle.

Theoretical and experimental investigation of an organic Rankine cycle for a waste heat recovery system

2009 ◽  
Vol 223 (5) ◽  
pp. 523-533 ◽  
Author(s):  
W Gu ◽  
Y Weng ◽  
Y Wang ◽  
B Zheng
Keyword(s):  
Heat Source ◽  
Entropy Generation ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Entropy Generation Rate ◽  
Working Fluid ◽  
Total Entropy ◽  
Waste Heat Recovery System ◽  
Cycle Efficiency

This article describes and evaluates an organic Rankine cycle (ORC) for a waste heat recovery system by both theoretical and experimental studies. Theoretical analysis of several working fluids shows that cycle efficiency is very sensitive to evaporating pressure, but insensitive to expander inlet temperature. Second law analysis was carried out using R600a as a working fluid and a flow of hot air as a heat source, which is not isothermal, along the evaporator. The result discloses that the evaporator's internal and external entropy generation is the main source of total entropy generation. The effect of the heat source temperature, evaporating pressure, and evaporator size on the entropy generation rate is also presented. The obtained useful power is directly linked to the total entropy generation rate according to the Gouy—Stodola theorem. The ORC testing system was established and operated using R600a as a working fluid and hot water as a heat source. The maximum cycle efficiency of the testing system is 5.2 per cent, and the testing result also proves that cycle efficiency is insensitive to heat source temperature, but sensitive to evaporating pressure. The entropy result also shows that internal and external entropy of the evaporator is the main source of total entropy generation.

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