Effect of Pressure Drop on Thermal and Exergetic Performance of Supercritical CO2 Recompression Brayton Cycle Integrated With a Central Receiver

2016 ◽  
Author(s):  
Ricardo Vasquez Padilla ◽  
Yen Soo Too ◽  
Andrew Beath ◽  
Robbie McNaughton ◽  
Wes Stein
Keyword(s):  
Pressure Drop ◽  
Surface Temperature ◽  
Supercritical Co2 ◽  
Brayton Cycle ◽  
Concentrated Solar Power ◽  
Pressure Drops ◽  
Effect Of Pressure ◽  
Central Receiver ◽  
Solar Receiver ◽  
Exergy Performance

Concentrated Solar Power using supercritical CO2 (S-CO2) Brayton cycles offers advantages of similar and even higher overall thermal efficiencies compared to conventional Rankine cycles using superheated or supercritical steam. In this paper, a S-CO2 Recompression Brayton cycle is integrated with a central receiver. The effect of pressure drops in heat exchangers and solar receiver surface temperature on the thermal and ex-ergetic performance of the recompression Brayton cycle with and without reheat condition is studied. Energy, exergy and mass balance are carried out for each component and first law and exergy destruction are calculated. In order to obtain optimal operating condition, optimum cycle pressure ratios are obtained by maximising the thermal efficiency. The results showed that under low solar receiver pressure drops and solar receiver temperature approach, the S-CO2 Recompression Brayton cycle has more thermal and exergy efficiencies than the no reheat case. Pressure drop reduces the gap between reheat and no reheat case, and for pressure drops in the solar receiver of 2.5% or higher, reheat has significant impact on thermal and exergy performance of the cycle studied. The overall exergy efficiency showed a bell shaped, reaching a maximum value between 19.5–22.5% at turbine inlet temperatures in the range of 660–755 °C for solar receiver surface temperature approach among 100–200 °C.

Effect of Pressure Drop and Reheating on Thermal and Exergetic Performance of Supercritical Carbon Dioxide Brayton Cycles Integrated With a Solar Central Receiver

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Ricardo Vasquez Padilla ◽  
Yen Chean Soo Too ◽  
Andrew Beath ◽  
Robbie McNaughton ◽  
Wes Stein
Keyword(s):  
Carbon Dioxide ◽  
Pressure Drop ◽  
Supercritical Carbon Dioxide ◽  
Surface Temperature ◽  
Brayton Cycle ◽  
Pressure Drops ◽  
Central Receiver ◽  
Maximum Value ◽  
Solar Receiver ◽  
Exergy Performance

Concentrated solar power using supercritical carbon dioxide (S-CO2) Brayton cycles offers advantages of similar or higher overall thermal efficiencies than conventional Rankine cycles using superheated or supercritical steam. The high efficiency and compactness of S-CO2, as compared with steam Rankine cycles operating at the same temperature, make this cycle attractive for solar central receiver applications. In this paper, S-CO2 Brayton cycle is integrated with a solar central receiver that provides heat input to the power cycle. Three configurations were analyzed: simple, recompression (RC), and recompression with main intercooling (MC). The effect of pressure drop in heat exchangers and solar receiver and solar receiver surface temperature on the thermal and exergetic performance of the CO2 Brayton cycle with and without reheat condition was studied. Energy, exergy, and mass balance were carried out for each component and the cycle first law and exergy efficiencies were calculated. In order to obtain optimal operating conditions, optimum pressure ratios were obtained by maximizing the cycle thermal efficiency under different pressure drops and solar receiver temperature conditions. Optimization of the cycle first law efficiency was carried out in python 2.7 by using sequential least squares programing (SLSQP). The results showed that under low pressure drops, adding reheat to the S-CO2 Brayton cycle has a favorable effect on the thermal and exergy efficiencies. Increasing pressure drop reduces the gap between efficiencies for reheat and no reheat configuration, and for pressure drop factors in the solar receiver above 2.5%, reheat has a negligible or detrimental effect on thermal and exergy performance of S-CO2 Brayton cycles. Additionally, the results showed that the overall exergy efficiency has a bell shape, reaching a maximum value between 18.3% and 25.1% at turbine inlet temperatures in the range of 666–827 °C for different configurations. This maximum value is highly dependent on the solar receiver surface temperature, the thermal performance of the solar receiver, and the solar field efficiency. As the solar receiver surface temperature increases, more exergy destruction associated with heat transfer losses to the environment takes place in the solar receiver and therefore the overall exergy efficiency decreases. Recompression with main intercooling (MC) showed the best thermal (ηI,cycle > 47% at Tin,turbine > 700 °C) and exergy performance followed by RC configuration.

Design of an Experimental Test Facility for Supercritical CO2 Brayton Cycle

2014 ◽  
Author(s):  
Pardeep Garg ◽  
Pramod Kumar ◽  
Pradip Dutta ◽  
Thomas Conboy ◽  
Clifford Ho
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Supercritical Co2 ◽  
Exchange Process ◽  
Test Facility ◽  
Brayton Cycle ◽  
Pressure Drops ◽  
Loop Design ◽  
Indian Institute Of Science ◽  
Cycle Temperature

A supercritical CO2 test facility is currently being developed at Indian Institute of Science, Bangalore, India to analyze the performance of a closed loop Brayton cycle for concentrated solar power (CSP) generation. The loop has been designed for an external heat input of 20 kW, a pressure range of 75–135 bar, flow rate of 11 kg/min, and a maximum cycle temperature of 525 °C. The operation of the loop and the various parametric tests planned to be performed are discussed in this paper. The paper addresses various aspects of the loop design with emphasis on design of various components such as regenerator and expansion device. The regenerator design is critical due to sharp property variations in CO2 occurring during the heat exchange process between the hot and cold streams. Two types of heat exchanger configurations 1) tube-in-tube (TITHE) and 2) printed circuit heat exchanger (PCHE) are analyzed and compared. A PCHE is found to be ∼5 times compact compared to a TITHE for identical heat transfer and pressure drops. The expansion device is being custom designed to achieve the desired pressure drop for a range of operating temperatures. It is found that capillary of 5.5 mm inner diameter and ∼2 meter length is sufficient to achieve a pressure drop from 130 to 75 bar at a maximum cycle temperature of 525 °C.

scholarly journals A Novel Solar Receiver for Supercritical CO2 Brayton Cycle

2019 ◽  
Vol 158 ◽  
pp. 339-344 ◽  
Author(s):  
Liang Teng ◽  
Yimin Xuan
Keyword(s):  
Supercritical Co2 ◽  
Brayton Cycle ◽  
Solar Receiver

Dimensionless Analysis of Pressure Drop and Heat Transfer on HTGR Coupled With Closed Brayton Cycle

2010 ◽  
Author(s):  
Zhenjia Yu ◽  
Xiaoyong Yang ◽  
Xiaoli Yu ◽  
Jie Wang
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Compression Ratio ◽  
High Efficiency ◽  
Great Influence ◽  
Brayton Cycle ◽  
Local Pressure ◽  
Reynolds Analogy ◽  
Pressure Drops ◽  
Frictional Pressure Drop

High temperature gas-cooled reactor with direct helium turbine cycle is based on the closed Brayton cycle. Its outstanding feature is the high efficiency of power generation. Pervious researches showed that recuperator was the key component to promote the cycle’s efficiency. And pressure drops in components were unavoidable in actual projects and had significant influence on cycle efficiency. A dimensionless model was proposed to analyze cycle’s features of HTGR coupled with gas turbine. The parameters’ effect on cycle’s efficiency was analyzed, with full consideration of the frictional and local pressure drops respectively. Under the restriction of materials and state-of-art of technologies, it showed that the cycle’s efficiency depended on compression ratio, recuperator’s effectiveness and pressure drops of components. However the pressure drop ratios of different components were inherently connected due to the closed cycle. Furthermore pressure drops inside the recuperator were also the function of effectiveness of the heat transfer based on the Reynolds analogy. Therefore cycle’s efficiency just depended on recuperator’s effectiveness with fixed compression ratio. So there existed optimal recuperator’s effectiveness and maximum cycle’s efficiency, which varied with the pressure ratio and other parameters as temperature ratio. The calculation also indicated that the pressure drop in pipes was close to that in heat exchangers. That was, the local pressure drop and frictional pressure drop should be considered respectively, and the local pressure drop made quite large reduction of cycle’s efficiency. The result also showed that local pressure drop had great influence on parameters such as optimal compression ratio and recuperator’s effectiveness.

scholarly journals Pressure drop and stability of flow in Archimedean spiral tube with transverse corrugations

2016 ◽  
Vol 20 (2) ◽  
pp. 579-591 ◽  
Author(s):  
Milan Djordjevic ◽  
Velimir Stefanovic ◽  
Marko Mancic
Keyword(s):  
Pressure Drop ◽  
High Heat ◽  
Geometrical Parameters ◽  
Archimedean Spiral ◽  
Number Range ◽  
Spiral Tube ◽  
Pressure Drops ◽  
Transfer Rates ◽  
High Heat Transfer ◽  
Solar Receiver

Isothermal pressure drop experiments were carried out for the steady Newtonian fluid flow in Archimedean spiral tube with transverse corrugations. Pressure drop correlations and stability criteria for distinguishing the flow regimes have been obtained in a continuous Reynolds number range from 150 to 15 000. The characterizing geometrical groups which take into account all the geometrical parameters of Archimedean spiral and corrugated pipe has been acquired. Before performing experiments over the Archimedean spiral, the corrugated straight pipe having high relative roughness e/d = 0.129 of approximately sinusoidal type was tested in order to obtain correlations for the Darcy friction factor. Insight into the magnitude of pressure loss in the proposed geometry of spiral solar receiver for different flow rates is important because of its effect upon the efficiency of the receiver. Although flow in spiral and corrugated geometries has the advantages of compactness and high heat transfer rates, the disadvantage of greater pressure drops makes hydrodynamic studies relevant.

Viability Assessment of a Concentrated Solar Power Tower With a Supercritical CO2 Brayton Cycle Power Plant

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Ali Sulaiman Alsagri ◽  
Andrew Chiasson ◽  
Mohamed Gadalla
Keyword(s):  
Energy Storage ◽  
Molten Salt ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Supercritical Co2 ◽  
Solar Power ◽  
Capacity Factor ◽  
Brayton Cycle ◽  
Concentrated Solar Power ◽  
Solar Power Tower

The aim of this study was to conduct thermodynamic and economic analyses of a concentrated solar power (CSP) plant to drive a supercritical CO2 recompression Brayton cycle. The objectives were to assess the system viability in a location of moderate-to-high-temperature solar availability to sCO2 power block during the day and to investigate the role of thermal energy storage with 4, 8, 12, and 16 h of storage to increase the solar share and the yearly energy generating capacity. A case study of system optimization and evaluation is presented in a city in Saudi Arabia (Riyadh). To achieve the highest energy production per unit cost, the heliostat geometry field design integrated with a sCO2 Brayton cycle with a molten-salt thermal energy storage (TES) dispatch system and the corresponding operating parameters are optimized. A solar power tower (SPT) is a type of CSP system that is of particular interest in this research because it can operate at relatively high temperatures. The present SPT-TES field comprises of heliostat field mirrors, a solar tower, a receiver, heat exchangers, and two molten-salt TES tanks. The main thermoeconomic indicators are the capacity factor and the levelized cost of electricity (LCOE). The research findings indicate that SPT-TES with a supercritical CO2 power cycle is economically viable with 12 h thermal storage using molten salt. The results also show that integrating 12 h-TES with an SPT has a high positive impact on the capacity factor of 60% at the optimum LCOE of $0.1078/kW h.

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