Comparison of direct and indirect natural draft dry cooling tower cooling of the sCO2 Brayton cycle for concentrated solar power plants

Duniam, Sam; Jahn, Ingo; Hooman, Kamel; Lu, Yuanwei; Veeraragavan, Ananthanarayanan

doi:10.1016/j.applthermaleng.2017.10.169

Cited by 46 publications

(29 citation statements)

References 23 publications

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“…Beside novel structure, some novel heat transfer fluid is also applied for the solar receiver and solar thermal power. Duniam et al [30] proposed the sCO 2 Brayton cycle for concentrated solar power plants, and sCO 2 can be an important heat transfer fluid for the receiver, heat exchange and power cycle. Guo et al [31] analyzed the thermodynamic performance CO 2 -based binary mixtures within the molten salt solar power tower system.…”

Section: Introductionmentioning

confidence: 99%

Nonuniform Heat Transfer Model and Performance of Molten Salt Cavity Receiver

Wang

Ding

2020

Energies

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The temperature distribution and thermal efficiency of a molten salt cavity receiver are investigated by a nonuniform heat transfer model based on thermal resistance analysis. For the cavity receiver MSEE in Sandia National Laboratories, thermal efficiency in this experiment is about 87.5%, and the calculation value of 86.93–87.79% by a present nonuniform model fits very well with the experimental result. Different from the uniform heat transfer model, the receiver surface temperature in the nonuniform heat transfer model is remarkably higher than the backwall temperature. The incident radiation flux plays a primary role in thermal performance of cavity receiver, and thermal efficiency approaches to maximum under optimal incident radiation flux. In order to increase thermal efficiency, various methods are proposed and studied, including heat convection enhancement by an increase of flow velocity or the decrease of the tube diameter and number of tubes in the panel, and heat loss decline by a decrease of view factor, surface emissivity and insulation conductivity. According to calculation results by different modes of the nonuniform heat transfer model, the thermal efficiency of the cavity receiver is reduced by nonuniform heat transfer caused by variable fluid temperature or variable circumferential temperature, so thermal efficiency calculated by variable fluid temperature and variable circumferential temperature is lower than that calculated by average fluid temperature and bilateral uniform circumferential temperature for 0.86%.

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Section: Introductionmentioning

confidence: 99%

Nonuniform Heat Transfer Model and Performance of Molten Salt Cavity Receiver

Wang

Ding

2020

Energies

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“…The numerical model was validated using the experimental results published by Adebiyi and Hall which is close to the value of interest for large size FTHEs designs [50]. The sCO2 inlet temperature is 15.4℃ (referring to test case 1.2 in Table 3-2).…”

Section: Validation Of Numerical Solutionmentioning

confidence: 70%

“…For the simulations for the two other tube diameters of 15.75 mm and 24.36 mm, the generated meshes maintain this same approximate + value. solar power plant [50]. This value is also located within the mass flux range that is applicable to most sCO2 heat exchanger (gas coolers) designs [22,24,33,38,39,194,205].…”

Section: Appropriateness Of Simulation Tool To Sco2 Cooling and Grid mentioning

confidence: 81%

“…For the proposed sCO2 Brayton cycles in CST applications [65,178,179], the cooling system, that works near the critical point, is a crucial component. Preliminary research [50] demonstrated that in this application, higher cycle efficiencies and more compact cooling tower designs could be achieved using direct air-cooling compared to indirect cooling that would involve a separate cooling water loop. In direct cooling, the air-cooled finned tube heat exchangers (FTHEs) employed in the Natural Draft Dry Cooling Tower (NDDCT) need large pipes to reduce the pressure drop, to increase the heat rejection and to meet the higher sCO2 mass flow rate required for such applications (compared to those in residential air-conditioning and refrigeration systems).…”

Section: Introductionmentioning

confidence: 99%

“…The proposed sCO2 Brayton cycle for CST power generation [64,212] will benefit from direct cooling of sCO2 that outperforms the indirect cooling in terms of cycle efficiency and cooling tower compactness [50].With direct cooling, the sCO2 transfers heat directly to the main cooling medium, which is going to be air for most future CST power plants in Australia which will be built inland with limited access to water. Instead of those small diameter tubes ( ≤ 10.7 mm) used in the residential air-conditioning and refrigeration applications, the air-cooled finned tube heat exchangers (FTHEs) employed in direct cooling of natural draft dry cooling towers (NDDCTs) need to be large pipes (diameter might be over than 20 mm [50]) to reduce the pressure drop at the high sCO2 mass flow rates for such applications. Lower pressure drops and higher Nusselt numbers were found in past experimental research with larger tube diameters [22,33,43,44], and pipe diameter has a substantial impact on the applicability range of the heat transfer equations [39,43,194].…”

Section: Introductionmentioning

confidence: 99%

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Computational investigations on heat transfer of turbulent supercritical CO2 in large tubes using RANS modelling

Wang¹

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Owing to the potential to offer higher cycle efficiency, supercritical carbon dioxide (sCO2) is considered as the promising alternative to replace conventional working fluids, such as steam, for the next-generation power cycles embedded in Concentrating Solar Thermal (CST) applications. Gaining in-depth understandings on flow and heat transfer characteristics of turbulent sCO2 near critical point Publications included in this thesisWith permission by the University of Queensland Policy 4.60.07 (Alternate Thesis Format Options), scholarly works during candidature are included and form the main parts of this thesis. The contexts of four chapters (Chapter 3, 4, 5 and 6) have been published in peer reviewed journals and the review work (Chapter 2) has been submitted to a peer-review journal. Clear statements of authorship and contribution are provided as follows.

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Techno‐economic analysis of a hybrid solar‐geothermal power plant integrated with a desalination system

Aviles

Sabri

Hooman

2021

Intl J of Energy Research

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This paper proposes the use of a hybrid 5 MW power generation system combining concentrated solar thermal and solar photovoltaic technology where the efficiency of the power block is increased by taking advantage of hot water from a low-temperature geothermal source. Aiming at a case study for Winton in Queensland the pertinent meteorological data are used for our simulations.In addition, the paper analyzes the feasibility of including a thermal desalination technology that uses the waste heat from the power block for producing clean water from wastewater. Our design replaces the traditional dry cooling system with a water-cooled heat exchanger to remove the waste heat from the power block. Finally, this work explores the ratio of concentrated solar thermal and photovoltaic electricity production that optimizes the levelized cost of electricity and water production. the results indicate that the incorporation of the desalination system does not produce a significant increase in this value, and the optimal ratio of electricity production is obtained when the photovoltaic system contributes to 27.5% of the total electricity generation. Our water production cost can be as low as 40 ₵/m 3 while for the combined system our minimum levelized cost of electricity figures out at 12.4 ₵/kWh to generate the base load with thermal storage.

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Comparison of direct and indirect natural draft dry cooling tower cooling of the sCO2 Brayton cycle for concentrated solar power plants

Cited by 46 publications

References 23 publications

Nonuniform Heat Transfer Model and Performance of Molten Salt Cavity Receiver

Nonuniform Heat Transfer Model and Performance of Molten Salt Cavity Receiver

Computational investigations on heat transfer of turbulent supercritical CO2 in large tubes using RANS modelling

Techno‐economic analysis of a hybrid solar‐geothermal power plant integrated with a desalination system

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