Synergistic effects of a swirl generator and MXene/water nanofluids used in a heat exchanger pipe of a negative CO₂ emission gas power plant

Abstract

The focus on optimizing heat exchangers contributes to improved temperature control mechanisms, ensuring the sustainable operation of innovative power plants working toward negative CO₂ emissions. In the realm of oxy-combustion within Negative CO₂ Emission Power Plants (nCO₂PP), the temperature of combustion products surpasses 3000 $(\mathrm{K}).$ Addressing this challenge, the imperative arises to reduce these elevated temperatures to a manageable 1100$(°\mathrm{C}).$ This critical cooling process is achieved through the injection of water, facilitated by the implementation of heat exchangers. The study delves into the optimization of heat transfer within the heat exchanger pipe, specifically tailored for the context of a nCO₂PP. Employing a numerical simulation, the investigation explores the impact of vortex generator geometry, vane angles, single and dual propeller-type swirl generators, and the integration of a novel class of fluid, MXene/water nanofluid. Initially, the study scrutinizes propeller-type geometry at vane angles spanning from 15° to 60°. The enhanced swirl flow associated with lower vane angles leads to improved fluid mixing, fostering more effective heat transfer. Results showed that the 15-degree vane angle, with a wider circumferential coverage, may result in increased wall contact, influencing heat transfer efficiency. Subsequently, at Re = 6000, incremental rates of the Nusselt number ($\frac{{\mathit{\text{Nu}}}_n-{\mathit{\text{Nu}}}_s}{{\mathit{\text{Nu}}}_s}$%), for θ = 15°, 30°, 45°, and 60° are 175.1, 108.8, 90.7, and 40.3%, respectively. Also, the increment rates of Friction Factor $\left(\frac{f_n}{f_s}\right)$ for aforementioned vane angle are 38.48, 9.26, 4.08, and 2.42%, respectively. In addition, for ${\varnothing }_{\mathit{\text{MXene}}}=0.5\%,$ the Nusselt number experiences considerable increments of 22.94, 24.17, 24.70, and 24.707% at Reynolds numbers of 6000, 12,000, 18,000, and 24,000, respectively, compared to pure water, emphasizing the potential of MXene to enhance heat transfer efficiency.

Keywords:

• Heat exchanger
• MXene nanoparticles
• power plant, optimization
• swirl generator

Disclosure statement

No potential conflict of interest was reported by the author(s).

Authors’ Contributions

Milad Amiri: Conceptualization, Methodology, Data curation, Formal analysis, Investigation, Resources, Software, Validation, Visualization, Writing - original draft, Writing - review & editing. Paweł Ziółkowski: Data curation. Dariusz Mikielewicz: Conceptualization, Supervision, Project administration, Funding acquisition.

Additional information

Funding

The research leading to these results has received funding from the Norway Grants 2014–2021 via the National Center for Research and Development. Article has been prepared within the frame of the project: “Negative CO₂ emission gas power plant” - NOR/POLNORCCS/NEGATIVE-CO2- PP/0009/2019–00 which is co-financed by programme “Applied research” under the Norwegian Financial Mechanisms 2014–2021 POLNOR CCS 2019 - Development of CO₂ capture solutions integrated in power and industry processes.