Numerical analysis of heat transfer to water flowing in rifled tubes at supercritical pressures

Shen, Zhi; Yang, Dong; Li, Yaode; Liang, Ziyu; Wan, Luoma

doi:10.1016/j.applthermaleng.2018.01.053

Cited by 17 publications

(2 citation statements)

References 16 publications

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“…A turbulence model was used to calculate ε and 𝑘 to close the equations. Previous simulations of supercritical water in vertical IRTs [20,21] have indicated that the SST k-ω model gives better predictions for supercritical fluids in IRTs and is accurate in the near-wall region. Hence, the SST model is used in present study.…”

Section: Turbulence Modelmentioning

confidence: 99%

Numerical Study of Supercritical R134a Heat Transfer in a Horizontal Ribbed Tube for Trans-Critical ORC Systems

Wang¹,

Lu²,

Fang³

et al. 2021

Proceedings of the 2nd International Conference on Fluid Flow and Thermal Science (ICFFTS'21)

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Internally ribbed tubes can improve TORC (Trans-critical Organic Rankine Cycle) heat transfer economics and safety by improving the heat transfer coefficient and restricting buoyancy effects in horizontal flows. The heat transfer characteristics of supercritical organic fluids in internally ribbed tubes need to be more thoroughly understood. The present study calculated the flow and temperature fields in a horizontal ribbed tube to analyze the heat transfer enhancement of super critical R134a and the buoyancy effects on the heat transfer. The results show that the heat transfer enhancement near the pseudo critical point is mainly caused by the large specific heat effect in the boundary layer. The buoyancy enhances the radial direction velocities (x and y directions) and reduces the axial speed (z direction) along the top of the horizontal tube. The lower axial speed reduces the turbulent kinetic energy and the top side heat transfer coefficient as a result. The simulation results were also compared with the heat transfer in a smooth horizontal tube and vertical ribbed tube with upwards flow. The results showed that the spiral follow induced by the internal ribs strongly restricts the buoyancy flow. Vertical upwards flow has a higher overall heat transfer coefficient and no circumferential temperature gradients, which improves the heat transfer economics and safety in TORC systems. Hence, vertical flow heat exchangers should be considered in TORC systems due to the improved heat transfer.

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Section: Turbulence Modelmentioning

confidence: 99%

Numerical Study of Supercritical R134a Heat Transfer in a Horizontal Ribbed Tube for Trans-Critical ORC Systems

Wang¹,

Lu²,

Fang³

et al. 2021

Proceedings of the 2nd International Conference on Fluid Flow and Thermal Science (ICFFTS'21)

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“…The results of numerical and experimental analyses of the process of the heat exchange between a vertical rifled tube and the water flowing up inside are presented in [1]. It was established that the inner wall temperature varied in the circumferential direction, reaching the highest values at the intersection of the rib base and the front wall, and the lowest values-at the intersection of the rib tip and the tube rear wall.…”

Section: Introductionmentioning

confidence: 99%

Testing of Heat Transfer Coefficients and Frictional Losses in Internally Ribbed Tubes and Verification of Results through CFD Modelling

Grądziel

Majewski²,

Majdak

et al. 2021

Energies

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This paper presents experimental determination of the heat transfer coefficient and the friction factor in an internally rifled tube. The experiment was carried out on a laboratory stand constructed in the Department of Energy of the Cracow University of Technology. The tested tube is used in a Polish power plant in a supercritical circulating fluidized bed (CFB) boiler with the power capacity of 460 MW. Local heat transfer coefficients were determined for Reynolds numbers included in the range from ~6000 to ~50,000, and for three levels of the heating element power. Using the obtained experimental data, a relation was developed that makes it possible to determine the dimensionless Chilton–Colburn factor. The friction factor was also determined as a function of the Reynolds number ranging from 20,000 to 90,000, and a new correlation was developed that represents the friction factor in internally ribbed tubes. The local heat transfer coefficient and the friction factor obtained during the testing were compared with the CFD modelling results. The modelling was performed using the Ansys Workbench application. The k-ω, the k-ε and the transition SST (Share Stress Transport) turbulence models were applied.

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Numerical Simulation on Heat Transfer Characteristics of Steam-Water Two-Phase Flow in Smooth Tube and Rifled Tube

Sun

Shi

et al. 2021

Advances in Heat Transfer and Thermal Engineering

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Numerical analysis of heat transfer to water flowing in rifled tubes at supercritical pressures

Cited by 17 publications

References 16 publications

Numerical Study of Supercritical R134a Heat Transfer in a Horizontal Ribbed Tube for Trans-Critical ORC Systems

Numerical Study of Supercritical R134a Heat Transfer in a Horizontal Ribbed Tube for Trans-Critical ORC Systems

Testing of Heat Transfer Coefficients and Frictional Losses in Internally Ribbed Tubes and Verification of Results through CFD Modelling

Numerical Simulation on Heat Transfer Characteristics of Steam-Water Two-Phase Flow in Smooth Tube and Rifled Tube

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