Effects of Volute Structure on Energy Performance and Rotor Operational Stability of Molten Salt Pumps

Li, Q.; Zhang, R.; Xu, H.

doi:10.47176/jafm.16.08.1741

Effects of Volute Structure on Energy Performance and Rotor Operational Stability of Molten Salt Pumps

Document Type : Regular Article

Authors

¹ College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China

² College of Agricultural Science and Engineering, Hohai University, Nanjing 211100, China

10.47176/jafm.16.08.1741

Abstract

A double-volute molten salt pump with two outlet pipes is proposed based on the original pump model. A numerical approach coupling finite element analysis and computational fluid dynamics (CFD) is implemented to investigate the operational stability and energy performance of two molten salt centrifugal pumps for high-temperature molten salt. The entropy production of the single-volute and double-volute molten salt pumps is investigated. The effects of the volute structures on the mechanical behavior of the impeller and shaft are considered. According to the findings, the local entropy production in the molten salt pump is dominated by the local pulsating entropy production (Spro-T), with the double-volute scheme achieving reduced energy loss. A visualization of the flow field and the local entropy production rate (LEPR) distributions indicate that the LEPR is positively correlated with the complexity of the flow, and higher levels of turbulence intensity lead to greater LEPR. The double-volute scheme enhances the complexity of the flow in the impeller, resulting in an increase in the LEPR compared with the single-volute design. However, the LEPR in the whole double-volute molten salt pump is reduced compared with the single-volute design. It is discovered that the double-volute molten salt pump experiences a less radial hydraulic force. Although the double-volute design has a slightly higher maximum equivalent stress on the impeller than the single-volute scheme, the rotor deformation is significantly less. In general, the double-volute scheme reduces energy loss and ensures better structural stability.

Keywords

Main Subjects

Pumps and hydraulic turbines

References

Barth, D. L., Pacheco, J. E., Kolb, W. J., & Rush, E. E. (2002). Development of a high-temperature, long-shafted, molten-salt pump for power tower applications. Journal of Solar Energy Engineering, 124(2), 170–175. https://doi.org/10.1115/1.1464126##

Cheng, W. J., Gu, B. Q., & Shao, C. L. (2017a). A numerical study on the steady flow in molten salt pump under various conditions for improved hydraulic performance. International Journal of Numerical Methods for Heat and Fluid Flow, 27(8), 1870–1886. https://doi.org/10.1108/HFF-06-2016-0238##

Cheng, W. J., Gu, B. Q., Shao, C. L., & Wang, Y. (2017b). Hydraulic characteristics of molten salt pump transporting solid-liquid two-phase medium. Nuclear Engineering and Design, 324, 220–230. https://doi.org/10.1016/j.nucengdes.2017.08.036##

Cheng, W. J., Shao, C. L., & Zhou, J. F. (2019). Unsteady study of molten salt pump conveying mediums with different viscosities. International Journal of Heat and Mass Transfer, 137, 174–183. https://doi.org/10.1016/j.ijheatmasstransfer.2019.03.095##

Duan, L., Wu, X. L., Ji, Z. L. & Fang, Q. X. (2015). Entropy generation analysis on cyclone separators with different exit pipe diameters and inlet dimensions. Chemical Engineering Science, 138, 622–633. https://doi.org/10.1016/j.ces.2015.09.003##

Egusquiza, E., Valero, C., Huang, X. X., Jou, E., Guardo, A., & Rodriguez, C. (2012). Failure investigation of a large pump-turbine runner. Engineering Failure Analysis, 23, 27–34. https://doi.org/10.1016/j.engfailanal.2012.01.012##

Fei, Z. D., Zhang, R., Xu, H., Feng, J. G., Mu, T. & Chen, Y. H. (2022). Energy performance and flow characteristics of a slanted axial-flow pump under cavitation conditions. Physics of Fluids, 34(3), 035121. https://doi.org/10.1063/5.0085388##

Gao, Z. W., Wang, J., Liu, Z. X., Wei, Y. D., Wang, J. Y., & Mao, Y. (2020). Effects of different inlet structures on the flow field of cyclone separators. Powder Technology, 372, 519–531. https://doi.org/10.1016/j.powtec.2020.06.014##

Gu, J. R., Gao, B., Ni, D., Li, C., & Zhong, Y. M. (2022). Investigation on the unsteady pressure pulsations and related vortical structures in a molten salt pump. Energy Science and Engineeringو 10(8), 2858–2876. https://doi.org/10.1002/ese3.1175##

Gu, Y. D., Pei, J., Yuan, S. Q., Wang, W. J., Zhang, F., Wang, P., Appiah, D., & Liu, Y. (2019). Clocking effect of vaned diffuser on hydraulic performance of high-power pump by using the numerical flow loss visualization method. Energy, 170, 986–997. https://doi.org/10.1016/j.energy.2018.12.204##

Huan, Y. Y., Liu, Y. Y., Li, X. J., Zhu, Z. C., Qu, J. T., Zhe, L., & Han, A. D. (2021). Experimental and numerical investigations of cavitation evolution in a high-speed centrifugal pump with inducer. Journal of Hydrodynamics, 33(1), 140-149. https://doi.org/10.1007/s42241-021-0006-z##

Jin, Y. X., Zhang, D. S., Song, W. W., Shen, X., Shi, L., & Lu, J. X. (2022). Numerical study on energy conversion characteristics of molten salt pump based on energy transport theory. Energy, 244, 122674. https://doi.org/10.1016/j.energy.2021.122674##

Kang, C., Li, Q., Li, M. Y., & Teng, S. (2020). Deposition of solid particles exposed to the suction of dual pumps in the tank of a pumping station. Powder Technology, 361, 727–738. https://doi.org/10.1016/j.powtec.2019.11.049##

Kang, C., Lu, C., Seah, K. G. & Zhang, W. (2022). Cavitation characteristics during startup process of a condensate pump with splitter blades. Journal of Applied Fluid Mechanics, 15(4),1099-1109. https://doi.org/10.47176/jafm.15.04.1082##

Kang, C., Mao, N., Pan, C., Zhu, Y., & Li, B. (2017). Effects of short blades on performance and inner flow characteristics of a low-specific-speed centrifugal pump. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy, 231(A4), 290–302. https://doi.org/10.1177/0957650917695672##

Kang, C., Zhu, Y., & Li, Q. (2020). Effects of hydraulic loads and structure on operational stability of the rotor of a molten-salt pump. Engineering Failure Analysis, 117, 104821. https://doi.org/10.1016/j.engfailanal.2020.104821##

Kock, F., & Herwig, H. (2004). Local entropy production in turbulent shear flows: A high-Reynolds number model with wall functions. International Journal of Heat and Mass Transfer, 47(10), 2205–2215. https://doi.org/10.1016/j.ijheatmasstransfer.2003.11.025##

Kock, F., & Herwig, H. (2005). Entropy production calculation for turbulent shear flows and their implementation in CFD codes. International Journal of Heat and Fluid Flow, 26(4), 672–680. https://doi.org/10.1016/j.ijheatfluidflow.2005.03.005##

Kumar, M., Venkateshwaran, A., Kumar, M. S. S. P., Sreekanth, M., Jebaseelan, D., & Sivakumar, R. (2022). Strength analysis of a regenerative flow compressor and a pump based on fluid-structure coupling. Materials Today: Proceedings, 51, 1619–1624. https://doi.org/10.1016/j.matpr.2021.10.477##

Li, Q., Kang, C., Teng, S., & Li, M. Y. (2019). Optimization of tank bottom shape for improving the anti-deposition performance of a prefabricated pumping station. Water, 11(3), 602. https://doi.org/10.3390/w11030602##

Lin, T., Zhu, Z. C., Li, X. J., Li, J., & Lin, Y. P. (2021). Theoretical, experimental, and numerical methods to predict the best efficiency point of centrifugal pump as turbine. Renewable Energy, 168(5), 31-44. https://doi.org/10.1016/j.renene.2020.12.040##

Liu, C., Zhou, J. Z., Duan, R., Liu, Y., & He, Y. X. (2021). Fluid-structure coupling analysis of inlet ball valve on pumped-storage power station under extreme conditions. Journal of Physics: Conference Series, 1983(1), 012012. https://doi.org/10.1088/1742-6596/1983/1/012012##

Moshfeghi, M., Song, Y. J., & Yong, H. X. (2012). Effects of near-wall grid spacing on SST-K-ω model using NREL Phase VI horizontal axis wind turbine. Journal of Wind Engineering and Industrial Aerodynamics, 107–108, 94–105. https://doi.org/10.1016/j.jweia.2012.03.032##

Pei, J., Yuan, S. Q., & Yuan, J. P. (2014). Dynamic stress analysis of sewage centrifugal pump impeller based on two-way coupling method. Chinese Journal of Mechanical Engineering, 27(2), 369–375. https://doi.org/10.3901/CJME.2014.02.369##

Peiró, G., Gasia, J., Miró, L., Prieto, C. & Cabeza, L. F. (2017). Influence of the heat transfer fluid in a CSP plant molten salts charging process. Renewable Energy, 113, 148–158. https://doi.org/10.1016/j.renene.2017.05.083##

Shao, C. L. & Zhao, Y. (2017). Numerical study of the dimensionless characteristics and modeling experiment of a molten salt pump that transports viscous fluids. International Journal of Numerical Methods for Heat and Fluid Flow, 27(9), 2131–2153. https://doi.org/10.1108/HFF-07-2016-0267##

Shao, C. L., He, A. X., Zhang, Z. Y. & Zhou, J. F. (2019). Study on the transition process of a molten salt pump transporting media with crystalline particles by modeling test and numerical simulation. International Journal of Numerical Methods for Heat and Fluid Flow, 29(9), 3263–3289. https://doi.org/10.1108/HFF-12-2018-0807##

Shao, C. L., Zhou, J. F. & Cheng, W. J. (2015). Experimental and numerical study of external performance and internal flow of a molten salt pump that transports fluids with different viscosities. International Journal of Heat and Mass Transfer, 89, 627–640. https://doi.org/10.1016/j.ijheatmasstransfer.2015.05.087##

Smith, D. C., Rush, E. E., Matthews, C. W., Chavez, J. M., & Bator, P. A. (1994). Operation of Large-Scale Pumps and Valves in Molten Salt. Journal of Solar Energy Engineering, 116(3), 137–141. https://doi.org/10.1115/1.2930072##

Teng, S., Kang, C. & Zhou, M. (2020). Hydraulic characteristics and structural stability of the rotor of a molten-salt pump. Journal of Applied Science and Engineering, 23(1), 117–128. https://doi.org/10.6180/JASE.202003_23(1).0013##

Yu, A., Tang,Y. B., Tang, Q. H., Cai, J. G., Zhao, L. & Ge, X. F. (2022). Energy analysis of Francis turbine for various mass flow rate conditions based on entropy production theory. Renewable Energy, 183, 447–458. https://doi.org/10.1016/j.renene.2021.10.094##

Zhang, H. H., You, H. L., Lu, H. S., Li, K., Zhang, Z. Y. & Jiang, L. X. (2020). CFD-rotordynamics sequential coupling simulation approach for the flow-induced vibration of rotor system in centrifugal pump. Applied Sciences, 10(3), 1186. https://doi.org/10.3390/app10031186##

Zhang, Z. H., Dong, S. J., Jin, R. Z., Dong, K. J., Hou, L. A. & Wang, B. (2022). Vortex characteristics of a gas cyclone determined with different vortex identification methods. Powder Technology, 404, 117370. https://doi.org/10.1016/j.powtec.2022.117370##

Zhou, H., Shi, H., Lai, Z. Y., Zuo, Y. H., Hu, S. H. & Zhou, M. X. (2020). Migration and phase change study of leaking molten salt in tank foundation material. Applied Thermal Engineering, 170, 114968. https://doi.org/10.1016/j.applthermaleng.2020.114968##