Testing of Heat Transfer Coefficients and Frictional Losses in Internally Ribbed Tubes and Verification of Results through CFD Modelling
Sławomir Grądziel,
Karol Majewski,
Marek Majdak,
Łukasz Mika,
Karol Sztekler,
Rafał Kobyłecki,
Robert Zarzycki,
Małgorzata Pilawska
Affiliations
Sławomir Grądziel
Department of Energy, Faculty of Environmental Engineering and Energy, Cracow University of Technology, Jana Pawła II 37, 31-864 Cracow, Poland
Karol Majewski
Whirlpool Corporation, ul. Bora-Komorowskiego 6, 51-210 Wrocław, Poland
Marek Majdak
Department of Energy, Faculty of Environmental Engineering and Energy, Cracow University of Technology, Jana Pawła II 37, 31-864 Cracow, Poland
Łukasz Mika
Department of Thermal and Fluid Flow Machines, Faculty of Energy and Fuels, AGH University of Science and Technology, Mickiewicza 30, 30-059 Cracow, Poland
Karol Sztekler
Department of Thermal and Fluid Flow Machines, Faculty of Energy and Fuels, AGH University of Science and Technology, Mickiewicza 30, 30-059 Cracow, Poland
Rafał Kobyłecki
Department of Advanced Energy Technologies, Częstochowa University of Technology, Dąbrowskiego 69, 42-201 Częstochowa, Poland
Robert Zarzycki
Department of Advanced Energy Technologies, Częstochowa University of Technology, Dąbrowskiego 69, 42-201 Częstochowa, Poland
Małgorzata Pilawska
Department of Heat Processes, Air Protection and Waste Disposal, Faculty of Environmental Engineering and Energy, Cracow University of Technology, Warszawska 24, 31-155 Cracow, Poland
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.
