Performance comparison of heat exchangers using sextant/trisection helical baffles and segmental ones

doi:10.1016/j.cjche.2019.07.006

Abstract

Abstract: The shell side flow fields of both sextant and trisection helical baffle heat exchangers are presented on meridian and multilayer hexagon slices. It verifies that the performance of sextant schemes is better than those of the other kinds of helical baffle heat exchangers. The main mechanisms are due to the restricted leakage flow in the minimized gaps with increased baffle number and by one row of tubes dampen the leakage flow in the circumferential overlapped area of the adjacent helical baffles. The performance features were simulated on two different angled sextant helical heat exchangers and each compared with two trisection ones of either identical helical pitch or identical incline angle. The results verified that the performances of helical heat exchangers are mainly determined by the helical pitch rather than the baffle incline angle. The average values of comprehensive index h_oΔp_o^-1/3 of the trisection helical schemes T-24.1° and T-29.7° are correspondingly 3.47% and 3.34% lower than those of the sextant ones X-20° and X-25° with identical helical pitches. The comparison results show that the average values of shell side h.t.c. h_o and comprehensive index h_oΔp_o^-1/3 of the optimal dual helix sextant scheme DX30° are respectively 7.22% and 23.56% higher than those of the segment scheme S100.

Key words: Heat transfer, Computational fluid dynamics, Convection, Helical baffle heat exchangers, Sextant helical baffles

摘要： The shell side flow fields of both sextant and trisection helical baffle heat exchangers are presented on meridian and multilayer hexagon slices. It verifies that the performance of sextant schemes is better than those of the other kinds of helical baffle heat exchangers. The main mechanisms are due to the restricted leakage flow in the minimized gaps with increased baffle number and by one row of tubes dampen the leakage flow in the circumferential overlapped area of the adjacent helical baffles. The performance features were simulated on two different angled sextant helical heat exchangers and each compared with two trisection ones of either identical helical pitch or identical incline angle. The results verified that the performances of helical heat exchangers are mainly determined by the helical pitch rather than the baffle incline angle. The average values of comprehensive index h_oΔp_o^-1/3 of the trisection helical schemes T-24.1° and T-29.7° are correspondingly 3.47% and 3.34% lower than those of the sextant ones X-20° and X-25° with identical helical pitches. The comparison results show that the average values of shell side h.t.c. h_o and comprehensive index h_oΔp_o^-1/3 of the optimal dual helix sextant scheme DX30° are respectively 7.22% and 23.56% higher than those of the segment scheme S100.

关键词: Heat transfer, Computational fluid dynamics, Convection, Helical baffle heat exchangers, Sextant helical baffles

Yaping Chen, Hongling Tang, Jiafeng Wu, Huaduo Gu, Shifan Yang. Performance comparison of heat exchangers using sextant/trisection helical baffles and segmental ones[J]. Chinese Journal of Chemical Engineering, 2019, 27(12): 2892-2899.

Yaping Chen, Hongling Tang, Jiafeng Wu, Huaduo Gu, Shifan Yang. Performance comparison of heat exchangers using sextant/trisection helical baffles and segmental ones[J]. 中国化学工程学报, 2019, 27(12): 2892-2899.

References

[1] R. Bjørk, A. Sarhadi, N. Pryds, N. Lindeburg, P. Viereck, A thermoelectric power generating heat exchanger:Part I-Experimental realization, Energ. Convers. Manage. 119(2016) 473-480.
[2] J. Yang, W. Liu, Numerical investigation on a novel shell-and-tube heat exchanger with plate baffles and experimental validation, Energ. Convers. Manage. 101(2015) 689-696.
[3] L. Ma, K. Wang, M.S. Liu, D. Wang, T. Liu, Y.Q. Wang, et al., Numerical study on performances of shell-side in trefoil-hole and quatrefoil-hole baffle heat exchangers, Appl. Therm. Eng. 123(2017) 1444-1455.
[4] H.F. Elattar, A. Fouda, S.A. Nada, et al., Thermal and hydraulic numerical study for a novel multi tubes in tube helically coiled heat exchangers:Effects of operating/geometric parameters, Int. J. Therm. Sci. 128(2018) 70-83.
[5] M. Mellal, R. Benzeguir, D. Sahel, et al., Hydro-thermal shell-side performance evaluation of a shell and tube heat exchanger under different baffle arrangement and orientation, Int. J. Therm. Sci. 121(2017) 138-149.
[6] D.K. Mohanty, Application of firefly algorithm for design optimization of a shell and tube heat exchanger from economic point of view, Int. J. Therm. Sci. 102(2016) 228-238.
[7] U. Salahuddin, M. Bilal, H. Ejaz, A review of the advancements made in helical baffles used in shell and tube heat exchangers, Int. Commun. Heat Mass 67(2015) 104-108.
[8] J.F. Zhang, Y.L. He, W.Q. Tao, 3D numerical simulation on shell-and-tube heat exchangers with middle-overlapped helical baffles and continuous baffles-Part II:Simulation results of periodic model and comparison between continuous and noncontinuous helical baffles, Int. J. Heat Mass Transf. 52(2009) 5371-5380.
[9] Z.G. Zhang, D.B. Ma, X.M. Fang, X.N. Gao, Experimental and numerical heat transfer in a helically baffled heat exchanger combined with one three-dimensional finned tube, Chem. Eng. Process. 47(9-10) (2008) 1738-1743.
[10] Y.P. Chen, Y.J. Sheng, J.F. Wu, C. Dong, Numerical simulation on flow field in circumferential overlap trisection helical baffle heat exchanger, Appl. Therm. Eng. 50(1) (2013) 1035-1043.
[11] B. Jiang, S. Yan, L. Zhang, X. Xiao, Numerical research of stream analysis on helical baffles heat exchangers, J. Eng. Thermophys-Rus. 26(2) (2017) 272-290.
[12] J. Lutcha, J. Nemcansky, Performance improvement of tubular heat exchangers by helical baffles, Chem. Eng. Res. Des. 68(3) (1990) 263-270.
[13] P. Stehlik, J. Nemcansky, D. Kral, L.W. Swanson, Comparison of correction factors for shell-and-tube heat exchangers with segmental or helical baffles, Heat Transfer Eng. 15(1) (1994) 55-65.
[14] M.J. Andrews, B.I. Master, Three-dimensional modeling of a helixchanger heat exchanger using CFD, Heat Transfer Eng. 26(6) (2005) 22-31.
[15] P. Stehlik, V. Wadekar, Different strategies to improve industrial heat exchanger, Heat Transfer Eng. 23(6) (2002) 36-48.
[16] M. Mellal, R. Benzeguir, D. Sahel, H. Ameur, Hydro-thermal shell-side performance evaluation of a shell and tube heat exchanger under different baffle arrangement and orientation, Int. J. Therm. Sci. 121(2017) 138-149.
[17] Q.W. Wang, G.D. Chen, Q.Y. Chen, M. Zeng, Review of improvements on shell andtube heat exchangers with helical baffles, Heat Transf. Eng. 31(10) (2010) 836-853.
[18] J. Wen, H. Yang, S. Wang, S. Xu, Y. Xue, H. Tuo, Numerical investigation on baffle configuration improvement of the heat exchanger with helical baffles, Energ. Convers. Manage. 89(2015) 438-448.
[19] W.J. Du, H.F. Wang, L. Cheng, Effects of shape and quantity of helical baffle on the shell-side heat transfer and flow performance of heat exchangers, Chinese J. Chem. Eng. 22(3) (2014) 243-251.
[20] N.T. Farhad, Z.S. Movassag, R. Kazem, T.A. Reza, Baffle space impact on the performance of helical baffle shell and tube heat exchangers, Appl. Therm. Eng. 44(2012) 143-149.
[21] Y.P. Chen, A novel helix baffled heat exchanger suitable for tube bundle arrangement with equilateral triangles, Petro. Chem. Equip. 37(6) (2008) 1-5(in Chinese).
[22] Y.P. Chen, R.B. Cao, J.F. Wu, C. Dong, Y.J. Sheng, Experimental study on shell side heat transfer performance of circumferential overlap trisection helical baffle heat exchangers, Proc. ASME 2011 Int. Mech. Eng. Congr. Expo., Denver 2011, pp. 27-33.
[23] C. Dong, Y.P. Chen, J.F. Wu, R.B. Cao, Y.J. Sheng, M.L. Ni, Experimental study on comprehensive performance of water to water heat transfer at shell-side of trisection helical baffle heat exchangers, J. Chem. Eng. 63(3) (2012) 721-727(in Chinese).
[24] Y.P. Chen, W.H. Wang, J.F. Wu, C. Dong, Experimental investigation on performances of trisection helical baffled heat exchangers for oil/water-water heat transfer, Energ. Convers. Manage. 101(2015) 460-469.
[25] M.S. Zeyninejad, T.F. Nemati, K. Razmi, R.T. Azar, Tube bundle replacement for segmental and helical shell and tube heat exchangers:Performance comparison and fouling investigation on the shell side, Appl. Therm. Eng. 51(1-2) (2013) 1162-1169.
[26] C. Dong, Y.P. Chen, J.F. Wu, Flow and heat transfer performances of helical baffle heat exchangers with different baffle configurations, Appl. Therm. Eng. 80(2015) 328-338.
[27] Y.P. Chen, R.B. Cao, C. Dong, J.F. Wu, M.C. Wang, Numerical simulation on performances of trisection helical baffle heat exchangers with small baffle incline angles, Numer. Heat Tr. A-Appl. 69(2) (2016) 180-194.
[28] C. Dong, Y.P. Chen, J.F. Wu, Comparison of heat transfer performances of helix baffled heat exchangers with different baffle configurations, Chinese J. Chem. Eng. 23(1) (2015) 255-261.
[29] Y.P. Chen, J.F. Wu, Optimum structure of helical baffle heat exchangers and new manufacture technology of baffles, Petro. Chem. Equip. 44(1) (2015) 1-5(in Chinese).
[30] H.D. Gu, Y.P. Chen, J.F. Wu, S.F. Yang, Numerical study on performances of small incline angle helical baffle electric heaters with axial separation, Appl. Therm. Eng. 126(2017) 963-975.