Analytical Study of Nonstationary Modes in Recuperative Heat Exchangers

Авторы: Aleksandrov A.A., Akatev V.A., Tyurin M.P., Borodina E.S., Sedlyarov O.I. Опубликовано: 17.10.2020
Опубликовано в выпуске: #5(92)/2020  
DOI: 10.18698/1812-3368-2020-5-60-71

Раздел: Физика | Рубрика: Теплофизика и теоретическая теплотехника  
Ключевые слова: analytical studies, direct-flow heat exchanger, counter-flow heat exchanger, convective heat exchange, turbulent flow, system of convective heat exchange equations, Bessel function

Recuperative heat exchanger transient operation modes during the start-up were considered in order to identify the time for establishing the stationary mode. This is important in carrying out technological processes that require constancy in values of certain parameters ensuring both product quality and process safety. The research was carried out using the analytical method for direct-flow and counter-flow heat exchangers. It was demonstrated that stationary state establishment in the direct-flow heat exchangers occurs immediately after the heat carrier gets into the apparatus. It should be noted that the entire apparatus reaches the stationary mode, when the slower heat carrier arrives at the apparatus output section. In case of a heat exchanger with the heat carrier counter-flow, it was found out that at the moment of the less heated heat carrier appearing at the apparatus output section, it was having the highest temperature. Then the temperature was decreasing, and after passing its minimum was beginning to oscillate along a curve with the damping amplitude. In the case under consideration, the stationary process started, when the dimensionless time value was ϕ ≥ 0.5. The indicated solution was obtained under assumption that thermal and physical characteristics were constant in time and space. It was assumed that total heat capacity of the heat exchanger heat transferring wall was infinitesimal. This assumption is valid with an error of up to 1 % at Fo ≥ 100, which is the case in most practical cases. For apparatuses under study, a formula was also obtained for the time required to reach the stationary state

This work was supported by the Ministry of Science and Higher Education of Russian Federation (agreement no. 175-11-2019-087 of 18.12.2019)


[1] Tyurin M.P., Sazhin B.S., Soshenko M.V. Osnovnye protsessy i apparaty energo-sberegayushchikh tekhnologiy tekstil’nykh i khimicheskikh predpriyatiy [Main processes and equipment of energy-saving technologies for textile and chemical enterprises]. Moscow, KSU Publ., 2008.

[2] Ratel G., Mercier P., Icart G. Heat exchanger in transient conditions. In: Roetzel W., Heggs P.J., Butterworth D. (eds). Design and Operation of Heat Exchangers. EUROTHERM Seminars, vol. 18. Berlin, Heidelberg, Springer, 1992, pp. 111--120. DOI: https://doi.org/10.1007/978-3-642-84450-8_10

[3] Gogus Y.O., Ataer E.O. Transient behaviour of heat exchangers. Int. Symp. Transient Convective Heat Transfer, 1996.DOI: https://doi.org/10.1615/ICHMT.1996.TransientConvHeatTransf.280

[4] Saberimoghaddam A., Bahri Rasht Abadi M.M. Transient thermal study of recuperative tube in tube heat exchanger operating in refrigeration system using experimental test and mathematical simulation. IAChE, 2017, vol. 14, no. 3, pp. 3--18.

[5] Gopalakrishnan N., Srinivasa Murthy S. Mixed convective flow and thermal stratification in hot water storage tanks during discharging mode. Appl. Sol. Energy., 2009, vol. 45, no. 4, pp. 254--261. DOI: https://doi.org/10.3103/S0003701X09040070

[6] Ruan B., Jacobi A.M., Li L. Effects of a countercurrent gas flow on falling-film mode transitions between horizontal tubes. Exp. Therm. Fluid Sci., 2009, vol. 33, iss. 8, pp. 1216--1225. DOI: https://doi.org/10.1016/j.expthermflusci.2009.07.009

[7] Aleksandrov A.A., Akat’ev V.A., Tyurin M.P., et al. Results of experimental studies of heat-and-mass transfer processes in a two-phase closed thermosyphon. Herald of the Bauman Moscow State Technical University, Series Natural Sciences, 2018, no. 4 (79), pp. 46--58 (in Russ.). DOI: https://doi.org/10.18698/1812-3368-2018-4-46-58

[8] Rabinovich G.D. Teoriya teplovogo rascheta rekuperativnykh teploobmennykh apparatov [Thermal calculation theory of recuperative heat exchangers]. Minsk, AN BSSR Publ., 1963.

[9] Malinowski L., Bielski S. An analytical method for calculation of transient temperature field in the counter-flow heat exchangers. Int. Commun. Heat Mass Trans., 2004, vol. 31, iss. 5, pp. 683--691. DOI: https://doi.org/10.1016/S0735-1933(04)00055-7

[10] Tyurin M.P., Borodina Y.S., Osmanov Z.N. Investigation of processes of heat and mass exchange in a closed two-phase thermosiphon for the development of energy conserving technologies in the production of edible phosphates. Fibre Chem., 2018, vol. 49, no. 6, pp. 388--393. DOI: https://doi.org/10.1007/s10692-018-9905-3

[11] Aleksandrov A.A., Akat’ev V.A., Tyurin M.P., et al. Solution to external and internal heat and mass transfer problems for closed two-phase thermosyphon. Herald of the Bauman Moscow State Technical University, Series Natural Sciences, 2017, no. 4 (73), pp. 109--121 (in Russ.). DOI: http://dx.doi.org/10.18698/1812-3368-2017-4-109-121

[12] MacArthur J.W., Grald E.W. Unsteady compressible two-phase flow model for predicting cyclic heat pump performance and a comparison with experimental data. Int. J. Refrig., 1989, vol. 12, iss. 1, pp. 29--41. DOI: https://doi.org/10.1016/0140-7007(89)90009-1

[13] Valueva E.P., Popov V.N. Numerical simulation of the process of nonstationary conjugate heat transfer in turbulent flows of liquid in channels. High Temp., 1997, vol. 35, no. 6, pp. 904--912.

[14] Tyurin M.P. Povyshenie effektivnosti tekhnologicheskikh protsessov i utilizatsiya teplovykh otkhodov. Diss. d-ra tekh. nauk. [Raising efficiency of technological processes and disposal of thermal waste. Cand. Sc. (Eng.) Diss.]. Moscow, KSU, 2002 (in Russ.).

[15] Sobolev S.L. Uravneniya matematicheskoy fiziki [Equations of mathematical physics]. Moscow, Nauka Publ., 1992.