Русская версия English version
Home / 2019 issue 1 / Calculation of heat exchangers taking into account the flow structure

Calculation of heat exchangers taking into account the flow structure

T.M. Farakhov, E.P. Afanasyev, A.G. Laptev

Vestnik IGEU, 2019 issue 1, pp. 11—17

Download PDF

Abstract in English: 

Background. Heat exchangers, used in various industries as well as at thermal power plants, have different performance characteristics, designs and overall dimensions, but despite the existence of such a considerable variety of designs, their calculation is most often carried out based on the ideal flow displacement model. In some cases, this may lead to an underestimation of the heat transfer area. In this regard, it is important to develop a mathematical model and algorithm for calculating heat exchangers taking into account the reverse mixing of heat carriers, when the flow structure differs from the model of ideal displacement.

Materials and methods. The article makes use of the method of numbers of transfer units, as in case of mass transfer, corrected for the backmixing of the coolants. The correction is performed using the modified Peclet number of the flow structure, which leads to a small increase in the length of the heat exchanger tubes, and consequently, the heat transfer area.

Results. Expressions for calculating the length of the tubes and heat transfer area taking into account the backmixing of the flow have been obtained. Equations have been given for calculating the main parameter of the flow structure models – backmixing ratio.

Conclusions. The presented approach improves the calculation accuracy of heat exchangers with intensifiers, for example, of channels with random packings, coiled elements, various inserts, etc.

 

References in English: 

1. Kudinov, I.V. Matematicheskoe modelirovanie gidrodinamiki i teploobmena v dvizhushchikhsya zhidkostyakh [Mathematical modeling of hydrodynamics and heat transfer in moving fluids]. Saint-Petersburg: Lan¢, 2015. 208 р.

2. Marinyuk, B. Raschety teploobmena v apparatakh i sistemakh nizkotemperaturnoy tekhniki [Calculations of heat transfer in devices and systems of low-temperature equipment]. Moscow: Mashinostroenie, 2015. 272 p.

3. Rudskoy, A.I., Lunev, V.A. Matematicheskoe modelirovanie gidrodinamiki i teploobmena v dvizhushchikhsya zhidkostyakh [Mathematical modeling of hydrodynamics and heat transfer in moving fluids]. Saint-Petersburg: Lan¢, 2015. 208 р.

4. Komissarov, Yu.A., Gordeev, L.S., Vent, D.P. Protsessy i apparaty khimicheskoy tekhnologii [Processes and devices of chemical technology]. Moscow: Khimiya, 2011. 1230 p.

5. Kafarov, V.V., Glebov, M.B. Matematicheskoe modelirovanie osnovnykh protsessov khimicheskikh proizvodstv [Mathematical modeling of the main processes of chemical production: a university study guide]. Мoscow: Vysshaya shkola, 1991. 400 р.

6. Razinov, A.I., Klinov, A.V., D'yakonov, G.S. Protsessy i apparaty khimicheskoy tekhnologii [Processes and apparatuses of chemical technology]. Kazan': KNITU, 2017. 860 p.

7. Golovanchikov, A.B., Vorotneva, S.B. Modelirovanie raboty dvukhtrubnogo teploobmennika s uchetom teplodiffuzii gazovogo teplonositelya [Simulation of double-tube heat exchanger operation taking into account the heat diffusion of the gas coolant]. Izvestiya vuzov. Khimiya i khimicheskaya tekhnologiya, 2015, vol. 58, issue 9, pp. 58–62.

8. Golovanchikov, A.B., Vorotneva, S.B., Dul'kin, B.A. Vliyanie struktury potokov i termicheskogo soprotivleniya na tekhnologicheskie parametry dvukhtrubnogo teploobmennika [Influence of flow structure and thermal resistance on the process parameters of the double-tube heat exchanger]. Izvestiya VolgGT, 2014, no. 25(152), pр. 121–126.

9. Laptev, A.G., Farakhov, T.M., Dudarov-skaya, O.G. Modeli turbulentnoy vyazkosti i peremeshivaniya v kanalakh i nasadochnykh protochnykh smesitelyakh [Models of turbulent viscosity and mixing in channels and packing flow mixers]. Zhurnal prikladnoy khimii, 2013, vol. 86, issue 7, pp. 1112–1121.

10. Laptev, A.G., Farakhov, T.M., Afanas'ev, E.P. Effektivnost' nagrevaniya topliv i masel v intensifitsirovannykh teploobmennikakh [Heating efficiency of fuels and oils in intensified heat exchangers]. Khimicheskoe i neftegazovoe mashinostroenie, 2018, no. 9, pр. 11–15.

11. Plotnikov, L.V., Zhilkin, B.P., Brodov, Yu.M. Vliyanie poperechnogo profilirovaniya vpusknykh i vypusknykh truboprovodov porshnevykh dvigateley na teplomekhanicheskie kharakteristiki potokov [Influence of cross-profiling of inlet and outlet pipelines of piston engines on thermal and mechanical characteristics of flows]. Izvestiya vysshikh uchebnykh zavedeniy. Problemy energetiki, 2017, vol. 19, no. 1–2, pp. 119–126.

12. Brodov, Yu.M., Aronson, K.E., Ryabchi-kov, A.Yu. Povyshenie effektivnosti teploobmennykh apparatov paroturbinnykh ustanovok za schet primeneniya profil'nykh vitykh trubok [Improving the efficiency of heat exchangers of steam turbine units through the use of profile twisted tubes]. Izvestiya vysshikh uchebnykh zavedeniy. Problemy energetiki, 2016, no. 7–8, pp. 72–78.

13. Isaev, S.A., Baranov, P.A., Leont'ev, A.I., Popov, I.A. Intensification of a laminar flow in a narrow microchannel with single-row inclined oval-trench dimples. Technical Physics Letters, 2018, vol. 44, no. 5, pp. 398–400.

14. Leont'ev, A.I., Kuzma-Kichta, Yu.A., Popov, I.A. Teplomassoobmen i gidrodinamika v zakruchennykh potokakh [Heat and mass transfer and hydrodynamics in swirling flows]. Teploenergetika, 2017, no. 2, pр. 36–54.

 

Key words in Russian: 
теплообмен, структура потока, обратное перемешивание, поверхность теплопередачи, диффузионная модель, тепловая эффективность
Key words in English: 
heat transfer, flow structure, backmixing, heat transfer area, diffusion model, thermal efficiency
The DOI index: 
10.17588/2072-2672.2019.1.011-017
Downloads count: 
37