Use of new similarities Bl and Blturb. to optimize the calculation and selection of heat exchange equipment for working with nanofluid coolants
The problem of correct, exact calculation and selection of the optimal heat exchange equipment at use in it of nanoliquid heat carriers was investigated in the work. Classical numerical equations, which are widely used in the calculation and selection of heat exchangers with nanofluids, especially at temperatures above 50 °C, give an error of (15–20) % or more. This leads to the fact that the selected heat exchange equipment may not work efficiently with excessive consumption of thermal energy. A new approach to heat transfer processes is considered, taking into account the theory of J. Businesque, which gives an idea of turbulent viscosity and thermal conductivity, as well as comparing the resistance of the coolant flow to the nanoparticle with surface forces and considering turbulent fluid as Newtonian. It is shown that the consideration of the behavior of a nanoparticle in a turbulent liquid coolant without taking into account surface forces is inaccurate and erroneous. The physical content of the previously obtained new numbers of similarity Bl and Blturb is considered and the possibility of their effective application in the new numerical equation obtained by us for the calculation of heat exchangers using nanofluid coolants is shown. The existing express method of estimating the efficiency of nanorluids use in heat exchangers on the basis of classical numerical equations is analyzed and a new express method on the basis of a new numerical equation and new numbers of similarity Bl and Blturb is proposed. The proposed express calculation method shows that a mixture of H2O + EG (60:40) improves the heat transfer properties of water by + 12.86 %, and a mixture of (H2O + EG (60:40) + 1.5 % TiO2) and (milk) + 0.5 % pumpkin seed oil) – by +16.75 %, which corresponds to the experiments and our calculations, and the known express method based on classical numerical equations shows a deterioration of – 4.5 % and, accordingly, by – 1.2 %. An example of calculating the optimal shell-and-tube heat exchanger according to the new algorithm when heating milk with hot water with the addition of mixtures (H2O + EG (60:40) + 1.5 % TiO2) and accordingly (milk + 0.5 % pumpkin seed oil) fully confirms the correctness of the new express –method.
Bіlonoga, Y., & Maksysko, O. (2018). Specific features of heat exchangers calculation considering the laminar boundary layer, the transitional and turbulent thermal conductivity of heat carriers. International Journal of Heat and Technology, 36(1), 11–20. doi: 10.18280/ijht.360102.
Bіlonoga, Y., & Maksysko, O. (2019). The laws of distri-bution of the values of turbulent thermo-physical characteristics in the volume of the flows of heat car-riers taking into account the surface forces. Interna-tional Journal of Heat and Technology, 36(1), 1–10. doi: 10.18280/ijht.370101.
Bіlonoga, Y., Stybel, V., Maksysko, O., & Drachuk, U. (2020). A New Universal Numerical Equation and a New Method for Calculating Heat-Exchange Equip-ment using Nanofluids. International Journal of Heat and Technology, 38(1), 151–164. doi: 10.18280/ijht.380117.
Dytnerskij, Y. I. (1991). Basic processes and devices of chemical technology (Manual of engineering). Moskwa. Chemistry, 14–70.
Gnielinski, V. (1976). New equations for heat and mass transfer in turbulent pipe and channel flow. Interna-tional Chemical Engineering, 16(2), 359–368. URL: https://ui.adsabs.harvard.edu/abs/1975STIA...7522028G/abstract.
Hamid, K. Abdul, Azmi, W., Mamat R., Usri, N., & Najafi, G. (2015). Effect of temperature on heat transfer co-efficient of titanium dioxide in ethylene glycol-based nanofluid, Journal of Mechanical Engineering and Sciences, 8, 1367–1375. doi: 10.15282/jmes.8.2015.11.0133.
Li, Q., & Xuan, Y. M. (2004). Flow and Heant Transfer Performances of Nanofluids Inside Small Hydraulic Diameter Flat Tube. Journal of Engineering Thermo-physics, 25(2), 305–307.
Pak, B., & Cho, I. (1998). Hydrodynamic and heat trans-fer study of dispersed fluids with sub-micron metallic oxide particles. A Journal of Thermal Energy Genera-tion, Transport, Storage, and Conversion, 11(2), 151–170. doi: 10.1080/08916159808946559.
Petukhov, B. (1970). Heat Transfer and Friction in Turbu-lent Pipe Flow with Variable Physical Properties. Ad-vances in Heat Transfer, 6, 503–564. doi: 10.1016/S0065-2717(08)70153-9.
Quadrio, M., & Ricco, P. (2011). The laminar generalized Stokes layer and turbulent drag reduction. Journal of Fluid Mechanics, 667, 135–157. doi: 10.1017/S0022112010004398.
Rudyak, V. Ya. (2013). Viscosity of Nanofluids – Why It Is Not Described by the Classical Theories. Advances in Nanoparticles, 2(3), 266–279. doi: 10.4236/anp.2013.23037.
Sajadi, A., & Kazemi, M. (2011). Investigationof turbu-lent convective heat transfer and pressure drop of TiO2/water nanofluid in circular tube. International Communications in Heat and Mass Transfer, 38(10), 1474–1478. doi: 10.1016/j.icheatmasstransfer.2011.07.007.
Sivashanmugam, P. (2012). Application of nanofluids in heat transfer. An Overview of Heat Transfer. Phe-nomena. Chapter, 14. doi: 10.5772/52496.
Xuan, Y., & Li, Q. (2003). Investigation on convective heat transfer and flow features of nanofluids. Journal of Heat Transfer, 125(1), 151–155. doi: 10.1115/1.1532008
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