In this work, the effects of the pressure drop (i.e. the Bejan number in dimensionless term) and of the Prandtl number have been investigated with reference to optimal geometries for maximizing the heat transfer density under forced convection of shear thinning fluids. Constructal Design associated with Design of Experiments and Response Surface methodologies have been employed to search computationally for the optimals. More specifically, after having fixed the power law index value, n, equal to 0.4, we studied the effect of the Bejan number, Be, ranging from 10(4) to 10(5) (for Pr = 1) and the effect of the Prandtl number, Pr, ranging from 1 to 10 (for Be = 10(5)) on the maximum dimensionless heat transfer density. The optimal geometries here detected differ much from those referred to Newtonian fluids, as a consequence of the non-linear stress behavior with respect to strain rate. We observed that the optimal aspect ratio of the elliptical tubes, r(opt) highlights different (opposite) behaviours with the augmentation of Be and Pr: while r(opt) decreases as Be increases, it augments with higher Pr, suggesting that for flows characterized by thermal diffusivity the tubes should be more slender horizontally for better heat transfer performance. In the meantime, assigned r(opt), the dimensionless optimal distance between tubes, (S)over-tilde(0), proved to be practically independent of all the tested values of Bejan number and Prandtl number.

Effect of Bejan and Prandtl numbers on the design of tube arrangements in forced convection of shear thinning fluids: A numerical approach motivated by constructal theory / Klein, R.J.; Zinani, F.S.F.; Rocha, L.A.O.; Biserni, C.. - In: INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER. - ISSN 0735-1933. - STAMPA. - 93:(2018), pp. 74-82. [10.1016/j.icheatmasstransfer.2018.02.017]

Effect of Bejan and Prandtl numbers on the design of tube arrangements in forced convection of shear thinning fluids: A numerical approach motivated by constructal theory

Biserni, C.
2018

Abstract

In this work, the effects of the pressure drop (i.e. the Bejan number in dimensionless term) and of the Prandtl number have been investigated with reference to optimal geometries for maximizing the heat transfer density under forced convection of shear thinning fluids. Constructal Design associated with Design of Experiments and Response Surface methodologies have been employed to search computationally for the optimals. More specifically, after having fixed the power law index value, n, equal to 0.4, we studied the effect of the Bejan number, Be, ranging from 10(4) to 10(5) (for Pr = 1) and the effect of the Prandtl number, Pr, ranging from 1 to 10 (for Be = 10(5)) on the maximum dimensionless heat transfer density. The optimal geometries here detected differ much from those referred to Newtonian fluids, as a consequence of the non-linear stress behavior with respect to strain rate. We observed that the optimal aspect ratio of the elliptical tubes, r(opt) highlights different (opposite) behaviours with the augmentation of Be and Pr: while r(opt) decreases as Be increases, it augments with higher Pr, suggesting that for flows characterized by thermal diffusivity the tubes should be more slender horizontally for better heat transfer performance. In the meantime, assigned r(opt), the dimensionless optimal distance between tubes, (S)over-tilde(0), proved to be practically independent of all the tested values of Bejan number and Prandtl number.
2018
Effect of Bejan and Prandtl numbers on the design of tube arrangements in forced convection of shear thinning fluids: A numerical approach motivated by constructal theory / Klein, R.J.; Zinani, F.S.F.; Rocha, L.A.O.; Biserni, C.. - In: INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER. - ISSN 0735-1933. - STAMPA. - 93:(2018), pp. 74-82. [10.1016/j.icheatmasstransfer.2018.02.017]
Klein, R.J.; Zinani, F.S.F.; Rocha, L.A.O.; Biserni, C.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/634741
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