Heat transfer from a cylinder and finned tube in a pulsating crossflow

Perwaiz, J.; Base, T. E.

doi:10.1016/0894-1777(92)90037-6

Cited by 19 publications

(3 citation statements)

References 12 publications

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“…Many researchers have concluded that the intensification of heat transfer in pulsating flows is associated with the phenomenon of vortex resonance [20,[35][36][37]. Additionally, authors [17,19,22,24,38,39] have mentioned the restructuring of the flow structure, a decrease in the boundary layer, the mixing of large-scale vortex structures, and additional turbulization of the flow.…”

Section: Introductionmentioning

confidence: 99%

Local Heat Transfer Dynamics in the In-Line Tube Bundle under Asymmetrical Pulsating Flow

et al. 2022

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The pulsating flow is one of the techniques that can enhance heat transfer, therefore leading to energy saving in tubular heat exchangers. This paper investigated the heat transfer and flow characteristics in a two-dimensional in-line tube bundle with the pulsating flow by a numerical method using the Ansys Fluent. Numerical simulation was performed for the Reynolds number Re = 500 with different frequencies and amplitude of pulsation. Heat transfer enhancement was estimated from the central tube of the tube bundle. Pulsation velocity had an asymmetrical character with a reciprocating flow. The technique developed by the authors to obtain asymmetric pulsations was used. This technique allows simulating an asymmetric flow in heat exchangers equipped with a pulsation generation system. Increase in both the amplitude and the frequency of the pulsations had a significant effect on the heat transfer enhancement. Heat transfer enhancement is mainly observed in the front and back of the cylinder. At a steady flow in these areas, heat transfer is minimal due to the weak circulation of the flow. The increase in heat transfer in the front and back of the cylinder is associated with increased velocity and additional flow mixing in these areas. The maximum increase in the Nusselt number averaged over space and time in the entire studied range was 106%, at a pulsation frequency of 0.5 Hz and pulsation amplitude of 4.5. A minimum enhancement of 25% was observed at a frequency of 0.166 Hz and amplitude of 1.25.

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Section: Introductionmentioning

confidence: 99%

Local Heat Transfer Dynamics in the In-Line Tube Bundle under Asymmetrical Pulsating Flow

et al. 2022

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“…Perwaiz and Base [6] found that for low, dimensionless external frequencies the heat transfer relative to the steady state decreases, while the opposite trend was found for high frequencies. The maximum external frequency was however close to the natural shedding frequency.…”

Section: Introductionmentioning

confidence: 96%

Numerical simulation of the flow and heat transfer around a cylinder with a pulsating approaching flow at a low Reynolds number

Papadakis

Bergeles

2001

Proceedings of the Institution of Mechanical Engineers, Part C:

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Two-dimensional numerical simulations of flow and heat transfer around a cylinder at a Reynolds number Re= 100 have been performed in order to investigate the effect of imposed inlet velocity pulsation on the heat transfer and flow fields. First the code is validated against existing results from the literature and then several external frequencies are examined. The numerical results confirm the existence of a vortex shedding lock-on regime where the wake behaves in a very ordered manner (completely periodic). Outside the lock-on region the flow is quasiperiodic. The length and centre of the mean recirculating zone downstream of the cylinder are also affected by the external pulsation. Regarding heat transfer, the results indicate that by imposing an external velocity pulsation, the root mean square (r.m.s.) of the local Nusselt number Nu increases, but the mean value increases only in the area downstream of the separation point. The mechanism responsible for this is identified: hot fluid is engulfed by stronger vortices (compared with the steady approaching flow case) shed from the upper and lower side of the cylinder and returned close to the downstream stagnation point. This mechanism also explains the observed variation in Nu with time. In the front part of the cylinder, the Nu varies almost sinusoidally and closely follows the imposed external velocity pulsation. The results indicate also that there is a range of external frequencies where the time and spatially averaged Nu number is maximized.

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“…Many researchers conclude that the intensi-fication of heat transfer in pulsating flows is associated with the phenomenon of vortex resonance [20,[35][36][37]. Also, authors [17,19,22,24,38,39] mentioned the restructuring of the flow structure, a decrease in the boundary layer, mixing of large-scale vortex structures, and additional turbulization of the flow.…”

Section: Introductionmentioning

confidence: 99%

Local Heat Transfer Dynamics in the In-Line Tube Bundle under Asymmetrical Pulsating Flow

Haibullina¹,

Hayrullin²,

Balzamov³

et al. 2022

Preprint

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The pulsating flow is one of the techniques which can enhance heat transfer, therefore leading to energy saving in tubular heat exchangers. This paper investigates the heat transfer and flow characteristics in a two-dimensional in-line tube bundle with the pulsating flow by a numerical method using the Ansys Fluent. Numerical simulation is performed for Reynolds number Re = 500 with different frequencies and amplitude of pulsation. Heat transfer enhancement was estimated from the central tube of the tube bundle. Pulsation velocity had an asymmetrical character with a reciprocating flow. The technique developed by the authors to obtain asymmetric pulsations was used. This technique allows simulating an asymmetric flow in heat exchangers equipped with a pulsation generation system. Increase in both the amplitude and the frequency of the pulsations has a significant effect on heat transfer enhancement. Heat transfer enhancement is mainly observed in the front and back of the cylinder. At a steady flow in these areas, heat transfer is minimal due to the weak circulation of the flow. The increase in heat transfer in the front and back of the cylinder is associated with increased velocity and additional flow mixing in these areas.

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Heat transfer from a cylinder and finned tube in a pulsating crossflow

Cited by 19 publications

References 12 publications

Local Heat Transfer Dynamics in the In-Line Tube Bundle under Asymmetrical Pulsating Flow

Local Heat Transfer Dynamics in the In-Line Tube Bundle under Asymmetrical Pulsating Flow

Numerical simulation of the flow and heat transfer around a cylinder with a pulsating approaching flow at a low Reynolds number

Local Heat Transfer Dynamics in the In-Line Tube Bundle under Asymmetrical Pulsating Flow

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