An analytical study of pulsating laminar heat convection in a circular tube with constant heat flux

Yu, Jianjun; Li, Zhixin; Zhao, Tianshou

doi:10.1016/j.ijheatmasstransfer.2004.06.029

Cited by 78 publications

(32 citation statements)

References 17 publications

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“…This result is in agreement with the previous findings of Yu et al [25] and Chattopadhyay et al [26].…”

Section: Resultssupporting

confidence: 94%

“…To summarise the results that we have obtained so far: (a) we have previously found (reference [18]) that pulsations enhances heat transfer downstream of a backwards facing step, (b) in the work presented in this paper we observe that pulsation enhances heat transfer inside a cavity, and (c) in the work presented in this paper we observe that pulsation does not exert influence when a straight channel is considered (in agreement with the results of references [25,26]). To try to gather additional information on the subject, we have performed an additional series of unsteady computations on a forward facing step.…”

Section: Resultssupporting

confidence: 89%

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Pulsating flow and convective heat transfer in a cavity with inlet and outlet sections

Velázquez

Arias

Montañés

2009

International Journal of Heat and Mass Transfer

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ARTICLE INFO ABSTRACT Keywords:Cavity Unsteady flow Convective heat transfer This paper deals with the study of 2-D, laminar, pulsating flow inside a heated rectangular cavity with different aspect ratios. The cooling liquid (water with temperature dependent viscosity and thermal conductivity) comes and leaves the cavity via inlet and outlet ports. The flow topology is characterised by the large recirculation regions that exist at inner corners of the cavity. These low velocity regions cause the heat transfer to be small when compared, for instance, to that of a straight channel. We study the effect that a prescribed pulsation at the inlet port has on the cavity heat transfer. This pulsating boundary condition, of the unsteady Poiseuille type, is described by its frequency and the amplitude of the pressure gradient. The time averaged Reynolds number of the flow, based on the hydraulic diameter of the inlet channel, is 100 and we consider that the dimensionless pulsation frequency (Strouhal number) varíes in the range from 0.0 to 0.4. We show that the prescribed pulsation enhances heat transfer in the cavity and that the mechanism that causes this enhancement appears to be the periodic change in the recirculation flow pattern generated by the pulsation. Regarding the quantitative extent of heat transfer recovery, we find that appropriate selection of the pulsation parameters allows for the cavity to behave like a straight channel that is the configuration with the highest Nusselt number.

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“…This result is in agreement with the previous findings of Yu et al [25] and Chattopadhyay et al [26].…”

Section: Resultssupporting

confidence: 94%

Section: Resultssupporting

confidence: 89%

Pulsating flow and convective heat transfer in a cavity with inlet and outlet sections

Velázquez

Arias

Montañés

2009

International Journal of Heat and Mass Transfer

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“…Conversely, the experimental and numerical study performed in an incompressible oscillatory pipe flow with uniform heat flux by Zhao and Cheng [4] demonstrated a monotonic increase in the HTC with increasing dimensionless frequency, in agreement with the experiments of Leong and Jin [6] performed in a foam-filled channel. Yu et al [7] solved analytically the heat transfer problem in an incompressible pulsating pipe flow with uniform heat flux. Interestingly, the authors reported no effect on the time-averaged HTC due to pulsation.…”

Section: Introductionmentioning

confidence: 99%

Heat transfer augmentation in unsteady conjugate thermal systems – Part II: Applications

Mathie

Nakamura

Markides

2013

International Journal of Heat and Mass Transfer

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Many energy conversion and other thermal-fluid systems exhibit unsteady convective heat exchange. In such systems, generic spatiotemporal variations in the flow give rise to variations in the heat flux for a given fluid-solid temperature difference, which can be interpreted as spatiotemporal fluctuations of the instantaneous heat transfer coefficient. These variations can lead to unsteady conjugate heat transfer, in which the exchanged heat flux arises from an interaction between the bulk fluid temperature and the temperature in the solid. Further, the nonlinear coupling between the fluctuating temperature differences and the heat transfer coefficient can lead to an effect we refer to as augmentation, which quantitatively describes the ability of a particular arrangement to have a different time-mean heat flux from the product between the mean heat transfer coefficient and the mean temperature difference across the fluid. It is important to be able to understand and to model in a simple framework the effects of the material properties, the geometry and the character of the heat transfer coefficient on the thermal response of the fluid-solid system, and consequently to predict the overall heat transfer performance of these systems. This paper, which follows on from its predecessor (Mathie and Markides, 2012a), is concerned with the phenomenon of augmentation in simple, one-dimensional, unsteady and conjugate fluid-solid systems. A simple semi-analytical one-dimensional model of heat transfer with a time-varying heat transfer coefficient, which was presented in Mathie and Markides (2012a), is applied herein to two different paradigm problems. Such a model can be an important tool in the design of improved heat exchangers and thermal insulation, through for example, the novel selection of materials to exploit these augmentation effects. The first flow considered is a thin, wavy fluid film flowing over a heated plate. This film flow exhibits a periodic fluctuation in the heat transfer coefficient, that is linked to the wavy interfacial deformations of free surface of the liquid film. The second flow considered concerns the heat transfer behind a backwards-facing step, which exhibits broadband fluctuations in the heat transfer coefficient due to the flow separation and turbulence behind * Corresponding author.

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“…Yu et al (2004) summarize this situation by classifying previous works into four categories according to the conclusion being reached: (a) pulsation enhances heat transfer (Mackley & Stonestreet, 1995;Faghri et al, 1979) (b) pulsation deteriorates heat transfer (Hemida et al, 2002) (c) pulsation does not affect heat transfer (Yu et al, 2004), and (d) heat transfer enhancement or deterioration may occur depending on the flow parameters (Cho & Hyun, 1990). Although, the main conclusion reached by Yu et al (2004) was that pulsation neither enhances nor deteriorates heat flow and that the same result was found by Chattopadhyay et al (2006), who showed that pulsation has no effect on the time-averaged heat transfer along straight channels, other results show that forced flow pulsation enhances convective mixing and affects Nusselt number (Kim & Kang, 1998;Velazquez et al, 2007). These works show how the heat transfer reaches its maximum for a specific frequency of oscillation and decreases for both higher and lower values of frequency.…”

Section: Introductionmentioning

confidence: 99%

Heat Transfer Enhancement for Weakly Oscillating Flows

Benavides¹

2011

Heat Transfer - Theoretical Analysis, Experimental Investigations and Industrial Systems

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An analytical study of pulsating laminar heat convection in a circular tube with constant heat flux

Cited by 78 publications

References 17 publications

Pulsating flow and convective heat transfer in a cavity with inlet and outlet sections

Pulsating flow and convective heat transfer in a cavity with inlet and outlet sections

Heat transfer augmentation in unsteady conjugate thermal systems – Part II: Applications

Heat Transfer Enhancement for Weakly Oscillating Flows

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