An experimental investigation of heat transfer to pulsating pipe air flow with different amplitudes

Zohir, A. E.; Habib, Mohamed A.; Attya, A. M.; Eid, A.

doi:10.1007/s00231-005-0036-z

Cited by 36 publications

(13 citation statements)

References 19 publications

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“…Results showed that the heat transfer enhancement factor can be larger than 1.2. Many other valuable experimental studies reported an enhancement in heat transfer due to the pulsation (Zohir et al 2006, Ji et al 2008, Baffigi and Bartoli 2010. However, some studies such as Elsayed et al's work (Elshafei et al 2008), reported the pulsation would downgrade the heat transfer compared to that in steady flow.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Heat Transfer and Fluid Flow around the Rectangular Flat Plane Confined by a Cylinder under Pulsating Flow

Zheng

Yang

et al. 2016

JAFM

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Fluid flow around and heat transfer from a rectangular flat plane with constant uniform heat flux in laminar pulsating flows is studied, and compared with our experimental data. Quantitatively accurate, second-order schemes for time, space, momentum and energy are employed, and fine meshes are adopted. The numerical results agree well with experimental data. Results found that the heat transfer enhancement is caused by the relative low temperature gradient in the thermal boundary layer, and by the lower surface temperature in pulsating flows. In addition, the heat transfer resistance is much lower during reverse flow period than that during forward flow period. The flow reversal period is about 180 degree behind the pulsating pressure waves. Besides, spectrum results of the simulated averaged surface temperature showed that the temperature fluctuates in multiple-peaked modes when the amplitude of the imposed pulsations is larger, whereas the temperature fluctuates in a single-peaked mode when the amplitude of the imposed pulsation is small.

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Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Heat Transfer and Fluid Flow around the Rectangular Flat Plane Confined by a Cylinder under Pulsating Flow

Zheng

Yang

et al. 2016

JAFM

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“…They reported that the secondary flow in helical coils with pulsating flow becomes so complicated that occur more than two circulations in a cross-section with the appearance of secondary flow reversal. Effect of pulsation on the heat transfer coefficient of air in a pipe, was studied experimentally by Zohir et al [20]. They evaluated the Heat transfer characteristics under different conditions of Reynolds number, pulsation frequency, pulsation location and tube diameter for both laminar and turbulent pulsating pipe flows.…”

Section: Introductionmentioning

confidence: 99%

“…As an active technique, pulsation in fluid flow is another method of heat transfer enhancement. Widespread studies have been allocated to pulsating flows and their associated heat transfer problems over the past decades [8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Martinelli et al [8] initiated the work on heat transfer characteristics of pulsating flow in 1943.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of heat transfer and flow of Al2O3/water nanofluid in a spiral-coil tube for turbulent pulsating flow

et al. 2015

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K Thermal conductivity (W/m K) L Length of tube (m) m Mass flow rate (kg/s) N Revolution per minute of the rotating valve spindle (rpm) Pe Peclet number Pr Prandtl number Q Heat transfer rate (W) r Inner radius of tube (m) R Radius of spiral coil (m) Re Reynolds number T Temperature (K) U Average overall heat transfer coefficient (W/m 2 K) V Average velocity of mean flow (m/s) Wo Womersly number, Wo = D i 2 υ ω Greek letters α Thermal diffusivity (m 2 /s) µ Dynamic viscosity (kg/m s) ρ Density (kg/m 3 ) υ Kinematic viscosity (m 2 /s) ω Angular pulsation frequency (1/s) ∞ Ambient medium ϕ Nanoparticle volumetric fraction Superscript -Average Subscripts ave Average i Inlet m Mean o Outlet pu Pulsated st SteadyAbstract In the past two decades, enhancement of heat transfer characteristics of original fluid using nanofluids has been proposed by a large number of researchers. In this paper, an experimental study was carried out to investigate effect of pulsation on heat transfer of fluid flow inside a spiral-coil tube. In order to perform the experiments, a hot water reservoir tank was prepared and the spiral-coil was immersed horizontally inside the tank. Average temperature of the hot water bath was kept constant at 60 °C to establish a quiescent region of uniform temperature. The experiments were conducted in turbulent flow regime using distilled water and Al 2 O 3 /water nanofluid at 0.5, 1, and 1.5 % particle volume concentration. Results showed that overall heat transfer coefficient of the base fluid flow increases by using nanofluid or pulsation into the base fluid flow up to 14 %. Heat transfer results also indicated that combination of the nanofluid and the pulsation into the fluid flow can increase significantly the overall heat transfer coefficient up to 23 %. List of symbolsA Inside heat transfer area (m 2 ) C p Specific heat capacity (J/kg K) D i Inner diameter of tube (m) f Frequency (Hz)

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“…In the article [4] authors point on heat exchange rate increase on average by 30% due to heat transfer agent pulsations in tube when Reynolds number is 1643 and impulses frequency is 1 Hz. The date are given for fluid flows with Reynolds numbers in the range from 750 to 12 320, frequency range between 1 and 10 Hz and for different tubes diameters.…”

Section: Introductionmentioning

confidence: 99%

Heat transfer at in-line tube bank under low-frequency asymmetrical impulses impact on fluid flow

Khaibullina

Hayrullin

Sinyavin

et al. 2014

EPJ Web of Conferences

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Abstract. External heat transfer coefficient changing from corridor tube bundle to the reverse cross fluid flow with low-frequency asymmetrical pulsations was analyzed experimentally. The experiments were performed for Reynolds numbers in the tube bundle in the range of 100 ≤ Re ≤ 500 and changing of flow impulses frequency was limited with values 0.125 ≤ f ≤ 0.5 Hz, fluid pulsations amplitude in the tube bundle corresponded to 0.5 d ≤ A ≤ 1.2 d mm. A comparison of steady and non-steady conditions was made. The most efficient regime of pulsations in the studied range was found.

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An experimental investigation of heat transfer to pulsating pipe air flow with different amplitudes

Cited by 36 publications

References 19 publications

Numerical Investigation of Heat Transfer and Fluid Flow around the Rectangular Flat Plane Confined by a Cylinder under Pulsating Flow

Numerical Investigation of Heat Transfer and Fluid Flow around the Rectangular Flat Plane Confined by a Cylinder under Pulsating Flow

Characteristics of heat transfer and flow of Al2O3/water nanofluid in a spiral-coil tube for turbulent pulsating flow

Heat transfer at in-line tube bank under low-frequency asymmetrical impulses impact on fluid flow

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