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1

Effect of some parameters on the thermohydraulic characteristics of a channel heat exchanger with corrugated walls

100%

Ameur H. , Sahel D.

Journal of Mechanical and Energy Engineering

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2019

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tom Vol. 3, No 1

53--60

EN

The present work is a numerical modeling of the flow of a viscous fluid provided with convective heat transfer in a rectangular channel. We focus on the influence of the shape of corrugations which are present on the channel walls. Three shapes of corrugations are studied and which are: the rectangular, triangular and semi-circular shape. Also, effects of the height and number of corrugations on the fluid dynamics and thermal characteristics of the exchanger are highlighted. The working fluid is non-Newtonian (having a shear thinning behavior modeled by the Otswald law). The obtained results reveal that the presence of corrugations yields a major change in the heat exchange execution. In terms of superiority of heat transfer ratio, the cases under investigation can be classified as follows: rectangular > triangular > semi-circular. However and in terms of low pressure drop, this ranking is reversed. Furthermore, the triangular and semicircular shapes were found to have almost similar effects.

2

Pool boiling on horizontal tube, evaluation of ten correlations

100%

Baki T. , Sahel D.

Archive of Mechanical Engineering

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2023

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tom LXX, nr 4

481--495

EN

The heat transfer coefficient during the pool boiling on the outside of a horizontal tube can be predicted by correlations. Our choice was based on ten correlations known from the literature. The experimental data were recovered from the recent work, for different fluids used. An evaluation was made of agreement between each of the correlations and the experimental data. The results of the present study firstly showed a good reliability for the correlations of untsov [10], Stephan and Abdeslam [11] with deviations of 20% and 27%, respectively. Also, the results revealed acceptable agreements for the correlations of Kruzhlin [6], Mc Nelly [7] and Touhami [15] with deviations of 26%, 29% and 29% respectively. The remaining correlations showed very high deviations from the experimental data. Finally, improvements have been made in the correlations of Shekriladze [12] and Mostinski [9], and a new correlation was proposed giving convincing results.

3

A new correlation for predicting the hydrothermal characteristics over flat tube banks

80%

Sahel D. , Ameur H. , Boudaoud W.

Journal of Mechanical and Energy Engineering

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2019

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tom Vol. 3, No 3

273--280

EN

The flat tubes are necessary apparatus to design the modern heat exchangers. In this context, a CFD (computational fluid dynamics) study has been achieved to explore the influence of the flat tube size on the heat transfer characteristics in cross-flow over flat tube banks. The calculations are performed with the help of the computer software (Fluent) which is based on the finite volume method to solve the continuity, momentum and energy equations. The numerical investigations are achieved for laminar flow (Reynolds numbers changing from 50 to 800), two dimensional flows and incompressible fluids. Some predicted results are compared with available experimental data of the literature and a satisfactory agreement is observed. The obtained results show a decrease in the heat transfer coefficient with increased size of the flat tube. A new valuable empirical correlation is suggested for the prediction of heat transfer coefficients over a flat tube bank. The proposed correlation may be useful for engineers to predict the heat transfer rates in such devices without requirements of experimental measurements.

4

Effect of Trenched Hemispherical Pin Fins on Cooling Performance of Heat Sink

51%

Yousfi A. , Bellahcene L. , Alqurashi F. , Sahel D. , Teggar M. , Laouer A. , Arıcı M. , Kchaou M.

Advances in Science and Technology. Research Journal

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2024

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tom Vol. 18, no 3

33--44

EN

Pin fins have the potential to improve the thermal performance of various engineering devices. Modified pin fins could further increase their thermal performance in a passive way at lower cost. This study is aimed to numerically investigate the thermal performance of trenched hemispherical pin fins heat sink (THPFHS) and the influence of parameters including the trench number (N=1, 3 and 5) and thickness (e =1 to 5 mm). The simulations are performed using a CFD software considering turbulent air flow conditions. Results show that the use of aluminum fins fitted with one trench in the middle of the hemispherical pin fin considerably increases the local heat transfer. Furthermore, all studied configurations show high thermal performance factor (HTPF) compared with the conventional CPFHS (cylindrical pin fins heat sink). For this new configuration (THPFHS), Nu increases by 45% while the thermal resistance reduces by 42%, compared to the baseline case. On the other hand, this improved performance results in 50% pressure drop penalty. Moreover, the obtained results show a significant improvement in the performance mainly at high Re.