Effects of in-line deflectors on the overall performance of a channel heat exchanger

Abstract

The turbulent convective thermal transfer in channel heat exchangers (CHEs) is studied numerically via the CFD (Computational Fluid Dynamics) method. Deflectors are inserted on the hot bottom walls of the heat channel to enhance the hydrothermal characteristics. Various shapes of in-line deflectors are considered, namely: rectangular (a/b = 0.00), cascaded rectangular-triangular (a/b = 0.25, 0.50, and 0.75), and triangular (a/b = 1.00) shapes. From the obtained results, the inclusion of in-line deflectors with a/b = 0.75 has given the most significant thermal enhancement factor, which was higher than that for a/b = 0.00, 0.25, 0.50, and 1.00 by about 5.36, 5.06, 67.27, and 3.88%, respectively. Also, the in-line cascaded deflector' case (a/b = 0.75) shows an increase in the enhancement factor (η) from 4 to 15.

Enhanced Heat Transfer by Oil/Multi-Walled Carbon Nano-Tubes Nanofluid

“…Higher T values are found on both sides of the FUFB, especially on the front. The area containing the hot deflector is higher in terms of temperature compared to the same area in the absence of the fin, as confirmed by many studies [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]37]. On the other hand, high T gradients (TGs) are evident on the front and undersides of the solid parts from the FUFB, and also along the hot exchanger wall behind the SUFB.…”

“…Figure 1c highlights the characteristics of all surfaces of the exchanger. The inlet of the exchanger conduit is subjected to a fluid flow with an axial speed related to the Re values (Reynolds number), as stated in some indexed papers such as Menni et al [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35], Demartini et al [36], and Nasiruddin and Kamran Siddiqui [37]. Five different speeds are simulated in order to demonstrate the effect of flow rate on various dynamic and thermal phenomena.…”

“…Modeling the baffles in terms of their geometry is the goal and path of many researchers in order to update the thermal and energy performance of various solar exchangers (see Kamali and Binesh [12], Wang et al [13], Fawaz et al [14], Boonloi and Jedsadaratanachai [15], Tamna et al [16], Nanan et al [17], Menni [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] in Table 1). The effect of both deflector dimension and flow rate has also been analyzed for complex geometrical obstacles, such as helical baffles.…”

Improved Heat Transfer in W-Baffled Air-Heat Exchangers with Upper-Inlet and Lower-Exit

“…The arrangement of obstacles, such as baffles, fins, and ribs, within channels, are among the effective methods used by many researchers and investigators in their numerical and experimental studies. For example, see Berner et al [1], Habib et al [2], Yuan et al [3], Cheng and Huang [4], Hong and Hsieh [5], Bazdidi-Tehrani and Naderi-Abadi [6], Demartini et al [7], Li and Kottke [8], Mousavi and Hooman [9], Pirouz et al [10], Mokhtari et al [11], Webb and Ramadhyani [12], Wen et al [13], Dong et al [14], Skullong et al [15], Thianpong et al [16], Nanan et al [17], Promvonge [18], Du et al [19], and Menni et al [20][21][22][23][24][25][26][27][28][29][30]). These studies have adopted many obstacles in various forms to give channels with high energy efficiency.…”

Application of Cylindrical Fin to Improve Heat Transfer Rate in Micro Heat Exchangers Containing Nanofluid under Magnetic Field

“…This technique causes a better mixing of fluid, destroying the viscous sub-layer and creating confined swirls. Th generation of confined swirls results in thermal resistance abatement and, hence, intensifies the heat transfer [1][2][3][4][5][6]. Another technique to enhance the thermal efficiency of thermal devices is to use nanofluids that have higher thermal conductivity than common fluids [7][8][9][10][11][12].…”