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The performance of heat exchangers is severely limited by airside thermal resistance. The effect of redirection louvers (RLs) on the airside thermal performance of a compact flat-tube louvered fin heat exchanger was investigated. A steady-state 3D numerical analysis was conducted for different fin configurations by varying the number of RLs (NRL =...
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... blocking topology of the fin configuration with one RL is shown in Figure 3. Grid orthogonality and quality were ensured to be high for all generated grids. A structured hexahedral grid over the entire computational domain is illustrated in Figure 4. ...
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In the present work, three-dimensional numerical analysis was carried out for thermo-fluid analysis of annular fin-and-tube heat exchangers (AFTHE) with circular fins and elliptical fins having varying Reynolds number (𝑅𝑒) changed from 4000 to 9000. The effects of the angle of attack (𝛼 ) and the ratio of long diameter to short diameter (LDR) for e...
Citations
... To maintain uniform inlet air velocity and to ensure that there is no recirculation of air, the length of the upstream and the downstream regions are kept four and ten times the fin pitch, respectively as described in Refs. [24,33]. ...
The rectangular channel louvered-fin compact heat exchanger (LFCHE) is the most efficient type that has been served in a radiator. However, with this type of heat exchanger, the pressure drop rises by three to four times as the heat transfer increases, which results in decreasing performance. This research is aimed to numerically investigate the louver edges (vertical, inclined, and horizontal) effect on LFCHE performance at different louver angle (θ) with air inlet velocities ranging from 1 to 30 m/s. A total of twelve models are made and simulated. The result revealed that the horizontal edge decreases the pressure drop up to 24.2% with a 1.01% increase in outlet air temperature over the base model (inclined edge). Thus, louver edge has design which results in higher and lower effect on pressure drop and temperature change, respectively. The research investigated the effects of louver edges using different performance evaluation criteria. At 10 m/s (Relp = 972.33) the horizontal edge increases the volume goodness (jf) factor up to 21.49% over the base model. Similarly, the horizontal edged fins resulted in maximum increment of jf-factor by 22% and 25% as compared with inclined edge for louver angles θ of 24 ° (at low Relp) and 20 ° (at high Relp), respectively. Generally, the horizontally edged LFCHE is proven to have higher performance in cooling the coolant with a minimum air side pressure drop.
... Reynolds number, Nusselt number, Colburn factor-j, friction factor-f and performance evaluation criteria (PEC) are defined as follows [32]. ...
In this paper, the effects of slotted height at different fin pitches are analyzed in detail, aiming to investigate the function and optimal ratio of slotted height to fin pitch. In the cases of high Reynolds number for louver fin, the ?bimodal phenomenon? of heat transfer coefficient begins to appear with the increasing slotted height. As the slotted height is about half of the fin pitch, the heat transfer coefficient has a local minimum value, of which there are two peaks on both sides. However, the pressure drop has been increasing with the increasing slotted height. The optimal slotted height under different fin pitches is more instructive than the optimal louver angle. For slit fin, the heat transfer coefficient increases first and then decreases with the increasing slotted height, so does the pressure drop. Meanwhile, as the slotted height is about 0.3~0.45 times and 0.5~0.65 times of fin pitch for louver fin and slit fin respectively, the comprehensive performance can reach a maximum. In general, louver fin has higher comprehensive performance than slit fin. However, for the fin pitch assigned to 1.8 mm and large slotted height, the louver fin has a comprehensive performance roughly similar to the slit fin.
The shape of louver fins has the significant influence on the radiator performance. Based on the existing radiator with wasp-waisted tube type, this research changes the end shape of traditional rectangular louver fin, develops a new type of spindle-shaped louver fin (SSLF), and studies the influence of spindle end angle of new louver fin on the air side heat transfer and resistance performance in the range of Reynolds number 500–3500 by numerical simulation. The research shows that the spindle design at the end of the new louver fin effectively reduces the pressure loss of air at the end and forms a low-speed zone near the wall of the fin when air flows through the fin, which improves the convection heat exchange efficiency between the fin and air. When the Reynolds number is 3500, the pressure drops of SSLF1#, SSLF2# and SSLF3# at different angles are 27.63%, 21.31% and 12.43% lower than those of traditional louver fins, respectively. The convection heat transfer coefficient increased by 0.84%, 5.33% and 2.69% respectively. At Reynolds number 500–2300, the PEC value of SSLF2 # is the highest, reaching 1.179. At Reynolds number 2300–3500, the PEC value of SSLF1 # is the highest, reaching 1.123.
