Numerical Investigation of Thermal-Flow Characteristics in Heat Exchanger with Various Tube Shapes

Abstract

In this study, eight configurations of oval and flat tubes in annular finned-tube thermal devices are examined and compared with the conventional circular tube. The objective is to assess the effect of tube flatness and axis ratio of the oval tube on thermal-flow characteristics of a three-row staggered bank for Re (2600 ≤ Re ≤ 10,200). It has been observed that the thermal exchange rate and Colburn factor increase according to the axis ratio and the flatness, where O1 and F1 provide the highest values. O1 produces the lowest friction factor values of all the oval tubes at all Re, and F4 gives 13.2–18.5% less friction than the other tube forms. In terms of performance evaluation criterion, all of the tested tubes outperformed the conventional circular tube (O5), with O1 and F1 obtaining the highest values. The global performance criterion of O1 has been found to be 9.6–45.9% higher as compared to the other oval tube geometries at lower values of Re, and the global performance criterion increases with the increase in flatness. The F1 tube shape outperforms all the examined tube designs; thus, this tube geometry suggests that it be used in energy systems.

Optimization of Laminar Boundary Layers in Flow over a Flat Plate Using Recent Metaheuristic Algorithms

“…For global searches, the new states of their agents are determined by the randomly selected search agent rather than the best-known state. Global searching is shown in Model Equations ( 18) and (19). In the equations, → X rand is the randomly picked search agent [28].…”

“…Apart from the studies mentioned above, many studies involve heat transfer optimization [16][17][18][19][20][21][22]. When evaluated in general, it has been seen that numerical optimization solutions and basic heuristic optimization techniques are used in heat transfer.…”

Three-dimensional assessment of thermal-hydraulic behaviour in heat exchangers fitted by wavy annular fins

“…The Reynolds number used in this study, which is dependent on the outside diameter of the tube collar, D c = D t + 2d f , and the maximum speed at the smallest free flow crosssection u max ranges from 4400 to 14300. This results in the airflow being incompressible, turbulent, steady-state, and 3-D [19][20][21][22]. Based on previous research for annular fins [15, 16,…”

Numerical study to predict optimal configuration of wavy fin and tube heat exchanger with various tube shapes

“…For the case of natural convection thermal exchange, Unger et al [10] analyzed the impact of flat-tube shapes and dimensions on thermal-flow characteristics for four rows of annular FTHEs. It was found that, for staggered tube arrangement, the conventional circular tube and flat tube pattern (with an axis ratio of 1:2.1) gives the highest heat exchanger efficiency.…”

“…Unfortunately, the majority of research studies have separately investigated the effect of tube ellipticity and flatness in FTHEs. Also, only Zeeshan et al [1] and Djeffal et al [10] numerically analyzed the heat transfer and flow physics in FTHEs using circular, oval, and flat shapedtubes, whereas, in the case of sinusoidal wavy FTHEs, no research has been done on the influence of these tube forms. Hence, the purpose here is to examine the influence of tube shapes with sinusoidal wavy fins for two-row staggered bundles using the RNG k   turbulence model of ANSYS FLUENT 18.2.…”