Thermo-Fluid Performance Comparison of an in-Line Perforated Baffle With Oppositely Oriented Rectangular-Wing Structure in Turbulent Heat Exchanger

Abstract

This research study examined the effects of a novel swirl airflow design on the rate of heat transfer in a tubular heat exchanger with axial flow. The novel design consisted of 16 rectangular air deflectors placed in opposite directions, positioned at varying angles of inclination. These deflectors were embedded on circular perforated baffle plates, which were spaced equidistantly apart at different pitch ratios. Hot water was supplied to heat exchanger tubes whose arrangement remained constant throughout the experiment, while atmospheric air is flown over tube bundle at Reynolds number that ranged from 16 × 10<sup>3</sup> to 3 × 10<sup>4</sup> . The effect of pitch ratio and inclination angle on the thermal enhancement factor was experimentally analyzed. The findings demonstrated that using an opposite-oriented deflector baffle plate with an inclination angle of 30 deg and a pitch ratio of 1 resulted in an average improvement of 1.17 in the thermal enhancement factor compared to a heat exchanger without a baffle plate, tested under similar conditions.

Thermal hydraulic performance of a tubular heat exchanger with in‐line perforated baffle with shutter type saw tooth turbulator

“…The maximum performance value can be found in Table 3. A remarkable TEF value of 1.42 was attained within the specified Re range, with a PR of 1.2 and e/h = 0.4, when α was set at 30°as seen in Figure 16; also upon comparison with published work by Rahman 36 shows that the oppositely oriented rectangular deflector is inferior in performance when compared to sawtooth profile shutter-type and an improvement of 14.3% in TEF is seen when α = 30°at PR = 1.2 at e/h = 0.3 to sawtooth profile.…”

“…To determine this metric, the Nu and f values acquired from the STBP air duct are compared to those obtained without baffle (j 0 , f 0 ), which are considered reference values. [30][31][32]36…”

“…Rahman 35 further perforated the conical baffle plate and attached rectangular flow deflectors, resulting in a 22% enhancement in thermal efficiency. In another analysis, 36 he utilized two 16 rectangular shutter-type flow deflectors to induce turbulence, resulting in a 1.17 improvement in thermal efficiency when PR was 1 and α was 30. Furthermore, Rahman 37 conducted further research on the impact of triangular shutter-type flow deflector baffle plates, which showed an additional improvement in the thermal efficiency of the HX.…”

“…They have made advancements by using coiled structures, 38 twisted strips, 39 and coneshaped rings with perforations. 40 Different patterns of perforation 41,42 with deflectors, including triangles, 36 rectangles, 32 circles, and trapezoids, 30,31 saw tooth ribs 27 and guide vanes, 24 have been studied to determine the most effective way to increase heat transfer per unit pressure drop. However, there is still limited knowledge about saw tooth profile deflectors and their implication as multiple flow deflectors on baffle plates as turbulence promotors in HX.…”

Review on Nanofluids: Preparation, Properties, Stability, and Thermal Performance Augmentation in Heat Transfer Applications

“…The ratio of the enhancement rate indicating the surge in HT to f is known as THP. Equations and present the primary criteria for evaluating the THP of the thermal system. − Models above a THP of 1 are considered advantageous, whereas models below this threshold are deemed unfavorable. The flow and thermal characteristics of nanofluids play a crucial role in evaluating and enhancing their performance.…”