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Author: search.filters.author.Wongcharee, K.Subject: search.filters.subject.Heat exchanger

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    Experimental investigation and ANN prediction of heat transfer enhancement in a heat exchanger tube utilizing twin corrugated twisted tapes
    (2025-12-01)
    Du, Y.
    ;
    Wongcharee, K.
    ;
    Thianpong, C.
    ;
    Chuwattanakul, V.
    ;
    Chamoli, S.
    This report introduces a novel twin-corrugated twisted tape (TC-TT) insert designed to enhance heat transfer in exchanger tubes. The key innovation lies in the twin-corrugated structure, which generates a twin-swirl flow effect. The corrugated surface synergistically increases flow disturbance and expands the effective heat transfer area. The studied parameters were twist ratios (y/w = 3.0, 3.5, and 4.0) and corrugation angles (θ = 45°, 60°, 75°, and 90°) at 6,000 ≤ Re ≤ 20,000. The results show that using twin-corrugated twisted tapes increases the average Nusselt number by roughly 60–135% compared to a plain tube and by 16–35% compared to a conventional single-twisted tape, confirming the effectiveness of this structural modification. This enhancement is primarily due to the combination of double swirling-flows and enhanced effective heat transfer generated by the corrugated surface. Reducing the corrugation angle (θ) and twist ratio (y/w) led to increases in the Nusselt number (Nu), friction factor (f), and thermal performance factor (TPF). Within the studied range, the Nusselt number, friction factor, and thermal performance factor reached maximum values of 5.18, 0.153, and 1.44, respectively, at a twist ratio of 3.0, a corrugation angle of 45°, and Re = 6,000. Regression analysis was utilized to develop correlations for the Nu and f, considering the Re, Pr, y/w, and θ as influencing variables. The proposed correlations for predicting the friction factor and Nusselt number have errors within ±3% and ±2%, respectively. In addition, an artificial neural network (ANN) was developed for predicting the thermal performance values occurring below the experimental study range. The optimal state ANN model shows remarkable prediction accuracy with R<sup>2</sup> of 0.965.
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    Multi objective optimization of TiO2/water nanofluid flow within a heat exchanger enhanced with loose-fit delta-wing twisted tape inserts
    (2022-02-01)
    Thianpong, C.
    ;
    Wongcharee, K.
    ;
    Safikhani, H.
    ;
    Chokphoemphun, S.
    ;
    Saysroy, A.
    A hybrid technique by using TiO<inf>2</inf>/water nanofluid together with loose-fit delta-wing twisted tape (LTT-W) was employed for heat transfer enhancement. Experiments encompassed the TiO<inf>2</inf>-water nanofluids having concentration (φ) of 0.05%–0.15 vol% and the loose-fit delta-wing twisted tapes having two different wing arrangements (co- and counter arrangement) and three loose-fit ratios (c/D) of 0.0, 0.15, and 0.2. Experimental revealed that the system with combined enhancement technique gave considerably higher heat transfer than the one without enhancement technique. This can be attributed to the combined influences of swirling flow and higher thermal conductivity of the working fluid. Heat transfer rate and thermohydraulic performance rose with the decrease of loose-fit ratio and the rise of nanofluid concentration. The maximum thermohydraulic performance (TPF) of 1.36 was obtained at c/D = 0.0 and φ = 0.15%. The Multi-Objective Optimization (MOO) was also performed to study the optimal thermohydraulic performance by using GMDH models and NSGA II algorithms. The Pareto front, which contains very useful information, were extracted for both co and counter arrangements. The Pareto fronts have recognized very accurately, the best boundary of the experimental data with respect to the lowest friction factor and highest Nusselt number.
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    Thermal performance of heat exchanger tube installed with triple twisted-tapes
    (2020-09-01)
    Samutpraphut, B.
    ;
    Promthaisong, P.
    ;
    Wongcharee, K.
    ;
    Eiamsa-Ard, S.
    ;
    Chuwattanakul, Varesa
    A current study deals with the numerical analysis of heat transfer intensification, flow-thermal fields, local heat transfer distribution, friction factor and thermal performance behavior of the heat exchanger tubes installed with triple twisted tapes. Each set of triple twisted tapes consists of three twisted tapes having an identical twist ratio. Twisted tapes of interest have three different twisted ratios (y/w = 1.0, 1.5 and 2.0). Simulation was performed for the turbulent flow with Reynolds numbers (Re) ranging from 5000 to 20,000. Numerical results indicate that the use of triple twisted-tapes leads to heat transfer enhancement. Nusselt number (Nu) and friction factor (f) increase while thermal performance factor () decreases with decreasing twist ratio of triple twisted tapes. The Nusselt numbers of the tubes installed with triple twisted-tapes having twist ratios of 1.0, 1.5 and 2.0 are higher than those of the plain tube by around 3.34-4.45, 2.75-3.65 and 2.56-3.41 times, respectively. Friction factors (f) of the tubes installed triple twisted-tapes with twist ratios of 1.0, 1.5 and 2.0 are increased up to 46.1-49.7, 24.16-26.04 and 15.86-17.09 times, respectively, as compared to those of the plain tube. The maximum thermal performance factors of 1.21, 1.23 and 1.32 are obtained by using triple twisted tapes with y/w = 1.0, 1.5 and 2.0 at the Reynolds number of 5000.