Thermal-Hydraulic Performance and Optimization of Tube Ellipticity in a Plate Fin-And-Tube Heat Exchanger

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Hua Zhu ◽  
Zhuo Yang ◽  
Tariq Amin Khan ◽  
Wei Li ◽  
Zhijian Sun ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Friction Factor ◽  
Hydraulic Performance ◽  
Pareto Optimal ◽  
Maximum Heat ◽  
Tube Heat Exchanger ◽  
Simulation And Optimization ◽  
Colburn Factor ◽  
Overall Performance

The flow field inside the heat exchangers is associated with maximum heat transfer and minimum pressure drop. Designing a heat exchanger and employing various techniques to enhance its overall performance has been widely investigated and is still an active research. The application of elliptic tube is an effective alternative to circular tube which can reduce the pressure drop significantly. In this study, numerical simulation and optimization of variable tube ellipticity is studied. The three-dimensional numerical analysis and a multi-objective genetic algorithm (MOGA) with surrogate modeling are performed. Tubes in staggered arrangement in fin-and-tube heat exchanger are investigated for combination of various elliptic ratios and Reynolds numbers. Results show that increasing elliptic ratio increases the friction factor due to increased flow blocking area, however, the effect on the Colburn factor is not significant. Moreover, tube with lower elliptic ratio followed by higher elliptic ratio tube has better thermal-hydraulic performance. To achieve the best overall performance, the Pareto optimal strategy is adopted for which the computational fluid dynamics (CFD) results, artificial neural network (ANN), and MOGA are combined. The tubes elliptic ratio and Reynolds number are the design variables. The objective functions include Colburn factor (j) and friction factor (f). The CFD results are input into ANN model. Once the ANN is computed, it is then used to estimate the model responses as a function of inputs. The final trained ANN is used to drive the MOGA to obtain the Pareto optimal solution. The optimal values of these parameters are finally presented.

Thermal-Hydraulic Performance and Optimization of Tube Ellipticity in a Plate Fin-and-Tube Heat Exchanger

2018 ◽  
Author(s):  
Zhuo Yang ◽  
Tariq Amin Khan ◽  
Wei Li ◽  
Hua Zhu ◽  
Zhijian Sun ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Friction Factor ◽  
Pareto Optimal ◽  
Maximum Heat ◽  
Tube Heat Exchanger ◽  
Maximum Heat Transfer ◽  
Colburn Factor

The flow field inside the heat exchangers is associated with maximum heat transfer and minimum pressure drop. Designing a compact heat exchanger and employing various techniques to enhance its overall performance has been widely investigated and still an active research field. However, few researches deal with thermal optimization. The application of elliptic tube is an effective alternative to circular tube which can reduce the pressure drop significantly. In this study, numerical simulation and optimization of variable tube ellipticity is studied at low Reynolds numbers. The three-dimensional numerical analysis and a multi-objective genetic algorithm (MOGA) with surrogate modelling is performed. Two row tubes in staggered arrangement in fin-and-tube heat exchanger is investigated for combination of various elliptic ratio (e = minor axis/major axis) and Reynolds number. Tube elliptic ratio ranges from 0.2 to 1 and Reynolds number ranges from 150 to 750. The tube perimeters are kept constant while changing the elliptic ratio. The numerical model is derived based on continuum flow approach and steady-state conservation equations of mass, momentum and energy. The flow is assumed as incompressible and laminar due to low inlet velocity. Results are presented in the form of Colburn factor, friction factor, temperature contours and streamline contours. Results show that increasing elliptic ratio increases the friction factor due increased flow blocking area, however, the effect on the Colburn factor is not significant. Moreover, tube with lower elliptic ratio followed by higher elliptic ratio tube has better thermal-hydraulic performance. To achieve maximum heat transfer enhancement and minimum pressure drop, the Pareto optimal strategy is adopted for which the CFD results, Artificial neural network (ANN) and MOGA are combined. The tubes elliptic ratio (0.2 ⩽ e ⩽ 1.0) and Reynolds number (150 ⩽ Re ⩽ 750) are the design variables. The objective functions include Colburn factor (j) and friction factor (f). The CFD results are input into ANN model. Once the ANN is computed and its accuracy is checked, it is then used to estimate the model responses as a function of inputs. The final trained ANN is then used to drive the MOGA to obtain the Pareto optimal solution. The optimal values of these parameters are finally presented.

scholarly journals Research on the Thermal Hydraulic Performance and Entropy Generation Characteristics of Finned Tube Heat Exchanger with Streamline Tube

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5408
Author(s):  
Zuoqin Qian ◽  
Qiang Wang ◽  
Song Lv
Keyword(s):  
Heat Exchanger ◽  
Entropy Generation ◽  
Thermal Performance ◽  
Flow Characteristics ◽  
Hydraulic Performance ◽  
Finned Tube ◽  
Tube Heat Exchanger ◽  
Finned Tube Heat Exchanger ◽  
Overall Performance ◽  
Present Simulation

Thermal hydraulic performance of the fin-and-tube heat exchanger is presented in this paper. The purpose of this investigation was to investigate the heat transfer mechanism and flow characteristics in the finned tube heat exchanger with streamline tube. The streamline tube in this paper had the streamline cross section which was composed of a semicircle and a half diamond. Three-dimensional numerical simulation was presented and validated by the experiment and the other numerical simulation from public articles. The present simulation had good agreement with the experimental results. The difference of the j factor and f factor between the experimental results and present simulation results by k-ε-enhance model was less than 7.6%. The geometrical parameters were considered as every single variable to investigate the thermal hydraulic performance. The results showed that smaller transversal and larger tube pitch provided greater compactness and better thermal performance. Moreover, a larger angle was not only beneficial to enhance the thermal performance, but also helpful to improve the overall performance. Secondly, the effects of angle on the heat transfer performance and fluid flow characteristics were investigated as the perimeter kept constant. It was shown that the overall performance of the streamline tube was better than the circular tube. Lastly, the entropy generation including frictional entropy generation and the thermal entropy generation were analyzed. It can be concluded that by using the streamline tube, the wake region can be obviously reduced, and thermal performance can be improved.

Impact of an Anisotropic Fin Surface Design on the Thermal-Hydraulic Performance of a Plain-Fin-and-Tube Heat Exchanger

2011 ◽  
Author(s):  
Rong Yu ◽  
Andrew D. Sommers ◽  
Nicole C. Okamoto ◽  
Koushik Upadhyayula
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Hydraulic Performance ◽  
Normal Operation ◽  
Surface Design ◽  
Tube Heat Exchanger ◽  
Silane Coating ◽  
Side Pressure

In this study, we have explored the effectiveness of heat exchangers constructed using anisotropic, micro-patterned aluminum fins to more completely drain the condensate that forms on the heat transfer surface during normal operation with the aim of improving the thermal-hydraulic performance of the heat exchanger. This study presents and critically evaluates the efficacy of full-scale heat exchangers constructed from these micro-grooved surfaces by measuring dry/wet air-side pressure drop and dry/wet air-side heat transfer data. The new fin surface design was shown to decrease the core pressure drop of the heat exchanger during wet operation from 9.3% to 52.7%. Furthermore, these prototype fin surfaces were shown to have a negligible effect on the heat transfer coefficient under both dry and wet conditions while at the same time reducing the wet airside pressure drop thereby decreasing fan power consumption. That is to say, this novel fin surface design has shown the ability, through improved condensate management, to enhance the thermal-hydraulic performance of plain-fin-and-tube heat exchangers used in air-conditioning applications. This paper also presents data pertaining to the durability of the alkyl silane coating.

Design optimization of a shell and tube heat exchanger with staggered baffles using neural network and genetic algorithm

2021 ◽  
pp. 095440622110057
Author(s):  
Kizhakke Kodakkattu Saijal ◽  
Thondiyil Danish
Keyword(s):  
Heat Transfer ◽  
Genetic Algorithm ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Orientation Angle ◽  
Design Parameters ◽  
Outer Diameter ◽  
Maximum Heat ◽  
Tube Heat Exchanger ◽  
Shell And Tube

A shell and tube heat exchanger with staggered baffles (STHX-ST) is designed by integrating the features of both segmental and helical baffles, which produces a helical flow in the shell side. This work studies the effect of different parameters on the performance of the STHX-ST through numerical analysis. Shell inner diameter, tube outer diameter, baffle cut, baffle spacing, and baffle orientation angle are the design parameters. Multi-objective optimization using genetic algorithm (GA) is carried out to maximize the heat transfer rate while minimizing the pressure drop. The objective functions for optimization are approximated using artificial neural networks (ANNs). The training data for ANNs are simulated from CFD analysis as per the Taguchi orthogonal test table. The optimal solution obtained from the Pareto front has a maximum heat transfer of 154555 W for a minimum pressure drop of 88083.86 Pa.

scholarly journals Combination Effect of Baffle Arrangement and Hybrid Nanofluid on Thermal Performance of a Shell and Tube Heat Exchanger Using 3-D Homogeneous Mixture Model

Mathematics ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 881
Author(s):  
Mashhour A. Alazwari ◽  
Mohammad Reza Safaei
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Thermal Performance ◽  
Heat Removal ◽  
Hybrid Nanofluid ◽  
Distilled Water ◽  
Reference Case ◽  
Maximum Heat ◽  
Tube Heat Exchanger ◽  
Shell And Tube

In this study, thermal performance and flow characteristics of a shell and tube heat exchanger equipped with various baffle angles were studied. The heat exchanger was operated with distilled water, and a hybrid nanofluid at three concentrations of 0.04% and 0.10% of GNP-Ag/water within Reynolds numbers ranged between 10,000 and 20,000. The thermophysical properties of nanofluid varied with temperature and nanoparticles’ concentration. The baffle angles were set at 45°, 90°, 135°, and 180°. Results showed that the calculated Nusselt number (Nu) could be improved by adding nanoparticles to the distilled water or increasing the fluid’s Reynolds number. At a low Re number, the Nu corresponding to baffle angle of 135° was very close to that recorded for the angle of 180°. At Re = 20,000, the Nu number was the highest (by 35% compared to the reference case), belonging to a baffle angle of 135°. Additionally, results related to friction factor and pressure drop showed that more locations with fluid blocking were observed by increasing the baffle angle, resulting in increased pressure drop value and friction. Finally, the temperature streamlines counter showed that the best baffle angle could be 135° in which maximum heat removal and the best thermal performance can be observed.

THE EFFECT OF VORTEX GENERATOR BASE LENGTH ON THERMAL HYDRAULIC PERFORMANCE ACROSS FIN-AND-TUBE HEAT EXCHANGER

2017 ◽  
Vol 79 (7-3) ◽  
Author(s):  
Mohd Fahmi Md Salleh ◽  
Mazlan Abdul Wahid ◽  
Seyed Alireza Ghazanfari
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Transfer Enhancement ◽  
Vortex Generator ◽  
Hydraulic Performance ◽  
Base Length ◽  
Transfer Enhancement ◽  
Tube Heat Exchanger ◽  
Baseline Case

Heat transfer enhancement is believed can be achieved by using vortex generator. In the past decades, many researches have been performed to investigate the effect of various vortex generator geometry and parameters including vortex generator angle of attack and height. However, less study has been conducted to investigate the influence of vortex generator length at different arrangement towards the heat transfer performance across the fin-and-tube heat exchanger (FTHE). Therefore, the effects of different strategy on the rectangular winglet vortex generator (RWVG) base length towards the thermal hydraulic performance across the FTHE were numerically investigated in this study. Two types of RWVG arrangement known as common flow down (CFD) or common flow up (CFU) arrangement were used and placed behind four rows of tube in inline arrangement. Total of 7 cases were investigated including the default RWVG, extended front and extended back for both RWVG in CFD and CFU arrangement together with FTHE without vortex generator which was set as the baseline case. The Reynolds number ranged from 500 to 900. It was found that the size of the wake region behind the RWVG contributed to the additional pressure drop penalty across the FTHE. Meanwhile, different thermal characteristics were found for different base length strategy in CFD and CFU arrangement. For RWVG arranged in CFD and CFU arrangement, the extended back case shows the highest heat transfer enhancement with 5 – 25 % and 5 – 15 % increment compared to the baseline case respectively. Based on JF factor evaluation, default RWVG in CFU arrangement provide better heat transfer enhancement than the pressure drop penalty compared to other RWVG cases with average JF factor value is 0.8. Nonetheless, none of the tested cases shows higher JF factor value than the baseline case.  

Determination of Pressure Drop of Pure Water Flowing Upward Direction in a Double Tube Heat Exchanger Having Smooth and Microfin Tubes

2014 ◽  
Author(s):  
Alican Çebi ◽  
Ali Celen ◽  
Ahmet Selim Dalkılıç ◽  
Mustafa Kemal Sevindir ◽  
Somchai Wongwises
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Friction Factor ◽  
Test Section ◽  
Pure Water ◽  
Cooling Water ◽  
Tube Heat Exchanger ◽  
Upward Direction ◽  
Microfin Tubes

Single phase friction factor and pressure drop behavior of smooth and microfin tubes are studied experimentally. The vertical test section was working as a counter flow double tube heat exchanger with water flowing in the inner smooth and microfin tubes having varying inner diameters and cooling water flowing in the annulus. Pressure drop of water due to cooling in upward flow in inner tubes is determined by experiments. Inner tube mass flow rate was between 0.023 kg/s to 0.100 kg/s while test section inlet temperatures were 40°C and 60°C. Effect of Reynolds number on pressure drop is also investigated and Blasius type friction factor correlations are developed for both smooth and microfin tubes.

Investigation and Development of Proposed General Pressure Drop and Heat Transfer Correlations for Laminar Flow in a Toroidal Coiled Tube System

2004 ◽  
Author(s):  
Anthony J. Bowman ◽  
Hyunjae Park
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Friction Factor ◽  
Radius Of Curvature ◽  
Straight Tube ◽  
Coiled Tube ◽  
Tube Heat Exchanger ◽  
Curved Tube

In this paper, the laminar flow pressure drop and heat transfer correlations published and applied to plain, coiled tube heat exchanger systems are extensively investigated. It was found that most correlations obtained for toroidal geometric systems have been applied to the analysis of helical and spiral tube systems. While toroidal (and helical) coils have a constant radius of curvature about the coil center-point (and center-line), spiral coils have a continuously varying radius of curvature, in which the flow does not reach a typical fully developed flow condition. The centrifugal forces, arising from the curved flow path, contribute to the enhancement of heat transfer (at the cost of additional pressure drop) over straight tube heat exchangers of the same length. In this paper, using published correlations and available experimental test data for pressure drop and heat transfer in toroidal tube systems, the proposed general correlations are developed by using a filtered-mean multiple regression method. The Coiling Influence Factors for the friction factor and heat transfer, CIFf and CIFh, respectively; defined and used in the authors’ previous works [1,2,3] it was found that the deviations between the proposed and published correlations are within about 3% for friction factor and 5–20% for heat transfer, depending on working fluid. In order to assess the validity of applying the generalized correlations developed in this work for toroidal tube systems, onto other curved tube systems, a numerical analysis of toroidal coil systems, using the commercially available CFD package (Fluent 6) has been explicitly performed. A comparison is made between the CFD result for average heat transfer (CIFh) with that predicted by the proposed general correlation for toroidal coils and available experimental data. As an extension of this work, a comparison of curved tube over straight tube heat exchanger effectiveness is made to highlight its use as a design optimization parameter and motivation for additional coiled tube heat exchanger research.

scholarly journals Numerical Investigation and Optimization on Shell Side Performance of A Shell and Tube Heat Exchanger with Inclined Trefoil-Hole Baffles

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4138 ◽  
Author(s):  
Yue Sun ◽  
Xinting Wang ◽  
Rui Long ◽  
Fang Yuan ◽  
Kun Yang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Shell Side ◽  
Maximum Heat ◽  
Tube Heat Exchanger ◽  
Shell And Tube ◽  
The Heat Transfer Coefficient

In this work, a shell and tube heat exchanger with inclined trefoil-hole baffles (STHX-IT) is proposed, and the numerical simulation is conducted to investigate the flow and heat transfer characteristics. A shell and tube heat exchanger with segmental baffles (STHX-SG) is also studied for the performance comparison. The results show that the heat transfer coefficient and pressure drop of the STHX-IT is averagely lower by 23.89% and 44.19% than those of the STHX-SG, but the heat transfer coefficient per pressure drop is higher by 36.38% on average. Further, the parametric studies of the inclination angle θ, trefoil-hole number n, and baffle cut δ are carried out for the STHX-IT. According to the numerical results, n and δ have more notable influence on shell side performance than θ. In detail, the heat transfer coefficient and pressure drop decrease slightly with θ increasing, and the overall performance is approximately equal; both the heat transfer coefficient and pressure drop decrease with the respective rising of n and δ, but the comprehensive performance shows a growing trend. Considering the synthetic effects of structural parameters, the multi-objective structure optimization using the genetic algorithm combined with the artificial neural networks is fulfilled. As a result, the Pareto front is obtained to characterize the behaviors of the maximum heat transfer rate and minimum pressure drop. The STHX-IT with the θ = 5.38°, n = 6, and δ = 43% is decided as the optimal solution by the TOPSIS method, whose Q/Δp is 2.34 times as much as that of the original STHX-SG.

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