Three-dimensional fin-tube expansion process to achieve high heat transfer efficiency in heat exchangers

2019 ◽  
Vol 33 (9) ◽  
pp. 4401-4406
Author(s):  
Seong-Yeop Kang ◽  
Sae-Rom So ◽  
Yong Son ◽  
Seonghun Park ◽  
Man-Yeong Ha ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Three Dimensional ◽  
High Heat ◽  
Transfer Efficiency ◽  
Expansion Process ◽  
Heat Transfer Efficiency ◽  
High Heat Transfer ◽  
Fin Tube ◽  
Tube Expansion

Heat Transfer Enhancement of Double-Tube-Type Heat Exchanger by Petal-Shaped Tube (Study on Optimum Tube Shape)

2018 ◽  
Vol 11 (1) ◽  
Author(s):  
Toshihiko Shakouchi ◽  
Yusuke Matsumoto ◽  
Koichi Tsujimoto ◽  
Toshitake Ando
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
High Heat ◽  
Practical Applications ◽  
Heat Transfer Efficiency ◽  
High Heat Transfer ◽  
Tube Shape ◽  
Tube Type ◽  
Wetted Perimeter ◽  
Fin Tube

Abstract Heat exchangers are used widely in many fields, and various kinds of exchanger have been developed according to the requirement of the practical applications. Recently, heat exchangers that are highly efficient or compact have become more desirable from the viewpoint of energy conservation, and several new types have been developed, such as a compact fin tube type and a double tube type having an inner pipe with a special geometry. In this study, the flow and heat transfer characteristics of a petal-shaped double tube with a large wetted perimeter of six and five petals and five shallow petals and the effect of tube shape on the heat transfer and heat transfer efficiency were examined experimentally. The heat transfer of the double tube with a petal-shaped inner tube was increased because of the large wetted perimeter, but the pressure loss by friction increased. The optimal shape of the petal-shaped double tube with a high heat transfer performance and the greatest efficiency is discussed.

scholarly journals Enhanced Heat Transfer Characteristics of Graphite Concrete and Its Application in Energy Piles

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Qingwen Li ◽  
Lu Chen ◽  
Haotian Ma ◽  
Chung-Ho Huang
Keyword(s):  
Heat Transfer ◽  
High Heat ◽  
Transfer Efficiency ◽  
Heat Transfer Characteristics ◽  
Enhanced Heat Transfer ◽  
Energy Pile ◽  
Transfer Characteristics ◽  
Heat Transfer Efficiency ◽  
High Heat Transfer ◽  
Energy Piles

The latest research on energy piles demonstrates that most scholars are focusing their attention on optimization by designing more efficient heat exchanger coils, analyzing the heat pump matching parameters, and so on. However, after more than 20 years of development, these traditional methods for improving the heat transfer efficiency of energy piles have reached a bottleneck, and a new approach for the continued enhancement of this technology must be investigated. In this study, powdered graphite with high heat transfer characteristics was included in a concrete mix to create graphite concrete piles with enhanced heat transfer characteristics. The results from theoretical analysis, laboratory testing, and numerical simulation indicate that using graphite to improve the heat transfer efficiency of a concrete material is an effective method for enhancing the thermal efficiency of an energy pile system. The research results also show that the heat transfer coefficient of the concrete exhibits greater improvement when the graphite content is greater than 15% under the same environmental temperature. After studying the performance of the proposed graphite concrete energy pile under different environmental temperatures (10°C, 20°C, 30°C, and 40°C), the results indicate that the working efficiency of the energy pile is better in the summer than in the winter. Finally, parameters such as the cast-in pipe configuration and pile spacing are optimized.

scholarly journals Heat Transfer and Bearing Characteristics of Energy Piles: Review

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6483
Author(s):  
Jinli Xie ◽  
Yinghong Qin
Keyword(s):  
Heat Transfer ◽  
Low Cost ◽  
High Heat ◽  
Heat Pumps ◽  
Transfer Efficiency ◽  
Ground Source Heat Pumps ◽  
Heat Transfer Efficiency ◽  
High Heat Transfer ◽  
Energy Piles ◽  
Composite Energy

Energy piles, combined ground source heat pumps (GSHP) with the traditional pile foundation, have the advantages of high heat transfer efficiency, less space occupation and low cost. This paper summarizes the latest research on the heat transfer and bearing capacity of energy piles. It is found that S-shaped tubes have the largest heat transfer area and the best heat transfer efficiency; that energy piles need to be designed conservatively, such as adjusting the safety coefficient, number and spacing of the piles according to the additional temperature loads; and that unbalanced surface temperature has not been resolved, caused by uneven refrigeration/heating demand in one cycle. A composite energy pile applied to water-rich areas is proposed to overcome the decay of bearing and heat transfer performance. Besides, most of the heat transfer models are borehole-oriented and will fit for energy piles effectively if the models support variable ground temperature boundary conditions.

scholarly journals Heat Transfer Enhancement of Circular- and Petal- Shaped Double-Tube-Type Heat Exchangers by Triple Ones

Energies ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 6590
Author(s):  
Toshihiko Shakouchi ◽  
Kazuma Yamamura ◽  
Koichi Tsujimoto ◽  
Toshitake Ando
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Cold Water ◽  
High Heat ◽  
Hot Water ◽  
Compact Heat Exchangers ◽  
Heat Transfer Efficiency ◽  
High Heat Transfer ◽  
Tube Type ◽  
Counter Current

Conventional circular double or triple tube type heat exchanger, DHE or THE, is one of the compact heat exchangers; a large number of studies have been performed to improve their heat transfer performance. The authors demonstrated that a petal-shaped special DHE with a large wet perimeter yields a high heat transfer efficiency, η. In this study, the DHE with six or five petals-, five shallow petals-, and circular-inner tubes were used. To further improve the η of the DHE, a THE with a petal-shaped inner tube along with the middle and outer circular tubes were used. Hot water flowed through the inner tube and cold water flowed through the middle and outer tubes as a counter current flow. The heat transfer was approximately equal; however, the flow resistance (pressure loss) of the outer tube of the DHE could be decreased using the middle and outer tubes under the same amount of cold water as the DHE; consequently, the η could be improved. In addition, the effect of changing the flow path of the hot- and cold-water flows on the η was examined.

scholarly journals Flow and Heat Transfer Simulation Analysis of 3D Compact Heat Exchanger

2021 ◽  
Vol 88 (3) ◽  
pp. 71-87
Author(s):  
G. Sashwin Nair ◽  
Ahmed N. Oumer ◽  
Azizuddin Abd Aziz ◽  
Januar Parlaungan Siregar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Inclination Angle ◽  
Heat Exchangers ◽  
Simulation Analysis ◽  
Three Dimensional ◽  
High Heat ◽  
Ansys Fluent ◽  
High Heat Transfer ◽  
Fin Spacing

Compact heat exchangers (CHEs) are one of the most commonly used heat exchangers in the industry due to their superior advantages over other types of heat exchangers. Various geometric (fin spacing, tube inclination angle, etc) and process (such as flow velocity, temperature, etc) parameters affect the performance of such compact HEs. This research aims to examine the effects of fin spacing, tube inclination angle, and airflow velocity on heat transfer and pressure drop performance of CHE in both inline and staggered configurations. A three-dimensional (3D) numerical method with the aid of Ansys FLUENT software was carried out for the laminar flow condition. Based on the obtained results, the highest average heat transfer coefficient was observed at 120° for both tube arrangements while the lowest average pressure drop penalty is at 30°. Therefore, the recommended inclination angle when high heat transfer is needed is at 120° while if the pumping power is the major problem, 30 °or 150° is recommended. based on the London area goodness factor (j/f), 30° and 150° show the highest value for both configurations. The j/f factor decreases with the increase of Reynolds number for both configurations. In addition, 120° shows the lowest j/f which can be due to the high pressure drop.

scholarly journals Numerical Analysis of Airside Characteristics in Plain and Wavy Heat Exchangers in the Turbulent Flow Regime

2011 ◽  
Author(s):  
M. Ruhul Amin ◽  
Santhosh K. Ramachandran
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Friction Factor ◽  
Heat Exchangers ◽  
High Heat ◽  
Efficiency Index ◽  
Turbulent Regime ◽  
High Heat Transfer ◽  
Colburn Factor ◽  
Fin Tube

Numerical investigation has been performed to study the heat transfer and pressure drop characteristics of plain-fin-tube and wavy-fin tube heat exchangers. Performance results are presented in terms of non-dimensional parameters, friction factor and Colburn factor. The flow rate is varied over the range of 2000 ≤ ReH ≤ 7000 in the turbulent regime. The analysis was performed using a finite volume method. Comparisons with experimental data are performed to validate the code. Parametric study is performed to investigate the effects of transverse pitch and wavy angle. It is observed that an increase in transverse pitch results in a decrease in thermal and hydraulic characteristics. On the other hand with the increase of wavy angle, resulting in the increase of the number of corrugations, both the friction factor and Colburn factor increased. The critical balance between high heat transfer and pressure drop is analyzed using the efficiency index. The tube layout in the staggered form is seen to have better heat transfer characteristics than the in-lined layout for both the configurations.

Numerical Study on the Effect of Dislocation Relationship on Resistance Characters of the Ceramic Oxidation Bed Based on Fluent Software

2011 ◽  
Vol 347-353 ◽  
pp. 3798-3803
Author(s):  
Yong Qi Liu ◽  
Xiang Chun Chen
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Numerical Study ◽  
High Heat ◽  
Transfer Efficiency ◽  
Heat Transfer Efficiency ◽  
High Heat Transfer ◽  
Fluent Software ◽  
Resistance Loss ◽  
Overall Resistance

As ceramic oxidation bed has high heat transfer efficiency, now, great attention has been given on it. In the oxidation bed, between the honeycomb holes of the fore-and-aft blocks of ceramic honeycombs, there are dislocation relationships. The effect of dislocation relationship on the pressure drop of the oxidation bed was numerically simulated by Fluent software. The results show that, between the two blocks of closely adjacent ceramic honeycombs, when a gap distance of 1mm was left, compared to the situation the gap distance is 0, the overall resistance loss of the oxidation bed reduced vast.

scholarly journals Thermo-Hydraulic Performance of U-Tube Borehole Heat Exchanger with Different Cross-Sections

2021 ◽  
Vol 13 (6) ◽  
pp. 3255
Author(s):  
Aizhao Zhou ◽  
Xianwen Huang ◽  
Wei Wang ◽  
Pengming Jiang ◽  
Xinwei Li
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Heat Resistance ◽  
Cross Sections ◽  
Three Dimensional ◽  
Thermal Response ◽  
Transfer Efficiency ◽  
Cross Sectional ◽  
Heat Transfer Efficiency ◽  
Oval Tube

For reducing the initial GSHP investment, the heat transfer efficiency of the borehole heat exchange (BHE) system can be enhanced to reduce the number or depth of drilling. This paper proposes a novel and simple BHE design by changing the cross-sectional shape of the U-tube to increase the heat transfer efficiency of BHEs. Specifically, in this study, we (1) verified the reliability of the three-dimensional numerical model based on the thermal response test (TRT) and (2) compared the inlet and outlet temperatures of the different U-tubes at 48 h under the premise of constant leg distance and fluid area. Referent to the circular tube, the increases in the heat exchange efficiencies of the curved oval tube, flat oval tube, semicircle tube, and sector tube were 13.0%, 19.1%, 9.4%, and 14.8%, respectively. (3) The heat flux heterogeneity of the tubes on the inlet and outlet sides of the BHE, in decreasing order, is flat oval, semicircle, curved oval, sector, and circle shapes. (4) The temperature heterogeneity of the borehole wall in the BHE in decreasing order is circle, sector, curved oval, flat oval, and semicircle shapes. (5) Under the premise of maximum leg distance, referent to the heat resistance of the tube with a circle shape at 48 h, the heat exchange efficiency of the curved oval, flat oval, semicircle, and sector tubes increased 12.6%, 17.7%, 10.3%, and 7.8%, respectively. (6) We found that the adjustments of the leg distance and the tube shape affect the heat resistance by about 25% and 12%, respectively. (7) The flat-oval-shaped tube at the maximum leg distance was found to be the best tube design for BHEs.

Development of Heat Exchanger Fouling Model and Preventive Maintenance Diagnostic Tool

2007 ◽  
Vol 2 (2) ◽  
Author(s):  
H. Zabiri ◽  
V. R. Radhakrishnan ◽  
M. Ramasamy ◽  
N. M. Ramli ◽  
V. Do Thanh ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Predictive Model ◽  
Diagnostic Tool ◽  
Preventive Maintenance ◽  
Heat Exchangers ◽  
Waste Heat ◽  
A Priori ◽  
Transfer Efficiency ◽  
Heat Transfer Efficiency

The Crude Preheat Train (CPT) is a set of large heat exchangers which recover the waste heat from product streams back to preheat the crude oil. The overall heat transfer coefficient in these heat exchangers may be significantly reduced due to fouling. One of the major impacts of fouling in CPT operation is the reduced heat transfer efficiency. The objective of this paper is to develop a predictive model using statistical methods which can a priori predict the rate of the fouling and the decrease in heat transfer efficiency in a heat exchanger in a crude preheat train. This predictive model will then be integrated into a preventive maintenance diagnostic tool to plan the cleaning of the heat exchanger to remove the fouling and bring back the heat exchanger efficiency to their peak values. The fouling model was developed using historical plant operating data and is based on Neural Network. Results show that the predictive model is able to predict the shell and tube outlet temperatures with excellent accuracy, where the Root Mean Square Error (RMSE) obtained is less than 1%, correlation coefficient R2 of approximately 0.98 and Correct Directional Change (CDC) values of more than 90%. A preliminary case study shows promising indication that the predictive model may be integrated into a preventive maintenance scheduling for the heat exchanger cleaning.

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