Comparison of heat transfer rates between a straight tube heat exchanger and a helically coiled heat exchanger

The work presented is an effort to realize the changes occurring for convective coefficients of heat transfer in STHX fitted with inclined baffles. Effort has been undertaken using Fluent, a commercially available CFD code ona CAD model of small STHX with inclined baffles with cold liquid flowing into the tubes and hot liquid flowing in the shell. Four sets of CFD analysis have been carried out. The hot liquid flow rate through shell compartments varied from 0.2 kg/sec to 0.8 kg/sec in steps of 0.2 kg/sec, while keeping the cold liquid flow condition in tube at 0.4 kg/sec constant. Heat transfer rates, compartment temperatures, and overall heat transfer coefficients, for cold liquid and hot liquid, were studied. The results given by the software using CFD approach were appreciable and comparatively in agreement with the results available by the experimental work, which was undertaken for the same set of inlet pressure conditions, liquid flow rates, and inlet temperatures of liquid for both hot and cold liquids. The experimental output results were also used to validate the results given by the CFD software. The results from the CFD analysis were further used to conclude the effect of baffle inclination on heat duty. The process thus followed also helped realize the effects of baffle inclination on convective heat transfer coefficient of the liquid flow through the shell in an inclined baffle shell and tube heat exchanger. The temperature plots for both cold and hot liquid were also generated for understanding the compartmental temperature distributions inclusive of the inlet and outlet compartments. The heat duty for a heat exchanger has been found to increase with the increase in baffle inclinations from zero degree to 20 degrees. Likewise, the convective heat transfer coefficients have also been found to increase with the increase in baffle inclinations.

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Comparative Experimental Study on Performance of Corrugated Tube and Straight Tube Heat Exchanger

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.560-561.156 ◽

2012 ◽

Vol 560-561 ◽

pp. 156-160

Author(s):

Lin Ping Lu ◽

Liang Ying

Keyword(s):

Heat Transfer ◽

Experimental Study ◽

Heat Exchanger ◽

Pressure Drop ◽

Heat Exchangers ◽

Straight Tube ◽

Lower Stress ◽

Shell Side ◽

Tube Heat Exchanger ◽

Corrugated Tube

The experiments on heat transfer coefficient, pressure drop and thermal stress were done to heat exchangers with corrugated tubes and staight tubes. By analyising and comparing the heat transfer coeffient, pressure drop in tube side and shell side and axial force and stress, some conclusions can be conducted that the corrugated tube heat exchanger has better heat transfer coeffient, higher pressure drop and much lower stress caused by temperatur difference, also, it has obvious advantages under the circumstance of low Reynolds number and high temperature difference.

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Heat transfer analysis of double tube heat exchanger with wavy inner tube

Thermal Science ◽

10.2298/tsci210628266h ◽

2021 ◽

pp. 266-266

Author(s):

Ceren Hasgül ◽

Gülşah Çakmak

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Numerical Study ◽

Three Dimensional ◽

Heat Transfer Analysis ◽

Wave Number ◽

Straight Tube ◽

Flow Conditions ◽

Ansys Fluent ◽

Tube Heat Exchanger

In this study, the effect of the design on the heat transfer is numerically investigated by using the "wavy inner tube" in a double-pipe heat exchanger. A wavy inner tube was used in the design to give a turbulent effect to the fluid along the inner tube of a double tube heat exchanger. In numerical study, ANSYS 12.0 Fluent code program was used, and the basic protection equations were solved for steady-state, three-dimensional and turbulent flow conditions. The study was examined at Reynolds numbers ranging from 2700 to 5300. The obtained results were compared with the experimental data performed under the same conditions. As a result of this comparison, after it was seen that the results obtained from the numerical analysis and the experimental results were compatible with each other, the wave number of the inner tube was increased and analyzed with the ANSYS fluent code program. When the data obtained as a result of the analyzes were evaluated, it was seen that the highest heat transfer was obtained from the 16 wave tube heat exchanger, which has the highest number of waves and under counter flow conditions. The increase in heat transfer increased by 270% compared to the straight tube.

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The Testing and Model Validation of an Additively Manufactured Twisted Tube Heat Exchanger

ASME 2019 Heat Transfer Summer Conference ◽

10.1115/ht2019-3500 ◽

2019 ◽

Author(s):

John D. Bernardin ◽

Kyle Ferguson ◽

David Sattler

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Transfer Rate ◽

Straight Tube ◽

Cfd Model ◽

Tube Heat Exchanger ◽

Twisted Tube ◽

Overall Heat Transfer Coefficient ◽

Shell And Tube ◽

Tube Shell

Abstract Performance enhancements in heat exchanger design and manufacturing have been achieved over the past several decades through a combination of improved thermal-hydraulic modeling and experimentation tools, enhancements in material formulations and associated property characterizations, and new manufacturing methods. Most recently, Additive Manufacturing (AM) methods have matured sufficiently that they are now being considered as realizable heat exchanger fabrication methods. More complex, compact, and efficient designs can be achieved with AM methods that could not be easily obtained through more traditional manufacturing techniques. This study expands upon a previous work [1] in which an optimized twisted tube shell and tube stainless steel heat exchanger was designed, analyzed, and fabricated with a Direct Metal Laser Sintering (DLMS) AM method. In that study, the twisted tube heat exchanger performance was a considerable improvement over that of a traditional straight tube shell and tube heat exchanger. In the present study, the AM twisted tube heat exchanger was subjected to thermal-hydraulic tests to measure its performance and to identify any necessary refinements to the previous CFD model. For the conditions used in this study, the experimental data will show how the previous CFD model over-predicted the twisted tube heat exchanger’s heat transfer rate of 2,297 W and under predicted its overall heat transfer coefficient of 1,008 W/m2/K. Interrogation of the CFD model found that this discrepancy was due to the utilization of a k-ε turbulence model. Once this turbulence characterization was replaced with a more suitable shear transport model, the numerical predictions and experimental measurements of total heat transfer rate and overall heat transfer coefficient were in very close (∼10%) agreement. When combined with the previous study, this current work reveals how a complex, twisted tube shell and tube heat exchanger can be designed with existing CFD modeling tools and efficiently manufactured with current AM technologies to significantly improve its performance over a more traditionally manufactured straight tube version of the heat exchanger.

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

Process Industries ◽

10.1115/imece2004-59872 ◽

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.

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Performance of Heat Exchanger with Nanofluids

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1021.160 ◽

2021 ◽

Vol 1021 ◽

pp. 160-170

Author(s):

Amer Hameed Majeed ◽

Yasmin Hamed Abd

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Flow Rate ◽

Hot Water ◽

Transfer Coefficients ◽

Maximum Enhancement ◽

Transfer Rates ◽

Tube Heat Exchanger ◽

Heat Transfer Coefficients ◽

Cold Fluid

The effect of adding nanomaterial of aluminum oxide (Al2O3), titanium oxide (TiO2) and zirconium oxide (ZrO2) in different concentrations of 0.25, 0.5, 0.75, 1.0, and 1.25 g/L to the cold fluid (water) turbulently flowing with different flow rates of 75, 100, 125, 150, and 175 L/min in tube side countercurrently to hot water flowing with a constant flow rate of 60 L/min in the shell side of shell and tube heat exchanger on the heat transfer rates and overall heat transfer coefficients are experimentally studied. It is found that the addition of nanomaterials gives rise to outlet cold (nano) fluids temperatures causing to enhancement averagely 7.74, 11.25, and 17.38 percent for ZrO2, TiO2, and Al2O3 respectively in heat transfer rate and averagely 12.72, 19.47, and 28.71 percent for ZrO2, TiO2, and Al2O3 respectively in overall heat transfer coefficients. The maximum enhancement values in heat transfer rates and in overall heat transfer coefficients are attained at a flow rate of 150 L/min of cold fluid.

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Experiments on a Crossflow Heat Exchanger With Tubes of Lenticular Shape

Journal of Heat Transfer ◽

10.1115/1.3245623 ◽

1983 ◽

Vol 105 (3) ◽

pp. 571-575 ◽

Cited By ~ 20

Author(s):

E. K. Ruth

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Cross Section ◽

Reynolds Numbers ◽

Transfer Rates ◽

Tube Heat Exchanger ◽

Pressure Losses ◽

Circular Tubes

Measurements of pressure losses and heat transfer rates were made for an unconventional crossflow heat exchanger with tubes of lenticular cross section so spaced to reduce variation in the velocity of the fluid outside the tubes, thus reducing separation and drag. The results of these experiments are reported for various tube spacing and demonstrate that the performance of the lenticular tube heat exchanger is superior to that of conventional circular tubes by 20 percent at Reynolds numbers of 20,000 to 50,000.

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Heat Transfer Characteristics of Inclined Helical Coil Tube by Forced and Free Convection : A Review

International Journal of Scientific Research in Science Engineering and Technology ◽

10.32628/ijsrset207257 ◽

2020 ◽

pp. 322-328

Author(s):

Sagar S. Gaddamwar ◽

Rajeshkumar U. Sambhe

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Thermal Power ◽

Relative Advantage ◽

Outer Side ◽

Helical Coil ◽

Straight Tube ◽

Tube Heat Exchanger ◽

Heat Transfer Augmentation ◽

Augmentation Techniques

Aim of this review work is to examine the relative advantage of using an inclined helical coil tube heat exchanger for high-pressure syngas under various industries application. It observed that the heat transfer in the helical coil tube is higher as compared to the straight tube due to their shape. Inclined helical coil tube heat exchanger offers advantageous over straight tubes due to their compactness and increased heat transfer coefficient. The increased heat transfer coefficients are a consequence of the curvature of the coil, which induces centrifugal forces to act on the moving syngas. Due to the curvature effect, the fluid streams in the outer side of the pipe moves faster than the syngas streams on the inner side of the tube. Heat transfer augmentation techniques refer to various methods used to increase the heat transfer rate without changing much the overall performance of the system. The arrangements are useful in a variety of applications where more heat transfer rates desired. Some of the claims involved in heat exchanger used in Thermal Power plants, process industries, air-conditioning equipment, heating and cooling in evaporators, radiators for space vehicles, automobiles, refrigerators. These techniques broadly of three types viz. passive, active, compound heat transfer augmentation techniques. The present paper reviews the experimental investigation of free and forced convection heat transfer from different helical coiled tubes.

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