Pitch Ratio Research Articles

Experimental Study on the Bond Performance of Steel–Basalt Fiber Composite Bars in Concrete

Steel–basalt fiber composite bars (SBFCBs) exhibit excellent strength, elastic modulus, toughness, corrosion resistance, and low cost. Understanding the bond performance between SBFCBs and concrete is important for evaluating the mechanical behavior of SBFCB-reinforced concrete structures. In this study, the bond–slip performance of SBFCB in concrete was experimentally assessed via pullout and beam bond tests. The influence of various factors on the bond performance was discussed, and the bond mechanism between SBFCB and concrete was analyzed. The results indicate that reducing the thread pitch ratio in the SBFCB can reduce slippage at the postpeak bonding stress–slip curve. The bond strength of the SBFCB was significantly improved by sandblasting. Longer bond lengths correspond to smaller average bond strengths in SBFCB. The load corresponding to the maximum bond strength of a specimen with a bond length of 10d was determined as the ultimate load value for the SBFCB. An increase in the SBFCB diameter had a negative impact on the bond strength. Moreover, an increase in the concrete cover thickness was conducive to improving the bond strength; if the thickness of the concrete cover was sufficiently increased, failure occurred owing to SBFCB tension rather than bonding. Based on the test results and the existing bond–slip model, a simple bond–slip constitutive model of the SBFCB embedded in concrete was proposed to simulate the pullout process of the SBFCB. Subsequently, the established bond–slip model can be used to analyze the mechanical performance of SBFCB-reinforced concrete structures.

The impact of using twisted double tube of innovative turbulator on the efficiency of a flat panel solar collector with geometric optimization

BackgroundFluids as water, ethylene glycol, etc. employed to enhance heat transfer, have a lower thermal conductivity (TC) coefficient compared to metals and even metal oxides. This paper presents computational fluid dynamics (CFD) simulation of the twisted double tube heat exchanger (HE) filled with two-phase MWCNT-TiO2/water hybrid nanofluid (Hnf). MethodsThe FLUENT 16 software is employed for numerical simulations of the HE with novel turbulator. The hybrid nanofluid is simulated using the two-phase mixture model and turbulent flow is modeled utilizing Realizable k-ε turbulence model. The Reynolds number (Re) alters from 7000 to 28000, the volume fraction of nanoparticles (φ) varies from 1.0 to 4.0%, and the pitch ratio of the innovative turbulator is 1.0, 2.0, 3.0, and 4.0. Outcomes proved average Nusselt number (Nuave) and pressure drop are strongly influenced by Re and φ. ResultsThe maximum thermal efficiency and HE pressure drop correspond to φ = 4%, Re = 28000, and a pitch ratio of 4. When φ = 4% and Re = 28000, adding turbulator with a pitch ratio of 4 inside the heat exchanger enhances Nuave by 106.92% in comparison with heat exchanger without turbulators. When φ = 4% and Re = 28000, adding turbulator with a pitch ratio of 4 inside the heat exchanger increases the pressure drop by 296.19% compared to HE without turbulators. Finally, exergy efficiency of HE with a turbulator with a pitch ratio of 4 is improved by 21.83% as Re increases from 7000 to 28000 when φ = 4%.

Numerical investigation on the performance of a solar air heater using inclined impinging jets on absorber plate with parallel and crossing orientation of nozzles

This work investigates the performance enhancement of a solar air heater using inclined impinging jets on the heater surface. Two main sets of arrangements are considered for the jet nozzles including the parallel and crossing orientation of nozzles in consecutive rows. The RNG k − ɛ model is employed to simulate the turbulent flow in the channel. The influence of different geometrical and operational parameters such as jet diameter ratio (Dj/Dh), inclination angle (α,β), stream wise pitch ratio (L/Dh), span wise pitch ratio (S/Dh), Re number and velocity ratio (Vr) on the hydraulic and thermal behavior of jet solar air heater was studied. Results showed that the proposed jet solar air heater improved the Nu number and thermohydraulic performance parameter compared to the conventional unimproved solar air heater. For the studied range of parameters, up to 4.26 times higher Nu number was obtained using the jet impingement compared to the smooth duct solar air heater. Moreover, it was shown that the amount of velocity ratio (Vr) is a significant factor when comparing the parallel and crossing orientations. Additionally, results indicated that the increment of stream wise and span wise pitch led to the increment of the Nu number while having a minor effect on the friction factor. For example, the increment of L/dh from 0.3 to 0.6 leads to the reduction of f/fs of case 1 and case 4 by 6.5% and 1.09%, respectively Also, the increment of the jet diameter first raises the thermohydraulic performance parameter, and then with a further increment of diameter, the amount of thermohydraulic performance parameter decreases.

Turbulent Heat Transfer Augmentation in a Square Channel by Augmenting the Flow Pattern with Novel Arc-Shaped Ribs

Solar water heaters (SWHs) are widely used in HVAC industries as well as in households for different heating purposes. The present numerical simulation focuses on the investigation of the thermo-hydraulic performance of novel semi-arc-rib SWHs. Semi-arc-shaped ribs in the square channel of the absorber plates with different pitch and height ratios are investigated in this study. The present novel modification disturbs the boundary layers by generating vortices, and thus, enhanced fluid mixing takes place. Water with a Reynolds number (Re) ranging from 4000 to 25,000 is used as a working fluid, and a 1.0 kW/m2 heat flux is imposed on the tube wall. The results demonstrate a significant increase in the Nusselt number (Nu) as the fluid layers localize behind each rib near the absorber plates, and at the same time, the number of swirls generated inside the tube and the frictional losses both increased noticeably. To ensure the effectivity of the present novel SWH geometry, the thermo-hydraulic performance (η) for each case was calculated, and it was found that in all the cases, it was greater than unity, which signifies that the present semi-arc-rib SWH is promising and can be used in HVAC industrial and household applications.

Design and performance optimization of solar water heating system with perforated obstacle using hybrid multi-criteria decision-making approach

Solar water heating system (SWHS) is a cost-effective technology with high household adoption rates worldwide. The performance of SWHS significantly deteriorates due to several factors, including design parameters as well as radiative and convective heat losses from the system, which considerably impair the system's efficiency. Novel designs and unique heat transfer techniques are increasingly being explored to improve the efficiency of SWHS. In this framework, the following research focuses on designing and optimizing an SWHS integrated with perforated delta obstacles. The influence of Reynolds number (400, 800, 1200), angle of attack (15°, 30°, 45°), and pitch ratio (0.5, 1, 1.5, 2.0) on the friction factor, Nusselt number, and thermo-hydraulic performance was investigated and optimized. The combination of Reynolds number = 1200, angle of attack = 45°, and pitch ratio = 1 yielded the most significant Nusselt number (90.55). In contrast, the combination of Reynolds number = 1200, angle of attack = 15°, and pitch ratio = 0.5 yielded the lowest friction factor (0.38). The largest thermo-hydraulic efficiency (2.75) was obtained using Reynolds number = 400, angle of attack = 45°, and pitch ratio = 1. Since no single SWHS design alternative can meet all desired performance criteria, selecting the best among SWHS design alternatives is not easy. Therefore, a hybrid multi-criteria decision-making approach called AHP (analytic hierarchy process)-ARAS (additive ratio assessment) was implemented, suggesting the SWHS design alternative having the angle of attack = 45°, Reynolds number = 1200, and pitch ratio = 1 satisfies the preset performance criteria. Finally, sensitivity analysis and validation with other decision-making approaches were performed to verify the proposed decision-making framework's effectiveness, proving the results' robustness.

Impact of vortex generator and two-phase MWCNT-MgO/water hybrid nanofluid on thermo-hydraulic performance and exergy and energy efficiency of a solar collector under Kuwait climatic conditions

The effect of curved vortex generators and two-phase MWCNT-MgO/water hybrid nanofluid (HNF) on thermo-hydraulic performance and exergy and energy efficiency of a solar collector in a turbulent flow regime is examined in this study. The simulations performed for the climatic conditions of Kuwait. The two-phase DWCNT-MgO/water HNF is modeled using the mixture model. The numerical study is performed for DWCNT-MgO/water HNF with a volume fraction (φ) range of 1–3%, Reynolds number (Re) range of 5000–20,000, and four Pitch Ratio (PR = 0 (Case A), PR = 0.1 (Case B), PR = 0.2 (Case C) and PR = 0.3 (Case D)). It is found that the average Nusselt number (Nuav) and pressure drop (Δp) are enhanced with Re and φ. At φ = 3% and Re = 20,000, placing the vortex generator with a PR = 0.3 (Case D) inside the solar collector causes the Nuav to improve by 83.09% as compared to the solar collectors without turbulators. In addition, the results demonstrated that the use of vortex generators is desirable in all PRs. For Case D and φ = 3%, the exergy efficiency is improved by 45.02% as Re is enhanced from 5000 to 20,000.

Investigation of film boiling over tandem arrangement of elliptical cylinders in vertical cross-flow of saturated liquid

The present study investigates the phenomenon of film boiling heat transfer for the tandem arrangement of elliptical heaters placed in cross-flow of saturated liquid (water) at near critical pressure conditions (P/Pc = 0.99), using the Eulerian approach-based volume of the fluid framework. The effect of vertical spacing between the heaters (pd = 7.5a to 12.5a), their aspect ratio (ψ = 0.4 to 1), degree of wall superheat (Jav/Prv = 0.6 to 1.8) and Reynolds number for liquid flow (Rel = 10 to 40) is investigated on the bubble departure dynamics and heat transfer characteristics. It is observed that the bubble departure size from the bottom heater has remained almost unchanged for all the situations whereas its departure frequency has increased upon an increase of Reynolds number and degree of superheat. The bubble size has varied significantly for the top elliptical heater and its departure frequency has increased with the decrease of aspect ratio and increase of pitch, Reynolds number and degree of superheat. The time-averaged heat transfer coefficient has increased upon an increase in pitch distance, aspect ratio, Reynolds number and degree of superheat, however, the rate of increase has diminished at a high degree of superheat.

Study on enhanced heat transfer of a phase change material slurry in transverse corrugated tubes

Enhancing the heat transfer of ice slurry is a key to improving its application. The outward transverse corrugated tube (OTCT) presents a better heat transfer enhancement as an effective passive flow control method. In this paper, the thermo-fluidic performance and enhanced heat transfer mechanism of ice slurry in OTCT are numerically studied using Euler-Euler multiphase model. The results indicated that turbulent vortex of ice slurry in OTCT is enhanced with the rise in the ratio of corrugation height to diameter (H/D), and declined with rising the of ratio corrugation pitch to diameter (P/D), and ratio of corrugation pitch to width (W/D). The ice concentration presents a periodic fluctuation along the flow direction. The values of H/D, W/D, and P/D have a significant influence on the mass transfer for ice slurry. And the ice particle concentration displays more even distribution as increasing H/D, and decreasing W/D and the P/D. The average flow resistance (fave) and Nusselt number (Nuave) increase with the increasing H/D and decreasing P/D, and decrease with increasing W/D. Nuave presents a linear increase with Re. For the inlet ice volume fraction of αin = 10%, Nuave enlarges significantly by increasing the Re from 4950 to 9540 for different H/D, P/D, and W/D values. The performance evaluation criterion (PEC) reaches a maximum value for different H/D and P/D at Re = 9540 when W/D = 0.4, αin = 10%. For bigger inlet ice particle concentration, the increment of Nuave of ice slurry in OTCT is more significant at higher Re compared with the smooth tube. Meanwhile, under higher ice concentration, the overall heat transfer performance is more prominent at large Re. Finally, the empirical correlations of the fave and Nuave are established to predict the thermal–hydraulic performance of ice slurry flowing through OTCT.

Effect of pitch and hole-hydraulic depth of perforated V-shaped baffles on the heat transfer and thermohydraulic performance of an air heater duct

The introduction of V-shaped or inclined perforated baffles in a heat exchanger duct influences the flow dynamics significantly and enhances its thermal performance. The appropriate spacing and perforation shape of baffles further improve the heat transfer mechanism. This work aims to experimentally compare the thermal attributes of a smooth air heater duct with those by incorporating perforated V-shaped baffles with staggered non-circular openings of a constant perforation ratio in the flow passage. The effects obtained on the Nusselt number (Nu), friction factor (f) and the thermohydraulic performance parameter (η) of the duct are studied under the turbulent airflow Reynolds number (Re) range of 5500 to 15,000 by modifying three different values of pitch ratio (p/H) and hole-hydraulic depth-to-baffle height ratio ([Formula: see text]) for both V-down and V-up arrays. The investigation also encompasses developing the correlations of criteria Nu, f and η. The results show that the Nu ameliorates by increasing [Formula: see text] at reduced p/H, whereas the f value increases by reducing the hole-hydraulic depth. The maximum Nusselt number ratio ([Formula: see text]) obtained for V-down and V-up baffles, respectively, are 3.36 and 3.58 at p/H of 1 and [Formula: see text] of 0.84 with the Re range of around 13,600. The V-down and the V-up array at p/H of 1 shows the maximum friction factor ratio ([Formula: see text]) as 11.9 and 13.14, respectively, for [Formula: see text] values of 0.74 and 0.79 at the extreme Re range. The V-up array at p/H of 3 with increased [Formula: see text] (0.84) outperforms obtaining the highest η value of 1.67. The correlations developed show good agreement between the experimental and predicted data.

Comprehensive 3E analyses of a parabolic trough collector equipped with an innovative combined twisted turbulator

The Parabolic trough collector (PTC) is one of the most well-known equipment in renewable energy. Today, it is also a renewable source for refining and transferring power to a low-carbon economy. The present study aims to investigate the effect of the geometrical shape of the Receiver cross-section in the PTC and to investigate the effect of placing the innovative combined twisted turbulator (CTT) in it. The receiver is simulated with three different geometric shapes circular cross-section (CCS), vertical elliptical cross-section (VECS), and horizontal elliptical cross-section (HECS). The PTC contains a two-phase MWCNT-GO/Syltherm 800 hybrid nanofluid (HNF), simulated using the mixture model. In this study, numerical simulations have been conducted for Reynolds numbers (Re) of 5000 to 20,000, volume fractions (ϕ) of 1 and 2% of nanoparticles, and pitch ratios (PR) of 0.5 to 2 of the innovative CTT. The results obtained from the present study show that the geometrical change of the cross-section of the receiver is very effective in the hydrodynamic performance of the PTC. Also, placing the innovative CTT in Receiver has consistently increased thermal performance and energy efficiency. The performance evaluation criteria (PEC) index is always greater than 1 in all numerical simulation modes. Therefore, innovative CTT is always desirable in terms of the PEC index. The maximum exergy efficiency is Re = 10,000, ϕ= 0.02, and PR = 2. Based on the environmental analysis, the amount of carbon dioxide in the PTC equipped with an innovative CTT containing two-phase MWCNT-GO/Syltherm 800 HNF is 0.033 kg/day.

Investigation into the effect of twisted tape on the thermo-hydraulic performance and entropy generation of turbulent flow of mono and hybrid magnetic nanofluids inside a parabolic solar collector absorber tube by applying two-phase analysis

This research study examines the impact of applying a twisted tape on thermo-hydraulic performance as well as entropy generation related to the turbulent flow of mono and hybrid magnetic nanofluids inside a parabolic solar collector (PSC) absorber tube. In this study, two-phase water/multi-walled carbon nanotubes (MWCNTs) nanofluid and two-phase water/MWCNT-iron oxide nanofluid having the 1% volume fraction (VF) are applied as the working fluid. To model two-phase flow, the mixture model standard k-ε turbulence model and QUICK algorithm are utilized. This research study is implemented for diverse Reynolds numbers of 6000 to 24000 and some twisted tape's pitch ratios including 0.25, 0.50, and 0.75. In addition, the standard k-ε turbulence model is then applied for modeling the turbulent flow. The obtained results obtained by the numerical study demonstrate that using the twisted tape in solar collectors could improve thermo-hydraulic performance in comparison to the solar collector with no particular twisted tape. Also, the considered HT related to the collector having twisted tape is more than that without twisted tape in all cases, i.e., thermo-hydraulic performance coefficient is always greater than 1. The results reveal that using magnetic hybrid nanofluid leads to better thermal performance than mono nanofluid. Finally, the entropy generation is reduced with the Reynolds number as well as the pitch ratio of the twisted tape. The highest value in PEC surge was about 27% owing to using of magnetic hybrid nanofluid, while for simple nanofluid, it was 22%. According to this case, the use of magnetic hybrid nanofluid is recommended.

In-plane fluidelastic instability study of a tube bundle with a rotated triangular layout and small pitch ratio

Since the shutdown of the San Onofre Nuclear Generating Station (SONGS), the question of the possibility of in-plane fluidelastic instability in the steam generators was raised. In a step to analyse the stability of the APR1400 steam generator, this paper reports on an experimental fluidelastic instability study in single phase (water) and two-phase (air–water) cross flow of the vertical tube bank in the steam generator. The study concerns the vibration behaviour of single flexible tube with an otherwise rigid array as well as fully flexible array. The tube pattern analysed is the rotated triangular array (60°) having a pitch spacing (P/D) of 1.33. This spacing is generally more confined than what is usually seen in the literature. Adjustable tube mounts allow the tubes to vibrate only in one direction, whether in the streamwise or transverse to the flow. The stability threshold in the transverse direction of such a tightly spaced rotated triangular array is somewhat lower than the other layouts. Damping of this rotated triangle array reaches its maximum value at a void fraction near 80%. Fluidelastic instability critical velocity in the streamwise direction was found to be much higher than the range of velocities implied by the ASME design guideline, which implies relatively high Connors constants. This was observed in the case of fully flexible array only, where cross-coupling between the tubes is significant. However, A single flexible tube did not undergo instability, which indicates that the streamwise instability is governed by the fluid stiffness mechanism.

Effect of Pitch Ratio of Tube Banks on Passive Acoustic Properties

Tube banks are common design elements in heat exchangers. The most common tube bank patterns are In-line tube banks and Staggered tube banks. These are characterized by their longitudinal and transverse pitch ratios (pitches to diameters). The tube bank with a pitch ratio of less than 1.25 is considered a compact tube bank and a pitch ratio greater than 2 is considered as widely spaced. In this paper, the attention is focused on the effects of pitch ratio in tube banks on its passive acoustics properties which are experimentally investigated. The flow duct experimentation is performed with and without flow to analyse the passive acoustic properties of tube banks. The Experiment is conducted for both the In-line and Staggered tube banks with pitch ratios from 1.2 to 2.5. Experimental results consist of scattering matrix coefficients and power balance. The results are compared to see the pitch ratio effect.

Численный анализ влияния относительного продольного и поперечного шагов на характеристики потока шахматного пучка труб каплевидной формы

The present work has been conducted to clarify flow behavior across staggered drop-shaped tubes bundle at various longitudinal and transversal pitch ratios (the tubes bundle configures in 18 cases). The investigation covers the effects of key design parameters of Reynolds numbers Re = (1.78--18.72) · 103, longitudinal pitch ratios (PL = 1.44, 1.54, 1.64, 1.74, 1.84 and 2.04) and transversal pitch ratios (PT = 1.24, 1.44, 1.64 and 1.82). ANSYS Fluent software package is used to predict the flow pattern around tubes. The results of this study showed that at a constant longitudinal pitch ratio, the minimum friction factor varies with the Reynolds number and transversal pitch ratio. As the Re increases, the friction factor decreases. The minimum values of the friction factor were achieved for (PL = 1.24 and PT = 1.44) at Re = 1.78 · 103, and (PT = PL = 1.64) at Re > 1.78 · 103. Correlation of the friction factor for the studied models were presented

Hydrodynamic and thermal entrance region assessment of turbulent flow through a circular tube with a tight-fit twisted tape insert, considering multifarious operating conditions and pitch ratios

Hydrodynamic and thermal entrance region assessment of turbulent flow through a circular tube with a tight-fit twisted tape insert, considering multifarious operating conditions and pitch ratios

Study on Calculating Method of the Super-transient Reactance of Permanent Magnet Motor and Analysis of Influencing Factors

This paper takes a salient pole permanent magnet wind generator as the research object and summarizes the calculation method of its super-transient reactance parameters. The analytical method and parameter identification method are selected to analyze the influencing factors of the direct axis super-transient reactance parameters. Finally, the variation law of direct axis super-transient reactance parameters with the number of parallel branches, short pitch ratio, and diameter of damping windings is obtained, which provides a certain reference for the dynamic performance evaluation of permanent magnet motors.

Effect of high-strength steel spirals on the seismic behavior of square concrete-filled steel tubular columns under high axial load ratio

Ductility of square concrete filled steel tubular (CFST) columns is generally significantly lower than that of circular ones, especially when they are under high level of axial loads. Many previous studies suggested that adding internal steel spiral stirrups is an effective measure to improve ductility of square CFST columns. To investigate the effect of high-strength steel (HSS) spirals on the seismic behavior of the HSS spiral-confined CFST (HSS-CFST) columns under high axial load ratio, 15 square CFST columns, including 3 conventional CFST columns without internal steel spirals, 3 normal-strength steel (NSS) spiral-confined CFST (NSS-CFST) columns, and 9 HSS-CFST columns were experimentally studied through the cyclic loading tests. The critical test parameters included the steel spiral pitch and axial load ratio. Final failure modes, hysteretic response, skeleton curves, strain distributions, ductility, energy dissipation capacity, and stiffness degradation of the specimens were investigated in detail. The experimental results indicated that (i) apparent outwardly local bucking of the steel tube and core concrete crushing were observed for all specimens in the plastic hinge regions at the ultimate state; (ii) adding both the NSS and HSS spirals would beneficial in improving the hysteretic behavior and energy dissipation capacity of square CFST columns, but contributions to these improvements made by the HSS spirals were more significant than that of the NSS ones; (iii) the increase of axial load ratio and internal steel spiral pitch would impair the load-carrying capability and ultimate deformation ability of square CFST columns; (iv) ductility of the NSS-CFST and HSS-CFST columns could be improved as the increased of spiral volume ratio and the ductility enhancement was more pronounced in the HSS-CFST columns; and (v) the internal steel spirals were helpful in delaying the stiffness degradation rate of square CFST columns, particularly for those specimens under a high axial load ratio of 0.8.

Numerical analysis of the effect of the blade number on the hydrodynamic performance of shaftless rim-driven thruster

In this work, numerical investigations were performed to the study the effect of blade number on the hydrodynamic performance of shaftless Rim-driven Thruster (RDT) with certain blade area ratio and pitch ratio. The work investigated and compared the thrust coefficient, torque coefficient and efficiency of the RDTs with different blade numbers. Additionally, this work detected and analyzed the pressure distribution on the blade surface and velocity distribution around the blade and in the wake. The results demonstrate that for a certain advance coefficient, the thrust coefficient and torque coefficient of the RDT increase with the blade number, however the efficiency of the RDT decreases with the increase of blade number. For the same cross-section and advance coefficient, the 7-blade RDT has higher thrust and torque than the 3-blade RDT due to the large friction and pressure difference between the suction and pressure surfaces. The high velocity of both RDTs appears at the junction between each blade and the duct, and the 7-blade RDT has higher velocity in the wake and in the cross-section than the 3-blade RDT. The 3-blade RDT has the high pressure at the leading edge on the suction surface of each blade. However, the 7-blade RDT has not only the high pressure at the leading edge, but also the high negative pressure at the blade root on the suction surface of each blade, so 7-blade RDT has higher torque that 3-blade RDT.

Effect of arc-shaped twisted-baffles on augmented heat transfer in a rectangular duct

In this current work, the effect of utilizing arc-shaped twisted-baffles (T-ABs) in a rectangular air channel on thermal performance factor (TPF) has been experimentally studied. In these experiments, the influence of the changes in parameters such as dimensions of pitch ratio (p/w), attached arc-shape angle (α), and Reynolds number (Re) are explored. The comparisons demonstrate that a channel mounted with arc-shaped twisted-baffles yielded considerably greater Nusselt numbers than a smooth channel, possibly attributable to multiple-impinging jets near the channel surface. Heat transfer enhancements of twisted arc-shaped baffles (T-AB) having larger attack angles were superior to those having smaller attack angles. The one with α = 90o offered greater heat transfer rates than the ones with α = 20o, 40o, 60o, and 80o by approximately 8%, 7%, 4%, and 2%, respectively. The superior heat transfer was attributed to the better contact between the working fluid and heat transfer surfaces. In addition, utilizing arc-shaped twisted-baffles with the lowest p/w of 4.0, in a channel produced stronger vortices and multiple impinging jets, which caused better fluid mixing than other p/w. The optimum condition is achieved using T-ABs at an attached arc-shape angle of α = 90o, p/w = 4.0 and Re = 4000, where the heat transfer rate (Nu), friction factor (f) and TPF are found to be, respectively, 3.31, 4.68 and 1.98 times greater than those of a plain channel.

Helically-coiled-wire-induced swirl flow heat transfer and pressure drop in a circular tube under velocities controlled

Systematic measurements of the swirl flow heat transfer by the helical coil-wire and the pressure drop across the helical coil-wire were made by the experimental water loop flow with exponentially increasing heat input at mass velocities G = 3928 to 13,496 kg/m2s, inlet liquid temperatures Tin=284.14 to 307.57 K and inlet pressures Pin=763.80 to 1027.85 kPa. Systematic measurements of the pressure drop across the helical coil-wire were performed without heating circular tube. The measurements were performed on the inner surface of a SUS304 circular test tube with an inner diameter of 6 mm, a heated length of 59.7 mm, and a thickness of 0.5 mm, in which a helical coil was inserted. SUS304 helical coiled wire with wire diameter dw=2.025 mm, coil diameter Dc=3.4917 mm, total length l = 370 mm, coil pitch 360° rotation pc=37.222 mm, and coil pitch ratio yc=pc/d = 6.204 was employed. The relationship between swirl velocity and pump input frequency and that between fanning friction factor and Reynolds number (Red=1.949 × 104 to 1.274 × 105) were clarified beforehand. On the other hand, the RANS (Reynolds mean Navier-Stokes simulation) equations for the k-ε turbulence model in a circular tube of 6 mm diameter and 626 mm length with helical coil inserted, considering the temperature dependence of the thermophysical properties concerned, were numerically solved for the heating of water on a heated section of 6 mm diameter and 60 mm length under the same conditions as the experiment by using the PHOENICS code. The helical coiled wire of dw =2.025 mm, Dc=3.4917 mm, l = 370 mm, pc=37.222 mm and yc=6.204 was installed at the same experimental location. The surface heat fluxes q and average surface temperatures Ts,av on a circular tube with a helical coil of yc =6.204 obtained theoretically were compared with the corresponding experimental values on the graph of q versus temperature difference between average heater inner surface temperature and liquid bulk mean temperature ΔTL [=Ts,av-TL, TL=(Tin+Tout)/2]. The numerical solutions for q and ΔTL were almost identical to the corresponding experimental values for q and ΔTL, with deviations from 0 to +20% for the ΔTL range tested here. The numerical solutions of the local surface temperature (Ts)z, the local average liquid temperature (Tf,av)z, and the local liquid pressure drop ΔPz were also compared with the corresponding experimental values of (Ts)z, (Tf,av)z, and ΔPz against heated length L or distance from the test section inlet Z, respectively. The numerical solutions of (Ts)z, (Tf,av)z and ΔPz differ from the corresponding experimental data of (Ts)z, (Tf,av)z and ΔPz within ± 5%. The thickness of the conductive sublayer δCSL [=(Δr)out/2] and non-dimensional thickness of the conductive sublayer y+CSL [=(fF/2)0.5ρlusw,cδCSL/μl] for turbulent heat transfer on a circular tube with helical coiled wire are clarified on the basis of numerical solutions in the swirl velocity usw,c ranging from 5.108 to 17.146 m/s. Correlations of Nusselt number Nud, δCSL, and y+CSL for the swirl flow heat transfer in a vertical circular tube with helical coil wire are also derived.