Adjacent Baffles Research Articles

Application of residence time distribution (RTD) to enhance the performance of perforated baffled constructed wetland under unsteady flow

The perforated baffle can significantly enhance the performance of the constructed wetland. In the present study, the effects of perforation shape, number of baffles, baffle position and perforation location on the flow pattern of wetlands were investigated using NaCl impulse-response tracer test, and perforated baffles were used to improve the nitrogen removal rate of the constructed wetland. The perforated baffle optimizes the flow pattern by reducing the peak height of the RTD curve and delaying the peak occurrence time. Triangle perforation exhibits better flow pattern optimization due to its smaller area. When the inlet flow rate is 100 mL/min, the mean residence time (Tm) increases by 0.25 h. The position of the perforated baffle has a more significant effect on the flow pattern, being able to better extend hydraulic residence time (HRT) when located at the height of H/2 substrate. In addition, the perforation locations of two adjacent baffles are not on the same vertical line, which can increase the horizontal water flow velocity and improve the space utilization of the wetland. Compared to the control check constructed wetland (CKCW) without baffles, the perforated baffled constructed wetland (PBCW) exhibited a higher NH4+-N removal rate of 84.53 ± 7.48 % during stable operation. This is mainly because the perforated baffle improves the utilization of dissolved oxygen (DO) while improving the water flow distribution and extending the HRT. In conclusion, perforated baffles have considerable potential to alleviate shock loading and enhance the performance of constructed wetlands.

Effect of inserted baffles on hydrogen heterogeneous reaction in planar catalytic micro combustor

Heterogeneous reaction characteristics of premixed H2/Air mixture are numerically investigated in micro combustor with coating platinum (Pt) catalyst on the inner wall. The well-designed combustor with the inserted baffle is committed to improving the transport of bulk species on the catalytic surface, therefore enhancing the fuel conversion ratio. A two-dimensional numerical model with detailed heterogeneous reaction mechanism is developed and verified. In this work, the numerical results reveal that the heterogeneous reaction rate and fuel conversion ratio are significantly improved in the combustor with inserted baffle. The velocity of gaseous mixture swiftly increases between the baffle and catalytic surface, resulting in the increasing adsorption-desorption of bulk species on the catalytic surface. The main influencing factors of inserted baffle body comprise of slit width between two ribs in the same row (W), rib length (L), distance between adjacent baffles row (D), number of baffle row (n) which are studied to obtain a set of optimized parameters of baffle in the well-designed combustor. The optimized parameters of the baffle are W = 0 mm, L = 0.4 mm, D = 4 mm and n = 4, which are employed in the combustor to obtain a high hydrogen conversion ratio. Moreover, the effect of different inlet velocities and equivalent ratios of the mixture on the heterogeneous reaction characteristics are carried out in the designed combustor. As the designed combustor performs well, and the improvement effect of the optimized baffle gradually increases together with the inlet velocity, particularly for high inlet velocity (7 m/s). The promotion effects of baffle in the designed combustor are presented when the rich and lean fuel are adopted at inlet velocity of 7 m/s. Finally, the relative parameters of this work can serve as a reference and guidance for the design of micro scale combustor.

High throughput millifluidics mixer with double triangle baffle for improvement of mixing performance and reduction of flow resistance designed by grey relational analysis

To improve the mixing performance and reduce flow resistance, in this study, a novel mixer with double triangle baffles was designed and optimized by the combination of CFD simulation and grey relation analysis method. Mixing index and Poiseuille number were selected as two key indexes to evaluate the mixing performance and flow resistance of the mixer. The orthogonal experiment was conducted with selecting the aspect ratio of baffles (α), the thickness of baffles (h), the spacing between adjacent baffles (c) and the number of baffles (d) as design variables. Among all design variables, d has the greatest influence on the mixer performances. The results show that the optimized mixer has a maximum increase of 14.25% in mixing index and a maximum decrease in Poiseuille number of 60.02%. Finally, the optimal configuration was scaled-up to centimeter level, which makes the mixer have high mixing performance, low flow resistance and high throughput at the same time. All the findings provide useful references for high throughput mixer design and optimization.

INSIGHT INTO AN EFFICIENT MICROMIXER WITH STAGGER ABREAST BAFFLES

Passive micromixers utilize no external energy input. It mainly depends on the structure change of microchannel to produce chaotic convection effect, which increases the contact surface and contact time between the fluid. The mixing efficiency of stagger non-abreast baffles (SNB) micromixer and stagger abreast baffles (SAB) micromixer is compared at five kinds of Reynolds (Res). It may affect the mixing efficiency including the height ([Formula: see text]) and number ([Formula: see text]) of baffles, the distance between two adjacent baffles, non-abreast baffles, and abreast baffles. As the [Formula: see text] of the baffles changes, it contributes to enhance the chaotic convection of the micromixer. When Re [Formula: see text], the worst mixing efficiency of the most efficient seven SABs ([Formula: see text], [Formula: see text] mm, [Formula: see text] mm, [Formula: see text]) micromixer reaches an astonishing 98%. The concentration change along the microchannel is studied in this paper. At low Re, SAB makes fluid contact zigzag in microchannel and enhances molecular diffusion. At high Re, SAB causes chaotic convection in the microchannel and completes the mixing quickly.

Reducing labyrinth seal leakage with application of axially arranged baffles with increasing height

Abstract For turbomachines, reducing seal leakage is beneficial for increasing the efficiency and reducing the energy consumption. This study proposes the design of the axially arranged baffles with increasing height to reduce the leakage of the labyrinth seal. Due to the existence of the axially arranged baffles with increasing height, the leakage fluid is guided to flow into the seal cavities. In each seal cavity, one large vortex is induced, and additional small vortexes are induced in the regions between adjacent baffles. The leakage flow resistance and kinetic energy dissipation of the leakage fluid are enhanced. To demonstrate the effectiveness of the new design, numerical comparisons are conducted between the labyrinth seals with and without axially arranged baffles with increasing height. Results show that the new seal can reduce the leakage flow rate by 37.7-38.8% compared with the labyrinth seal.

Performance investigation on the novel anti-leakage and easy-to-manufacture trisection helical baffle electric heaters

The difficult manufacturing of helical baffles hinders the widespread application of the enhancement technology and the shortcut leakage between adjacent baffles impairs the enhancement effects. To solve these two issues, the promising anti-leakage and easy-to-manufacture helical baffles with small inclined angle and folded structure are proposed, which can be produced by 2D laser cutting and simple mechanical folding. The influence of different helical baffle configurations, including three normal helical schemes, three axial separation helical schemes, three novel folded axial separation helical baffle schemes and a segmental scheme on the performance of electric heaters are numerically investigated. The equivalent angles of helical schemes adopted in this work are 15°, 20° and 25°, and the inclined angle of helical baffles under axial separation connection style is 10°. Compared with the corresponding axial separation scheme without folding, the leakage can be significantly decreased, the heat transfer coefficients h and the comprehensive indices h⋅Δp−1/3 of FH15(10)°, FH20(10)° and FH25(10)° are increased by 6.5%/2.3%, 12.2%/7.3% and 20.4%/13.0%, and the averaged tube wall temperatures Tw are decreased by 12.5 K, 25.4 K and 54.7 K, respectively. This research can provide feasibility for the extended application of helical baffles in electric heaters or heat exchangers.

Optimization of a shell and tube heat exchanger with staggered baffles using Taguchi method

In this work, Taguchi method is applied on the numerical simulation results of a shell and tube heat exchanger with staggered baffles (STHX-ST) for the purpose of optimizing its design parameters corresponding to maximum heat transfer rate and minimum pressure drop. An STHX-ST integrates the characteristics of a shell and tube heat exchanger with segmental baffles as well as helical baffles. The baffles in these heat exchangers are oriented in such a way that a constant clockwise or counter clockwise angle is maintained between the adjacent baffles. The analysis of the shell side of these heat exchangers in this work is carried out using computational fluid dynamics (CFD) by varying its design parameters. The rate of heat transfer obtained and total pressure drop across the shell side of the heat exchanger is calculated using CFD. A set of experiments are designed as an orthogonal array as per Taguchi method through combinations of design parameters such as shell inside diameter, tube outside diameter, baffle cut, baffle spacing and baffle orientation angle. CFD Simulations are carried out on each parameter combination in this array. Finally signal to noise ratio analysis is conducted on this array and two set of optimum design parameters corresponding to maximum heat transfer and minimum pressure drop is obtained. The optimum combination of variables for maximum heat transfer yields a maximum heat transfer rate of 141252 W and the optimum parameter combination for minimum pressure drop yields a minimum pressure drop of 58352.6 Pa.

Numerical investigation and experimental validation of thermo-hydraulic and thermodynamic performances of helical baffle heat exchangers with different baffle configurations

Helical baffle is deemed as a favorable substitute for segmental one. In the present paper, the investigations on fluid flow and heat transfer behaviors are conducted for heat exchangers with eight helical baffle configurations, involving the continuous helical (CH) scheme, quadrant helical (QH) scheme with diverse axial overlapped ratios and novel sextant helical (SH) scheme. The second law of thermodynamics analysis is exploited to further evaluate the irreversibility in helical baffle heat exchangers. Verifications between the experimental data and numerical predictions are performed, and a good agreement is achieved. The parallel and rotational components decomposed from shell-side velocity are detected, and a new conception of the swirl angle is advanced to reveal the stream pattern in helical channel. The leakages passing through conjunction notches between adjacent baffle plates are depicted to check the discrepancy between the spiral and pseudo-spiral flow states. It concludes that the alterations of baffle shapes and assembly arrangements influence the flow field properties significantly. By analyzing the heat transfer, resistance and comprehensive characteristics in shell side, the SH scheme possesses better thermo-hydraulic performance than the CH and QH schemes; moreover, the least entropy generation is received in the SH and QH schemes at low Reynolds number. In addition, larger axial overlapped ratio provides greater heat transfer coefficient and pressure drop but smaller their ratio as well as higher thermodynamic irreversible loss.

Passive micromixer with baffles distributed on both sides of microchannels based on the Koch fractal principle

AbstractSince the beginning of the 21st Century, the development of microfluidic chip technology has been very rapid and has attracted the attention of more and more scholars. As an important part of the microfluidic chip, the performance of the micromixer is critical. The fractal structure in the microchannels helps to improve the mixing performance of the micromixer and improve the mixing efficiency of the micromixer. The research results of other scholars are of great significance to the research of the present paper, which mainly studies the effect of changing the baffle state on the mixing efficiency of the micromixer based on the Koch fractal principle. Through simulation analysis, it was found that the mixing efficiency of the baffles distributed on both sides of the microchannel was higher than the mixing efficiency of the baffles distributed on the microchannel side. When the distance between adjacent baffles was divided into 0.15, 0.25 and 0.35 mm, simulated data suggested that the baffle distance of 0.15 mm was best. Increasing the number of baffles from six to eight groups increased the mixing path of the fluid in the microchannel and improved mixing efficiency. A comparison of mixing efficiencies of the 0°, 15° and 30° baffle angles revealed that very significant improvement in mixing efficiency was obtained at 30°. © 2019 Society of Chemical Industry

Experimental and numerical investigation on heat transfer and fluid flow performance of sextant helical baffle heat exchangers

As a promising substitute for the segmental ones, the helical baffles have been gradually popularized in shell-and-tube heat exchangers. Quadrant helical baffles are commonly utilized to induce a pseudo-spiral flow pattern in the shell side of helical baffle heat exchangers, but the triangular leakage loss at the conjunction notches between adjacent baffles has always been the bottleneck. An improved scheme of sextant helical baffle is thus presented as a means of leakage blockage in this work. The experimental approach is implemented and the computational model is established for experimental and numerical analysis of the performance of novel heat exchanger, and a good agreement is achieved by comparing measured data with numerical predictions. The modified flow field characteristic of sextant helical baffle heat exchangers (SHBHXs) is examined in detail in comparison with quadrant helical baffle heat exchangers (QHBHXs). It concludes that the reverse flow in the triangular leakage zone is partly dampened by virtue of special overlapped structure of adjacent sextant helical baffles, and shell-side axial velocity exhibits the feature of uniform distribution. The impact of incline angle is particularly evaluated on variations of shell-side heat transfer coefficient and shell-side pressure drop as well as their ratio, and then the relevant correlations for Nusselt number and friction factor are fitted in the calculation scope. Further comparison results reveal that the thermal performance and the comprehensive performance are much better while the pressure drop is much lower in SHBHXs than in QHBHXs, which can be explicated by a finer field synergy property in SHBHXs on the basis of the field synergy theory. This work can provide theoretical foundation for design and optimization of the new type heat exchanger.

Numerical analysis and optimization study on shell-side performances of a shell and tube heat exchanger with staggered baffles

With a view to possessing the characteristics of the simple fabrication of the shell and tube heat exchanger with segmental baffles (STHX-SG) and the helical flow of the shell and tube heat exchanger with continuous helical baffles (STHX-CH), a shell and tube heat exchanger with staggered baffles (STHX-ST) is proposed in this work. The baffles of the STHX-ST are arranged according to a certain rule that the adjacent baffles are staggered by a constant clockwise or counterclockwise angle in sequence. Comparisons of the heat transfer performance and pressure drop among the STHX-SG, STHX-CH, and STHX-ST are firstly carried out. Results show that the comprehensive performance of the STHX-ST is superior the STHX-SG and STHX-CH. The parametric studies about the baffle cut δ and staggered angle β are conducted for the STHX-ST. Moreover, the multi-objective optimization is carried out to obtain the optimal solutions using the genetic algorithm further. The relationships between the design variables (the baffle cut δ, staggered angle β, and number of baffles n) and objective functions (the heat transfer rate Q and pressure drop Δp) are characterized by the artificial neural networks. The STHX-ST, at the δ = 0.45, β = 79°, and n = 11, is determined as the optimal solution according to the TOPSIS selection. Meanwhile, it is proved that the STHX-SG, a special STHX-ST at the β = 180°, is not always the best choice from the view of heat transfer enhancement. The STHX-ST can provide a preferable and meaningful solution for more efficient energy utilization in industrial applications.

Overview of fatigue life assessment of baffles in Wendelstein 7-X

Wendelstein 7-X (W7-X), the world’s largest nuclear fusion experiment of modular stellarator type, started operation in 2015 and will be upgraded with a water cooled first wall for steady state operation in 2020. The first wall consists of a CFC armored island divertors, adjacent baffles, heat shields, and stainless steel wall panels. Baffle and heat shield segments consist of graphite tiles, bolted with low pre-stress onto heat sinks of CuCrZr that are in turn brazed onto water cooled steel pipes.Cracks were detected before installation in the baffles in the root of the brazed seam in over 100 locations. Such cracks are attributed to the imposed plastic deformation of the pipes to bring them into the final shape following the complex 3D geometry of the plasma vessel.This paper gives an overview of the experimental and numerical work using finite element method (FEM) and dual boundary element method (DBEM), including sub-modeling to assess the risk of a water leak during operation. Details of the numerical work is published in Giannella et al. (2017), Lepore et al. (2017) and Citarella et al. (2018).First fatigue crack growth experiments were carried out on pipe material and thermal-mechanical crack growth predictions were made with FEM and DBEM. It appeared that the Stress Intensity Factor (SIF) threshold of the ductile steel is only reached when large plastic strains occur, thus violating the field of application of linear elastic fracture mechanics to forecast crack growth.Afterwards, representative brazed pipe samples were manufactured and subjected to initial plastic deformation causing cracks in 11 out of 12 samples. Some samples were tested up to 60,000 bending load cycles. Two out of four samples failed after ∼35,000 cycles. Before and after the test, the shape of the cracks was measured using 3D computer tomography scans. Equivalence between thermal load in W7-X and the mechanical load in the cyclic test was determined with the numerical models to allow for a prediction of the fatigue life in W7X. Additional modeling showed that also plastic zones away from the cracks can limit the fatigue life.

Application of response surface method and multi-objective genetic algorithm to configuration optimization of Shell-and-tube heat exchanger with fold helical baffles

A kind of shell-and-tube heat exchangers with fold baffles was proposed to eliminate the triangular leakage zones between adjacent baffles. An effective algorithm combing second-order polynomial response surface method and multi-objective genetic algorithm was adopted to study the effect of fold baffle configuration parameters on the performance of flow and heat transfer. The helical angle, overlapped degree and shell-side inlet velocity were chosen as design parameters, and the Nusselt number and shell-side pressure drop were considered as objective functions. The results show that both the Nusselt number and shell-side pressure drop increase with the decrease of helical angle and shell-side inlet velocity, and increase with the increasing overlapped degree. A set of Pareto-optimal points were obtained, and the optimization results illustrate a good agreement with CFD simulation data with the relative deviation less than ±3%. And the empirical correlations of Nusselt number and friction coefficient were obtained based on response surface method, the helical angle and overlapped degree were fitted into empirical correlations as correction factors for the first time. It is found that the adjusted coefficient of determination of the Nusselt number and friction coefficient is 0.943 and 0.999, respectively, which illustrate the fitting is correct and reliable.

Numerical simulation on a novel shell-and-tube heat exchanger with screw cinquefoil orifice baffles

A novel shell-and-tube heat exchanger with screw cinquefoil orifice baffles is designed to grasp the weakness of the traditional shell-and-tube heat exchanger with cinquefoil orifice baffles. It specifically enhances the heat transfer coefficient in the area between adjacent baffles and enhances the shell-side fluid flushing ability on bundles. In the proposed shell-and-tube heat exchanger with screw cinquefoil orifice baffles, screw-type cinquefoil orifice baffles are installed in the shell side. Shell-and-tube heat exchanger with screw cinquefoil orifice baffle is compared with shell-and-tube heat exchanger with cinquefoil orifice baffles and the traditional shell-and-tube heat exchanger with segmental baffles by means of numerical simulations. The numerical result shows that the heat transfer coefficient and shell-side fluid flushing ability in the shell-and-tube heat exchanger with screw cinquefoil orifice baffle is higher than that in the shell-and-tube heat exchanger with cinquefoil orifice baffles and shell-and-tube heat exchanger with segmental baffles, for the shell-side fluid that is urged to flow in approximately continuous helical flow. Under the same shell-side mass flow rate, heat transfer coefficient of shell-and-tube heat exchanger with screw cinquefoil orifice baffle is about 9.2% higher than that of shell-and-tube heat exchanger with cinquefoil orifice baffles and shell-and-tube heat exchanger with segmental baffles by about 5.4% on average. The article presents a novel design thought when researchers design heat exchangers.

Hydraulic Network Modeling to Analyze Stream Flow Effectiveness on Heat Transfer Performance of Shell and Tube Heat Exchangers

In this article, stream flow effectivness is based on hydraulic network studied in the shell-side of a shell and tube heat exchange as a case study. For an appropriate heat exchangers rating design to meet a specified duty, it's better to consider each stream flow separately. Using the hydraulic network principals, a set of the correlations for calculating different stream flow rates in the cross and window area, leakage from tube-bundle and shell-baffle bypass are suggested. By the presented correlations, the actual flow direction and different stream flow rates of shell-side fluid for calculating of shell-side heat transfer and pressure drop in different regions between adjacent baffles has been taken into account. Also, the effects of each stream flow in each baffle section on the overall heat transfer coefficient (HTC) and pressure drop could be investigated. The comparison results of using these correlations and results of published values, like Bell-Delaware method and Kern correlations, is reasonable, which can be used in the optimum design of shell and tube heat exchangers with segmental baffles. Also, according to the results, the cross flow stream show much better heat transfer performance with lower pressure drop behavior than window stream at the same mass flow rates. Average heat transfer performance of window-section is almost 7-12% of overall heat transfer performance for studied case study.

An analysis of performance on trisection helical baffles heat exchangers with diverse inclination angles and baffle structures

Investigations of thermo-hydraulic performance were conducted on five trisection helical baffle heat exchangers with different inclination angles, baffle shapes, or connection patterns, and one segmental baffle heat exchanger (SEG). A comparative analysis of three sector baffle schemes with inclination angles of 10° (10°S), 15° (15°S), and 20° (20°S); an ellipse baffle scheme with an inclination angle of 15° (15°E); and an axial overlap sector baffle scheme with an inclination angle of 20° (20°D) was performed. Local images were constructed to obtain pressure loss characteristics and flow field distributions. The flow field characteristics, such as the Dean vortex secondary flow and bypass leakage between adjacent baffles, are clearly shown and discussed. The same inclination angle schemes have completely different properties because of the baffle shapes or connection patterns. The performance of the end-to-end scheme is superior to that of the axial overlap scheme, and the ellipse baffle scheme is inferior to the sector baffle scheme. The 20°S scheme has the optimum comprehensive index and lowest shell-side pressure loss. The 10°S scheme has the highest shell-side Nusselt number and shell-side pressure loss, and can be selected only when heat transfer capability is very important in an engineering application.

Effect of baffle geometry and air pressure on transient fluid slosh in partially filled tanks

Effects of baffle geometric parameters such as curvature, opening size and shape, and inclination on the transient load shift and slosh forces within a partly filled liquid tank are investigated under longitudinal and lateral acceleration fields using computational fluid dynamic (CFD) methods. Validity of the simulations is illustrated considering steady-state responses, and fundamental slosh frequencies of cleanbore and baffled tanks. The slosh forces imposed on the baffles and end caps are evaluated for different baffle design parameters. The results suggest that the liquid cargo load shift, longitudinal and lateral forces, and pitch moment due to transient fluid slosh are strongly influenced by the baffle shape, and opening size. It is further shown that sloshing with medium to high fill levels can cause substantial increase in pressure of air trapped between the end cap and baffle, and between adjacent baffles, which contributes considerably to the resultant forces on the baffles and opposes the force due to liquid phase of the flow.

Numerical investigation of the performances of axial separation helical baffle heat exchangers

Axial separation is a novel baffle connection configuration of circumferential overlap helical baffle heat exchangers which makes baffle incline angle seriation possible. The adjacent baffle plates are separated by sleeve tubes to form a greater pitched helix for enhancing heat transfer under required pressure drop with the least number of molds for reducing baffle manufacture cost. Numerical simulations of flow and heat transfer performances were conducted and the calculation results were verified by the experimental ones. Performance investigation was conducted on eight normal trisection helical baffle schemes with baffle incline angles from 15° to 23° and five axial separation schemes of equivalent 17–22° angles using 15° baffles. In the calculation scope the average deviations of heat transfer coefficients and pressure drops of the normal helical schemes are respectively about −1.97% and −8.11% per 1° deviation of incline angle. The axial separation schemes using 15° baffles with equivalent 21° and 22° incline angles have deviation values of heat transfer coefficient 1.21% and 1.33% lower and pressure drop 4.96% and 5.55% higher respectively than those of the normal 21° and 22° incline angle schemes. By adopting axial separation approach the seriation step of baffle incline angles can be extended to 8°.

An efficient and low resistant circumferential overlap trisection helical baffle heat exchanger with folded baffles

An efficient and low resistant circumferential overlap trisection helical baffle shell-and-tube heat exchanger with folded baffles (cothHXf) is presented. It is a modified trisection helical baffle heat exchanger with folded helical baffles for setting rods-and-spanning sleeves. It not only inherits all the merits of circumferential overlap helical baffle scheme, but also adds many additional advantages, such as supporting the inclined baffles with the least rods, simplifying the manufacturing process of spanning tubes and effectively inhibiting the reverse leakage at triangular areas between adjacent baffles. The improved flow characteristic and heat transfer enhancement mechanism of this heat exchanger were numerically investigated in comparison with conventional segmental baffles shell-and-tube heat exchanger (segHX). The flow fields within triangular area of adjacent baffles and nearby regions were depicted. The impacts of the folded baffles on shell-side helical flow, secondary vortex flow, and leakage pattern were analyzed. The distribution configurations of fields of velocity, pressure, temperature and local heat flow rate were revealed. The results show that the heat transfer performance and comprehensive performance evaluation indexes of the cothHXf are much better than those of the segHX while the pressure drop of the cothHXf is much lower than that of the segHX. The numerical simulation results of vivid distributions of flow and thermal fields of the cothHXf can provide theoretical basis for an engineering design and popularized industrial application of the new type heat exchangers.

Experimental investigation on performances of trisection helical baffled heat exchangers for oil/water–water heat transfer

The trisection helical baffled shell-and-tube heat exchangers have structural features of more suitable to the equilateral triangular tube layouts and less baffle parts. In particular the circumferential overlap trisection helical baffled shell-and-tube heat exchangers are of anti-shortcut structure that accommodates one row tubes in each circumferential overlapped zone between adjacent baffles for dampening shortcut leakage. The performance tests were conducted on both oil–water and water–water heat transfer in heat exchangers with equilateral triangle tube layout of 16 tubes including five helical baffle schemes with incline angles of 12°, 16°, 20°, 24°, 28° and a segmental baffled one for comparison. The test results show that both the shell side heat transfer coefficient ho and pressure drop Δpo increase but the comprehensive index ho/Δpo decreases with the increase of the mass flow rate of all schemes; and that the shell side heat transfer coefficient, pressure drop and the comprehensive index ho/Δpo decrease with the increase of the baffle incline angle at certain mass flow rate, except that the curves of comprehensive index ho/Δpo of 12° and 16° helical baffle schemes are almost coincide. The average values of shell side heat transfer coefficient, the comprehensive index ho/Δpo of the 12° helical baffled scheme are about 50% higher than those of the segmental one with almost same pressure drop. The correlation equations for shell side Nusselt number and axial Euler number are presented varying with axial Reynolds number, Prandtl number and helical baffle incline angle.