Shell Side Fluid Flow Research Articles

Study on Shell-Side Heat Transfer Enhancement Using Cinquefoil Orifice Mixed-Flow Baffle

Abstract For traditional heat exchangers, segmental baffles form a “dead zone” on the leeward side of the baffle, reducing heat transfer efficiency and causing significant pressure loss in the shell side. In response to these issues, this paper proposed a new type of baffle—the cinquefoil orifice mixed-flow baffle which introduces cinquefoil orifices on the segmental baffle. This design retains some cross-flow while also inducing longitudinal jet-flow as the fluid passes through the cinquefoil orifice. Numerical results found that the cinquefoil orifice baffle not only reduces the adverse effects of the “dead zone” but also enhances turbulence in the shell-side fluid flow due to the jet-induced entrainment effect, thereby improving heat transfer efficiency. With identical boundary conditions, the cinquefoil orifice mixed-flow baffle heat exchanger demonstrated superior shell-side heat transfer effectiveness compared to the traditional segmental baffle configuration. For the heat exchanger studied here, when the cinquefoil orifice is positioned closer to the baffle cut, the shell-side Nusselt number can increase by up to 18.8%, concurrently leading to a reduction of 4.62% in shell-side pressure drop. But it is also found that with increasing the number of cinquefoil orifices, the shell-side heat transfer efficiency did not increase monotonically, implying that in addition of the locations of the cinquefoil orifices, the proportion of the longitudinal jet-flow to the cross-flow could be optimized to get a best heat transfer efficiency.

Numerical Study on Enhanced Heat Transfer of Downhole Slotted-Type Heaters for In Situ Oil Shale Exploitation.

In order to improve the flow state of the heater shell side and enhance the performance evaluation of the heater, this paper proposes a perforated plate-type heater model. Based on Fluent, numerical studies are conducted on the heat transfer performance and shell-side fluid flow characteristics of a perforated plate-type heater. The variations of the heat transfer factor Nu, friction factor f, and evaluation parameter Nu/f1/3 are analyzed for different helix angles β and ratios of the long and short semiaxes of the circular holes on the heating plate under different Reynolds numbers Re. The results reveal that under the same shell-side Reynolds number Re, the heat transfer factor Nu shows an increasing trend with the increase in the proportion of the helix angle β. The heat transfer factor Nu for the heating plate with the hole shape ratio a/b = 1 does not exhibit significant improvement compared to hole shape ratios a/b = 0.8 and a/b = 0.6, but it increases by 4.87 to 7.07% compared to the hole shape ratio a/b = 0.4 in the perforated plate-type heater. On the other hand, the friction factor f decreases as the helix angle β and the ratio of hole shapes on the heating plate increase. The lowest friction factor f is observed for the helix angle β of 25° and the hole shape ratio a/b = 1 in the perforated plate-type heater. When the helix angle β is 25° and the hole shape ratio is a/b = 1, the evaluation parameter Nu/f1/3 reaches its highest value, indicating the optimal overall performance of the perforated plate-type heater.

Numerical and experimental study of a shell and tube heat exchanger for different baffles

AbstractIn the present work, the shell and tube heat exchanger (STHX) is designed based on The Tubular Exchanger Manufacturers Association standards with hot fluid (water) flowing on the shell side and cold fluid on the tube side. A comparison is made between the Nusselt number and friction factor obtained from numerical and experimental results of segmental baffles (SBs) and helical baffles (HB) with different baffle inclinations. The results show that SB provided a higher Colburn factor (js) when compared with HBs STHXs (20°, 30°, 40°, and 50°), but shell side pressure drop is lower for 40° HBs STHXs for the same shell side fluid flow rates.

CFD Analysis of Heat Transfer Enhancement of Shell Side Fluid Flow Over Inline, Non-circular Leading-Edge Wing Shape Tube

CFD Analysis of Heat Transfer Enhancement of Shell Side Fluid Flow Over Inline, Non-circular Leading-Edge Wing Shape Tube

A Numerical Approach to Study Shell-Side Fluid Flow in Shell-and-Tube Heat Exchangers

The detailed CFD simulation of the shell-side flow inside shell-and-tube heat exchangers results prohibitive for large-size components, due to the large number of tubes, together with the multi-scale nature of the flow features. To overcome this issue, the porous media approach can be adopted, substituting the tube bundle with a porous domain, where a suitable momentum sink term in the Navier-Stokes equation is provided. In this paper, a novel numerical approach to estimate the crossflow shell-side pressure drop is presented: a complete characterization of the tube bundle was performed by running 2D-CFD steady-state isothermal analyses, collecting pressure gradient magnitudes and directions for different mass flow rates and angles of attack of the incoming flow. The approach was validated against numerical results and compared to the methodologies currently available. Models, assumptions, and boundary conditions are herewith reported and thoroughly discussed, alongside the main results obtained.

Double-pass shell-and-tube heat exchanger performance enhancement with new combined baffle and elliptical tube bundle arrangement

Optimization of shell-side fluid flow and heat transfer of heat exchangers could be done by reforming the baffle and tube bundle structures. In this study, a new arrangement of baffles and tube bundles in the operation of the shell-and-tube heat exchanger is investigated. In the present research, the effect of the segmental baffle (SB), single-pass helical baffle (SPHB), double-pass helical baffle (DPHB), and double-pass combined helical-segmental baffle (DPCHSB) accompanied with the various elliptical tube bundles were studied and compared. Various tube bundle arrangement effects such as vertical, horizontal, and angled were studied. The fluid domain was simulated by CFD Software (Solid work Flow Simulation). By comparing the evaluation characteristics such as Q/Δp, and the efficiency evaluation coefficient (EEC) for all proposed baffle and tube bundle configurations, the angled-elliptical tube bundles showed the best performance rather than other studied tube bundles layouts. For the SPHB, the angled-elliptical tube bundle improved the EEC by 20.9 and 10.7% rather than the horizontal-elliptical and vertical-elliptical tube bundle arrangement, respectively. For the DPHB, the EEC of angled-elliptical increased by 15.7 and 22.4% rather than the horizontal-elliptical and vertical-elliptical tube bundle arrangement, respectively. For the DPCHSB, the EEC of angled-elliptical enhanced 30.3 and 14.8% rather than horizontal-elliptical and vertical-elliptical arrangement, respectively.

Different tube bundles effect on the shell-and-tube heat exchanger performance

Purpose This paper aims to present a numerical investigation on laboratory-scale segmental baffles shell-and-tube heat exchanger (STHX) having various tube bundles and baffle configuration. Design/methodology/approach To discover the higher performance the thermohydraulic behavior of shell-side fluid flow with circular, elliptical and twisted oval tube bundles with segmental and inclined segmental baffled is compared. Shell side turbulent flow and heat transfer are simulated by a finite volume discretization approach using SolidWorks Flow Simulation. To achieve greater configuration performance of this device, the following two approaches is considered: using the inclined baffle with 200 angles of inclination and applying the different tube bundle. Findings Different parameters as heat transfer rate, pressure drop (Δp), heat transfer coefficient (h) and heat transfer coefficient to pressure drop ratio (h/Δp) are presented and discussed. Besides, for considering the effect of pressure penalty and heat transfer improvement instantaneously, the efficiency evaluation coefficient (EEC) in the fluid flow and heat transfer based on the power required to provide the real heat transfer augmentation are used. Originality/value Obtained results displayed that, at the equal mass flow rate, the twisted oval tubes with segmental baffle decrease the pressure drop 53.6% and 35.64% rather than that the circular and elliptical tubes bundle, respectively. By comparing the (h/Δp) ratio, it can result that the STHX with twisted oval tubes bundle (both segmental and inclined baffle) has better performance than other kinds of the tube bundles. Present results showed that the values of the EEC for all provided models are higher than 1, except for elliptical tube bundles with segmental baffles. The STHX with twisted oval tube bundles and segmental baffle gives the highest EEC value equal to 1.16 in the range of investigated mass flow.

Experimental flow visualization study using particle image velocimetry in a helical coil steam generator with changing lateral pitch geometry

A full size section from a helical coil steam generator with five concentric coils with a helix-to-rod diameter ratio of 127 was constructed to study shell side fluid flow. The geometry has a constant transverse pitch ratio (a = 2.96), but changing lateral pitch ratio (b = 0.6–0.9) across the image planes of interest. Particle Image Velocimetry (PIV) with an index of refractive matching fluid technique was used to capture images of the flow behavior at these planes of interest. Experiments focused on visualizing cross-flow at the entrance and center regions of the test section at each plane of interest at Re = 8500. Analysis was conducted to study average vertical and transverse velocity components, vorticity and streamline fields for the shell side flow. Averaged results showed characteristic flow structures common of staggered cross-flow behavior within tube and shell heat exchangers. Select linear heights based on rod geometry show a consistent average velocity pattern across all three planes of interest regardless of lateral pitch ratio. Average velocity components do not suggest a correlation with lateral pitch ratio as previous studies with constant lateral pitch ratio designs have shown. The constantly changing geometry of this particular helical coil steam generator design affects the development and dependence of vortex formation and motion.

Characteristics of Fluid Flow and Heat Transfer in the Shell Side of the Trapezoidal-like Tilted Baffles Heat Exchanger

Periodic whole cross-section computation models are established for segmental baffle heat exchanger, shutter baffle heat exchanger, and trapezoid-like tilted baffle heat exchanger. The reliability of models is verified by comparing the simulated results to the results obtained from the Bell-Delaware method. Due to the orthogonal assembly of the baffles, the shell side fluid shows the twisty flow of trapezoid-like tilted baffle heat exchanger. The essential mechanism on disturbing flow and heat transfer enhancement is revealed by defining the non-dimensional factor η of the shell side fluid flow direction of heat exchanger and the field synergy principle. The results show that at the same Reynolds number, the shell side fluid convection heat transfer coefficient of trapezoid-like tilted baffle heat exchanger is 12.43%-24.33% and 6.71%-11.51% higher than those of segmental baffle heat exchanger and shutter baffle heat exchanger, respectively. The shell side fluid flow velocity field and the pressure gradient field of trapezoid-like tilted baffle heat exchanger and shutter baffle heat exchanger decreases compared with that of segmental baffle heat exchanger, so the shell side fluid flow resistance and pressure drop is increased; the shell side comprehensive performance of trapezoid-like tilted baffle heat exchanger is 5.85%-9.06% higher than that of segmental baffle heat exchanger, and 15.27%-23.28% higher than that of shutter baffle heat exchanger. In this study, a baffle structure with higher efficiency of the energy utilization for the heat exchanger is provided.

Numerical study of the dynamic and thermal field of a flow in a shell and tube heat exchanger

In order to gain an understanding of the mechanism of thermal performance increase in the shell side, a shell and tube heat exchanger is proposed in this study. Numerical investigations of the shell side fluid flow and heat transfer are performed using CFD Fluent software based on the model. The profiles and axial velocity fields, as well as the profiles and temperature distribution at the heat exchanger level were obtained for the whole geometry. The speed increases by 12 % of the reference speed in the shell.

Numerical analysis of shell-side flow-induced vibration of elastic tube bundle in heat exchanger

The responses of the flow-induced vibration of an elastic tube bundle subjected to the shell-side cross flow are investigated in this paper. The weak coupling method and the fluid solid interface are used to solve the fluid-structure interaction problem with consideration of the geometry and physical natures. The effects of the shell-side fluid flow velocity and the structural parameters on the flow-induced vibration are discussed. Numerical results demonstrate that the vibration frequency and amplitude at the monitor points increase with the increase of the shell-side water inlet velocity in all directions. The wall thickness and the external diameter of the elastic tube bundle have significant effects on the responses of the flow-induced vibration. The structural parameters affect the vibration frequency and amplitude, and the vibration equilibrium position in the water flow direction. The vibration frequency decreases with the increase of the tube external diameter. In addition, the vibration in the water flow direction has a lower equilibrium position when the elastic tube bundle has a larger wall thickness or smaller external diameter.

Numerical investigation on synthetical performance of heat transfer of planar elastic tube bundle heat exchanger

This paper studied the synthetical performance of heat transfer in the shell-side of planar elastic tube bundle heat exchanger using numerical simulation. The temperature distribution in shell-side was studied. The relation of average heat transfer coefficient, pressure drop and comprehensive heat transfer performance were also discussed considering varying Reynolds number and geometry parameters. Results demonstrate that the temperature distribution provides a possibility to improve heat transfer by arranging the tube bundle layout to produce a fully heated fluid within full-scale shell-side. For the effect of geometry parameter, tube pitch has a greater effect on heat transfer compared to the tube-row spacing. However, Reynolds number dominates the heat transfer and fluid flow in shell-side. As a result, a prediction correlation of average Nusselt number is developed based on Reynolds number using the multiple-regression analysis of MATLAB software. A quite outstanding comprehensive heat transfer performance can be obtained in the case of tube pitch 20mm. However, the high Reynolds number is more acceptable in the industry to enhance the heat transfer rate without considering the heat transfer difference caused by geometry parameter.

Experimental studies of shell-side fluid flow and heat transfer characteristics in a submerged combustion vaporizer

In this paper, an experimental apparatus was set up to study the two-phase mixture flow and heat transfer over a horizontal tube bundle on the shell-side of the submerged combustion vaporizer (SCV). The influences of the static water height, superficial flue gas velocity and heat load on the heat transfer characteristics were systematically examined. The experimental results revealed some interesting observation of the SCV, such as the circulation flow of water bath accompanying a great deal of gas bubbles and the highly thermal efficiency due to the direct-contact heat transfer between the highly turbulent two-phase mixture and staggered tube bundles. Finally, based on the experimental data, a new dimensionless, semi-theoretical empirical correlation was developed for two-phase mixture convection heat transfer over the staggered tube bundle on the shell-side of SCV. The discussion and correlation provided a framework for designing the SCV.

Experimental investigation on Al2O3–W, SiO2–W and ZnO–W nanofluids and their application in a shell and tube heat exchanger

In this research, overall performance of a shell and tube heat exchanger operated with Al2O3–W, SiO2–W, and ZnO–W nanofluids were experimentally investigated. Al2O3–W and SiO2–W nanofluids were prepared without using any surfactant. The polyvinylpyrrolidone (PVP) surfactant was used to stabilize ZnO–W and Fe3O4–W nanofluids. Photo capturing method was used to justify the stability. However, Fe3O4–W nanofluid has not been stabilized by PVP so it was not considered for further analysis. Highest convective heat transfer coefficient (hfT), overall heat transfer coefficient (Uo), and actual heat transfer (qfT) have been observed for ZnO–W and lowest effectiveness (ε), hfT, Uo and qfT have been found for SiO2–W. Approximately, 50%, 15%, and 9% enhancement in hfT have been found for ZnO–W, Al2O3–W, and SiO2–W nanofluids, respectively. About 35%, 26%, and 12% improvement of Uo were observed accordingly for using the above-mentioned nanofluids and qfT also improved around 51%, 32%, and 26%, respectively compared to water. Experimentally, in case 1 (at constant shell side fluid flow of 4lpm with different tube side fluid flow from 2 to 8lpm), highest performance can be attained at 6lpm using 0.3vol.% of ZnO–W (with PVP) nanofluid. Likewise, highest performance reached at 7lpm using 0.5vol.% of Al2O3–W and SiO2–W. In case 2 (at the constant tube side fluid flow of 4lpm with different shell side fluid flow from 2 to 8lpm), highest performance can be achieved at 8lpm for all nanofluids. However, overall performance of the shell and tube heat exchanger can be improved about 35% by using ZnO–W (with PVP) nanofluids.

Numerical Analysis of Shell-Side Fluid Flow in Shell-and-Tube Heat Exchanger

This work presents velocity field and flow resistance analysis on shell-side of shell-and-tube heat exchanger. Numerical investigations have been carried out using a finite volume method implemented in ANSYS Fluent code. In case of heat exchangers with a great number of tubes in bundle, the finite volume method numerical model representing real geometry of the apparatus becomes very complex and results in a high computing power demand. To overcome the above difficulty, an attempt has been made to represent the tube bundle using the continuum approach. The resulting pressure drop values have been compared with e.g. calculation results using HTRI code and exemplary values obtained from the real apparatus.

Conjugate heat and mass transfer in a skewed flow hollow fiber membrane bank used for liquid desiccant air dehumidification

Hollow fiber membrane tube bank has been increasingly used in various industries. Fluid flow in shell side is often projected at an impinging angle to the fiber bank due to the complicate structure of heat mass exchangers. However most previous researches concerned only on two ideal flow conditions, pure parallel flow or pure cross flow. The effects of skewed flow were not mentioned. In this research, fluid flow and transport phenomena in a skewed flow hollow fiber membrane bank for liquid desiccant air dehumidification are investigated. The boundary conditions on the membrane surfaces are determined by coupled heat and moisture transfer from tube side, through the membranes, and to the shell side. The governing differential equations of continuity, momentum, energy and concentration are solved by a finite volume method to obtain the shell-side convective heat and mass transfer coefficients, which are then experimentally validated. The influences of skewed angles from 0° to 90° on the heat mass transfer and friction properties are investigated. Correlations are proposed for the prediction of convective transfer coefficients and friction factors at different skewed angles.

A Numerical Study on the Shell-Side Turbulent Heat Transfer Enhancement of Shell-and-Tube Heat Exchanger with Trefoil-Hole Baffles

Shell-and-tube heat exchangers with trefoil-hole baffles are new type heat transfer devices and widely used in nuclear power system due to their special advantages, with the fluid flowing longitudinally on the shell side. However, very few related academic literature are available. In order to obtain an understanding of the underlying mechanism of shell-side thermal augmentation, a CFD model including inlet and outlet nozzles is proposed in the present study. Based on the RNG k-ɛ model, numerical investigations on shell-side fluid flow and heat transfer are conducted by using commercial CFD software FLUENT14.0. The results show that the fluid is fully developed after the first trefoil-hole baffle. The heat transfer coefficient and pressure drop vary periodically along the axial direction. Fluid velocity increases gradually and the jet flow forms in the region near baffles. The secondary flow is also produced on the two sides of baffles when the fluid flows through trefoil-hole baffle. The jet flow and secondary flow can decrease the thickness of boundary layer and then enhance the heat transfer.

Experimental Investigations on the Improvement of an Air Conditioning System with a Nanofluid-Based Intercooler

The present work is aimed to reduce the compressor load in a domestic air conditioning system, by introducing a shell-and-coil type heat exchanger as an intercooler. The intercooler uses initially a binary mixture of ethylene glycol:water at 30:70 ratio as a shell-side base fluid and later uses nanofluids with Al2O3 nanoparticles of different volume concentrations. The coefficient of performance (COP) of the system was estimated at different shell-side fluid flow rates of 1, 1.5 and 2 LPM. COP was found to increase with the decrease in the refrigerant temperature at the compressor inlet, due to the reduction in the compressor work input. A highest increment in the COP of around 31 % was observed for the base fluid and 49.32 % was observed for the 0.75 % nanofluid with a flow rate of 2 LPM compared with the case without intercooler. An appreciable reduction in power consumption of 12.24 % was also observed.

Research on Stress Intensity of Variable Cross-Section H-Type Structure in Heat Exchanger with Longitudinal Flow of Shell Side

The variable cross-section H-type structure, which is used in the new type of heat exchanger with longitudinal flow of shell side, could reduce the scour action of imports fluid on the tube bundle and prevent vibration of the tube bundle. It could also improve the state of the shell side fluid flow, reducing the flow dead zone, allowing for a more efficient use of the heat transfer area and improving the energy efficiency. The new structure will make the temperature and stress distribution in the heat distribution more complex, so it is necessary to analyze the stress intensity of the variable cross-section H-type structure. A three-dimensional finite element model of the variable cross-section H-type structure is established in this paper, and the surface temperature of the various parts of the heat exchanger are determined through temperature analysis. Using ANSYS Workbench software, thermal-stress analysis of the H -type structure with different structural parameters is tested, and the temperature and stress field are obtained. The results show that a Ring plate of H-type structure has a larger temperature gradient along the thickness direction. The maximum stress of the heat exchanger is 203.13 MPa, which occurred on the connections of the ring plate and jacket in the lower temperature side. The ring plate thickness of the H-type structure has a significant influence on its maximum stress. Therefore, a reasonable selection of ring plate thickness is important for the safety of the heat exchanger.

Experimental study of shell side flow-induced vibration of conical spiral tube bundle

Conical spiral tube bundles are widely used in enhancing the heat transfer via the flow-induced vibration in heat exchangers. The shell side flow-induced vibration of the conical spiral tube bundle is experimentally investigated in this paper. The experiment table was built and the operational modes, the vibration parameters of the tube bundle were analyzed. The results show that, the operational mode frequencies of the conical spiral tube are decreased as the shell-side fluid flow velocity increases, especially for the first order frequency. Within the parameter range of this experiment, the real working frequency of the conical spiral tube is between the 1st and the 2nd operational modes, and the free end vibration amplitude of the tube bundle increases greatly when the shell side fluid flow velocity exceeds a critical value.