Shell-side Fluid Research Articles

Performance characteristics of shell and tube heat exchanger using sectoral baffle

Shell and tube heat exchangers (STHX) play a vital role in a wide range of industrial processes and daily applications. The finite element method was used to solve continuity, momentum, energy, and k-ε turbulent equations that govern STHX. The simulation procedure (SP) was applied to STHX with a single segmental baffle (SB) and 90º, 120º, and 150º sectoral baffles (STB). The baffles were arranged along the tube at 0º, 60º, 120º, 180º, 240º, and 300º orientations. The SP was run at 323.15 and 278.15 K inlet temperatures for shell and tube, respectively, using water as shell-side fluid at a flow rate ranging from 0.5 to 2.50 kg/s. Velocities, temperatures, and pressure obtained from SP were used to evaluate the Relative Performance Index of all the STBs against SB as control. The numerical values of heat transfer coefficient (HTC) and pressure drops (PD) over the shell side along the length of STHX were compared with those obtained from Kern’s method, HTC of STBs was enhanced by 45%, 50%, 55%, 50%, 61%, and 50% with PD of 40%, 25%, 11%, 22%, − 21%, and 22% and performance evaluation coefficient (Q/ΔP) of 63%, 60%, 56%, 59%, 47%, and 59% with field synergy number of 41%, 47%, 53%, 46%, 59%, and 46% for STB90°, RSTB90°, STB120°, RSTB120°, STB150°, and RSTB150° respectively. From the analysis, it was evident that both the 90º and 120º sectoral baffles outperformed the SB, with the 90º sectoral baffle emerging as the most efficient configuration among all those evaluated. This study underscores the importance of baffle design in optimizing heat transfer performance in shell and tube heat exchangers.

Harvesting Rejected Heat by the Split A/C Condenser for Producing Warm Water

This study investigates the potential use of rejected heat by outdoor A/C units. Rather from being lost to the environment, the heat will be utilized to make warm water. An experimental setup was designed and constructed that cooled down the refrigerant heat of a condenser by tap water. R22 and tap water were used as hot and cold fluid, respectively. The inlet and outlet temperature of the shell side fluid i.e., water was measured by thermocouple. The mass flow rate of the inlet water was controlled by a valve and measured using a rotameter. The influence of inlet water temperature was also investigated in this study. It is found that recovered thermal energy decreased from 3.72 kW to 2.84 kW as mass flow rate of water decreased from 0.1 kg/s to 0.07 kg/s. When water flow rate decreased to 0.05 kg/s, thermal energy of 4.28 kW was recovered due to the rapid increase of water outlet temperature. Furthermore, this heat exchanger is utilized to determine the heat released by the condenser and the temperature of the condenser-generated hot water. IUBAT Review—A Multidisciplinary Academic Journal, 7(2): 44-63

Design Optimization of a Shell-and-Tube Heat Exchanger Based on Variable Baffle Cuts and Sizing

Abstract This article investigates the optimization of a shell-and-tube heat exchanger design through the optimization of baffle spacing and cut. This study focuses on the impact of baffle spacing (20–35%) and baffle cut percentage (20–35%) on heat transfer performance while considering the effect of the presence or the absence of seals. This study aims to optimize the heat exchanger design by using computational fluid dynamics (CFD) to reduce the pressure drop and increase the heat transfer. Studying the flow in heat exchangers is challenging due to its complex physics, especially in nonstandard geometries or novel fluid systems, which makes traditional methods relatively less accurate compared to modern approaches. The following fluid is so far uninvestigated for CFD analysis of heat exchangers: a mixture of 80% ethanol and 20% water is used as the tube-side fluid and water is used as the shell-side fluid. The Bell–Delaware method is employed for initial thermal analysis, followed by CFD simulations using ansys fluent to assess the influence of design modifications on heat transfer efficiency and pressure drop. The presence of seals is shown to improve the heat transfer efficiency by about 10.9% compared to the case when seals are absent, while optimal baffle spacing and baffle cuts are able to increase the efficiency of the heat exchanger by about 110% not inclusive of the effect of seals. Our findings show that the performance of a shell-and-tube heat exchanger is improved dramatically by the addition of seals and optimal selection of baffle cut and spacing.

Numerical investigation of the effect of the structure and number of spiral baffles on the vibration and heat transfer coefficient of spiral tubes within spiral tube heat exchangers

In response to the advantages of compactness and high efficiency of spiral elastic tube heat exchanger and its easy-to-vibrate characteristics, this study aims to further improve its heat transfer efficiency by utilizing fluid-induced vibration-enhanced heat transfer technology, so a design scheme of reverse baffle spiral tube heat exchanger (RB-STHE) is proposed to enhance the turbulence characteristics of the shell-side fluid by installing spiral baffles, thus promoting the vibration of the spiral tube. In this study, four new types of the RB-STHE (Model A, B, C, and D) were used as research objects, and the two-way fluid–structure coupling calculation method (using CFX and Transient Structure software) was adopted to systematically investigate the effect of fluid-induced spiral tube vibration on the comprehensive heat transfer coefficient (HTC) of the RB-STHE under different flow velocities and structure schemes, and based on the research data, the objective of no reduction in the comprehensive HTC and savings in the use of materials is taken as the goal, so as to put forward the improved Model C-1. The results show that: although the fluid-induced spiral tube vibration can effectively improve the HTC of the spiral tube, it also increases the pressure drop in the RB-STHE, and the larger the amplitude, the higher the degree of influence; among them, Model C is most affected by the spiral tube vibration, and its HTC and pressure drop are maximally enhanced by 6.33% and 5.85%, respectively. The change in the number of baffles has a significant effect on the comprehensive HTC of the RB-STHE. Compared to the Model D without a spiral baffle, the maximum improvement in the comprehensive HTC of Model C with one spiral baffle installed in the RB-STHE is 14%, while the Model A with four spiral baffles and the Model B with two spiral baffles have a maximum reduction in the comprehensive HTC of 20% and 3%, respectively. In addition, compared to Model C, the structure improved Model C-1 significantly reduces the size of the spiral baffle while effectively maintaining the comprehensive HTC of the RB-STHE, making the structure more reasonable, which provides a reference for heat exchanger design.

Review and Thermal Calculation of a Shell and Tube Heat Exchanger with Baffles in Cross - Counter Flow Arrangement

In one pass shell and tube heat exchanger with baffles one fluid flows inside of parallel tubes and other fluid flows outside of tubes in perpendicular to tube axis changing alternately its direction. Passing the window of the baffles the shell side fluid deviates its flow direction rapidly. This creates just behind the window of each baffle a so-called “dead volume” which renders a stagnation of flow. This dead volume assumed to be triangular in shape causing the flow behind the window to be conical.In this thermal model the “dead volume” taken into account and change of temperature of the shell side fluid during its flow from tube to tube is considered. The thermal analysis of the cross- counter flow arrangement for any number of tube in bundle with progressive changes in tube length has been carried out. The numerical computations with different tube and baffle numbers are performed. It is found that at the beginning the effectiveness of the heat exchanger increases distinctly with increasing tube number and baffle number. But after certain number of tube and baffles the increasing rate weakens and it becomes very small. Due to the presence of “dead volume” there is reduction in the thermally active heat transfer surface area which leads to a smaller value of Number of Transfer Units (NTU). Hence, the results of computation obtained in this paper with the consideration of the “dead volume” will provide lower value of the effectiveness than that of without the consideration of it.

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.

A novel design of double pipe heat exchanger with innovative turbulator inside the shell-side space

An innovative category of turbulators is implemented within the shell of a double pipe heat exchanger (DPHE). The impact of these turbulators on thermal performance and entropy generation is scrutinized through three-dimensional numerical simulations. Maintaining a constant Reynolds number of 500 for the fluid flowing within the shell, the tube's Reynolds number varies within the range of 3000 to 13,000. However, a simulation is performed with a shell-side/tube-side Reynolds number of 750/13000 to investigate the effects of shell-side Reynolds number on heat transfer. To enhance simulation accuracy, the thermophysical features of water, serving as the working fluid, are defined as temperature-dependent functions. Additionally, structured computational grids, featuring polyhedral cells forming the turbulators, are employed to discretize the solution domain. A notable concordance between the simulations' findings and existing experimental correlations is observed. The outcomes indicate that incorporating this turbulator type includes swirl flows, leading to a discernible enhancement in thermal performance. Specifically, for the case with three turbulators at Retube = 3000, the Nusselt number and pressure loss of the fluid flow within the shell show increments of 73% and 87%, respectively, compared to the conventional DPHE. The performance evaluation criterion (PEC) for the shell-side fluid attains a value of 1.41.

Analysis of Three-Dimensional Modeling and Simulation of Boiler Shell and Tube Heat Exchanger Baffles

The goal of this research is to model a three-dimensional steam-producing plant heat exchanger for industrial operations. With a certain tube bundle structure, inlet temperatures and the velocity of the tube and shell sides are used as input factors in the current investigation. The heat transfer study takes hot flue gas inside the tubes and steam on the shell side into account. The model was designed and simulated using ANSYS 2020 fluent for the analysis, which was authenticated by contrasting the output results to actual in-house operating data. According to the computational results, the proposed design allowed for a 9oC rise in shell-side fluid temperature. It has been discovered that installing more baffles in the steam flow channel increases the fluid pressure moving through the heat-exchanger. When compared to the WKX110 model, the velocity along the PMX110 length was more uniform. The velocity distribution indicates that the velocity is particularly high at the baffle turns. This is helpful because the high velocity encourages high convection transfer of heat in the region; therefore, the installation of this baffle improves heat exchange efficacy. The numerical PMX110 and WKX110 findings were validated with experimental data and found to be in good agreement.

Effect of Water-Based Nanofluids on the Generation of Entropy in a Shell and Helical Coil Heat Exchanger

A forced convection finding proves that entropy was generated as a result of the heat transfer between the fluids on the coil and the fluids on the shell side. It was found that entropy generation was affected by nanofluid concentration, coil-side fluid flow rate, shell-side fluid temperature, and agitator speed (500 rpm, 1000 rpm, and 1500 rpm) in this paper. The nanoparticle (Al2O3, CuO, and TiO2) weight fractions ranged from 0.3 to 2%. This paper investigates the friction entropy generation rate, the entropy generation ratio, and the thermal entropy generation rate of various nanofluids in laminar and turbulent flow conditions, using existing correlations to guide the investigation. The results revealed that the generation of entropy increased as the Dean number, SS, and fluid temperature on the shell side of the reactor were increased in the laboratory. And, found that the maximum entropy generation rate of Al2O3/water, CuO/water, and TiO2/water nanofluids occurred at 56.4 percent by weight of the nanofluid, 62.1 percent by weight of the nanofluid, and 48.1 percent by weight of the nanofluid.

Methodology for determining convective heat transfer coefficients on the tubesheet surface of shell-and-tube heat exchangers under single-phase flow

Designing shell-and-tube heat exchangers requires reliable methods to calculate the convective heat transfer coefficient (CHTC) on the tubesheet, due to its impact on thermal stress. To address this, we established numerical models for both the tube and shell sides of the tubesheet. Using computational fluid dynamics (CFD), we systematically investigated the distribution of convective heat transfer on the tubesheet surface and its variations with structural and process parameters. The results showed that when fluid flowed into the tubesheet, the average convective heat transfer coefficient on the tube side of the tubesheet surface was 26% higher than when it flowed out. Additionally, the average convective heat transfer coefficient in the perforated region of the tubesheet was 1.39 to 2.57 times greater than in its periphery. Furthermore, the local CHTC on the shell side of the tubesheet surface gradually decreased along the downstream direction from the inlet of the shell-side fluid. Through simulations conducted across various structural and process parameters, we derived empirical formulas to rapidly calculate the average CHTC on the tubesheet surface. These formulas incorporated a tubesheet porosity factor for the tube side and introduced a new method for calculating the equivalent tubesheet diameter on the shell side. Random testing verified that our proposed formula reliably predicted the numerical simulation results.

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.

Innovative method for heat transfer enhancement through shell and coil side fluid flow in shell and helical coil heat exchanger

Innovative method for heat transfer enhancement through shell and coil side fluid flow in shell and helical coil heat exchanger

MENINGKATKAN EFEKTIVITAS KONDENSOR VERTIKAL PIPA HELIKAL KOIL UNTUK DESTILASI MINYAK ATSIRI SEREH

The main focus of this research is to modify the straight pipe of the Citronella essential oil distillation condenser using a helical coil pipe to shorten the distillation time. This study aims to obtain an effective shell-side fluid volumetric rate to shorten the distillation time. The volumetric rate of the shell side fluid varies from 0.72 to 3.66 LPM at a constant pitch ratio of 2.10. Recording of data in the form of temperature, volumetric rate of shell side water, and tube side steam after steady state is reached. The experimental results show that the effectiveness increases with the increase in the volumetric flow rate of the shell side fluid, where the maximum effectiveness at the volumetric flow rate of 3.66 LPM is 69.99%, while the minimum effectiveness at the volumetric flow rate of 0.72 LPM is 44.39%. The results of the validation of the effectiveness of the condenser show a trend curve that is identical to the previous research, with an average deviation of 5.67%. The maximum volumetric flow rate with a minimum distillation time of 120 minutes with a condensate volume of 8 ml or 240 minutes is smaller than the result of straight-pipe condenser distillation by UKM. The maximum effectiveness is due to an increase in the Reynolds number on the shell side, which results in an increase in the actual heat transfer. It can be concluded that the maximum condenser effectiveness at a maximum volumetric rate of 3.66 LPM could be used for refining Citronella essential oil by SMEs.

Numerical analysis of vibration response of elastic tube bundle of heat exchanger based on fluid structure coupling analysis

Abstract A tube bundle heat exchanger is a typical heat exchange equipment that exchanges heat between two fluids with different temperatures. Through this equipment, one fluid can be cooled down and another fluid can be heated up to meet their respective needs. The equipment is widely used in chemical, petroleum, pharmaceutical, energy, and other industrial sectors, and is one of the indispensable and important equipments in chemical production. To improve the heat transfer performance and service life of the heat exchanger, a numerical analysis of the vibration response of the elastic tube bundle in the heat exchanger based on fluid–structure coupling analysis is proposed. Using the weak coupling method of fluid–structure coupling, the vibration response of multiple rows of elastic tube bundles induced by shell side fluid in a heat exchanger with different tube row spacing and different tube row numbers is studied numerically, and the effects of shell side fluid and tube side fluid on the vibration response of elastic tube bundles are compared and analyzed. The results show that the maximum relative error of monitoring point amplitude is 43.36% when H = 40 mm and 10.17% when H = 70 mm. For connection IV, the maximum relative error of monitoring point amplitude is 31.71% when H = 40 mm and 24.08% when H = 70 mm. This is because when H is small, the interaction between rows of tube bundles is strong, so the amplitude changes violently with the number of the tube bundle. The step-by-step calculation strategy of rough calculation and actuarial calculation proposed in this article can greatly reduce the calculation time and improve the calculation efficiency.

Numerical investigations on a triple fluid heat exchanger with helical and sinusoidal coils

A modification is made in the existing concentric heat exchanger design to enhance its heat duty. A standard concentric tube heat exchanger is modified by considering two inner tubes with a combination of helical and sinusoidal coils. Numerical studies are performed in this triple fluid heat exchanger to assess its thermal performance by taking into account mass flow rate, fluid temperatures, heat transfer, which are governed by fundamental heat transfer equations. Computational fluid dynamics simulation methodology together with local and element-by-element method is applied with a MatLab computer code. Hot water and milk fluids are used as working fluids in helical and sinusoidal coils, respectively. Cooling water is used as shell side fluid. The attainment of high heat-load-per-unit-area and high surface-area-to-volume ratio is used as optimizing parameter in the simulations. The helical coil provides an increase in heat transfer rate and overall heat transfer coefficient increases by a percentage 13% for varying hot fluid flow rates, when it is compared with the sinusoidal coil. The pressure drop for the helical coil increases, exponentially compared to the sinusoidal coil, thereby it shows a higher pumping power for the helical coil.

A numerical study of water based nanofluids in shell and tube heat exchanger

Abstract This numerical investigation is made to estimate the effect of Al2O3 and Cu nanofluids on heat transfer rate, friction factor and thermal performance factor of a shell and tube heat exchanger. Mass flow rates of shell side (water) fluid are varied. Water based nanofluids are used inside the tubes with 0.01, 0.03, and 0.05% volume concentrations of Al2O3 and Cu nanofluids. Nusselt number obtained from the present investigation is compared with Dittus–Bolter equation and Pongjet Pomvonge et al. and found to be in good agreement with a maximum deviation of 3%. The Nusselt number of the dispersed nanofluids increased with the increase of nanofluids volume concentrations and shell side mass flow rate. In this study, maximum enhancement in Nusselt number is 7.50%, 8.65%, and 9.61% for Al2O3, and 1.46%, 2.23%, and 3.18% for Cu nanofluid respectively at 0.01, 0.03, and 0.05% volume concentrations were compared to base fluid as water. Friction factor is highest by 58.00% at 0.05% volume concentration of Cu/H2O nanofluid when relate to Al2O3/H2O nanofluid. Thermal Enhancement factor achieved is highest for Al2O3/H2O nanofluid.

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

Analysis of the effect of baffles on vibration and heat transfer characteristics of elastic tube bundles

For improving the performance of heat exchangers by effectively utilizing the flow-induced vibration, a presence baffle elastic tube bundle heat exchanger, is proposed according to the absence baffle elastic tube bundle heat exchanger. Heat transfer and vibration characteristics of them at different velocities, using flow-solid coupling calculation, are studied and compared. The results show that baffle can improve flow uniformity of shell-side fluid and fully excites the elastic tube bundle vibration to improve its heat transfer performance. When inlet velocity becomes 1.0 m/s from 0.7 m/s, the maximum amplitude of two monitoring points on elastic tube bundle increased by 25.40% and 25.92% for absence baffle elastic tube bundle heat exchanger and by 42.44% and 42.97% for presence baffle elastic tube bundle heat exchanger; in non-vibration and vibration conditions, average heat transfer coefficient of the elastic tube bundle increased by 32.46% and 30.48% for absence baffle elastic tube bundle heat exchanger and by 31.16% and 31.36% for presence baffle elastic tube bundle heat exchanger. Compared to absence baffle elastic tube bundle heat exchanger, heat transfer performance and vibration-enhanced heat transfer of presence baffle elastic tube bundle heat exchanger are generally improved. And at low flow velocities, the improvement is more significant.

Research on enhancement of heat transfer by vortex-induced vibration of heat exchange tube bundles with elastic joints

In the field of fluid-induced vibration enhanced heat transfer in heat exchangers, the elastic tube bundle structure currently cannot reach the ideal state of fluid-induced vibration enhanced heat transfer and is prone to fatigue failure. In response to this problem, this article proposes to make full use of the shell-side fluid vortex-induced elastic tube bundle vibration to achieve the purpose of enhancing heat transfer, and innovatively design heat transfer tube bundles with elastic joins that can adapt to large-amplitude vibration and be not damaged by structural fatigue. Here, the dynamic modal characteristics and the fluid–solid coupling vibration heat transfer characteristics of the single heat transfer tube bundle with elastic joints are studied by numerical calculation. The results show that the low-order modes of this tube bundle include one-dimensional mode, two-dimensional mode, and three-dimensional mode. When the flow velocity is 0.1 m/s≤ u≤ 0.2 m/s, the fluid vortex-induced tube bundle produces a two-dimensional vibration response with a maximum amplitude of 9.2 mm. At the same time, the tube bundle vibration enhances heat transfer significantly. When the flow velocity u= 0.12 m/s, compared with the static circle tube under the same working condition, the heat transfer coefficient is increased by 11.8%. When the flow velocity u > 0.2 m/s, the fluid can stimulate the three-dimensional vibration response of the tube bundle, but the circular tube vibration no longer has the function of enhancing heat transfer. The research in this article will enrich the development of fluid-induced vibration enhanced heat transfer theory and promote its engineering application.