Shell Side Of Heat Exchanger Research Articles

Numerical simulation of heat transfer performance of spiral wound heat exchanger under sloshing condition

LNG floating production storage and offloading (FPSO) unit is a new type of floating production unit developed for offshore natural gas fields. It performs the functions of natural gas extraction, pretreatment, liquefaction, and storage. In this study, the heat transfer characteristics of a spiral-wound heat exchanger were studied using numerical simulations, which provides a basis for equipment selection and structural optimization of spiral-wound heat exchangers. The main research contents and conclusions are as follows. Under land-based simulation conditions, the heat transfer coefficient of the shell side of the spiral-wound heat exchanger decreases with an increase in the winding angle of the heat exchange tube, decreases with an increase in the spacing of the heat exchange tube, and increases with an increase in the outer diameter of the heat exchange tube. When the winding angle increased from 5° to 8°, the heat transfer coefficient decreased by 6.70%. The heat transfer coefficient of the shell side decreased by 13.21% when the heat exchange tube spacing increased from 14 to 17 mm. The heat transfer coefficient of the shell side increased by 22.89% when the outer diameter of the heat exchange tube increased from 9 to 12 mm. When the sloshing angle is constant, the heat transfer coefficient of the spiral-wound heat exchanger decreases with an increase in the winding angle and spacing of the heat exchange tubes, and increases with an increase in the outer diameter of the heat exchange tubes. When the structural parameters of the heat exchanger are constant, the heat transfer coefficient decreases as the sloshing angle increases. When the sloshing angle was less than 3°, the sloshing promoted heat transfer on the shell side. When the sloshing angle was higher than 7°, the heat transfer effect of the shell side deteriorated considerably, which weakened the heat transfer performance of the heat exchanger. When the sloshing period is constant, the heat transfer coefficient of the wound heat exchanger decreases with an increase in the winding angle and spacing of the heat exchange tubes, and increases with an increase in the outer diameter of the heat exchange tubes. When the structural parameters of the heat exchanger are constant, the heat transfer coefficient increases with sloshing period. When the sloshing period was greater than 15 s, the influence of sloshing on the heat transfer on the shell side of the heat exchanger was relatively weak.

Cause analysis of vibration in shell-and-tube heat exchanger

Heat exchanger is a universal process equipment, which is widely used in chemical industry, oil refining, thermal power and other industries. Shell-and-tube heat exchangers often fail prematurely due to flow-induced vibration. In this paper, aiming at the problem of severe vibration of shell-and-tube heat exchanger in an enterprise, the vibration acceleration sensors are used to measure the vibration of shell and tube side of heat exchanger. Through the analysis of the measurement results, it is found that when the flow rate on the shell side of the heat exchanger is greater than 50000 Nm3/h, the flow-induced vibration of the tube bundle occurs, and the vibration frequency is 57Hz, which is close to the natural frequency of the tube bundle. And the greater the flow rate on the shell side, the more intense the vibration. In order to reduce the vibration of heat exchanger, the damping measure of inserting baffles between tubes is adopted.

Numerical investigation of a nanofluidic heat exchanger by employing computational fluid dynamic

Shell-and-tube heat exchanger is widely applied in different industrial processes and energy systems. Utilized fluid in the heat exchanger and its thermophysical properties are among the key factors that influence the thermal performance and fluid flow in heat exchangers. Employing nanofluids, with enhanced thermal properties, can improve heat transfer rate of heat exchanger. In this regard, the current article concentrates on the numerical simulation of a shell-and-tube heat exchanger with baffle, utilizing multi-walled carbon nanotube/water nanofluid. In this regard, computational fluid dynamic is used for modeling. The applied turbulence model in this study is k- $$\varepsilon$$ which is selected based on the literature review. Heat transfer rate comparison in cases of utilizing the nanofluid in shell side of heat exchanger revealed high potential of the nanofluid in thermal performance improvement. Moreover, it was noticed that by using higher concentration of the nanofluid, more enhancement would be obtained which is owing to higher increment in the nanofluid effective thermal conductivity. Average increment in the heat transfer rate of the HE in case of using multi-walled carbon nanotube/water with 4% concentration is around 29.5% in comparison with the condition water is used as the operating fluid.

Experimental and CFD investigation of helical coil heat exchanger with flower baffle

The objective of this invention is to increase the resident time of coolant in the shell side of the helical coil heat exchanger by using flower baffle plates. This invention utilized to improve the heat transfer efficiency of the helical coil heat exchanger. The heat exchanger contains a hollow shell and helical coil as same as in a normal shell, In addition to it contains a flower baffle plate. The baffle plates are placed inside the shell side of heat exchanger in distance between two coils. These baffle plates arrange to reduce the pressure drop and fouling in heat exchanger with these arrangements of baffle plates, the heat exchanger can obtain a fully developed flow . The hot fluid flows through the helical coil in heat exchanger. The tube side flow rates varies from 2lpm to 6 lpm and shell side flow rates (2, 4, 5, 6, 8 lpm), respectively. The experiment is done for all the 10 cases to find the effective one. Also done the CFD analysis to validate the experiment values, the CFD results are good in agreement with the experiment results within an error percentage of 15%. The outlet temperature of the tube and shell side, effectiveness and exergy efficiency of heat exchanger also calculated and presented graphically.

Investigation of the thermal-hydraulic characteristics in the shell side of heat exchanger with quatrefoil perforated plate

Quatrefoil perforated plate (QPP) is a kind of whole circular support plate for the shell side of shell-and-tube heat exchanger (STHX), and the design and optimization of heat exchanger with this support structure are the key technologies to study and improve the performance of heat exchanger. The influences of the hole height and plate spacing of the QPP on the thermal-hydraulic performance of the heat exchanger were studied mainly by using computational fluid dynamics (CFD) method. And the reliability and accuracy of the numerical results were verified by compared with experimental results. With Reynolds number varying from 5000 to 20,000, the results show that the heat transfer coefficient and pressure drop in the shell side of the heat exchanger both increase with the decrease of the hole height and the plate spacing of the QPP, but the shell side heat transfer coefficient per unit pressure drop h/Δp decreases. Under the conditions of the same fluid flow rate and same plate spacing, compared with segmental baffle heat exchanger, the comprehensive performance h/Δp of heat exchanger with QPPs is improved by 27%–41%. The empirical correlations for Nusselt number and pressure drop in the shell side of heat exchanger with QPPs were obtained and the calculation deviation of correlations both are within ±10%, which can be used to guide engineering design and practice.

Analysis of flow dead zone in shell side of a heat exchanger with torsional flow in shell side

In order to improve the heat transfer efficiency of the heat exchanger, the characteristics of dead zone and its effect on thermal performance in the shell side of a novel heat exchanger with torsional flow were discussed. The residence time distribution method combining with the CFD were used to analyze quantitatively and qualitatively the flow dead zone. By optimizing the baffle arrangement, the minimum flow dead zone is reduced to 2.76%, and the maximum thermal performance is increased to 13.56%. The results show that the fraction of dead zone volume slightly from 10.42% to 10.28% when the Reynolds number increase from 4000 to 12,000 in the shell side of the heat exchanger with segmental baffle, and that decreases from 11.66% to 9.87% in the torsional flow heat exchanger. The dead zone in the shell side of heat exchanger with torsional flow is mainly affected by the shell inlet and the corner between the cylinder wall and the baffle. The volume ratio of the dead zone between the reverse arrangement and the forward arrangement are 24.11%, 27.96% and 31.65% respectively. The research results and methods provide a theoretical basis for the analysis and optimization of structure of heat exchanger.

Numerical and Experimental Investigation on Performance of Convex-Cut Baffles in Shell-and-Tube Heat Exchanger

In this study, comparative performance of single-segmental baffle and a newly developed baffle – convex-cut in shell-and-tube heat exchanger were both numerically and experimentally investigated. For the numerical analysis, three working fluids (engine oil, water and air) were successively utilised on the shell-side of heat exchangers with 30, 35, 40 and 45% convex-cut (CeC_STHE) and 25% segmental (SS_STHE) baffles, and the resulting models were solved in COMSOL Multiphysics. Experiments were carried out on 30% CeC_STHE and SS_STHE exclusively running on water. The data obtained were used to determine the weighted shell-side heat transfer coefficient and weighted performance factor of each heat exchanger. Hence, the results for all the ranges of Reynolds number indicate that the shell-side heat transfer coefficients of all the CeC_STHEs are lower than that of SS_STHE except for the 30% CeC_STHE. However, the SS_STHE showed greater pressure drop than the CeC_STHEs. The choice of working fluid had more influenced on the weighted shell-side heat transfer coefficient CeC_STHE. Moreover, the weighted performance factors of the CeC_STHEs indicated positive values. Thus, 30% CeC_STHE demonstrated a better performance while the 45% had the lowest performance.

Numerical investigation on non-Newtonian fluid flowing in heat exchanger with different elliptic aspect ratios and helical angles

In this paper, the heat transfer and flow performance of the non-Newtonian fluid on the shell side of heat exchanger combined with elliptic tubes and helical baffles were numerically investigated, different helix angles and helical aspect ratios were studied to improve the heat exchanger’s overall performance. An aqueous solution with 3.0% weight fraction of carboxymethyl cellulose (CMC) was selected as the working fluid, which was a kind of non-Newtonian fluid with low viscosity and good stability. The results showed that the increasing aspect ratio improve the heat transfer, but also lead to higher pressure drop. The heat exchanger with aspect ratio between 2.5 and 3.0 has the best heat transfer and flow performance. For the helical angle, both the heat transfer rate and pressure drop increase with the smaller angle. Thermal performance factor (TPF) is taken to evaluate the comprehensive performance, the result showed that when helical angle is 40°, both the TPF and the heat transfer coefficient per pressure drop ho·ΔPo−1 get the most satisfying value.

The Vibration Analysis of Tube Bundles Induced by Fluid Elastic Excitation in Shell Side of Heat Exchanger

Fluid elastic excitation in shell side of heat exchanger was deduced theoretically in this paper. Model foundation was completed by using Pro / Engineer software. The finite element model was constructed and imported into the FLUENT module. The flow field simulation adopted the dynamic mesh model, RNG k-ε model and no-slip boundary conditions. Analysing different positions vibration of tube bundles by selecting three regions in shell side of heat exchanger. The results show that heat exchanger tube bundles at the inlet of the shell side are more likely to be failure due to fluid induced vibration.

Evaluation of Nusselt number and effectiveness for a vertical shell-coiled tube heat exchanger with air bubble injection into shell side

Air bubble injection was employed to increase the heat transfer rate (Nusselt number) of a vertical shell and coiled tube heat exchanger in this article. Hot and cold water flowed into the coil side and shell side of heat exchanger, respectively, and air bubbles were injected inside the shell side of heat exchanger via a memorable method. Bubbles' vertical movement due to buoyancy forcing through the heat exchanger can enhance the heat transfer rate by mixing the thermal boundary layer, increasing the turbulence level of the fluid flow and increasing the shell-side fluid Reynolds number.

Optimization of heat transfer and pressure drop characteristics via air bubble injection inside a shell and coiled tube heat exchanger

Most recently, a couple of academic investigations have focused on air bubble injection (with a constant air flow rate) inside the shell-and-coiled-tube heat exchangers in order to increase the performance and effectiveness of these heat exchangers. However, the amount of air flow rate has great effects on these applications which have not been probed in previous studies. Moreover, in former papers, air flow has been injected inside the only shell side and not coil side of heat exchanger. Hence, in this experimental research, air bubbles is flowed inside the shell or coil side of heat exchanger with variant air flow rates to detect an optimum condition and also fill out this topic. Air flow rate was changed between 1LPM and 5LPM. Coil side water flow rate was kept at 1LPM (inlet temperature of 40°C) and shell side water flow rate was varied between 1LPM and 5LPM (inlet temperature of 15°C). Furthermore, pressure drop due to bubble injection is measured in this paper for aforesaid heat exchangers as another new parameter. Observations showed that the air flow rate and injection side (shell and coil) play key roles on the effect of bubble injection into the heat exchangers. Findings showed that, increment of air flow rate causes enhancement of overall heat transfer coefficient. Air injection into the shell side of the heat exchanger increased the overall heat transfer coefficient 6–187% depending on air flow rate.

Experiments on air bubbles injection into a vertical shell and coiled tube heat exchanger; exergy and NTU analysis

In this paper, attempts are made to increase the number of thermal units (NTU) and performance in a vertical shell and coiled tube heat exchanger via air bubble injection into the shell side of heat exchanger. Besides, exergy loss due to air bubble injection is investigated. Indeed, air bubble injection and bubbles mobility (because of buoyancy force) can intensify the NTU and exergy loss by mixing the thermal boundary layer and increasing the turbulence level of the fluid flow. Air bubbles were injected inside the heat exchanger via a special method and at new different conditions in this paper. It was demonstrated that the amount of NTU and effectiveness can be significantly improved due to air bubbles injection.

Experimental Study of Pressure Drop and Heat Transfer of Heat Exchangers with LASH Baffles

LASH or large-and-small-hole baffle is a new kind of baffle which induces axial flow in the shell-side of heat exchangers. In this paper, pressure drop and heat transfer of heat exchangers with LASH baffles were experimentally studied and compared with those in common heat exchangers with segmental baffle. It is founded that compared with the segmental baffles, pressure drops caused by LASH baffles are greatly decreased. Although the shell-side heat transfer coefficient with the LASH baffles is decreased, more comprehensive performance for heat exchangers with LASH baffles can be achieved.

판형 핀을 가진 원통-다관형 열교환기의 열전달 특성에 관한 연구

본 논문은 세 개의 서로 다른 관수(9, 13 그리고 19)를 가지는 원통-판형 핀 관의 원통 측에서의 열전달 성능을 실험적 방법으로 평가하였다 관외를 흐르는 오일은 관내를 흐르는 냉각수에 의해 냉각된다. 오일 쿨러의 원통-다관형 열교환기는 단일 셀 통로와 두 개의 관 통로로 구성되며, 관 내경은 8.82mm, 관 길이는 575mm이다. 오일의 질량 유량은 <TEX>$1.2{\sim}6.0m^3/h$</TEX>이며, 냉각수의 질량 유량은 <TEX>$0.6{\sim}3.0m^3/h$</TEX>이다. 실험결과 9개의 관수를 가지는 열교환기의 총합 열전달계수는 13개와 19개의 관수의 열전달계수보다 각각 약 1.8배와 2.3배 높게 나타났다. In this work, the experimental investigation was carried out to evaluate the heat transfer performance on the shell side of shell-and-plate finned tube heat exchanger with three different tube numbers(9, 13 and 19). Oil flowing on the shell side was cooled by cold water flowing inside the tubes. A shell-and-tube heat exchanger of an oil cooler consisted of one shell pass and two tube passes with the inner tube diameter of 8.82 mm and the tube length of 575 mm. Mass flow rate was varied from 1.2 to <TEX>$6.0\;m^3/h$</TEX> for oil and from 0.6 to <TEX>$3.0\;m^3/h$</TEX> for cold water, respectively. From the experiment of shell-and-plate finned tube heat exchanger, the overall heat transfer coefficient of heat exchanger with 9 tubes was compared with that of 13 and 19 tubes. It was found that the heat transfer coefficients in shell side of heat exchanger with 9 plate finned tubes showed averagely 1.8 times and 2.3 times higher than those of 13 and 19 tubes, respectively.

Prediction of Flow-Induced Vibrations in Tubular Heat Exchangers—Part I: Numerical Modeling

Flow-induced vibrations due to crossflow in the shell side of heat exchangers pose a problem of major interest to researchers and practicing engineers. Tube array vibrations may lead to tube failure due to fretting wear and fatigue. Such failures have resulted in numerous plant shutdowns, which are often very costly. The need for accurate prediction of vibration and wear of heat exchangers in service has placed greater emphasis on the improved modeling of the associated phenomenon of flow-induced vibrations. In this study, the elastodynamic model of the tube array is modeled using the finite element approach, wherein each tube is modeled by a set of finite tube elements. The interaction between tubes in the bundle is represented by fluidelastic coupling forces, which are defined in terms of the multidegree-of-freedom elastodynamic behavior of each tube in the bundle. Explicit expressions of the finite element coefficient matrices are derived. The model admits experimentally identified fluidelastic force coefficients to establish the final form of equations of motion. The nonlinear complex eigenvalue problem is formulated and solved to determine the onset of fluidelastic instability for a given set of operating parameters.

Hydrodynamic Studies on Heat Exchangers with Helical Baffles

The flow field in shell-and-tube heat exchangers with helical baffles was measured using laser Doppler anemometry (LDA). The influence on the velocity distribution, impulsive velocity by helix inclination angle, and flow rate was investigated. The influence on heat exchanging capability and flow resistance on velocity distribution was also investigated. The dimensions of the heat exchanger shell used in these experiments were 200 2 6 2 3,000 mm (inner diameter 2 wall thickness 2 length). The heat exchanger was made of organic glass and the tube bundle consisted of 52 tubes with external diameter of 15 mm. Six different inclination angles were designed in double-helix style: 30°, 35°, 40°, 42°, 45°, and 50°. The working flow medium under normal temperature was service water. Generally, the linear velocity and impulsive velocity will increase with decreasing helix inclination angle, which promotes the heat exchanging capability. With flow volume increasing, the velocity distribution along the diameter increases on average. The pressure drop increases with decreasing helix inclination angle. For all of the helix inclination angles tested, the minimum pressure loss took place at a certain Reynolds number; and at different helix inclination angles, the Reynolds number at which the minimum pressure loss occurs is different. In general, it was concluded that the optimum helix inclination angle depends on the Reynolds number of the working fluid on the shell side of heat exchanger.

Two-Phase Flow in Heat Exchangers and Pipelines

This paper discusses procedures for the prediction of pressure gradients, flow patterns, entrainment, and void fraction on the shell side of heat exchangers and in pipes during horizontal flow.