Shell Side Research Articles

Dynamics and heat transfer characteristics on tube side and shell side of micro-tube compact air-to-air heat exchanger

Applied to the design and selection of compact micro-tube heat exchangers for aviation, an experimental study on the flow and heat transfer performance on both the tube side and shell side of micro-tube heat exchangers was conducted based on the Wilson plot method. The results demonstrated that, although the fluid on the tube side entered the hydraulically smooth region earlier at Reh = 3000, the enhancement in the heat transfer performance and drag reduction characteristics was primarily manifested on the shell side. Compared with traditional empirical correlations, the shell-side Nusselt number showed a maximum enhancement of 47.99 %, and the flow resistance was reduced by a maximum of 59.84 %. Furthermore, a new evaluation index was employed to verify the performance of the heat exchanger. The results indicated that the heat exchanger exhibited advantages in designs requiring low flow resistance, compactness, and lightweight compactness.

Experimental research on distribution characteristics of biphasic fluids in the shell side of LNG spiral-wound heat exchangers under sloshing conditions

Experimental research on distribution characteristics of biphasic fluids in the shell side of LNG spiral-wound heat exchangers under sloshing conditions

Energy-economic analysis and optimization of a shell and tube heat exchanger using a multi-objective heat transfer search algorithm

This study presents the energy-economic analysis and optimization of a shell and tube heat exchanger. A water-water, segmental baffled shell and tube heat exchanger was designed using the Kern method and analysed by performing energy and economic modelling. The analysis is carried out considering the design variables on the shell side i.e. baffle cut, baffle spacing, shell diameter and tube side variables i.e. tube layout, tube outside diameter, number of tube passes and number of tubes. The multi-objective heat transfer search algorithm was used to optimize the heat exchanger for minimum total cost and maximum heat exchanger efficiency. Multiple optimal solutions were presented using the Pareto optimal curve. TOPSIS selection criteria was used to identify the optimum operating condition. Within the given bounds of the variables, the shell and tube heat exchanger can be operated at a minimum cost of 72,000 $/year resulting in 16.4 % efficiency, or, it can be operated at a maximum efficiency of 81.6 % with a total cost of 275,000 $/year. The scattered distribution of shell diameter, baffle spacing, number of tube passes and number of tubes between the lower and upper bound represent their substantial role in optimizing the heat exchanger performance. The number of tubes and tube passes showed the maximum variation in efficiency, while significantly less impact was observed when the tube layout was altered.

Thermal hydraulic analysis of a high-temperature gas reactor steam generator after loss of feed water accidents

The helical coil steam generator is widely employed in the energy conversion process of high-temperature gas-cooled reactors for its high thermal efficiency in producing superheated steam within the helical tubes. These tubes necessitate materials specifically designed to endure high temperatures, prevent ruptures, and ensure durability under various operational conditions. This study aims to identify the maximum temperatures arising from potential transients in the secondary system and to propose immediate safety measures for minimizing associated risks. The RELAP5/MOD3.4 code was used to simulate the behavior of the next generation nuclear plant steam generator's conceptual design using steady-state conditions. Following the validation of the model, the established steady-state conditions were utilized to simulate accident scenarios, including the feed water line break and the loss of feed water flow to the steam generator. The transient scenarios assumptions include closed flap valves and retained hot helium in the shell side. The simulation tasks were conducted both with and without activating the depressurization system, in order to assess its effect on the temperature of tubes on the wall side. The analysis results indicate that tube wall temperatures can reach 720 °C at the steam generator outlet region and 620 °C at the weld region. The immediate activation of the depressurization system with a controlled relief valve can effectively reduce these temperatures by 239 °C in the steam generator outlet and by 133 °C in the weld region. This also lowers the steam generator's secondary side pressure. As a result, an upgrade and enhancement of operational procedures is straightforward.

Numerical study of shell-side flow-induced noise characteristics of staggered straight tube bundle heat exchanger under different inflow conditions

This paper presents a numerical study on the shell-side flow noise characteristics of staggered straight tube bundle heat exchangers under varying inflow conditions. A three-dimensional numerical model of a compactly arranged staggered straight tube bundle heat exchanger was established. To validate the numerical model, a feasibility study using a cylindrical flow model was conducted. Subsequently, the large eddy simulation (LES) method was employed to investigate the unsteady shell-side flow field characteristics, and the vortex characteristics of the flow field were obtained based on the Q-criterion. Finally, the acoustic finite element method (FEM) was utilized to calculate and analyze the noise characteristics at the inlet and outlet positions of the heat exchanger shell side. The results show that the inflow angle has an influence on both the flow field and the acoustic field of the heat exchanger shell side. As the inflow angle increases, the flow stability decreases, horseshoe vortices replace boundary layer vortices, and the decrease in fluctuating pressure leads to a reduction in flow noise. Analysis of the sound pressure level spectrum indicates a line spectral characteristic at low frequencies, with high-frequency components experiencing rapid attenuation.

Effect of air bubble injection on the thermal performance of a vertical helical coiled tube heat exchanger: an experimental study

This study investigates the effect of air bubble injection on the thermal performance of a vertical counter-current coiled tube heat exchanger. A cylindrical PVC shell (height: 500 mm, diameter: 152.4 mm) was constructed to carry a copper coil with 11 regular turns and covered approximately 76% and 75% of the total shell height and diameter, respectively. The key operational parameters involving the shell side flow rate (2–10 L/min), the coil side flow rate (1–2 L/min), the air flow rate (0–10 L/min) and the temperature difference between the hot and cold fluids ((20 °C, 30 °C and 36 °C) were tested to determine the overall heat transfer coefficient (U). Air was injected into the shell side of the heat exchanger as bubbles with an average diameter of approximately 100 μm via a porous sparger. The results showed that air injection significantly enhanced U, with the highest improvement (158%) occurring at an air flow rate of 6 L/min, while the minimum improvement was 34%. Furthermore, the ratio of the overall heat transfer coefficient with air injection to that without air injection had its maximum value at a shell side flow rate of 6 L/min.

Three-dimensional CFD modeling for hollow fiber gas separation membrane modules based on a dual porous media model

Mathematical modeling is crucial to optimizing the design of the hollow fiber membrane (HFM) module. A Computational Fluid Dynamics (CFD) model enables efficient three-dimensional (3D) simulations of HFM modules, which integrates a dual porous media approach, significantly reducing computational costs. Validation against alternative simulations and experimental data confirms its prediction capability (<7% deviation). Comparative analyses demonstrate the superior reliability of the 3D approach over one-dimensional simulations. Detailed velocity, pressure, and concentration profiles for the shell and tube sides reveal optimization opportunities such as dead zones within the module. Aerometric studies show significant pressure drops (>30%) for smaller fiber diameters (<100μm) on the permeate side. The model's adaptability suggests broader applications in membrane gas separation processes with modifications. This research highlights the efficacy of CFD modeling in enhancing the design and optimization of HFM modules, highlighting the cost savings of the dual porous media approximation.

Evaluating the Thermal Performance of Shell-and-Tube Heat Exchangers: The Role of Flow Rate in Water-Based Systems

This research investigates the performance of water as a working fluid in the shell side of shell-and-tube heat exchangers (STHEs), explicitly analyzing how variations in flow rate influence the heat transfer coefficient, pressure drop, and friction factor characteristics. Experiments were conducted using an STHE with a SUS 201 stainless steel shell and a pure copper tube featuring an inner diameter of 10 mm and an outer diameter of 13 mm. The flow rates of the cold fluid varied at 9, 10, and 12 liters per minute (LPM), while the hot fluid flow was maintained at a constant rate of 6.67 LPM. A 600 W heater, regulated by a PID system, was utilized to evaluate thermal performance, with water serving as the hot fluid on the shell side and the cold fluid on the tube side. Results demonstrate a significant increase in both the heat transfer coefficient and the heat transfer rate with higher flow rates of the cold fluid, with the maximum heat transfer coefficient recorded at 12 LPM and the minimum at 9 LPM. The STHE exhibited high efficiency, with heat transfer rate differences between the shell and tube sides remaining below 5%. Although pressure fluctuations were observed with increasing flow rates, they did not substantially affect the friction factor, indicating a predominantly turbulent flow regime. These findings provide critical insights for optimizing heat transfer performance in STHEs, contributing to advancements in thermal management technologies and enhancing the design of efficient heat exchangers.

Numerical simulation and multi-objective optimization design of conjugate heat transfer in novel double shell-passes multi-layer helically coiled tubes heat exchangers

A novel double shell-passes multi-layer helically coiled tubes heat exchanger (DSMHCTHE) is proposed to improve the flow and heat transfer performance of the shell side. It was studied by using conjugate heat transfer numerical model. By changing coil diameter and pitch, the influence of coil torsion on the performance of the heat exchangers was investigated in the range of 0.0637–0.3183, and compared with the conventional multi-layer helically coiled tubes heat exchangers (MHCTHE). Two kinds of heat exchangers were optimized by using multi-objective optimization differential evolution algorithm. The results indicate that the coil pitch has a greater effect on the overall heat transfer coefficient, and the effects of coil pitch variations in the inner and outer helically coiled tubes follow different patterns. Compared with MHCTHE, the heat transfer rate of DSMHCTHE are increased by 13.9 %–19.1 %, the comprehensive performance is increased by 13.0 %–18.0 %, and the heat transfer entropy generation number and friction entropy generation number are lower. It shows that DSMHCTHE have better application potential as heat exchangers.

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 shell-tube latent heat thermal energy storage: Influence of metal foam inserts in both shell and tube sides

Enhancing heat transfer in latent heat thermal energy storage systems is of utmost importance to facilitate the efficient absorption and release of thermal energy. The primary objective of the current study is to investigate the influence of a metal foam layer on heat transfer enhancement in both the heat transfer fluid side and the shell side. The research explores the incorporation of a fixed 30 % foam layer, which can either extend along the tube wall or penetrate deeper into the shell, moving away from the heat transfer fluid tube. A local thermal non-equilibrium two-temperature heat equation model is utilized to mathematically model the interactions within the metal foam embedded in the heat transfer fluid tube and the phase change material domain. The governing equations are solved using the finite element method. The results indicate that adjustments to the inlet pressure and the metal foam shape parameter (FL) can significantly reduce the melting time, with a variation of approximately 40 %. Specifically, at a constant inlet pressure of 750 Pa, the energy storage power at a 90 % charging increases from 32.2 W (FL = 0.75) to 48.7 W (FL = 1.37). A modification of FL shape parameter increased the power output by 34 %.

Comprehensive analysis of polysulfone membrane humidifier in hydrogen fuel cell vehicles: Experimental and theoretical approaches

This study performed a comprehensive experimental and theoretical analysis of a shell-and-tube type gas-to-gas humidifier module in a 95 kW class hydrogen fuel cell vehicle. The humidifier module features a polysulfone hollow fiber membrane characterized by its hydrophilic and non-fluorinated properties. Experimental investigations were conducted to understand the impacts of the inlet temperature, relative humidity, and temperature differences on heat and mass transfer rates, and the approach dew point temperature (ADT). The results showed that the ADT increased from 12.42 to 15.89 °C with a temperature difference of 15 °C between the shell and tube inlet sides, as the flow rate increased from 1000 to 3400 L/min, with the highest performance observed at lower flow rates. Simultaneously, a detailed theoretical model was developed, incorporating a new dual-mode sorption approach that accounts for temperature dependency within the solution-diffusion mechanism across the membrane. The developed model was in good agreement with the experimental results, with a relative error of less than 5 %. Furthermore, the dynamic model accurately predicts the response of the humidifier module to step changes in feed flow rates, simulating load variations in the fuel cell vehicle. This provides valuable insights into the humidifier's adaptability and responsiveness, which are crucial for optimizing its performance under various operating conditions.

Effects of baffles and springs in shell and multi-tube heat exchangers: Comparative approach

Shell and multi-tube heat exchangers (SMTHX) are widely used in various industries such as power generation, chemical processing, and refrigeration due to their high efficiency and flexibility. Improving heat transfer within an SMTHX is critical for enhancing overall performance and efficiency. This study investigates the comparative effectiveness of using baffles versus spring wires to enhance heat transfer in SMTHXs. Both experimental and numerical analyses were conducted over a Reynolds number range of 8500–12500, focusing on key parameters such as the Nusselt number, pressure drop, and exergy efficiency. The experiments were performed with a variable cold water flow rate on the shell side and a constant flow rate on the tube side. The numerical model was validated against experimental results. The findings reveal that the Nusselt number increases to 62 with baffles and to 65.5 with spring inserts, representing improvements of 1.54 and 1.61 times, respectively, compared to a plain tube under identical conditions. While the pressure drop for baffles is significantly higher than for spring inserts, the springs show a pressure drop that is 87 % of that observed with baffles. Additionally, exergy efficiency is superior with spring inserts. These results demonstrate that spring inserts are more effective than segmental baffles in enhancing heat transfer in SMTHXs. The study provides valuable insights into the mechanisms of heat and fluid flow, supported by visualizations of velocity, temperature, and pressure contours and streamlines.

Experimental study on flow and heat transfer of High-Pressure helium flow in compact helical tube heat exchanger in HTGR

In this study, experiments were conducted on helium flow within a compact helical tube heat exchanger. High-temperature helium and deionized cooling water, flowing in opposite directions, were allocated to the shell side and tube side, respectively. The Reynolds number of helium ranged from 3 × 103 to 1.6 × 104 under an operational pressure of 2.1 MPa. Measurements were taken for helium temperature, tube outer-surface temperature distribution, pressure, and mass flow rate to illustrate the flow and heat transfer characteristics. Sensitivity analysis of thermal–hydraulic parameters, including heat transfer power and efficiency under various operational conditions, was performed. The convective heat transfer coefficient and pressure drop were calculated. The transition point (Re = 9000) between laminar and turbulent flow of helium on the shell side was identified, and empirical correlations for the Nusselt number and friction coefficient were proposed. The experimental results indicate that the heat transfer performance of helium in the compact helical tube heat exchanger exceeds that of water in large-scale helical tube heat exchanger by approximately 20.75 % under fully developed turbulence, while the flow resistance characteristics remain essentially consistent.

Theoretical modeling of process heat transfer mechanism in U-shaped molten salt heat exchanger

U-shaped tube molten salt heat exchanger (MSHE) plays an important role for further improving peak shaving capacity of coal-fired unit (CFU) coupled extraction thermal storage system (ETSS). Nevertheless, existing experimental approach cannot reveal process heat transfer characteristics (HTCs) of MSHE. Meanwhile, investigation exploring factors restricting heat transfer enhancement for MSHE in theory is still vacant. In this paper, a theoretical method for MSHE was developed to determine process mechanism of heat transfer to capture perspective of enhanced heat transfer. Heat transfer performance of U-tube MSHE was theoretically unpacked. Deliberating work was executed with inlet water flow rate of 69–139 kg/s, water temperature of 120–170 °C, salt flow rate of 28–58 kg/s and salt temperature of 350–400 °C. Whereupon, the process mechanism of heat transfer inside MSHE was obtained with redeeming lack of theoretical exploration.Research shows, total HTC respectively increases by 2.57 and 1.88 W/(m2·°C) with 10 °C increasing of molten salt inlet temperature (MSIT) and 14 kg/s ascension in condensate flow rate (CFR). It is signified thermal resistance of countercurrent section of MSHE mainly involving HTCs of MSHE with increment of MSIT and CFR. Such privileged sites are main factor restricting heat transfer enhancement. Moreover, total HTC respectively increases by 2.1 and 21.84 W/(m2·°C) with 10 °C upgrading in condensate inlet temperature (CIT) and 6 kg/s increment in molten salt flow rate (MSFR). Contrary to augmenting MSIT and CFR, HTCs changing of MSHE with CIT alteration and MSFR preferment mainly attributed to downstream section and inlet position of MSHE. Meanwhile, it is discovered significant impact is generated for HTCs of MSHE with specific heat changing in molten salt. Furthermore, it was proven that Bell method is suitable for calculating HTC of molten salt on shell side in U-shaped tube MSHE. The research contents in present work can provide reliable basis for optimal design and application of U-tube MSHE in CFU.

Inundation correlation research on the simulation of two-phase flow and heat transfer in a condenser

Abstract The performance of the condenser is important to keep the high efficiency of the instrument that converts thermal energy to power through steam. On the shell side of the condenser, there is a complex gas-liquid two-phase flow with coupled turbulence, phase change, and multi-component effects. Meanwhile, heat transfer and fluid flow are mutually coupled and interact with each other. This study carefully investigates a significant factor affecting the accuracy of two-phase model simulations in condensers. It’s found that the correction of the thermal resistance of the condensate plays a key role in good production. Starting from more accurate CFD calculation results of the two-phase flow, a method is derived that utilizes the liquid phase volume fraction for the correction. The simulated results obtained using this method show promising improvements compared to the complex approaches used by previous researchers.

Thermo Structural Analysis of Biomass Combustion Steam Generation Heat Exchangers Using Three Dimensional Numerical Modelling

Biomass with all its positive characteristics contains some elements and compounds that react negatively with stainless which are known for its usage in high temperature, corrosive prone and, hash environment. Therefore, it is pertinent to comparatively study the strength of various corrosive resistance metals to be able to have an alternative to stainless steel. The purpose of this study is to model and simulate a three-dimensional steam generating boiler plant heat exchanger for a biomass firing process. In the study, inlet temperature and operating temperature of shell and tube sides are taken as input parameters with a square pitch bundle arrangement. The heat transfer analysis is done by considering hot flue gas inside the tubes and steam on shell side to determine the thermal stress, strain and deformation distributions in the tubes and shell of the heat exchanger. The study also presented time-history analysis of the both shell and tubes to ascertain the material reactions within the specified time range. The comparison of deformations and the equivalent strain rate between the two designs indicated an excellent performance of the AL6XN over the 306L stainless steel. The strain amplitude for PMX110 and WKX110 sequentially dropped from 903 to 496 and 621 to 332 between the temperature range of 100 – 10000C respectively. The maximal equivalent strain values for the shells and tubes were 2.238e-003 and 1.294e-004 for PMX110 and 1.490e-003 and 3.212e-004 for WKX110 respectively. The highest deformation in both PMX110 and WKX110 were estimated as 6.729e-004 and 6.131e-004 for the shells and 1.441e-004 and 1.328e-004 for tubes respectively.

Experimental study on optimizing liquid distribution in spiral wound heat exchangers: Influence of two-phase flow parameters and geometry

The uneven liquid distribution in the shell side of a spiral wound heat exchangers (SWHEs) significantly deteriorates heat transfer in liquefied natural gas (LNG) processes. In this study, an air and water mixture was employed as a substitute for the working fluid to simulate the two-phase flow conditions in practical LNG SWHEs. The experimental investigation focused on the impact of key factors, including gas fraction, flow rate, tube pitch, and layer pitch, on liquid distribution. The findings reveal that the liquid non-uniformity index initially decreases with an increase in gas fraction, reaching an optimal gas fraction of 0.4 for achieving better liquid distribution; the liquid distribution deteriorates at high flow rates under two-phase flow conditions; the liquid distribution improves with a sparser tube pitch under two-phase flow conditions; the liquid distribution deteriorates with a sparser tube pitch at low flow rate under two-phase flow conditions, while the difference diminishes at high flow rate. Recommendations include extending the intermediate vapor quality zone and maintaining lower flow rates for enhanced uniformity in liquid distribution across the shell side. Moreover, appropriately increasing the tube pitch or reducing the layer pitch can further optimize the uniformity of liquid distribution.

Computational fluid dynamic model for the prediction of the unsteady operation process of a non-dispersive gold extraction from wastewater

The current study tries to investigate gold extraction in a membrane extractor in unsteady mode. The model was successfully validated using experimental results. The results showed that the diffusive flux on the zone close to the membrane surface is dominant in the first minutes of extraction but later the convective flux is the main flux, particularly at the centre of the shell side. The extraction time of one hour was not ample to extract all gold from the aqueous solution when the volume of solutions was 2000 mL and 3000 mL. Finally, the change in feed flow rate in the range of 30–55 cm3/min did not have a significant influence on the gold extraction time. However, the outlet dimensionless concentration of gold after one hour was increased from 0.24 to 44 with the increase of feed flow rate from 30 cm3/min to 55 cm3/min.