Zigzag Channels Research Articles

Nanorobot Swarms Made with Laser-Induced Graphene@Fe3O4 Nanoparticles with Controllable Morphology for Targeted Drug Delivery.

Magnetic nanorobot swarms can mimic group behaviors in nature and can be flexibly controlled by programmable magnetic fields, thereby having great potential in various applications. This paper presents a novel approach for the rapid and large-scale processing of laser-induced graphene (LIG) @Fe3O4-based-nanorobot swarms utilizing one-step UV laser processing technology. The swarm is capable of forming a variety of reversible morphologies under the magnetic field, including vortex-like and strip-like, as well as the interconversion of these, demonstrating high levels of controllability and flexibility. Moreover, the maximum forward motion speed of the nanorobot swarm is up to 2165 μm/s, and the drug loading and release ability of such a nanorobot swarm is enhanced about 50 times due to the presence of graphene, enabling the nanorobot swarm to show rapid and precise targeted drug delivery. Importantly, by controllable morphology transformation to conform to the complicated requirements for the magnetic field, the drug-loaded swarm can smoothly pass through a width-varying zigzag channel while maintaining 96% of the initial drug-loading, demonstrating that LIG @Fe3O4 NPs-based nanorobot swarm can provide effective and controllable targeted drug delivery in complex passages.

Numerical Comparative Investigating of PEMFC with Novel Hybrid Zigzag Channels: Reaction, Transport and Drainage Enhancements

The impact of flow channel design on mass transport and drainage in proton exchange membrane fuel cells (PEMFCs) is significant, thereby influencing the reaction rate. Based on conventional wavy design, this study introduces two novel hybrid zigzag flow channels (asynchronous and synchronous) with both zigzag sidewalls and bottom wall, aiming in further improving mass and heat transfer, as well as drainage capacity to achieve better fuel cell performance. Numerical simulations demonstrate that the net power densities of both asynchronous and synchronous hybrid zigzag channels show a 28.7% and 44.4% improvement at low voltage, respectively. The implementation of the asynchronous hybrid zigzag flow channel has been observed to result in a notable reduction in pressure drop, amounting to 9.2%, while concurrently enhancing power output by 10.7% in comparison to a conventional zigzag channel. Additionally, the novel hybrid zigzag designs improve mass transfer efficiency at high current density and exhibits better temperature distribution uniformity. Moreover, the volume of fluid simulations illustrate that hybrid zigzag channels are highly effective in removing accumulated water, surpassing the straight channel with a drainage rate exceeding 54%, as well as a lower surface liquid coverage.

Experimental study on thermal–hydraulic performance of a nature-inspired mini-channel heat exchanger manufactured by 3D printing

Zigzag-channel printed circuit heat exchangers (PCHEs) are widely used in nuclear energy, solar energy, and aerospace due to their good heat transfer performance. However, the high flow resistance of zigzag channels leads to large pumping power consumption and thus limits the overall performance. Although previous modified channels could reduce the flow resistance of PCHEs, they also bring a decrease in the heat transfer efficiency. Inspired by river islands, this study proposes a novel nature-inspired channel. The nature-inspired channel heat exchanger, along with a traditional zigzag-channel heat exchanger, were manufactured by 3D printing. The high-temperature air-air flow and heat transfer experiments show that the nature-inspired channel heat exchanger increases the average heat transfer rate by 1.5% and significantly reduces the pressure drop by 34.85%. The addition of airfoil fins at the corners effectively alleviates the flow resistance caused by flow separation, reattachment, and collision, leading to a higher Nusselt number and a lower Fanning friction factor. The Nusselt number of nature-inspired channel is 59% higher than that of the zigzag channel with a 15° inclined angle. This work demonstrates that the nature-inspired channel could significantly reduce the flow resistance while maintaining high heat transfer efficiency compared with the traditional zigzag channel.

Redesigning heat exchanger channels: A local entropy generation approach

This paper proposes a redesign technique for heat exchanger channels based on a Local Entropy Generation (LEG) analysis and numerical simulations. The approach first divides the computational domain into zones and then identifies the zones responsible for increasing irreversibilities due to viscous and heat transfer effects. By evaluating different geometric features and flow conditions, the wall shape is modified (zone by zone) with the configurations that offer the lowest local entropy generation rates. The redesigned channels demonstrate that sudden changes in geometry along the streamwise direction reduce the size of regions with high thermal entropy generation and promote the creation of vortices, thereby reducing the magnitude of thermal irreversibilities. Smooth wall shape transitions might not be desirable when the goal is to improve heat transfer. The redesign process enhances the thermal performance of the system without significantly increasing power demand. The proposed methodology is evaluated using three wavy channels with a non-uniform amplitude-to-wavelength ratio (β1,β2,andβ3) since they allow for better management of wall geometry. As demonstrated for case β1, the LEG analysis enables the construction of new channels with a thermal performance 3.9 % superior to those with a uniform amplitude-to-wavelength ratio of α = 0.16 (best-case scenario), but with approximately 20 % less pumping power. While this study employs wavy channels as a case study, the methodology is broadly applicable to various heat exchanger configurations, including trapezoidal, triangular, and zigzag channels, making it a versatile tool for improving thermodynamic performance across different designs.

Unveiling the enhanced catalytic performance of low-Si/Al-ratio beta-zeolite on C4 alkylation combing with experiments and molecular simulations

The acidity and pore structure of zeolite catalysts play a crucial role in the selectivity and stability of C4 alkylation due to the synergistic effect of reaction activity and diffusion. Herein, the effect of three acidic beta zeolites with different Si/Al ratios on adsorption, diffusion, and catalytic performance was studied using experiments and molecular simulations. The beta zeolite with the lower Si/Al ratio leads to the faster relative diffusion of isobutane to 1-butene and the smaller adsorption amount of alkylate products. Furthermore, the diffusion of molecules in the zigzag channel along the z direction of beta zeolites is much slower than other two directions. The experimental results indicate that lower Si/Al ratio cause the higher content of strong BAS in the zeolite, resulting in the higher hydride activity and the longer catalytic lifetime. This work provides a theoretical basis for the development of high catalytic activity zeolite catalysts.

Thermodynamic analysis and equilibration response time prediction of recuperator in the SCO2 Brayton cycle

The recuperator of supercritical carbon dioxide (SCO2) Brayton cycle significantly affects the system's flexible control due to its thermal inertia. In this study, the structural parameters and operating parameters of recuperator are considered to quantitatively analyze the law of their influence on equilibration response time. Chebyshev spectrum method has been innovatively applied to the one-dimensional dynamic response model of recuperator. The dynamic response time of recuperator under the condition of temperature variation on the hot side is analyzed. The results show that reducing the thermal inertia of solid wall (by increasing the specific surface area of recuperator) can effectively decrease the equilibrium time. Additionally, the rate of inlet temperature variation should not be too large to reduce the thermal inertia of fluid. The zigzag channel demonstrates better dynamic response characteristic than straight channel. A novel dimensionless formula, based on structure and operating parameters, is proposed to quantitatively characterize and predict the equilibrium time for both straight and zigzag channel, the error is within ±20 %. Moreover, a high-precision neural network is trained to predict the equilibrium time directly. The results provide significant theoretical and application support for alleviating the thermal inertia of PCHE and improving the flexibility of SCO2 system.

Si Nanorod Array Integrated Microfluidic Device for Enhanced Extracellular Vesicle Isolation

AbstractTumor‐derived extracellular vesicles (EVs) have attracted tremendous interest as one of the early cancer diagnostic markers. The major obstacle preventing EV‐based liquid biopsy is the efficient collection of EVs from the complex body fluid environment. This paper introduces a nanorod‐integrated microfluidic chip capable of immunoaffinity‐isolating EVs. Periodic silicon nanorod arrays in zigzag channels are prepared by nanosphere lithography. Nanorod sidewalls provide larger binding sites for antibodies, and their close interspacing to the EV sizes improves the binding probability. The fluid simulation results show that the significant increase in isolation efficiency also comes from the liquid perturbation enhanced by the particular nanorod arrangement. Under optimal operating conditions, plasma samples from patients (n = 14) with different types of cancers (hepatocellular carcinoma, colorectal cancer, and pancreatic adenocarcinoma) to the chip for EV isolation is applied. In this proof‐of‐concept study, the expression level of the epidermal growth factor receptor (EGFR) in isolated EVs is then quantified using droplet digital PCR, showing good diagnostic performance in cancer detection.

Mitigation of fouling with swirling flow induced in 3-D double-sided straight channel for printed circuit heat exchanger

Fouling should be considered in the design of a printed circuit heat exchanger (PCHE) for industrial applications. The swirling flow, which is known to mitigate fouling in heat exchangers, can incorporate this aspect; however, realizing these flow characteristics in compact heat exchangers such as PCHE is difficult. Thus, this study proposed a three-dimensional (3-D) designed PCHE channel. To induce swirling flow, it was designed to face two semicircular straight channels with angles such that the interaction between the mainstreams in different flow directions induced a swirling flow. Compared to conventional two-dimensional (2-D) PCHE channels (straight, zigzag, and airfoil channels), the swirling flow induced in the proposed 3-D PCHE channel uniformly increased the wall shear stress while minimizing flow separation or recirculation. This minimized the low wall shear stress that was more likely to be fouled. A comparative evaluation of the thermal-hydraulic performance of the investigated channels was conducted by comparing the volume goodness factors under the equal hydraulic diameter. The proposed 3-D channels exhibited the potential to mitigate fouling, as well as a thermal-hydraulic performance comparable to that of conventional 2-D PCHE channels. Therefore, the proposed 3-D channel can be suggested as an advanced PCHE design option for high thermal-hydraulic performance and mitigation of fouling. Furthermore, because the swirling flow is known to mitigate fouling in heat exchangers as well as the heat transfer deterioration of sCO2, a double-sided straight channel with swirling flow is expected to be competitive.

Numerical investigation on flow condensation in zigzag channel of printed circuit heat exchanger

The printed circuit heat exchanger (PCHE) has a great potential for the application in various compact energy systems. However, the there is no existing heat transfer and pressure drop correlations on condensation in PCHE zigzag semicircular channel. In this study, the flow and heat transfer characteristics of condensation in the PCHE zigzag semicircular channel were analyzed numerically. The flow patterns of annular flow, annular wavy flow and plug flow were observed in the channel, and the flow pattern transition line correlations were developed. As the mass flux increases, the transition vapor quality from annular flow to intermittent flow decreases gradually. Both the condensation pressure drop and the heat transfer coefficient reach their peaks as the vapor quality is around 0.78, and the pressure drop decreases with the increase of saturation temperature. The heat transfer coefficient decreases as the saturation temperature increases when the vapor quality is less than 0.6, while it increases slightly as the saturation temperature increases when the vapor quality is greater than 0.6. New correlations for condensation pressure drop and heat transfer in PCHE zigzag semicircular channel are developed. The average errors of the developed condensation pressure drop and heat transfer correlations are 11.0 % and 7.9 %, respectively.

Numerical investigation and optimization of a multi-stage Tesla-valve channel based photovoltaic/thermal module

As an essential form of solar energy utilization, photovoltaic/thermal modules (PV/T) have higher efficiency than solely photovoltaic or photothermal. With regard to the heat recovery issues of PV/T, a novel thermal management method by utilizing a Tesla-valve channel is proposed. Besides, the effect of channel number, Tesla-valve number, solar irradiation, water inlet velocity, as well as water inlet temperature are analyzed using a thermal-electrical-flow coupling CFD simulation. In comparison to the straight channel and zig-zag channel PV/T, reverse multi-stage Tesla-valve channel based PV/T (MSTV-PV/T) can further enhance the solar cell panel efficiency and reduce thermal stress with decreasing max and average temperature of solar cell panel by over 4.5 % and 3 %, respectively. Utilizing response surface methodology, the optimization of MSTV-PV/T performance is conducted with respect to both single and multi-objective criteria. Channel number 8 is the optimal design parameter for all optimization objectives, the maximum output thermal energy, output thermal exergy, and output electrical energy/exergy of the proposed MSTV-PV/T module can be achieved to 1376.34W, 76.74 W, and 432.86 W, respectively.

Nusselt number analysis of printed circuit heat exchangers with straight and zigzag channels

Printed Circuit Heat Exchangers (PCHEs) are applied in processes involving high temperatures and working pressures, such as the supercritical CO2 Brayton cycle. These devices are typically designed with semi-circular channels and zigzag paths to enhance thermal performance. In recent years, several Nusselt number correlations for zigzag channels have been proposed to estimate the thermal performance. However, under similar operating conditions and zigzag angles, these correlations yield divergent results for supercritical and non-supercritical condition. No study has compared these correlations to identify the most accurate one. Therefore, this research performed a thermal analysis of PCHEs operating with straight and zigzag channels, using fluids in normal and supercritical conditions. Additionally, it was evaluated existing Nusselt number correlations to determine which ones presents the best result. This study examined 37 Nusselt number correlations, analyzed four experimental studies available in the literature and evaluated a total of 374 experimental data. For straight channels, the error ranged from 3% to 27%, whereas for zigzag channels, the error varied between 3% and 84%. This demonstrates how correlations developed for the same application can lead to discrepant results.

A Halogen-Bond-Driven Artificial Chloride-Selective Channel Constructed from 5-Iodoisophthalamide-based Molecules.

Despite considerable emphasis on advancing artificial ion channels, progress is constrained by the limited availability of small molecules with the necessary attributes of self-assembly and ion selectivity. In this study, a library of small molecules based on 5-haloisophthalamide and a non-halogenated isophthalamide were examined for their ion transport properties across the lipid bilayer membranes, and the finding demonstrates that the di-hexyl-substituted 5-iodoisophthalamide derivative exhibits the highest level of activity. Furthermore, it was established that the highest active compound facilitates the selective chloride transport that occurs via an antiport-mediated mechanism. The crystal structure of the compound unveils a distinctive self-assembly of molecules, forming a zig-zag channel pore that is well-suited for the permeation of anions. Planar bilayer conductance measurements proved the formation of chloride selective channels. A molecular dynamics simulation study, relying on the self-assembled component derived from the crystal structure, affirmed the paramount significance of intermolecular hydrogen bonding in the formation of supramolecular barrel-rosette structures that span the bilayer. Furthermore, it was demonstrated that the transport of chloride across the lipid bilayer membrane is facilitated by the synergistic effects of halogen bonding and hydrogen bonding within the channel.

Thermal-hydraulic performance of printed circuit heat exchangers with various channel shapes under rolling conditions

The floating liquefied natural gas (LNG) facilities are located in deep oceans, where the harsh ocean conditions cause the facilities to sway and tilt. The rolling conditions in floating LNG systems affect the uniformity of gas–liquid distribution in heat exchangers. Thermal and hydraulic performances of printed circuit heat exchangers (PCHEs) with straight, zigzag, and trapezoidal channels are investigated under static and rolling conditions. The results reveal that all channels enhance heat transfer near the pseudo-critical point of LNG at a rolling period of 2 s and a rolling amplitude of 15°. The Nusselt number for the PCHE with a zigzag channel increases by 32.2% and 72.5% compared to those with straight and trapezoidal channels. The highest increase in comprehensive performance is obtained for the zigzag channel with an evaluation index of 1.23 under the rolling condition. Compared with under the static condition, the Nusselt number and Fanning friction factor for the zigzag channel increase by 12% and 28% under the rolling condition. The thermal performance is weakened by the nonuniform flow velocity and improved by the enhancement of flow turbulence. The thermal–hydraulic performance increases with the rolling period from 1 s to 3 s and the rolling amplitude from 15° to 45°. The maximum improvement of 65.3% and 97.2% in Nusselt number and Fanning friction factors is observed at a rolling period of 1 s and a rolling amplitude of 45°. The methods to suppress the deterioration of heat transfer in microfluidic channels under rolling conditions are proposed to satisfy the requirement of LNG with low-resistance and high-efficiency microfluidic structure.

Numerical investigation on flow and heat transfer characteristics of a PCHE with liquid lead–bismuth eutectic and sCO2 as working fluids

The Printed Circuit Heat Exchanger (PCHE) plays a critical role in the supercritical carbon dioxide (sCO2) power generation systems, directly impacting the efficiency of the Brayton cycle. In this study,A comparative analysis was conducted to assess the flow and heat transfer characteristics of liquid lead–bismuth eutectic and sCO2 in the combined channel PCHE, as well as in the straight channel and zigzag channel PCHEs. The results indicate that the combined channel configuration of the PCHE offers improvements in heat transfer performance without significantly increasing the resistance of liquid LBE. Additionally, this study analyzes the influence of fluid velocity, pressure, temperature, buoyancy forces and thermal acceleration on the heat transfer characteristics of the combined channel.Finally, the numerical calculation results are evaluated using typical heat transfer correlation equations from the literature to assess their applicability.

Investigation into the Acoustic Properties of Polylactic Acid Sound-Absorbing Panels Manufactured by 3D Printing Technology: The Influence of Nozzle Diameters and Internal Configurations.

Sound-absorbing panels are widely used in the acoustic design of aircraft parts, buildings and vehicles as well as in sound insulation and absorption in areas with heavy traffic. This paper studied the acoustic properties of sound-absorbing panels manufactured with three nozzle diameters (0.4 mm, 0.6 mm and 0.8 mm) by 3D printing from three types of polylactic acid filaments (Grey Tough PLA; Black PLA Pro; Natural PLA) and with six internal configurations with labyrinthine zigzag channels (Z1 and Z2). The absorption coefficient of the sample with the Z2 pattern, a 5.33 mm height, a 0.6 mm nozzle diameter and with Black PLA Pro showed the maximum value (α = 0.93) for the nozzle diameter of 0.6 mm. Next in position were the three samples with the Z1 pattern (4 mm height) made from all three materials used and printed with a nozzle diameter of 0.4 mm with a sound absorption coefficient value (α = 0.91) at 500 Hz. The highest value of the sound transmission loss (56 dB) was found for the sample printed with a nozzle size of 0.8 mm with the Z2 pattern (8 mm height) and with Black PLA Pro. The extruded material, the nozzle diameter and the internal configuration had a significant impact on the acoustic performance of the 3D-printed samples.

Comparing the partial cooling and recompression cycles for a 50 MWe sCO2 CSP plant using detailed recuperator models

Supercritical carbon dioxide (sCO2) power cycles are attractive for renewable energy technologies as they exhibit high thermal efficiencies, compact components, and reduced cycle complexity and levelized cost of energy (LCOE) relative to traditional steam power cycles. Consequently, numerous studies have investigated different layouts and operating parameters in search of an optimal cycle configuration. Two cycle layouts provide promising results, namely the partial cooling with reheating (PCRH) cycle, and the recompression with intercooling and reheating (RCICRH) cycle. Both cycles utilise recuperators with high heat transfer rates and literature suggests that the cost for the recuperators may account for a significant portion of the total plant capital expenditure. When modelling the recuperator, most cycle comparative studies employ simplified recuperator models where heat exchanger effectiveness or conductance is utilised to approximate heat transfer. These models do not consider the effect of recuperator size and geometry on heat transfer and pressure drop in detail. In this work, for a concentrated solar power (CSP) application, the performance and component size requirements of the cycles are evaluated parametrically for different cycle mass flow split ratios, pressure ratios, and ratio of pressure ratios across the compressors using detailed discretised one-dimensional (1D) recuperator models. Furthermore, the geometry of these models are optimised (by volume) for straight and zigzag channel printed circuit heat exchangers (PCHEs), widely accepted as the most suitable for this application. Finally, a high-level cost comparison is conducted. The results show that if appropriate pressure drop assumptions are made, a simplified model approach yields valid cycle level results when compared with the results obtained using detailed models which consider practical recuperator geometry. However, the pressures and temperatures within the recuperator may not be predicted to a sufficient level of accuracy. In addition to providing clarity regarding the interplay between key cycle process parameters and cycle performance, straight channel PCHEs provide better thermofluid performance than zigzag channel PCHEs. Furthermore, the RCICRH cycle requires larger turbomachinery and a marginally higher capital outlay for the power cycle, but offers superior thermal efficiencies and requires smaller heat exchangers. For sCO2-CSP applications employing dry cooling, this suggests that the RCICRH cycle requires a smaller solar field and cooling system, and may therefore offer increased revenue in adverse weather conditions where direct normal irradiance (DNI) is low and/or ambient temperatures are high. However, the PCRH cycle requires a smaller solar receiver system, a smaller thermal energy storage (TES) system, and smaller turbomachinery, the cost savings of which may outweigh the benefits of the RCICRH cycle.

OPTIMIZATION ANALYSIS OF PRINTED CIRCUIT HEAT EXCHANGER USED FOR HUMID AIR TURBINE CYCLE BY ECONOMY AND IRREVERSIBLE LOSS EVALUATION

The printed circuit heat exchanger (PCHE) is a prospective candidate with great application potential in humid air turbine cycles due to its high efficiency and compactness. In the present study, a one-dimensional heat transfer and flow resistance model of both straight and zigzag channels was established based on segmental thermal design. The impact of moisture content on thermal hydraulic characteristics, entropy generation, and entransy dissipation of PCHE was evaluated. A two-objective optimization of PCHE for the heat exchange process between flue gas and compressed air was performed. The cost, thermal effectiveness, entropy generation number, and entransy dissipation number were selected as the optimization objectives. The results indicate that as moisture content increases from 0 to 0.15 kg/ kg(d), the j factor decreases by 3%, the effectiveness reduces by 1.6% (straight channel) and 0.9% (zigzag channel), and the entropy generation number and the entransy dissipation number increase by 1.4% and 3.2%, respectively. Therefore, the heat recovery margin in the recuperator design should be amplified to meet the operation conditions of the variable moisture content. The entransy dissipation number of zigzag channels is 1.2 times greater than that of straight channels, which effectively distinguishes the irreversible loss of air in PCHE channels. The criteria to evaluate the optimization of entransy dissipation number is more comprehensive, as the coverage of effectiveness based on entransy dissipation number is broader than that of the entropy generation number, which changes from 0.716-0.788 to 0.769-0.788. The trade-off of cost and irreversible loss needs to be considered in application optimization.

Ethane-CO2 Mixture Adsorption in Silicalite: Influence of Tortuosity and Connectivity of Pores on Selectivity

Selective adsorption using nanoporous materials is an efficient strategy for separating gas mixtures. In a nanoporous material, pores can exist in different shapes and can have different degrees of inter-connectivity. In recent studies, both pore connectivity and tortuosity have been found to affect the adsorption and dynamical properties of ethane and CO2 in silicalite differently. Here, using Monte Carlo simulations, we investigate if these two attributes can affect the selective adsorption of one component from a mixture of ethane and CO2 in silicalite. For this, the adsorption of an equimolar mixture of ethane and CO2 is simulated in 12 models of silicalite—SnZm (n, m = 0, 1, 2, 3 or 4; with n and m denoting, respectively, the fraction (out of 4) of straight and zigzag channels of silicalite that are available for adsorption)—differing in degrees of pore connectivity and tortuosity. The adsorption selectivity in this system is found to exhibit a reversal with the adsorption dominated by ethane at low pressures (below ~1 atm) and by CO2 at higher pressures (above ~10 atm). Pore connectivity is found to suppress the selective adsorption of CO2 at higher pressures and also shifts the selectivity reversal to higher pressures. The selectivity reversal results from a competition between the polarizability-affected adsorption at lower pressures and efficient packing at higher pressures. The efficient packing of CO2 is a compounded effect resulting from the larger effective pore volume available for CO2 due to its stronger interaction with the pore surface and smaller molecular volume. CO2 molecules show a preference to adsorb in non-tortuous pores, and this preference is found to be stronger in the presence of ethane. The effects of pore connectivity and tortuosity elucidated here should be applicable to a wide range of natural and engineered nanoporous materials, and this knowledge could be used to identify materials with better capability for separating and storing CO2 based on their pore attributes.

A performance and eco-friendly bio-inspired waterborne anti-corrosion composite coating by low-defect PDA@g-C3N4 nanosheets

Due to the low volatile organic compound (VOC) emissions, waterborne coatings are gaining much attention. However, the weak barrier properties prevent them from being practical. In this study, a novel well-dispersed low-defective the g-C3N4 nanosheets are successfully prepared using urea and polydopamine, followed by the preparation of an extensible bio-inspired coating. The bio-inspired coating comprises of PDA@g-C3N4 nanosheets that are oriented and possess zigzag channels, rendering them impervious to corrosion factors. Electrochemical tests have demonstrated that the bio-inspired coating displays a substantially improved resistance of 1.18 × 1010 Ω cm2, surpassing the pure epoxy coating (6.77 × 107 Ω cm2) by three orders of magnitude. Moreover, the excellent corrosion resistance of the bio-inspired coating has been substantiated through salt spray tests. The development of bio-inspired composite coatings presents a novel avenue for investigating the synthesis of waterborne epoxy coatings with exceptional performance.

Numerical Analysis of the Thermal-hydraulic Performance of Supercritical LNG in Airfoil Fin PCHEs

Abstract As a novel, compact, and efficient plate-fin heat exchanger, the Printed Circuit Heat Exchanger (PCHE) is a prospective candidate for liquefied natural gas (LNG) vaporization at low-temperature and high pressure. Generally, the airfoil fin PCHE has better thermal-hydraulic performance than the zigzag channel PCHE. In this study, the thermal-hydraulic performance of supercritical LNG in PCHEs with different airfoil fin types and arrangements is investigated by numerical simulations. First, the effects of six different airfoil fin types, NACA0010, NACA0020, NACA0025, NACA0030, NACA 0040, and NACA 0050, on the thermal-hydraulic performances were studied. The results show that NACA0025 has the best comprehensive heat transfer performance. Then, the effects of staggered, vertical, and horizontal pitch of the airfoil fin arrangement on thermal-hydraulic performance were investigated. The results show that the optimal values of the dimensionless number for staggered and vertical arrangements are 1 and 4, respectively. The comprehensive performance does not change much when the dimensionless horizontal pitch number exceeds 3.0. Finally, the thermal-hydraulic performance of uniformly distributed, three front sparse and rear dense, and three front dense and rear sparse distributed airfoil fins was investigated. The results show that the front dense and rear sparse airfoil fins enhance and the front sparse and rear dense airfoil fins reduce the comprehensive performance compared to the uniform arrangement. The results show that a denser arrangement of airfoil fins near the quasi-critical point can improve the comprehensive performance while keeping the number of airfoil fins constant.