Flow Orientation Research Articles

A new angle to control concentration profiles at electroactive biofilm interfaces: Investigating a microfluidic perpendicular flow approach

To meet the growing interest in bioelectrochemical flow systems, we propose a new microfluidic-based approach to studying electroactive biofilms (EABs). Despite the near limitless range of available channel designs and reaction control sequences , one of the main drawbacks compared rotating disk electrode systems, is the typical non-uniformity in the concentration boundary layer above the EAB outer surface. This drawback undermines the claim that microfluidic electrochemical systems provide pristine operating conditions. We address this challenge through the use of simulations, backed by experiments, to investigate microfluidic design parameters (flow orientation, counter-electrode placement, and channel dimensions) that significantly enhance the boundary layer uniformity across the entire EAB surface. Simulations confirmed that the large asymmetries in the boundary layer thickness between the upstream and downstream edges in conventional tangential flow systems are strongly reduced by transitioning to a perpendicular flow orientation. Further optimizations in electrode placement and channel design nearly erased the remaining inhomogeneity in the boundary layer thicknesses.

Deterministic Manipulation of Heat Flow via Three-Dimensional-Printed Thermal Meta-Materials for Multiple Protection of Critical Components.

Heat dissipation is necessary for the safer operation of high-power electronic devices and high-capacity batteries. Thermal meta-materials can efficiently manipulate heat flow by molding natural materials into specific structures. In this study, we construct a three-dimensional-printed meta-material structure with efficient and deterministic heat conduction through combining the 2D boron nitride (BN) with nano-diamond (DM) bridging. A research of thermal conductivity and dielectric properties exhibits that the nanosized diamond-bridged and oriented 2D boron nitride endows efficient heat transfer and maintains low dielectric loss with low filler loading. The composites loaded with 19 wt% BN platelets and 1 wt% DM have the highest thermal conductivity of 3.687 W/(m·K) in the heat flow orientation, while the thermal conductivity is only 0.632 W/(m·K) in the vertical heading of heat flow. The thermal conductive networks with thermal meta-materials based on the structural characteristics have been designed to secure critical device components from the heat source and dissipate heat flow in a definite way. The infrared images show that the temperature difference of monitoring points in different directions on the BN-oriented composite substrate is 9 °C, which realizes the protection of the heat source and key components. This study shows the latent capacity of 3D-printed structured materials for critical device component protection and heat administration applications in electronic devices and electric equipment.

Spark anemometry applied through secondary current measurements in an optical spark ignition engine

As a technology, internal combustion engines feature high level of maturity. Nonetheless, there is still room for improvement, especially in terms of solutions that do not require significant changes to hardware components. The present work developed a method for evaluating in-cylinder fluid velocity around the spark plug based on measurements of secondary current intensity. This information can be used for reducing cycle-to-cycle variability and indirectly to increase fuel conversion efficiency. Compared to existing techniques that employ secondary voltage signals, the new procedure can be readily applied in spark ignition (SI) engines with standard ignition coil and plug. In a first phase calibration was performed on a dedicated flow rig with known fluid velocity around the spark plug. The new method was then tested on an optically accessible SI engine. Offset effects were minimized by performing relative spark duration measurements. More to the point, the discharge interval recorded during the working cycle was referenced to spark duration values recorded in quiescent conditions; this procedure can be applied on existing ignition systems without any changes in hardware. Imaging data ensured additional information on flow orientation during ignition. The results were compared to the voltage rise anemometry technique and were found to be in good agreement. Values were also directly comparable to tumble and turbulence intensity predicted by 0D/1D simulations.

Anomalous Magneto-Optical Response and Chiral Interface of Dipolar Excitons at Twisted Valleys.

An anomalous magneto-optical spectrum is discovered for dipolar valley excitons in twisted double-layer transition metal dichalcogenides, where the in-plane magnetic field induces a sizable multiplet splitting of exciton states inside the light cone. Chiral dispersions of the split branches make possible an efficient optical injection of the unidirectional exciton current. We also find an analog effect with a modest heterostrain replacing the magnetic field for introducing large splitting and chiral dispersions in the light cone. Angular orientation of the photoinjected exciton flow can be controlled by strain, with left-right unidirectionality selected by circular polarization.

Performance study of dual-phase CO[formula omitted] cooling on the example of the ATLAS ITk strip end-cap detector

The technique of evaporative CO2 cooling is one of the standard cooling options for high-energy particle detectors, such as the new ATLAS Inner Tracker (ITk) for the planned high-luminosity upgrade of the LHC by 2026. The advantages of CO2 are a high latent heat transfer at reasonable flow parameters, a low viscosity which allows to use small diameter cooling pipes with a low pressure drops, a well-suited temperature range for detector cooling between ＋25 and −40 °C and being an environment friendly alternative to many other currently used coolants. When comparing with a monophase coolant, the operation in the dual-phase regime comes with several parameters influencing the cooling performance.This paper contains the results of experimental studies performed to understand these influencing factors. For this, prototype structures from the ITk strip detector end-cap were used, like bare local support structures (‘cores’) or fully loaded structures (‘petals’). Here, the design is optimized to guarantee a good heat transfer between the silicon strip modules glued on the surface and the embedded titanium cooling pipe with the CO2 coolant. Systematic investigations on the thermal performance using infrared thermography are used to study the influence of dual-phase CO2 cooling parameters such as the orientation of CO2 flow. Moreover, the dependence of the pressure drop as a key parameter for the cooling performance on the applied heat load or the selected mass flow rate is investigated.

Confined Assembly of Colloidal Nanorod Superstructures by Locally Controlling Free-Volume Entropy in Nonequilibrium Fluids.

Long-range-ordered structures of nanoparticles with controllable orientation have advantages in applications toward sensors, photoelectric conversion, and field-effect transistors. The assembly process of nanorods in colloidal systems undergoes a nonequilibrium process from dispersion to aggregation. A variety of assembly methods such as solvent volatilization, electromagnetic field induction, and photoinduction are restricted to suppress local perturbations during the nonequilibrium concentration of nanoparticles, which are adverse to controlling the orientation and order of assembled structures. Here, a confined assembly method is reported by locally controlling free-volume entropy in nonequilibrium fluids to fabricate microstructure arrays based on colloidal nanorods with controllable orientation and long-range order. The unique fluid dynamics of the liquid bridge is utilized to form a local region, where the free volume entropy reduction triggers assembly near the three-phase contact line (TPCL), allowing nanorods to assemble in 2D closest packing parallel to the TPCL for the maximum Gibbs free energy reduction. By manipulating the orientation of liquid flow, microstructures are assembled with programmable geometry, which sustains polarized photoluminescence and polarization-dependent photodetection. This confined assembly method opens up perspectives on assemblies of nanomaterials with controllable orientation and long-range order as a platform for multifunctional integrated devices.

Oscillatory behavior with fiber orientation in the flow–vorticity plane for fiber suspension under large amplitude oscillatory shear flow

In fiber suspensions, fibers with three-dimensional orientation states are dramatically flow-oriented in the flow–flow gradient plane when the flow starts. In contrast, large strains are required for flow orientation in the flow–vorticity plane. Under oscillatory shear flow, when the strain amplitude is small, the flow orientation in the flow–vorticity plane is weakly induced, unlike that in the flow–flow gradient plane. The orientation in the flow–vorticity plane increases with the strain amplitude. At large strain amplitudes, fibers are oriented in the flow–flow gradient plane; thus, the rotational motion of fibers in the flow–flow gradient plane is dominant, i.e., fibers are almost flow-oriented in the flow–vorticity plane. However, contributions of the oscillatory behavior of fiber orientation in the flow–flow gradient and flow–vorticity planes to complex viscosity are unclear. In this study, the objective is to determine the contributions of fiber orientation in each plane to complex viscosity with the two initial orientation states (random and flow-oriented states) for the strain sweep test. The two initial orientation states were controlled by manipulating the upper disk of the parallel disk flow path. The initial random state was induced by sliding the upper disk up and down. The initial flow-oriented state was induced by rotating the upper plate. Furthermore, phase transition behaviors from the random to flow-oriented state in the flow–vorticity plane with increasing strain amplitude were qualitatively estimated as the orientation angle via visualization. Consequently, when the initial orientation was random, the fibers gradually vibrated in a medium strain amplitude region, and complex viscosity was higher than that of the initial flow-oriented state. In the conclusion, we divided the complex viscosity behavior of the strain sweep test into five strain amplitude regions and clarified the dominant orientation state in each region. It is conceivable that this result will help in understanding the relationship between fiber orientation and dynamic viscoelastic properties of fiber suspension like fiber-reinforced thermoplastics.

Research on route hierarchical control strategy from the perspective of macroscopic traffic network

In order to alleviate traffic congestion, transfer the regional orientation of macroscopic traffic flow to microscopic routes, and form a unified and coordinated framework of macro path decision and micro path decision, a vehicle route hierarchical control strategy is proposed from the perspective of network macro aggregated information. Firstly, according to the homogeneity of vehicle density distribution, a network is divided into several sub-regions, and then the macro-aggregate dynamic mapping relationship of each sub-area is analyzed. Secondly, a traffic equilibrium distribution model is established under heterogeneous macro path conditions to minimize the travel time of traffic flow. To bring macro traffic flow solved by the above model to the projected into the actual network level, the logit route model is used to guide macro traffic flow to the micro-scale road network with the help of a simplified network. Finally, the SUMO simulation platform is employed to achieve the solution and verification of the hierarchical vehicle path control method. The experimental results prove that the strategy can effectively reduce the congestion of the urban road network during peak hours and improve the traffic capacity of the road network. It is also demonstrated that macroscopic aggregate information is one of the reliable information sources for vehicle path control and guidance in a road network.

Vertical transport and retention behavior of polystyrene nanoplastics in simulated hyporheic zone

The ecological risk of microplastics (MPs) usually depends on their environmental behavior, however, few studies focused on the impact of hydrodynamic perturbations on the fate of MPs in hyporheic zone. This study chose quartz sand (250–425 μm) as simulated porous medium to investigate the transport of 100 nm polystyrene nanoplastics (PSNPs) under hydrodynamic factors, including flow rates (0.5, 1.0, and 2.0 mL/min), flow orientations (up-flow, down-flow, and horizontal-flow), and water saturations (50%, 80%, and 100%), as well as different salinities and temperatures. The breakthrough curves (BTCs) and retained profiles (RPs) of PSNPs were compared and analyzed by Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Due to the small size and moderate density of PSNPs, as well as high flow rates, the flow orientation exhibited little effect on the PSNP transport. However, high flow rate, low salinity, high water saturation, and low temperature would facilitate the mobility of PSNPs. The increase in salinity from zero to 35 PSU (practical salinity units) caused the compression of electrical double layer and weakened the electrostatic repulsion between PSNPs and sands, which dramatically decreased the penetration rate from 100% to zero. Especially, the lower energy barrier of PSNPs-PSNPs at 3.5 and 35 PSU (16.45 kBT and zero, respectively) facilitated the adsorption of PSNPs on sand via ripening mechanism. Due to the strong adsorption of PSNPs by sand at high salinity, the effect of flow rate on PSNP transport was more pronounced at low salinity. The mobility of PSNPs at 0.035 PSU was enhanced by 41.4%-75.3% as the flow rate increased from 0.5 to 2.0 mL/min, which was contributed from the reversible deposition in lower secondary energy minimum depth at low salinity and the stronger hydrodynamic drag force generated by the high flow rate. However, the sufficient molecular diffusion at low flow rate promoted the occupation of PSNPs on adsorption sites. In addition, the penetration rate of PSNPs decreased by 25.0% as the water saturation decreased from 100% to 50%, indicating that the film straining at the air-water interface would hinder the transport of PSNPs. Finally, temperature increase impeded the penetration of PSNPs by 6.26%-23.1% via blocking mechanism. Our results suggest that low-salinity, high-flow river systems may be at greater risk of MPs contamination due to enhanced vertical transport capability.

Heat transfer deterioration in vertical sCO2 cooling in 3 mm tube

In this publication, the cooling heat transfer coefficient (htc) is investigated in a 3 mm diameter tube with vertical flow orientation. Commonly used calculation methods of the heat transfer coefficient are presented. Although developed for heating of sCO2, the mixed convection criterion is used to evaluate the heat transfer deterioration. The effects of the CO2 mass flux of 141−354kg/m²s and bulk fluid temperatures of 20−50°C with a constant pressure of 80bar on the heat transfer were examined. The upwards flow shows a steady decrease in the htc with the reduction of the mass flux. However, the downwards flow shows significant effects of buoyancy. At low mass flux the distinct peak in the htc at the pseudocritical temperature (Tpc) disappears. The deteriorated heat transfer in the downwards flow showed significant lower wall temperatures compared to the upwards flow. The separate evaluation of the liquid-like and gas-like region indicates that the deterioration may vary based on the fluid properties. The results were regressed within +-15% in the forced convection region and +-40% in the mixed convection region. The comparison with the literature data of vertical cooling in 6 mm showed different behaviour which indicates an influence of the tube diameter.

Visualization study on oil retention and flow characteristics of R32/PVE oil in suction lines with different flow orientations

Oil retention characteristic and flow patterns of R32/PVE lubricant oil mixture in compressor suction lines were investigated. Smooth copper tubes with 10.7mm inner diameter and four tube orientations including horizontal flow, vertical upward flow and inclined upward flow with 45° and 60° inclined angles, were utilized as test samples. Saturation temperature and superheat degree were maintained at 7.5°C and 12°C, respectively. The operation conditions of refrigerant mass flux and nominal oil mass fraction covered ranges of 48.5−230 kg•m−2•s−1 and 1−5%, respectively. The oil retention amount was measured by the remove and weight technique. Based on the visualization technique, flow patterns of R32/oil mixture were also observed, identified and analyzed. The characteristic of flow patterns was greatly influenced by the thermophysical properties of refrigerant-oil mixture. Comparisons of existing flow pattern maps and wet wall fraction correlations were conduct to investigate the applicability. The experimental result showed that oil retention in suction lines increased with the decrease in refrigerant mass flux and increase in oil mass fraction. The oil retention amount of 60° inclination suction line was slightly higher than that for 45°. Additionally, the difference of oil retention among the four configurations becomes limited at high mass flux conditions.

Effects of drying and orientation to perennial refuges on aquatic biodiversity across two basins differing in aridity

AbstractIntermittent streams are globally distributed, comprise over half the length of the global river network, and are expected to become more prevalent. However, most studies of intermittent streams are conducted at extremes of scale, are limited in taxonomic and temporal scope, and focus exclusively on drying patterns. Here, we assessed how both flow intermittency and orientation to perennial refuges affect aquatic invertebrates and aquatic and semiaquatic vertebrates across 2 years within two intermittent river basins differing in their aridity. We used loggers to characterize flow intermittency and wet–dry mapping to determine orientation to perennial refuges of reaches. In winter and summer 2015 and 2016, we collected and identified invertebrates and visually surveyed vertebrates. Using permutational multivariate analyses of variance with distance matrices, we found distinct invertebrate communities by basin, flow class (perennial or intermittent), and season, and distinct vertebrate communities by basin, and between flow classes and seasons in the more arid basin. Invertebrate communities had higher beta diversity in the more arid than mesic basin, whereas the opposite was true for vertebrates. We identified indicator species for all combinations of basin and flow class, perennial reaches combined from both basins, each basin, and some combinations of flow class and season within basins. Flow intermittency and orientation to perennial refuge predictors correlated well with both invertebrate and vertebrate communities. However, we did not find nestedness of communities that differed significantly from that expected by chance in response to increasing flow intermittency or distance to refuges. Lastly, basin, flow intermittency, and orientation to perennial refuge predictors were generally important for modeling taxon richness and densities, and richness and densities decreased with increasing flow intermittency and distance to perennial refuges. Collectively, our data suggest that intermittent streams harbor unique biodiversity, but also that some taxa have context‐dependent responses to intermittency and orientation to perennial refuges. These findings also suggest that future increases in stream drying are likely to lead to changes to stream communities with high potential for the loss of aquatic biodiversity.

Flow visualization, heat transfer, and critical heat flux of flow boiling in Earth gravity with saturated liquid‐vapor mixture inlet conditions – In preparation for experiments onboard the International Space Station

This study investigates flow boiling of n-Perfluorohexane with saturated two-phase mixture inlet in a rectangular channel of dimensions 114.6 mm heated length, 2.5 mm width, and 5 mm-height. The experiments were performed as part of the Mission Sequence Testing of the Flow Boiling and Condensation Experiment's (FBCE) Flow Boiling Module (FBM) in the vertical upflow configuration in Earth gravity using the same experimental system that was launched to the International Space Station (ISS) in August 2021. The operating parameters varied are heating configuration (single- and double-sided), mass velocity (380–2400 kg/m2s), inlet quality (0.011–0.519), and inlet pressure (120–179 kPa). High-speed video photographs are presented to explain the two-phase flow patterns within the channel's heated length. Flow patterns are constituted by low-density and high-density fronts moving along the channel, with the high-density fronts gradually reducing in length due to evaporation. Heat transfer results in terms of flow boiling curves, streamwise wall temperature profiles, streamwise heat transfer coefficient profiles, and average heat transfer coefficients are presented and trends discussed. CHF data from the present experiments are combined with prior databases to compile a consolidated FBCE-CHF database for saturated inlet to expand the ranges of operating conditions and include other flow orientations in Earth gravity. Experimental CHF trends are also discussed. The interfacial lift-off model shows a good CHF predictive accuracy evidenced by a mean absolute error of 11.97% for this consolidated database after constraining it to mass velocities greater than or equal to 500 kg/m2s. Finally, this study confirmed reliability of the upcoming ISS experiments for saturated inlet conditions and the collected Earth-gravity data will be compared to ISS microgravity data.

Visualizing the invisible: User-centered design of a system for the visualization of flows and concentrations of particles in the air

This study presents two experiments addressing the representation of scientific data, in particular airflows, with a user-centered design approach. Our objective is to provide users feedback to data visualization designers to help them choose an air flow representation that is understandable and attractive for non-experts. The first study focuses on static markers allowing to visualize an airflow, with information characterizing the direction and the intensity. In a second study, carried out in an immersive virtual environment, two information were added, the temporal evolution and the concentration of pollutants in the air. To measure comprehension and attractiveness, participants were asked to answer items on Likert scales (experiment 1) and to answer User Experience Questionnaire (experiment 2). The results revealed that arrows seem to be a very common and understandable form to represent orientation and direction of flow, but that they should be improved to be more attractive by making them brighter and more transparent, as the representation could occlude the scene, especially in virtual reality. To solve this problem, we suggest giving the users the ability to define the specific area where they want to see the air flow, using a cross-sectional view. Vector fields and streamlines could therefore be applied in a virtual reality context.

Optimal Design and Analysis of Thermo-plastic product Chair Hand rest

The paper deals with the Design and mould flow analysis of injection moulding tool for Chair hand rest component. The part was analyzed with the mould flow software and accordingly, the injection moulding tool was designed. After mould flow analysis, considering the parameters (Possible gating location, runner location, fills time, Flow orientation, weld lines, etc) the manufacturing of the tool was done. Before the production of the component, there is a requirement of the moulding tool and moulding machine. The design is a very critical part and specialized area. Hence the tool should match the specification of the moulding machine to be accurate for producing the product. Keywords- injection moulding tool, best gate location, fills time, weld lines, Air traps.

A computationally efficient model for granular material piling in a container

This paper describes the development of a novel computationally efficient model to simulate the granular material piling process inside a container. The model computes both the granular material profile inside the container and spillage amount and location out of the container based on the cart geometry, impact location and orientation of flow of the grain transmitted into the container. The performance and utility of the grain fill model strategy is demonstrated via simulation of the grain piling process inside a grain cart during agricultural combine harvester grain unloading from the combine into a tractor-driven grain cart. The simulation demonstrates that the model can simulate both the grain profile change and spillage in real time. Experimental data collected from a benchmark system with LiDAR was used to quantify the model accuracy during grain unloading. The experimental results show that the model can achieve 0.2-m accuracy during a corn unloading process from an empty to a full grain cart.

Initiation of an Emulsion Microinfusion: Flow Direction Influences Delivery Onset Rate

Critically ill and anesthetized patients commonly receive life-sustaining medications by pump-driven continuous intravenous infusion. Microinfusion refers to delivering concentrated drugs with low flow carriers to conserve fluid administration. Most infused medications are water-soluble. Delivery onset lag times have been identified for microinfusions of water-soluble drugs or experimental surrogates. Drugs may be formulated as emulsions. Initiation of emulsion microinfusions has not been described. We tested in vitro the hypothesis that an emulsion's physical characteristics would influence its microinfusion delivery onset. We adapted an established in vitro model of pump-driven continuous intravenous microinfusion to compare the delivery of methylene blue as a surrogate for water-soluble drugs and a 10% lipid emulsion as a surrogate for a drug formulated as an emulsion. The drug surrogates joined the carrier with carrier flow vertically upwards, vertically downwards or horizontally. We measured the times to 5%, 50% and 95% of plateau delivery. Emulsion entry into a vertical (upwards) carrier flow resulted in a rapid initial emulsion delivery exceeding predictions of delivery models. Emulsion entry into both horizontal and vertical (downwards) carrier flows resulted in long lag times to steady state. Methylene blue delivery was unaffected by carrier flow orientation. Initiating microinfusion emulsion delivery with upward flow can result in a relative bolus, whereas long delivery lags would be expected with horizontal or downwards flow. An emulsion might carry a high potency drug having significant physiologic effects, e. g. clevidipine. Unrecognized, differences in initial emulsion delivery kinetics depending on carrier flow orientation may have clinical implications for both efficacy and safety.

Dual beam half Radial Line Slot Array (RLSA) antennas

ABSTRACT Dual-beam half Radial Line Slot Array (RLSA) antennas were introduced for the first time in this article. Their uniqueness lies in the fact that only half model of RLSA antennas was used instead of full circle models to ensure they are applicable in small devices. Moreover, the slots were placed on the antenna’s background, which is unusual, to produce a beam on the backside. It is important to note that the half RLSA and the antenna background used to produce the beam affected the power flow orientation within the antennas’ cavity, thereby, causing a center frequency shift problem. This led to the proposal of a technique of frequency design shift to overcome this problem by designing and simulating 120 dual-beam half RLSA models after which the best model was fabricated and measured to verify the simulation. The results showed the possibility of designing dual-beam antennas with symmetrical beams having 10.1 dB gain, 30° and 150° directions, and 37° beamwidths. It was discovered that this gain is 3 dB lesser than the value for a single beam antenna and this is suitable based on the theory of beam splitting. Moreover, the antenna was also able to perform low reflection and quite broad bandwidth for Wi-Fi needs. The design of the antenna was further verified based on the similarity between the results of the measurement and simulation.

Flow features of shallow cylindrical cavities subject to grazing flow

The flow behavior within shallow cavities of circular planform, subject to grazing flows, exhibits a strong dependence on the cavity depth (h)-to-diameter (d) ratio. In the present experimental study, the internal flow patterns within shallow circular cavities having a depth-to-diameter ratio of 0.15 ≤ h/d ≤ 1 have been extracted from mean static and unsteady surface pressure measurements collected on the cavity surfaces. In the literature, no comprehensive experimental study spanning this entire h/d range is available characterizing the flow behavior in shallow cylindrical cavities; only certain aspects of flow at select h/d are present in the current literature, and the present paper addresses this shortcoming. In agreement with the previous research on shallow cylindrical cavities, the mean flow orientation and the amplitude of large-scale pressure fluctuations within the cavity are observed to follow a non-monotonic function as the depth-to-diameter ratio is varied, with h/d = 0.5 exhibiting the greatest asymmetry in flow orientation. The division of the internal cavity flow into stable, switching, and flapping regimes established by previous related studies has been reevaluated, and utilizing a simple filtering technique, a modification to the classification of these flow regimes has been proposed for the present conditions. Furthermore, the observation of two high-frequency pressure oscillations, measured within the cavity for the flapping regime, has been linked to shear layer instabilities.

A State-of-the-Art Review on Two-Phase Flow-Induced Noise in Expansion Devices

This paper presents a state-of-the-art review of the literature concerning flow-induced noise in expansion devices. The topics covered are theoretical natural frequency models of bubbles with spherical and cylindrical shapes and flow-induced noise in capillary tubes, such as orifice, thermal and electric expansion valve. Several parametric conditions affect the flow-induced noise in capillary tubes, such as outlet capillary geometry, capillary inner diameter and length, flow orientation, outlet vapor quality, mass velocity, pressure drop, in/outlet flow pattern, evaporation temperature, and refrigeration cycle operational conditions. Despite the broad use of orifice, there is a lack of knowledge in the literature of flow-induced noise in these devices. The flow-induced noise seems primarily a function of mass velocity, vapor quality, and flow pattern. It seems that outlet intermittent flow patterns lead to significant noise in capillary tubes and expansion valves. In general, for the noise evaluated outside the expansion device, electric expansion valves exhibited higher sound pressure levels than capillary tubes. Furthermore, the present literature review indicates that efforts should be made to perform tests for a wide range of conditions evaluating the noise within and outside the expansion device, device wall acceleration and flow topology for current and new refrigerants, simultaneously.