Single-phase Approach Research Articles

Entropy optimization for nanofluid flow with radiation subject to a porous medium

Here hydrodynamic Darcy-Forchheimer nanofluid flow with entropy rate by a porous surface is examined. Mathematical background of current flow is developed through implementing single-phase approach. Here silver (Ag) and gold (Au) are used as nanoparticles, while sodium alginate ((C6H7NaO6)n) is considered as base fluid. Moreover, the impact of radiation, heat generation, Ohmic heating and dissipation are considered in energy equation. Feature of irreversibility (entropy rate) analysis is scrutinized. A set of suitable non-similar variables are employed for conversion of nonlinear partial system into dimensionless ordinary system. The obtained dimensionless systems are tackled through numerical scheme (ND-solve technique). Influence of physical variables on velocity field, Bejan number, thermal field and entropy generation are examined against both silver and gold nanoparticles. Reverse effect for entropy rate and velocity is noted through magnetic variable. Higher approximation of volume fraction has reverse effect on velocity and temperature. Bejan number is diminished for magnetic variable. An intensification in radiation effect increases thermal field. A reverse trend is seen for entropy and Bejan numbers for Brinkman number.

CFD MODELS FOR ANEURYSM ANALYSES AND THEIR USE IN IDENTIFYING THROMBOSIS FORMATION AND RISK ASSESSMENT

In this paper, the blood transport has been investigated using the single- and the two-phase methods. In the two-phase Euler–Euler approach, the blood is represented by two interpenetrating continua where the dispersed red blood cells (RBCs) of non-Newtonian characteristics are suspended in the continuous Newtonian plasma. The results of the two-phase model, where the RBC’s phase is assumed to be Carreau–Yasuda fluid, are validated against the experimental data. Furthermore, comparative analyses were performed in two patient-specific aneurysms, which indicated that for a given pulsatile flow rate, the two-phase blood approach is vitally advantageous over the single-phase assumption, and revealed a deeper inflow penetration, more complex flow structures and denser flow diversion zones in the aneurysm sac. It was obvious that the high OSI values calculated by the two-phase model covered much wider regions than the values predicted by the single-phase model. It was equally crucial that these regions coincided with the TAWSS values lower than the threshold that the single-phase approach can predict. Apparently, the single-phase model failed to spot sites of high rupture risk. The results were further exploited to identify the RBCs aggregation regions as, for example, the concave structures and narrow paths in the saccular aneurysms, for their possible use as the precursors of the thrombus formation.

Evaluation of Thermal Performance of Conically Shaped Micro Helical Tubes Using Non-Newtonian Nanofluids–A Numerical Study

Abstract Nowadays, the cooling and heating of micro-thermal devices have received a growing interest. To improve the thermal management of these micro-thermal devices, various efforts are being made by the researchers. In the present study, conically shaped micro helical tubes are used to investigate the coil side heat transfer rate and friction factor of non-Newtonian nanofluids under laminar flow conditions. For the numerical analysis, single-phase approach with commercial software ansys-fluent-19 has been utilized. Investigations encompass generalized Reynold numbers ranging from 306 to 2159 and four different curvature ratios (0.066, 0.076, 0.088, and 0.1) of conically shaped micro helical tubes. The inner diameter of the helical tube is 2 mm and contains 20 turns. Al2O3-based non-Newtonian nanofluids with volume concentrations of 0.0%, 0.1%, and 0.2% having base fluid of aqueous solution of carboxymethyl-cellulose (CMC) are used as the working fluid (hot) for the coil side, while in the shell side cold water is used. The results from numerical investigation are validated and found in good agreement with earlier experimental results. The results show that with the increase in the curvature ratio of conically coiled tubes both heat transfer rate and friction factor increase by 46% and 98% respectively, for base fluid at a curvature ratio of 0.1. Also, the present study reveals that adding nanoparticles to the base fluid enhances the heat transfer rate to a maximum value of 40%. Moreover, the maximum value of thermal performance factor (TPF) is found to be 1.52.

Combined infrared and hot air drying (IR-HAD) of sweet potato explored using a multiphase model: application of reaction engineering approach

For better understanding of transport phenomena, local evaporation rate and water vapor concentration should be taken into consideration when predicting drying behavior. However, to the best of our knowledge, there is no model which explicitly represents this. Predictive modeling of combined infrared-heating and hot air drying (IR-HAD) is useful to assist in designing new dryer units and manufacturing the products with desirable quality. As the quality changes are basically local phenomena, the model should be able to capture the local evaporation rate. In this study, for the first, time, spatial reaction engineering approach (S-REA) was developed and used to describe infrared-heating drying of the food materials by using the reaction engineering approach (REA) to represent local evaporation rate. Benchmarks against the single-phase approach and the results showed that the S-REA gave high accuracy toward the experimental data (R2 = 0.978–0.999). The S-REA successfully provided reasonable predictions of two-dimensional (2 D) profiles of moisture content, concentration of water vapor and temperature. This highlights the accuracy of the REA framework to describe the local evaporation rate during the infrared-heating. The REA-based predicted variables can then be applied to project the local quality parameters for quality assurance in food processing. The model is also ready to be used to audit energy demands in drying systems.

A robust single-phase approach for the numerical simulation of heat pipe

In this study, a single-phase approach is employed for the numerical simulation of heat pipe analysis. This is applied by selecting individual fluid for each zone and implementation of User Defined Functions (UDF)s to take care of the interfaces. Although the noted method is found to be contrary to the conventional multiphase approach, it removes the necessity of using multiphase simulations, thus simplifying the numerical setup. Moreover, it would inevitably boost the convergence stability and speeds up the solution time since it would remove the additional volume fraction equation. To evaluate the integrity of the current formulation, simulation of a 2-D flat heat pipe was performed, and all the field variables were carefully validated in different locations of the computational domain.

Numerical and CFD analysis of a heat transfer enhancement in turbulent flow through a circular pipe using nanofluid

This paper presents numerical and CFD simulation of an Al2O3-water nanofluid turbulent flow in a circular pipe which has a 36 mm diameter with a constant heat flux at the pipe wall using ANSYS FLUENT 2020 R2. The turbulent flow under different Reynolds numbers, from Re = 10000 to 50000 was used to process the numerical experiments. Different concentrations of nanoparticles, ranging from 1% to 4%, were used. The results were computed utilizing the single-phase approach. The coefficient of transfer of heat of nanofluids is found to be greater than that of base liquid. Enhancement in transfer of heat is also observed with rising in volume concentration of particles.

Numerical investigation on turbulent flow and heat transfer characteristics of ferro-nanofluid flowing in dimpled tube under magnetic field effect

• This is the first study on dimpled tube under magnetic field effect. • Effects of dimple geometry and magnetic field on the thermal and hydrodynamic behaviour have been investigated. • The Nu enhances with increasing volume fraction of magnetic nanoparticle. • The highest PEC is obtained for Ha = 75, magnetic nanoparticle fraction of 2.5 vol% and dimpled tube with P 2 /d = 7.5. For the aim of increasing the heat transfer enhancement, a hybrid method in which active and passive heat recovery techniques have been used together. The usage of nanofluid, MHD and dimpled fins tube have not been utilized together so far. Regarding this issue, this study is the first numerical study to determine effect of usage of three effects together comprehensively. In this study, thermo-hydraulic performance of Fe 3 O 4 /H 2 O nanofluid (ferro-nanofluid) flow inside dimpled tube under magnetic field effect has been examined numerically. The main purpose of the study is to obtain numerical data for turbulent flow in the spherical dimpled tubes providing some aid to design a highly efficient thermal energy storage devices. Dimple geometry with nondimensional pitch ratio ( P/d = 3.75, 7.50 and 11.25 ), Hartmann number ( Ha = 75, 150, 225) and nanoparticle volume fraction ( φ = 0.5, 1.0 and 2.5 vol % ) are the parameters investigated in this study. The numerical analyses have been carried out Reynolds number ranging from 10,000 to 50,000 at a constant heat flux at 20 kW/m 2 . The simulations have been built up by Realizable k- ε turbulence model and single-phase approach. Also, “MagnetoHydroDynamic” ( MHD ) module has also been activated for defining magnetic field effect. The results showed that Nusselt number increases with increasing Reynolds number and decreasing pitch ratio. The dimple geometry type of P/d = 7.50 has been determined as the most efficient dimple geometry type. In the case of highest magnetic field intensity, the highest Nusselt number increment (72.48%) has been obtained for φ = 2.5 vol% compared to the base fluid of distilled water using as the working fluid for smooth tube. The highest PEC value was also obtained as 1.126 for the case of P/d = 7.5, φ = 2.5 vol% and Ha = 75. In addition, the effect of magnetic field intensity on velocity and temperature distributions has been presented with contour graphs.

Experimental and CFD Analysis of GW70 based Cu Nanofluids in a Parallel Flow Heat Exchanger

The Nusselt number, overall heat transfer, and convective heat transfer coefficients of glycerol-water-based Cu nanofluids flowing in a parallel flow double pipe heat exchanger are estimated using CFD analysis. Single-phase fluid approach technique is used in the analysis. Ansys 19.0 workbench was used to create the heat exchanger model. Heat transfer tests with nanofluids at three flow rates (680<Re<1900) are carried out in a laminar developing flow zone. For testing, a 500 mm long concentric double pipe heat exchanger with tube dimensions of ID=10.2 mm, OD= 12.7 mm, and annulus dimensions of ID=17.0 mm, OD= 19.5 mm is employed. Copper is utilized for the tube and annulus material. This study employed three-particle volume concentrations of 0.2 percent, 0.6 percent, and 1.0 percent. The mass flow rates of hot water in the tube are 0.2, 0.017, and 0.0085 kg/s, while the mass flow rates of nanofluids in the annulus are 0.03, 0.0255, and 0.017 kg/s. The average temperature of nanofluids is 36°C, whereas hot water is 58°C. In comparison to base liquid, the overall heat transfer coefficient and convective HTC of 1.0 percent copper nanofluids at 0.03 kg/s are raised by 26.2 and 46.2 percent, respectively. The experimental findings are compared to CFD values, and they are in close agreement.

Optimization of heat transfer in shell-and-tube heat exchangers using MOGA algorithm: adding nanofluid and changing the tube arrangement

The purpose of this study is to assess the impact of a wide variety of parameters to maximize the heat transfer rate using nanofluid, baffles, different Reynolds numbers (Re), different tube arrangements, and various geometry dimensions using the multi-objective genetic algorithm (MOGA) algorithm. The ANSYS FLUENT software, the SIMPLE algorithm as well as single-phase approach are employed for simulations. The study was performed for volume fractions (φ) of 0% to 4% and 10,000 < Re < 20,000. The results are presented for rectangular and triangular arrangements of tubes. It is demonstrated that in the rectangular configuration, the average Nusselt number (Nu ave) is 34.38 when number of baffles (NB) of 10, φ = 4%, Re = 20,000. For the same values of φ and Re, when NB = 10, Nu ave is enhanced by 7.4% and 10.4% compared to the cases in which NB = 6 and 8, respectively. However, for the triangular arrangement of tubes, Nu ave=35.15. For the same values of φ and Re, when NB = 10, Nu ave is enhanced by 5.7% and 11.4% compared to the cases in which NB = 6 and 8, respectively. Also, the triangular arrangement has about 2.1% more thermal efficiency than the rectangular one when NB, φ, and Re are maximum. Unlike the smaller figure for tubes mounted in the heat exchanger to transfer heat compared to other studies, the addition of nanofluid and using baffles lead to employing the heat exchanger for practical applications. However, a larger number of baffles causes a higher pressure drop. Hence, the optimization is performed using MOGA to reduce the pressure drop.

Significance of variability in magnetic field strength and heat source on the radiative-convective motion of sodium alginate-based nanofluid within a Darcy-Brinkman porous structure bounded vertically by an irregular slender surface

The dynamical behavior and thermal transportation feature of an enhanced MHD convective Casson bi-phasic flows of sodium alginate-based nanofluids are examined numerically in a Darcy-Brinkman medium bounded by a vertical elongating slender concave-shaped surface. The mathematical framework of the present flow model is developed properly by adopting the single-phase approach, whose solid phase is selected to be metallic or metallic oxide nanoparticles. Besides, the influence of thermal radiation is taken into consideration in the presence of an internal variable heat generation. A set of feasible similarity transformations are applied for the conversion of the governing PDEs into a nonlinear differential structure of coupled ODEs. An advanced differential quadrature algorithm is employed herein to acquire accurate numerical solutions for momentum and energy equations. For validating the obtained numerical findings, extensive comparison tests are carried out in this sense. The results of the current exploration show that the wall heat transfer rate and the frictional effect are strengthened with the loading of nanoparticles and weakened with the mounting values of the heat source parameters. However, the magnetic parameter exhibits a reverse trend concerning those engineering quantities. Statistically, the slope linear regression method (SLRM) proves that the aurum-sodium alginate nanofluid presents the higher frictional factor, whereas the copper oxide-sodium alginate is the more thermal performant nanofluid.

Numerical Analysis of Mixed Convective Heat Transfer from a Square Cylinder Utilizing Nanofluids with Multi-Phase Modelling Approach

The present study deals with the numerical simulation of mixed convective heat transfer from an unconfined heated square cylinder using nanofluids (Al2O3-water) for Reynolds number (Re) 10–150, Richardson number (Ri) 0–1, and nanoparticles volume fractions (φ) 0–5%. Two-phase modelling approach (i.e., Eulerian-mixture model) is adopted to analyze the flow and heat transfer characteristics of nanofluids. A square cylinder with a constant temperature higher than that of the ambient is exposed to a uniform flow. The governing equations are discretized and solved by using a finite volume method employing the SIMPLE algorithm for pressure–velocity coupling. The thermo-physical properties of nanofluids are calculated from the theoretical models using a single-phase approach. The flow and heat transfer characteristics of nanofluids are studied for considered parameters and compared with those of the base fluid. The temperature field and flow structure around the square cylinder are visualized and compared for single and multi-phase approaches. The thermal performance under thermal buoyancy conditions for both steady and unsteady flow regimes is presented. Minor variations in flow and thermal characteristics are observed between the two approaches for the range of nanoparticle volume fractions considered. Variation in φ affects CD when Reynolds number is varied from 10 to 50. Beyond Reynolds number 50, no significant change in CD is observed with change in φ. The local and mean Nusselt numbers increase with Reynolds number, Richardson number, and nanoparticle volume fraction. For instance, the mean Nusselt number of nanofluids at Re = 100, φ = 5%, and Ri = 1 is approximately 12.4% higher than that of the base fluid. Overall, the thermal enhancement ratio increases with φ and decreases with Re regardless of Ri variation.

Designing artificial neural network of nanoparticle diameter and solid–fluid interfacial layer on single‐walled carbon nanotubes/ethylene glycol nanofluid flow on thin slendering needles

AbstractIn this study, an artificial neural network (ANN) has been developed to predict the boundary layer flow of a single‐walled carbon nanotubes nanofluid toward three different nonlinear thin isothermal needles of paraboloid, cone, and cylinder shapes with convective boundary conditions. Different effects of particle diameter and solid–fluid interface coating have been taken into account in the thermal conductivity model of nanofluid in which ethylene glycol has been used as the base fluid. Single and dual phase approach is used to establish the management model under the phenomenon of zero heat and mass flux. A dataset has been developed for different scenarios of the fluid model by changing the relevant parameters with the Runge–Kutta based shooting technique. Two different ANN models have been developed to predict Nusselt number and skin friction coefficient (SFC) values. The values obtained from ANN models have been compared with the numerical data, which are the target values. In addition, mean square error and R values have also been examined in order to analyze the prediction performance of ANN models more comprehensively. The calculated R values for Nusselt number and SFC were obtained as 0.9999. The results obtained showed that ANN can predict Nusselt number and SFC values with high accuracy.

Numerical analysis on heat transfer of parabolic solar collector operating with nanofluid using Eulerian two-phase approach

Parabolic trough solar collector (PTSC) is an effective solar harvesting system that can be combined to various systems with different working fluids. This research presents a novel investigation on a PTSC system in which nanofluids are used to transfer heat energy. CFD analysis is performed according to FVM method to complement the study. Syltherm 800 oil is used as the main operating fluid augmented with CuO nanoparticles to investigate thermal and hydrodynamic behaviors of the solar system comprehensively. To simulate the nanofluid the two-phase model and the single phase approach are applied. The results indicate that increasing the nanofluid volume concentration improves the coefficient of heat transfer, performance evaluation criteria and the collector thermal efficiency.

A combined approach for modeling multi-echelon multi-period decentralized supply chain.

In this paper, a multi-echelon, multi-period, decentralized supply chain (SC) with a single manufacturer, single distributor and single retailer is considered. For this setting, a two-phase planning approach combining centralized and decentralized decision-making processes is proposed, in which the first-phase planning is a coordinated centralized controlled, and the second-phase planning is viewed as independent decentralized decision-making for individual entities. This research focuses on the independence and equally powerful behavior of the individual entities with the aim of achieving the maximum profit for each stage. A mathematical model for total SC coordination as a first-phase planning problem and separate ones for each of the independent members with their individual objectives and constraints as second-phase planning problems are developed. We introduce a new solution approach using a goal programming technique in which a target or goal value is set for each independent decision problem to ensure that it obtains a near value for its individual optimum profit, with a numerical analysis presented to explain the results. Moreover, the proposed two-phase model is compared with a single-phase approach in which all stages are considered dependent on each other as parts of a centralized SC. The results prove that the combined two-phase planning method for a decentralized SC network is more realistic and effective than a traditional single-phase one.

Capabilities and Limitations of 3D-CFD Simulation of Anode Flow Fields of High-Pressure PEM Water Electrolysis

In this work, single-phase (liquid water) and two-phase (liquid water and gaseous oxygen) 3D-CFD flow analysis of the anode of a high pressure PEM electrolysis cell was conducted. 3D-CFD simulation models of the anode side porous transport layer of a PEM electrolyzer cell were created for the flow analysis. For the geometrical modelling of the PTL, two approaches were used: (a) modelling the exact geometry and (b) modelling a simplified geometry using a porosity model. Before conducting two-phase simulations, the model was validated using a single-phase approach. The Eulerian multiphase and the volume-of-fluid approaches were used for the two-phase modelling and the results were compared. Furthermore, a small section of the PTL was isolated to focus on the gas bubble flow and behaviour in more detail. The results showed plausible tendencies regarding pressure drop, velocity distribution and gas volume fraction distribution. The simplified geometry using the porous model could adequately replicate the results of the exact geometry model with a significant reduction in simulation time. The developed simulation model can be used for further investigations and gives insight into two-phase flow phenomena in the PTL. Additionally, the information obtained from simulation can aid the design and evaluation of new PTL structures.

RETRACTED ARTICLE: Irreversibility of hybrid nano-powder within permeable tank with MHD

To manage the convective flow through a permeable geometry, Lorentz and gravity forces were applied in this simulation. In equations of velocity, permeability and MHD effects as well as gravity force have been involved. To calculate the values of scalars, CVFEM was employed for last form of equations which were achieved with incorporating Ω. Testing fluid within the enclosure is hybrid nanomaterial and for predicting its features, single phase approach was utilized. Higher values of Ra and Da makes convective flow to increase, while Lorentz forces make the conduction mode to increase and reduce the velocity of carrier fluid. Temperature of elliptic surface augments about 14.2% and 25% with rise of K and buoyancy but it augments about 7.14%. Sgen,th decreases about 22.2% with rise of Ra. Sgen,f reduces by 33% with growth of Da. Amounts of Be augment about 11.33% and 3.47% with growth of Ha and Da, while augment for Ra leads to reduction of Be about 67.92%. Nu decreases about 26.15% with augment of Ha, while rise of Da makes Nu to increase about 12.32%.Please check and confirm that the authors and their respective affiliations have been correctly identified and amend if necessary.okAuthor names: Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Also, kindly confirm the details in the metadata are correct.ok

Thermohydraulic performance of water mixed [formula omitted] and graphene-oxide nanoparticles for nuclear fuel triangular subchannel

The study compares the thermohydraulic performance of Al2O3-water, TiO2-water and Graphene-Oxide–water as a coolant which should be used in the triangular subchannel of a nuclear fuel assembly. Critical assessment of both the local and global parameters were evaluated for 1%, 2% and 4% volume fraction of each nanolfluids. The mixture of the nanofluids were considered to be homogeneous. Furthermore, the research looked into the impact of various particle sizes on heat transfer and pressure drop. The simulations proceeded assuming single phase approach, under turbulent flow conditions. The numerical findings were compared to traditional correlations for inlet Reynolds numbers ranging from 20,000 to 80,000, revealing a perfect match.The results shows that increase in nanoparticle inclusion lead to enhancing the heat transfer. The increased thermal flow lowers the surface temperature of the clad fuel, raising the thermal safety margin in the reactor fuel-clad. Furthermore, as the volume fraction rose, the pressure drop increased dramatically. Considering both the increase in heat transfer and pressure drop, the report of thermal performance shows that among all the coolants 4% volume fraction of Al2O3-water acts as a potential candidate in the triangular array of a Hexagonal Rod Bundle.

Heat Transfer Performance of Uni-Directional and Bi-Directional Lid-Driven Cavities Using Nanoparticle Enhanced Ionic Liquids (NEILS)

Two-dimensional numerical investigation has been carried out using an in-house CFD code to obtain the heat transfer performance of normal, uni-directional and bi-directional lid-driven cavity. The 2D in-house code is based on single phase approach for studying steady state laminar flows. Pure water (PW), ionic liquid (IL): 1-ethyl-3-methylimidazolium methanesulfonate; [C2mim][CH3SO3], ionic liquid mixtures (PW + IL) and alumina (Al2O3) nanoparticle enhanced ionic liquids (NEILS) are used in the present investigation. The thermophysical properties of all the heat transfer fluids used in the present numerical investigation were obtained from the experimentally measured data available in the literature. The obtained results showed that uni-directional lid-driven cavity exhibits 68.78 % higher Nuavg value at Re = 1900 in comparison with normal lid-driven cavity for pure water. The use of [C2mim][CH3SO3] ionic liquid also enhances the heat transfer performance by exhibiting 115.48 % higher Nuavg value in comparison with pure water at Re = 1900. Moreover, 15 % wt Al2O3 nanoparticles in 0.25PW + 0.75IL gives 21.2 % and 161.16 % higher heat transfer performance in comparison with ionic liquid and pure water respectively at Re = 1900. Furthermore, it is also observed that 10 % wt Al2O3 nanoparticles in 0.25PW + 0.75IL shows similar heat transfer performance like ionic liquid at all Re.

Comparative Analysis of Nanofluid Coolant in a Car Radiator using CFD

A computational analysis was performed to ascertain the effect of nanofluids on heat transfer in a flat tube heat exchanger of a car radiator. The nanofluids Al2O3/H2O and CuO/H2O were used with nanoparticles of different diameter in the range of 10-60 nm. A single-phase approach was implemented in the analysis. The heat transfer coefficient was calculated at various Reynolds numbers (250, 750, 1250, and 1750) with several nanoparticle concentration by volume of 1%, 3%, and 6%. Results indicated that the heat transfer rate increased with increase in the concentration by volume of nanoparticles. Whereas the decrease in the diameter of nanoparticle favored higher heat transfer rates. Therefore, the maximum heat transfer rate was observed at 6% concentration and at 10nm diameter size for both types of nanoparticles analyzed in this study for flat tube car radiator. The Al2O3/H2O nanofluid showed higher heat transfer rates than the CuO/H2O nanofluid at all Reynolds numbers.

Multiferroic Aurivillius Bi4Ti2-xMnxFe0.5Nb0.5O12 (n = 3) compounds with tailored magnetic interactions.

Aurivillius compounds with the general formula (Bi2O2)(An-1BnO3n+1) are a highly topical family of functional layered oxides currently under investigation for room-temperature multiferroism. A chemical design strategy is the incorporation of magnetically active BiMO3 units (M: Fe3+, Mn3+, Co3+ …) into the pseudo-perovskite layer of known ferroelectrics like Bi4Ti3O12, introducing additional oxygen octahedra. Alternatively, one can try to directly substitute magnetic species for Ti4+ in the perovskite slab. Previous reports explored the introduction of the M3+ species, which required the simultaneous incorporation of a 5+ cation, as for the Bi4Ti3-2xNbxFexO12 system. A larger magnetic fraction might be attained if Ti4+ is substituted with Mn4+, though it has been argued that the small ionic radius prevents its incorporation into the pseudo-perovskite layer. We report here the mechanosynthesis of Aurivillius Bi4Ti2-xMnxNb0.5Fe0.5O12 (n = 3) compounds with increasing Mn4+ content up to x = 0.5, which corresponds to a magnetic fraction of 1/3 at the B-site surpassing the threshold for percolation, and equal amounts of Mn4+ and Fe3+. The appearance of ferromagnetic superexchange interactions and magnetic ordering was anticipated and is shown for phases with x ≥ 0.3. Ceramic processing was accomplished by spark plasma sintering, which enabled electrical measurements that demonstrated ferroelectricity for all Mn4+-containing Aurivillius compounds. This is a new family of layered oxides and a promising alternative single-phase approach for multiferroism.