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This work covers a numerical analysis of the design and optimization of a thermoelectric cooler (TEC) operated by a thermoelectric generator (TEG). The aim of the work was to design the optimum mini refrigerator for tractors and also to provide cooling using the energy produced in the TEG used in the tractor. Thanks to the TEC powered with the TEG system, farmers will be able to preserve their food during working hours without additional fuel consumption. When the literature is examined, no study has been found in which cooling is done by using the compressor air of turbocharged systems. Therefore, this work will make an important contribution to the literature. According to the numerical results obtained, while the electrical power requirement was 34.78 W at an outdoor temperature of 30 °C, it was 26.54 W at an outdoor temperature of 15 °C. In other words, while the coefficient of performance was obtained as 0.301 at 15 °C, it was determined as 0.219 at 30 °C. In addition, while the electrical power value produced by the TEG system used in the tractor for an outdoor temperature of 15 °C was 50.71 W, it was 38.84 W at an outdoor temperature of 30 °C. [ABSTRACT FROM AUTHOR]

The properties of an inductive RF discharge placed in a longitudinal external magnetic field with an induction of less than 70 G at frequencies of 2, 4, and 13.56 MHz are studied. The dependences of the region of existence of the discharge, the efficiency of the RF power input and the structure of the RF magnetic field on the external magnetic field induction are studied experimentally. The experimental results are compared with calculations based on a previously developed electromagnetic discharge model. It is shown that the local maximum of the plasma density observed at weak magnetic fields is associated with the resonant excitation of waves in the plasma source. The excited wave is close to a transverse helicon at a frequency of 2 MHz, and its properties approach the Trivelpiece–Gould wave at a frequency of 13.56 MHz,. [ABSTRACT FROM AUTHOR]

This study numerically surveys the effects of several main parameters of an agitated anaerobic digester on mixing rate and power input. Numerical simulation is conducted employing the Finite Volume Method (FVM), and it is validated with available experimental data. The results indicate that doubling the blade length enhances the mixing rate and the power input by 39.9% and 13.5 times, respectively; increasing the number of blades (from 4 to 6) improves the mixing rate by 12.5% and makes the power input grow 1.4 times; and decreasing the blade tilt angle from 45° to 30° causes the mixing rate to drop by 14% and decreases the power input 1.8 times. Furthermore, the observations show that the mixing rate and power input are adversely influenced by the wastewater concentration. At last, the most effective impeller design, among 144 cases investigated, is found and suggested. [ABSTRACT FROM AUTHOR]

Compositionally graded Ti(4–12 wt% Mo) alloys were successfully prepared by laser directed energy deposition (L-DED) using two hoppers from Ti and Ti-15Mo master alloy powders. Detailed SEM, EDS and XRD analysis reveals the variation of the microstructure and consequently explains the evolution of the microhardness with the Mo concentration. High laser power is required to dissolve Ti-15Mo particles, to improve the homogeneity of the material at the scale of particle size, and to achieve a smooth linear gradient of the chemical composition. In the bottom part of the samples, the microstructure consists of elongated beta grains of the length of several mm containing big α-Ti laths. With increasing Mo concentration, the volume fraction of α phase decreases. Starting from the composition of about 9 wt% Mo the presence of ω phase was detected. Microhardness values span over a wide range of 270–550 HV and are affected by phase composition. The highest values of microhardness are achieved at around 10 wt% of Mo. However, phase composition and microhardness depend also on the utilized laser power and position in the sample determining the cooling rates. L-DED is capable of producing functionally graded materials (FGM) on the basis of metastable β-Ti alloys providing large variations of mechanical properties within a single sample/product.

Microcarrier suspension performance and ensemble-averaged flow fields at the just-suspended condition are studied in a scale-down mimic of the Allegro STR single-use bioreactor range (abbreviated A-STR) and compared to an equivalent standard cylindrical configuration (abbreviated S-STR). Four commercial microcarriers were assessed to determine the required impeller agitation rate and corresponding power input per unit volume to achieve suspension – Cytodex™ 1, Cytodex™ 3, Cytopore™ 1, and Hillex® II microcarriers. The A-STR operating in down-pumping mode (DP) achieved homogenous microcarrier suspension at considerably lower power input when compared to the other baffled configurations. For the A-STR (DP), the power input per unit volume demand was 67.8 % lower than the A-STR in up-pumping mode (UP), 77% lower than the S-STR (DP) and 66.8 % lower than the S-STR (UP). Flow structures investigated at the just-suspended condition, in the transitional regime, were in line with those previously presented in the turbulent regime at considerably higher Reynolds number. This indicates that the normalised flow structures presented in this work are representative of those in the commercial Allegro STR range, despite operating at significantly reduced scale and Reynolds number. Removal of baffles resulted in substantially reduced power input required to achieve homogenous suspension in all configurations – other than the A-STR (DP), which exhibited relatively similar performance to the corresponding baffled configuration. Considering adherent cell sensitivity and mixing implications, and based on the results found in this work, the baffled A-STR (DP) is recommended for achieving microcarrier suspension at the lowest specific power input. • Microcarrier suspension is characterised in a scale-down mimic of the Allegro STR. • Homogenous suspension can be achieved at reduced power input in the cubical geometry. • The implications of baffles on suspension efficiency are explored. [ABSTRACT FROM AUTHOR]

The hydrodynamic characterization of bioreactors is an integral element in the industrial development of cell and gene therapy platforms where mild process conditions with low power inputs are desired. In this technology, modular single‐use equipment is frequently used for which accurate techniques to measure or predict scaling parameters, such as power input, are of high interest. In this work, computational fluid dynamics as well as two experimental approaches are used to determine the power input in a small‐scale bioreactor and validate the employed techniques. Particular attention is given to the implications arising from low‐speed operation with low power input conditions. [ABSTRACT FROM AUTHOR]

The hydromechanical stress is a relevant parameter for mammalian cell cultivations, especially regarding scale-up processes. It describes the mechanical forces exerted on cells in a bioreactor. The maximum local energy dissipation rate is a suitable parameter to characterize hydromechanical stress. In literature, different studies deal with the effects of hydromechanical stress on CHO cells in stirred tank reactors. However, they often focus on lethal effects. Furthermore, systematic examinations in smaller scales like shake flasks are missing. Thus, this study systematically considers the influence of hydromechanical stress on CHO DP12 cells in shake flask cultivations. By utilizing online monitoring of the oxygen transfer rate, the study simplifies and enhances the resolution of examinations. Results indicate that while lethal effects are absent, numerous sub-lethal effects emerge with increasing hydromechanical stress: The process time is prolonged. The time of glucose and glutamine depletion, and the lactate switch correlate positively linear with the logarithmic average energy dissipation rate while the maximum specific growth rate correlates negatively. Strikingly, the final antibody concentration only declines at the highest tested average energy dissipation rate of 3.84 W kg -1 (only tested condition with a turbulent flow regime and therefore a higher maximal local energy dissipation rate) from about 250 mg L -1 to about 180 mg L -1 . This study presents a straightforward method to examine the impact of hydromechanical stress in shake flasks, easily applicable to any other suspension cell line. Additionally, it offers valuable insights for scale-up processes, for example into stirred tank reactors., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

The selection of highly recombinant protein (RP)-productive Chinese hamster ovary (CHO) cell lines is widely carried out in shake flasks. It is assumed that increases in the operating parameters in shake flasks lead to impairments in cell growth and RP production. These effects in cells metabolism are widely associated with high mass transfers and hydrodynamic stress. This study examined the impact of commonly used operational parameters on growth and specific productivity (qP) of two CHO cell lines differentially secreting a humanized anti-hIL8 monoclonal antibody (mAb) and cultured in 250 ml flasks. The evaluated parameters are filling volume (10, 15, and 20%), shaking frequency (60 and 120 revolutions per minute -rpm-), and orbital diameter (25.4 and 19 mm). The analysis of the oxygen transfer was done in terms of the measured volumetric mass transfer coefficient (kLa) and of the hydrodynamics in terms of power input per unit volume of liquid (P/V), the turbulent eddy length scale measured by the Kolmogorov's microscale of turbulence, the energy dissipation rate, the average shear stress, and the shear rate. Though almost all measured kinetic and stoichiometric parameters remained unchanged, mAb titer included, significant differences were found in maximum cell concentration, 10–45% higher in conditions with lower values of kLa and P/V. Changes in glucose metabolism contributing to qP were only shown in the higher producer cell line. Non-lethal responses to elevated oxygen transfer and shear stress might be present and must be considered when evaluating CHO cell cultures in shake flasks. [ABSTRACT FROM AUTHOR]

Ohmic cooking is considered a fast and homogeneous process. However, achieving heating uniformity depends on several process parameters and intrinsic product characteristics. Furthermore, reference indicators for evaluating the ohmic process and generating reliable comparisons with conventional cooking are still lacking. The objective of this study was to investigate the reliability of the use of power input and cooking value as process indicators. The results showed that the specific ohmic power did affect only the heating rate but not the heating uniformity and the tissue softening rate. Therefore, the power input as process acceleration tool is not sufficient as stand-alone process indicator because other critical parameters (i.e., electrical conductivity) need to be taken into account to display the complex product-process-interactions. The cooking value was proven to be not valid as indicator for ohmic heating, as it does not take into account additional effects not attributable to only thermal exposure. • The specific ohmic power input affects the heating rate but not the tissue softening rate. • The c-value parameter is insufficient for comparing ohmic and conventional cooking processes. • The application of ohmic cooking reduces processing times. • The use of ohmic heating allows for a reduction of power consumption. [ABSTRACT FROM AUTHOR]

Stirred tank reactors are one of the crucial equipments in the chemical, biochemical, pharmaceutical, and food industries. The design of mechanically agitated vessels contains two main tasks: to find appropriate geometry of the system (such as vessel shape, impeller types, and others) and to choose suitable driving force that would supply required power input for operational conditions reach. The ungassed power input prediction is necessary for the effective industrial design of the engine. The ungassed power input depends on many variables such as tank geometry, used impeller type, and properties of the batch. This work focuses on the influence of the batch composition, impeller type, and impeller diameter on ungassed power consumption. Experiments were performed in laboratory and pilot plant scale vessels while using various operational conditions (such as impeller type, impeller diameter, batch viscosity, and others). Due to a wide range of operational conditions, the obtained results could be transferable to other systems with similar geometry up to industrial conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three models applied to predict ion recovery: kinetics, empirical, and phenomenological. • The phenomenological model showed the best fit to the experimental data. • This model had a high correlation coefficient, indicating its reliability and accuracy. • The developed model can predict the removal rate of both nickel ions and water. Predicting ion flotation performance using appropriate modeling is necessary for process design. Few literature studies have presented a suitable flotation kinetic model for the removal rate of heavy metal ions. This study assesses two empirical kinetic models, one of which is newly developed, and a recently developed phenomenological kinetic model for the prediction of the ion removal rate constant. The models are evaluated against experimental data using parameters such as the effect of power/energy input, bubble size, airflow rate and collector/nickel ratio on nickel ion flotation performance. The k = PS b empirical kinetic model, commonly used in mineral flotation, cannot accurately predict the rate constant for ion flotation as additional parameters are required. The new empirical kinetic model, developed for ion flotation, is better than the k = PS b empirical kinetic model, but there are still some inaccuracies in prediction. The phenomenological kinetic model, developed for mineral flotation, is the most accurate model for predicting ion flotation and requires only one fitted parameter (c 1) at each superficial gas velocity. The correlation coefficients between measured and predicted rate constants for the k = PS b empirical kinetic model, the new empirical kinetic model and the phenomenological kinetic model are 0.773, 0.934, and 0.983 respectively. [ABSTRACT FROM AUTHOR]

• Impact of internals (probes/baffles) on power number for 5 small scale bioreactors with different impeller types. • Improved scaling protocols based on power number to take into account number and size of internals. • A method to estimate the power number of a commercial reactor configurations from an unbaffled one. • Assessment of local flow variation in proximity of a probe for two reactors agitated with a radial and an axial turbine. • Proposal of a novel streamlined geometry for probe sleeves which can reduce power number to values closer to those of unbaffled vessels, which are most commonly used in the scaling process. This study characterises the power requirements and flow patterns in several commercial stirred tank bioreactors with working volumes ranging from 60 mL to 1 L, and investigates the isolated impact of internals, i.e. baffles and probes, on the power number, P 0. Results show that the presence of probes leads to a rise of the turbulent power number, P 0 , equivalent to the presence of baffles, and as the number of internals increases the variation of P 0 gets smaller until it plateaus for large probe quantity and high-volume blockage. Internals have a greater impact on flow with radial flow impellers, causing a significant increase in P 0 in comparison to axial flow impellers. An experimental and computational flow dynamics study is also conducted to investigate the interaction between the probe wake and the impeller trailing vortices, and an estimate is provided of the form drag from the pressure distribution acting on the probe, with a good agreement to the corresponding power number increase. A comparison between P 0 data obtained from conventional-cylindrical and novel-streamlined probe configurations shows that optimising probe geometry and location with respect to the incoming flow can be an effective approach for reducing power requirements, local values energy dissipation rate and stress levelsinside the tank. This study provides valuable insights into the impact of internal components and flow type on power input per unit volume, P / V , in small-scale bioreactors and supports the development of more robust scaling procedures for the biopharma industry. [ABSTRACT FROM AUTHOR]

Effects of processing parameters on the temperature field and axial shortening of linear-friction-welded joint of TC11 and TC17 titanium alloys are investigated by numerical simulation and experimental methods. The 2D model, which is simplified as a rigid body and a deformable body, is built on the basis of the LFW principle by ABAQUS/explicit software. LFW experiments are developed to verify the rationality of the model by measuring the temperature field and axial shortening. The results show that, during the friction phase, the temperature rises linearly with increasing friction time and decreasing axial shortening, heating rates slightly increase with increasing friction pressures and decrease with increasing amplitudes, and cooling rates increase with increasing friction pressures and amplitudes in the forging phase. The unilateral axial shortenings of TC11 and TC17 increase nearly linearly with increasing power input. The appropriate power input for the welded joint is measured to be in the range of 2.4 × 107 to 3.36 × 107 W/m2 based on the tensile properties and fracture morphologies. The corresponding microstructure of the welded zone (WZ) consists of a large number of fine lath martensites α′ on the TC11 side and coarsened β phases with a small amount of precipitations on the TC17 side. [ABSTRACT FROM AUTHOR]

The article is concerned with the issues of the drive of small diameter knitting machines. In connection to the proposal of optimum structure of the driving systems of the machine, there have been analysed the possibilities of precisely controlled servo drives. An optimised structure of the drives allows for the utilisation of precisely defined position and velocity functions. There is applied here the function of a polynomial of 7th degree, proposed for impact-free course of the acceleration, and it is compared with the results corresponding to the existing structure of drives of knitting machines. At the same time, there is analysis and comparison of the consumption of electric power by the original and optimised systems.

The aim was to compare the anthropometrics, biomechanics and energetics in young swimmers of different competitive levels. Seventy-five boys aged between 11 and 13 years-old with a broad range of performances were ranked based on their personal best time in the men’s 100m freestyle event and then split-up into three tiers (Tier-1, i.e., top-tier, best performers; Tier-2, mid-tier; Tier-3, lower-tier). A set of anthropometric features was measured (height, body mass, arm span and trunk transverse surface area). Stroke kinematics (speed, stroke length, stroke frequency) was assessed by a Speedo-meter. Swim efficiency was then estimated (stroke index, speed fluctuation, Froude efficiency). Hydrodynamics assessment encompassed the estimation of active drag and drag coefficient by velocity perturbation method and a set of dimensionless numbers (Froude, hull speed, Reynolds). Mechanical power (to overcome drag, transfer of kinetic energy to water, external power) and power input were derived. There was a significant variation with moderate effect sizes in all anthropometric features but the trunk transverse surface area. Tier-1 swimmers were taller, heavier and with longer limbs than remaining counterparts. There were also significant variations in the stroke kinematics with moderate-large effect sizes. Tier-1 swimmers showed higher stroke frequency, stroke length, speed, stroke index and propelling efficiency but lower speed fluctuations. Reynold number, Froude number and hull speed were significantly higher in Tier-1 swimmers, denoting large effect sizes. The mechanical power and power input delivered were significantly higher in tier-1 swimmers, showing moderate effect sizes. As a conclusion, it was noted significant variations, with moderate-large effect sizes, among the three tiers, for the vast majority of the selected variables. The better performances by tier-1 swimmers were related to their anthropometrics, biomechanics and energetics.

The continued growth and evolving lifestyles of the human population require the urgent development of sustainable production in all its aspects. Microalgae have the potential of the sustainable production of various commodities; however, the energetic requirements of algae cultivation still largely contribute to the overall negative balance of many operation plants. Here, we evaluate energetic efficiency of biomass and lipids production by Chlorella pyrenoidosa in multi-tubular, helical-tubular, and flat-panel airlift pilot scale photobioreactors, placed in an indoor environment of greenhouse laboratory in Central Europe. Our results show that the main energy consumption was related to the maintenance of constant light intensity in the flat-panel photobioreactor and the culture circulation in the helical-tubular photobioreactor. The specific power input ranged between 0.79 W L−1 in the multi-tubular photobioreactor and 6.8 W L−1 in the flat-panel photobioreactor. The construction of multi-tubular photobioreactor allowed for the lowest energy requirements but also predetermined the highest temperature sensitivity and led to a significant reduction of Chlorella productivity in extraordinary warm summers 2018 and 2019. To meet the requirements of sustainable yearlong microalgal production in the context of global change, further development towards hybrid microalgal cultivation systems, combining the advantages of open and closed systems, can be expected.

• Experimental data on impeller power for pilot-plant and laboratory fermenters are presented. • Several impeller types and their combinations are used in the experiments in coalescent batch. • The effect of impeller diameter is experimentally studied for several impeller types. • The correlation shapes are suggested to estimate the impeller power in industrial design. In mechanically agitated gas–liquid contactors design, transport characteristics such as volumetric mass transfer coefficients, power input, and gas hold-up often become the key parameters. Therefore, their values should be estimated as precisely as possible. The power input is usually used as the scale of energy dissipation for other characteristics. The goal of this work is to establish reliable power input correlations for industrial processes design, where the coalescent batch is used. The experiments were carried out in a pilot-plant and laboratory vessel. Different types of impellers, as well as their different diameters, were used, and also the combinations of radially and axially pumping impellers on a common shaft. Energy consumption was measured in a multi-impeller vessel with different impeller frequencies and several gas flows. Correlation equations describing the behavior of individual impellers were evaluated. The correlations we suggested can be used for impeller power prediction in industrial scale vessels under a wide range of operational conditions. [ABSTRACT FROM AUTHOR]