Mode Of Operation Research Articles

Magnetic reduction of gas back-mixing in bubbling fluidized beds with Geldart-B magnetizable particles

This study investigated the performance of magnetic fields in reducing gas back-mixing in bubbling fluidized beds with Geldart-B magnetizable particles. The Peclet number (Pe) and axial dispersion coefficient (Da,g) were determined using the one-dimensional dispersion model. A weak magnetic field reduced gas back-mixing to a certain extent, while a moderate field resulted in minimal decrease. The performance of a strong magnetic field varied significantly depending on the operation mode. Under the magnetization-FIRST operation mode, gas back-mixing was significantly reduced. The corresponding Pe and Da,g were calculated as ∼76 and ∼3.6 × 10−4 m2/s, indicating that the gas flow approached the ideal plug-flow manner. However, when the magnetization-LAST operation mode was used, the strong magnetic field failed to mitigate gas back-mixing. Therefore, the performance of magnetic fields in reducing gas back-mixing depended not only on their intensity but also on their application sequence to the gas flow field.

Multi-User Optimal Load Scheduling of Different Objectives Combined with Multi-Criteria Decision Making for Smart Grid

Load balancing between required power demand and the available generation capacity is the main task of demand response for a smart grid. Matching between the objectives of users and utilities is the main gap that should be addressed in the demand response context. In this paper, a multi-user optimal load scheduling is proposed to benefit both utility companies and users. Different objectives are considered to form a multi-objective artificial hummingbird algorithm (MAHA). The cost of energy consumption, peak of load, and user inconvenience are the main objectives considered in this work. A hybrid multi-criteria decision making method is considered to select the dominance solutions. This approach is based on the removal effects of criteria (MERECs) and is utilized for deriving appropriate weights of various criteria. Next, the Vlse Kriterijumska Optimizacija Kompromisno Resenje (VIKOR) method is used to find the best solution of load scheduling from a set of Pareto front solutions produced by MAHA. Multiple pricing schemes are applied in this work, namely the time of use (ToU) and adaptive consumption level pricing scheme (ACLPS), to test the proposed system with regards to different pricing rates. Furthermore, non-cooperative and cooperative users’ working schemes are considered to overcome the issue of making a new peak load time through shifting the user load from the peak to off-peak period to realize minimum energy cost. The results demonstrate 81% cost savings for the proposed method with the cooperative mode while using ACLPS and 40% savings regarding ToU. Furthermore, the peak saving for the same mode of operation provides about 68% and 64% for ACLPs and ToU, respectively. The finding of this work has been validated against other related contributions to examine the significance of the proposed technique. The analyses in this research have concluded that the presented approach has realized a remarkable saving for the peak power intervals and energy cost while maintaining an acceptable range of the customer inconvenience level.

Significance analysis and evaluation of the impact of a new sustainable ecosystem on the microenvironment of multi-level thermal humidity

Active living walls represent sustainable green technology that improves indoor thermal environment. However, the improvement effect of active living walls in these environments still needs to be further explored, especially with regard to humidity. This study aims to effectively improve the indoor thermal humidity microenvironment of residential buildings, a new sustainable ecosystem (NSES) was developed. NSES integrates plants, spray cooling, and a fan, offering four operation modes, all controlled through intelligent monitoring based on the indoor conditions. Under the working scale of limited space in the microenvironment, evaluating system performance has solved the problem of thermal comfort. In addition, subjective questionnaires are used to evaluate human thermal comfort indicators. The results indicate that (1) Mode 1 exhibits the best performance on the microenvironment throughout the season at a distance of 0.5 m horizontally and 1.1 m vertically from NSES; as the vertical height and horizontal distance increase, performance gradually weakens. (2) Under the conditions of 0.5 m horizontal distance and 1.1 m vertical height, NSES has the best improvement effect on the microenvironment on sunny summer days; an average temperature decrease of 5.6 °C and an average humidity increase of 27.5 % were achieved. (3) NSES can improve human comfort, with thermal comfort zones ranging from 22.4 to 24.3 °C in autumn, and 22.4–23.8 °C in spring. These results highlight the potential value of NSES in improving the microenvironment and enhancing human thermal comfort. This study emphasizes the importance of NSES in appropriately selecting distance, height, season, and climate.

Collaborative Optimization of a Matrix Manufacturing System Based on Overall Equipment Effectiveness

When several traditional flow-shop lines operate in parallel, the operation mode with no communication between production lines will no longer be the optimal production paradigm. This paper describes matrix manufacturing systems (MMS) in a general manner from the perspective of related works, comparing different manufacturing organizational forms and their characteristics. Subsequently, MMS are extracted during the parallel production of multiple surface mount technology (SMT) lines. An overall equipment effectiveness (OEE) online calculation model and a collaborative optimization method are proposed based on the OEE of the MMS. The innovative idea of this study is to divide existing multiple parallel SMT lines into MMS. The efficiency of each matrix unit (MU) was calculated, and a collaborative optimization method was proposed based on an indicator (OEE). In this paper, an example of eight SMT lines is presented. The partitioning of MUs, OEE calculation of each MU, and the low OEE unit collaborative optimization method are described in detail. Through a case study, the architecture of the collaborative optimization model for the MMS was constructed and discussed. Finally, the improvement in the OEE proved the effectiveness and usability of the proposed architecture.

Application of artificial intelligence technologies at substantiation of effective control algorithms for the electrical engineering complex of urban electric transport traction electrical equipment

Background. Studies on the current state and development trends of urban ground public electric transportation in Russia highlight the urgent need for innovative technologies. These innovations should focus on designing and operating new types of rolling stock, traction electrical equipment, and promising types of electric traction. At the same time, special attention should be paid to building autonomous control systems for electric transportation using artificial intelligence technologies. Aim. This study aims to explore the application of neural networks to develop algorithms for effectively controlling the electrical engineering complex of traction electrical equipment in urban ground rail electric transport. Materials and Methods. The research utilized data from studies on the traction electrical equipment modes of rolling stock. These studies were conducted through both computer simulations and field experiments under real operating conditions of urban electric transport using different control algorithms. By applying probability theory and mathematical statistics, the analysis identified the correlations between operational and energy parameters of rolling stock movement and the operational mode of its traction electrical equipment. Results. The identified correlation dependencies informed the design of an effective network architecture, including its size and complexity, as well as the composition of their training samples. This led to the development of an original, simplified algorithm for determining effective control parameters for the electrical complex of traction electrical equipment during the movement of a vehicle on a given section of track. Conclusion. The research concluded that using “simple” neural networks for calculating the parameters of effective control of traction electrical equipment operation modes in urban electric transport provides higher speed and sufficient accuracy compared to complex neural network models. These results are valuable for developers of intelligent control systems for streetcar transportation.

MODELING OF SYSTEMS WITH THE PHOTOVOLTAIC POWER SOURCE AND WATER PUMPS

The article is devoted to the calculation of systems consisting of a solar photovoltaic power source and water pumps. It is noted that such systems can be used both in households or industry, and in agriculture, in particular for irrigation. Several variants of water pumps are shown. An analysis of the operational modes where the photovoltaic power source is connected to the pump has been carried out. The selection of equipment was carried out and the expediency of using a system with an electric energy booster was indicated. A booster for providing current during start-up modes can be a capacitor, a battery of capacitors or an ionistor. Emphasis is placed on the fact that for doing of such systems it is necessary to apply modeling with the use of electrical models. It is shown that for developing of electric models of solenoid-based pumps and pumps based on rotating direct current motors, it is necessary to use the methods of electromechanical analogies. Electrical models of a photovoltaic power source and, based on analogies, a solenoid-based pump and a direct current motor-based pump with permanent magnet excitation and parallel excitation were developed. When developing electrical models, controlled sources of voltage and current were used with mutual influence of the electrical and mechanical parts of the pumps. The need to use direct current motors with parallel excitation is indicated, as they are more stable to emergency modes. It is also stated that in general, the mechanical load of the rotating part of motors is non-linear and depends on the number of revolutions of the shaft. A nonlinear resistance that models a nonlinear mechanical load is shown, and it is noted that the higher-order nonlinearity is insignificant. Conclusions are drawn and further development in the direction of the use of digital technologies is outlined.

Current Profiling Control for Torque Ripple Reduction in the Generating Mode of Operation of a Switched Reluctance Motor Drive

The benefits of utilizing Switched Reluctance Motor (SRM) drives in traction applications can be realized fully by improving the electromagnetic performance of the machine in the generating mode of operation. This is because the generating capability of an SRM drive could be utilized for regenerative braking and also for the machine to generate power for the vehicle while the engine is in operation. In this paper, a current profiling-based control strategy is proposed to reduce the torque ripple in an SRM drive in the generating mode. The reference current profile is determined using a multi-step computation method to minimize torque ripple and maximize the average torque. The reference current profile is derived based on the reference torque command by utilizing the torque–current–angle look up table. The flux linkage characteristics of the SRM are considered when deriving the phase reference current profile. Then, the performance of the proposed profiling method, analytical linear and cubic torque sharing functions (TSFs), and the average torque optimization scheme are compared using simulation results. Finally, an experimental correlation is performed to validate the efficacy of the proposed control scheme.

High current density operation of proton exchange membrane fuel cells at a constant relative humidity

To further reduce the size and cost of proton exchange membrane fuel cells, it is desired to operate at high current densities exceeding 2 A/cm2, and consequently achieve power densities above 1 W/cm2. In a prior one-dimensional modeling study that employed the Engineering Equation Solver (EES), it was suggested that proton exchange membrane fuel cells might operate at current densities as high as 10 A/cm2 and even more when appropriate operating and channel dimensions are chosen, and perforated metal plates are used as porous transport layers instead of carbon fiber papers. The current study verifies the general findings of the previous 1-D model by a 3-D multiphase computational fluid dynamics model in Ansys CFX to obtain additional insights. Operating a proton exchange membrane fuel cell at a constant humidity (100%, 80%, 60%) from the inlet to the outlet at the cathode side appears feasible, and results for a current density above 6 A/cm2 were obtained. This mode of operation is promising also for automotive applications.

High current density operation of proton exchange membrane fuel cells at a constant relative humidity

To further reduce the size and cost of proton exchange membrane fuel cells, it is desired to operate at high current densities exceeding 2 A/cm2, and consequently achieve power densities above 1 W/cm2. In a prior one-dimensional modeling study that employed the Engineering Equation Solver (EES), it was suggested that proton exchange membrane fuel cells might operate at current densities as high as 10 A/cm2 and even more when appropriate operating and channel dimensions are chosen, and perforated metal plates are used as porous transport layers instead of carbon fiber papers. The current study verifies the general findings of the previous 1-D model by a 3-D multiphase computational fluid dynamics model in Ansys CFX to obtain additional insights. Operating a proton exchange membrane fuel cell at a constant humidity (100%, 80%, 60%) from the inlet to the outlet at the cathode side appears feasible, and results for a current density above 6 A/cm2 were obtained. This mode of operation is promising also for automotive applications.

Parametric correction in the control system of the electric propulsion of autonomous underwater vehicles affected by random inputs

The paper deals with the problem of controlling a DC propulsion motor of an autonomous underwater vehicle using a bidirectional non-isolated DC-DC converter. An automatic speed control system with a parametric controller was developed in the Matlab / Simulink package. To reduce energy conversion stages, dc-dc converters are often used to control dc motors AUV. The result of the work is an adaptive control system for the speed of the AUV propeller, which would provide high accuracy for a wide range of speeds and at the same time limit the maximum current and voltage at the armature. The indicators of the quality of performance in various modes of operation were determined, maps of the controller settings were compiled, and parametric correction was introduced. The operation of the system is analyzed and drawbacks are eliminated, such as voltage surges when switching from one speed to another, a decrease in overshoot and settling time. The performance of the system is analyzed under the conditions of random inputs from the propeller. The description of the laboratory stand for the study of the control system is given. A description of the laboratory study of the operation of the "DC converter—engine" system under conditions of random fluctuations in the moments on the motor shaft is given. It is shown that the proposed system has shown itself well under laboratory conditions and the experimental results are consistent with modeling in Matlab / Simulink.

Improved Understanding of PEMFC Stack Durability Testing through Comprehensive In-Situ and Ex-Situ Characterization Techniques

Durability testing of Proton Exchange Membrane Fuel Cells for mobile applications remains a critical challenge. While most academic studies focus on single-cell testing, there are only few publications on stack testing of technical relevant sizes. This study utilizes comprehensive characterization techniques to enhance understanding of PEMFC stack durability, aiming to meet the currently targeted durability targets. A 5,500-hour long-term test, based on the Auto Stack Industry (ASI) test protocol, was performed on a 7-cell short stack of 240 cm² active area. In-situ techniques, such as spatially resolved current density measurement, cyclic voltammetry, and electrochemical impedance spectroscopy, provided real-time degradation insights, while ex-situ methods, including FIB-SEM analysis, infrared thermography or contact angle measurements provided information on material degradation mechanisms. Membrane degradation was found to be negligible. Slight thinning of the cathode indicates carbon corrosion of the catalyst support. Catalyst aging was observed in the form of Pt band formation and Co leaching. Gas diffusion layers showed hydrophobicity loss, and increased resistance in bipolar plates contributed to reduced performance. Our findings demonstrate that PEMFC stacks operated under automotive drive cycle protocols can meet the actual targeted durability objectives. Moreover, it illustrates the degradation phenomena that occur under realistic operating conditions and modes, and how they evolve over the duration of thousands of hours of operation.

Improved Understanding of PEMFC Stack Durability Testing through Comprehensive In-Situ and Ex-Situ Characterization Techniques

Durability testing of Proton Exchange Membrane Fuel Cells for mobile applications remains a critical challenge. While most academic studies focus on single-cell testing, there are only few publications on stack testing of technical relevant sizes. This study utilizes comprehensive characterization techniques to enhance understanding of PEMFC stack durability, aiming to meet the currently targeted durability targets. A 5,500-hour long-term test, based on the Auto Stack Industry (ASI) test protocol, was performed on a 7-cell short stack of 240 cm² active area. In-situ techniques, such as spatially resolved current density measurement, cyclic voltammetry, and electrochemical impedance spectroscopy, provided real-time degradation insights, while ex-situ methods, including FIB-SEM analysis, infrared thermography or contact angle measurements provided information on material degradation mechanisms. Membrane degradation was found to be negligible. Slight thinning of the cathode indicates carbon corrosion of the catalyst support. Catalyst aging was observed in the form of Pt band formation and Co leaching. Gas diffusion layers showed hydrophobicity loss, and increased resistance in bipolar plates contributed to reduced performance. Our findings demonstrate that PEMFC stacks operated under automotive drive cycle protocols can meet the actual targeted durability objectives. Moreover, it illustrates the degradation phenomena that occur under realistic operating conditions and modes, and how they evolve over the duration of thousands of hours of operation.

Quality control of functioning of the structure “object-thermoelectric cooler-heat sink” of the system of providing thermal modes

The analysis of the mathematical model of the system of providing thermal modes with the use of thermoelectric cooling to assess the influence of the conditions of heat exchange of the heat sink with the medium on the main parameters, reliability indicators and dynamic characteristics of a single-cascade thermoelectric cooler at a given temperature level of cooling, medium temperature, geometry of branches of thermoelements for different current operating modes is considered. The results of calculations of the main significant parameters, reliability indicators, dynamic and energy characteristics of a single-cascade cooler and heat sink of the selected design at a given temperature level of cooling, medium temperature, thermal load, geometry of branches of thermoelements for various characteristic current operating modes are given, when the conditions of heat exchange on the heat sink of the given design under variation of the heat transfer coefficient. It is shown that with the increase of air flow velocity on the heat sink the heat transfer coefficient increases and thus the temperature drop on the heat sink of the thermoelectric cooler with the medium decreases, which allows to significantly reduce the relative failure rate of the cooler and thus increase the probability of failure-free operation of the whole device. When operating a system for providing thermal modes comprising a cooling device, a heat sink, and an electric fan used for dissipating heat output to the environment, different modes of operation of the electric fan (air flow rate) can be used. With the increase in air flow rate of the electric fan increases the velocity of air flow in the live section of the heat sink of a given design, which leads to an increase in the heat transfer coefficient. This, in turn, makes it possible to reduce the temperature drop at a given design of the system for ensuring thermal modes. The possibility of control of reliability indicators, namely, relative intensity of failures and probability of failure-free operation of thermal mode systems of different designs (current modes, number of thermocouples, surface area of the heat sink) at a given cooling level (medium temperature, thermal load, geometry of thermocouples) under changing conditions of heat exchange of the heat sink with the medium is considered.

Analysis of Effective Use of Interactive Video in International Chinese Education

With the passage of time, many colleges and universities around the world have set up online classes and integrated the course teaching assistance system into them. With the innovation of science and technology, the use of interactive video in offline teaching is becoming more and more common. By integrating it into the offline learning education system, students’ enthusiasm in class can be significantly improved, and it can also be widely used in international Chinese classes. Therefore, this paper takes international Chinese education as an example. By studying the overall situation of international Chinese classrooms, teachers discuss the operation mode of interactive video in offline teaching, and put forward relevant suggestions, hoping to help international Chinese classroom teachers improve teaching quality and consolidate students’ academic performance. By introducing new teaching concepts, teachers’ teaching methods can be greatly improved, and at the same time, students’ active participation can be promoted, making it easy and practical to conduct a robust assessment of students’ learning progress.

Modeling of the temperature field in the soil massive for different operating modes of the ground source heat pump

The paper considers modeling the influence of the operating modes of the ground source heat pump for heating and air conditioning systems using geothermal source of energy from borehole on the temperature of the soil formation around the borehole with the account of climate conditions of Ukraine. The proposed methodology of modelling of the ground source heat pump with the account of reversible direction of heat flow for heating and cooling work modes contributes to the field of energy system models. The ultimate goals are to obtain criterion dependencies for calculating the operating parameters of a geothermal borehole and to develop a methodology for designing geothermal boreholes taking into account their long-term operation in a cyclic mode. The idea behind the method allows high spatial and temporal resolution as well as the inclusion of the technical details of the power system and formation the temperature of the soil massive around the borehole for the climate conditions of the Ukraine and South-East Regions of Europe. The novelty of this method is the usage of a parametric approach is chosen to analyze different reversible operating modes of the ground source heat pump for heating and cooling. This provides insights on the systematic effects of ground source heat pump operation with regeneration with limitation on reaching negative temperatures at the bottom of the borehole, which can lead to ice formation, an increase in the volume of soil massive during freezing and destruction of pipelines. The article describes the change in the temperature of the soil mass under the operating conditions of a heat pump in two modes - stationary and with alternating "heat supply - cooling (air conditioning)" for long-term operation. Based on the obtained results it was revealed that when a geothermal borehole operates with an alternating direction of heat flow (with regeneration), the long-term consequences of operation associated with the deviation of the soil massive temperature from the background value are reduced. The additional novelty aspect of modelling was obtained for the operating parameters of a geothermal source of energy with the account of longterm reversible operating mode of the heat pump. The energy balance model is well suited for the analysis of temperature in the bottom part of the geothermal boreholes was revealed for heating and air conditioning systems due to the non-stationary thermal loads determined by climatic conditions of the Ukraine and South-East Regions of Europe. The obtained results may serve as a new approach to optimization technical and economic indicators of geothermal boreholes during operation of the ground source heat pump operating with the account of reversible direction of heat flow for heating and cooling work modes to have continuous improvement of energy efficiency

Model of the non-stationary thermal processes in the ground heat pump system

One of the main directions for improving heat supply systems is the tendency to switch to low-temperature heating systems by using heat pump units is the tendency of implementation the low-temperature heating systems based on the use of heat pump units. In the work, the main attention is focused on the improvement of thermal parameters and circuit design features of elements of the heat pump system of heat supply using soil energy. For this purpose, the toolkit of mathematical modelling of processes in ground heat pumps is applied, taking into account the climatic conditions of Ukraine. The paper proves the technical possibility of creating an autonomous system of alternative heat supply for energy-saving technologies with the possibility of using ground energy, taking into account environmental requirements. It is substantiated that the use of the proposed systems is a promising direction for Ukraine, which is experiencing a shortage of its own energy resources, because it provides an opportunity to increase the share of organic fuel substitution and reduce the volume of heat emissions into the environment. A mathematical model of heat processes in the elements of the heat exchange equipment of the heat pump system based on renewable energy (soil energy) and secondary energy (wastewater) was developed, taking into account environmental requirements (preventing hypothermia of the soil during the operation of soil pipes and damage to vegetation, respectively), which allows choosing a rational mode of operation of the system under seasonal climatic changes and technological conditions. Numerical modelling of heat processes in elements of the heat exchange equipment of the heat pump system using groundwater and waste water was performed, and the energy and environmental efficiency of the system under variable climatic and technological factors was determined. Analysis and generalization of the calculation results of the heat pump heat supply systems using alternative energy based on the proposed mathematical model, taking into account environmental requirements (preventing thermal relaxation of the soil) allows to take into account the change in the temperature gradient around the soil heat exchanger and more accurately determine the heat flow from each section of the heat exchanger. It has been established that for heat pumps with soil heat exchangers, the maximum substitution ratio of the traditional fuel is 75 %, and the economically feasible quantity of soil heat exchangers is 9 units. Heat pumps using waste water can completely replace traditional heat supply systems. For individual consumers, it is possible to recommend heat pump units with soil heat exchangers, at the same time, it is necessary to provide a backup source of energy to increase the reliability of heat supply.

The fate of severe acute respiratory syndrome coronavirus-2 and pepper mild mottle virus at various stages of wastewater treatment process

This study investigated the efficiency of the treatment processes of wastewater treatment plants (WWTPs) to remove severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and pepper mild mottle virus (PMMoV) from the wastewater and sewage sludge, as well as the influence of the mode of operation on the quality of the treated wastewater. SARS-CoV-2 and PMMoV were detected and quantified at different stages of the wastewater and sludge treatment process of three major WWTPs in Stockholm, Sweden. The results showed that primary, biological, and advanced membrane treatment processes are effective in removing SARS-CoV-2 from the wastewater with removal efficiencies of 99–100 % for all WWTPs, while the virus was accumulated in the primary and waste-activated sludges due to higher affinity to biosolids. Operation strategies such as bypass reintroduced the virus into the treated wastewater. The WWTPs achieved relatively low PMMoV removal efficiencies (63–87 %) most probably due to the robust capsid structure of the virus. Anaerobic digestion could not completely remove SARS-CoV-2 and PMMoV from the sludge leading to increased levels of SARS-CoV-2 and PMMoV in dewatered sludge. The study gives an overview of WWTPs’ role in tackling pathogen spread in society in the event of a pandemic and disease breakout.

Digital Migration Infrastructure in return-writing: visualizing the migration landscape of India.

Digitization has carved out the migration patterns of immigrants over the recent years of increased technological interventions in human mobility. Migration infrastructures, which typically refer to the physical, commercial, humanitarian, and governmental modes of operation, are multidimensional in nature. Digital infrastructures are equally important to the physical ones as digital technologies facilitate these migration processes through agents like hardware, software, and mediating actors. Amongst the multiple forms of migration, the concept of return-writing and nostalgia-struck-returnees encompass individuals whose life trajectories run parallel to the homeland. The narrative of return to the homeland emerges aβs a dominant motif in literature due to the rising trends of globalization, the writers' reflection on their own migrant experiences, and publishing trends meeting the demand of the global book market. The objective is to assess the role of digital migration infrastructures in return migrations to India through a close reading of the selected texts and review of postcolonial literary theories by using conditional operation in Python. The study here explores the varied nuances of return migration with a primary focus on the external conditions of travel in migration literature. The paper aims to analyze the genre of return-writing in Indian English literature, through three novels over a period of two decades, i.e., from 2000-2023. The selected texts, beginning with Amit Chaudhuri's A New World (2000), Gun Island (2019) by Amitav Ghosh, and Devika Rege's novel Quarterlife (2023), offer a panoramic view of return migration. These novels are extensive in the time period of technological interventions and in depiction of return migration. The Python code examines the extent of existence of a set of digital migration infrastructure keywords by analyzing the content of the novels and creates bar plots and charts to offer a visual representation of the classification results. The resulting trend traces the increased intervention of Digital Migration Infrastructure in the recent migration literature.

The patterns of changes in the degree of lubrication of the crankshaft bearings of car engines depending on the parameters of the load-speed modes of operation

The practice of operating machines and mechanisms indicates that bearing wear is one of the main reasons for limiting their durability. This especially applies to the sliding bearings of crankshafts of car engines, where the intensity of wear of their working surfaces significantly depends on the properties of the lubricant. An experimental study of the wear resistance of the sliding bearings of the crankshafts of car engines was carried out on the KI-5543 model break-in and braking stand. In experimental studies, BELZONA Super E-Metal insulating material was used to provide electrical isolation of the main and connecting rod bearings of the crankshaft from the cylinder block of the car engine. The experimental dependencies of the values of the criteria characterizing the degree of lubrication of the friction surfaces on the parameters of the load-speed modes (the moment of the applied force and the frequency of rotation of the crankshaft) were obtained. The ranges of values of the investigated parameters, in which the effective operation of the sliding bearings of the crankshaft of car engines is implemented, have been revealed.

Kinetic-free sizing criterion for the thermally controlled scale-up of batch fine-chemical processes

A number of newly developed exothermic reactions of the fine-chemical industry can be safely tested at the industrial scale in an existing batch reactor since they cannot lead to dangerous reactor overpressures even under adiabatic conditions. However, when the process is scaled from a laboratory to an industrial reactor, the normal decrease of the heat transfer efficiency per unit volume can be so relevant that at the industrial scale the process cannot be thermally controlled, leading to a lower and less reproducible quality of the final product. In these cases, the industrial reactor must be equipped with an external heat transfer surface in addition to that provided by the reactor jacket only. The sizing of such an additional surface through conventional tools requires the knowledge of the heat release rate in the recommended temperature range and hence of the system kinetic behavior, which is often a missing information in the fine-chemical industry due to the fragmentation of the involved processes. In this work, a kinetic-free sizing criterion is presented for the temperature-controlled scale-up of intrinsically safe exothermic reactions carried out in the batch mode of operation, allowing for a simple and general estimation of the required heat transfer surface at the industrial scale from the analysis of the pseudo-adiabatic temperature trends measured during the original industrial batches. The proposed methodology has been validated using a set of process information about the final nitration step for the synthesis of an API as well as industrial-scale data collected during the scale-up of a water-in-oil emulsion polymerization for the synthesis of a polycationic thickener used in the cosmetic industry.