13 pages, 3033 KiB  
Article
Experimental and Discrete Element Model Investigation of Limestone Aggregate Blending Process in Vertical Static and/or Conveyor Mixer for Application in the Concrete Mixture
by Lato L. Pezo, Milada Pezo, Anja Terzić, Aca P. Jovanović, Biljana Lončar, Dragan Govedarica and Predrag Kojić
Processes 2021, 9(11), 1991; https://doi.org/10.3390/pr9111991 - 8 Nov 2021
Cited by 3 | Viewed by 2381
Abstract
The numerical model of the granular flow within an aggregate mixture, conducted in the vertical static and/or the conveyor blender, was explored using the discrete element method (DEM) approach. The blending quality of limestone fine aggregate fractions binary mixture for application in self-compacting [...] Read more.
The numerical model of the granular flow within an aggregate mixture, conducted in the vertical static and/or the conveyor blender, was explored using the discrete element method (DEM) approach. The blending quality of limestone fine aggregate fractions binary mixture for application in self-compacting concrete was studied. The potential of augmenting the conveyor mixer working efficiency by joining its operation to a Komax-type vertical static mixer, to increase the blending conduct was investigated. In addition the impact of the feed height on the flow field in the cone-shaped conveyor mixer was examined using the DEM simulation. Applying the numerical approach enabled a deeper insight into the quality of blending actions, while the relative standard deviation criteria ranked the uniformity of the mixture. The primary objective of this investigation was to examine the behavior of mixture for two types of blenders and to estimate the combined blending action of these two mixers, to explore the potential to augment the homogeneity of the aggregate fractions binary mixture, i.e., mixing quality, reduce the blending time and to abbreviate the energy-consuming. Full article
(This article belongs to the Special Issue DEM Simulations and Modelling of Granular Materials)
Show Figures

Graphical abstract

16 pages, 919 KiB  
Article
Multi-Rate Data Fusion for State and Parameter Estimation in (Bio-)Chemical Process Engineering
by Robert Dürr, Stefanie Duvigneau, Carsten Seidel, Achim Kienle and Andreas Bück
Processes 2021, 9(11), 1990; https://doi.org/10.3390/pr9111990 - 8 Nov 2021
Cited by 2 | Viewed by 2042
Abstract
For efficient operation, modern control approaches for biochemical process engineering require information on the states of the process such as temperature, humidity or chemical composition. Those measurement are gathered from a set of sensors which differ with respect to sampling rates and measurement [...] Read more.
For efficient operation, modern control approaches for biochemical process engineering require information on the states of the process such as temperature, humidity or chemical composition. Those measurement are gathered from a set of sensors which differ with respect to sampling rates and measurement quality. Furthermore, for biochemical processes in particular, analysis of physical samples is necessary, e.g., to infer cellular composition resulting in delayed information. As an alternative for the use of this delayed measurement for control, so-called soft-sensor approaches can be used to fuse delayed multirate measurements with the help of a mathematical process model and provide information on the current state of the process. In this manuscript we present a complete methodology based on cascaded unscented Kalman filters for state estimation from delayed and multi-rate measurements. The approach is demonstrated for two examples, an exothermic chemical reactor and a recently developed model for biopolymer production. The results indicate that the the current state of the systems can be accurately reconstructed and therefore represent a promising tool for further application in advanced model-based control not only of the considered processes but also of related processes. Full article
(This article belongs to the Section Process Control and Monitoring)
Show Figures

Figure 1

16 pages, 3126 KiB  
Article
Functional Ingredients and Food Preservative in Immature Persimmon “Tekka-Kaki”
by Akiyoshi Sawabe, Natsumi Ohnishi, Sachiko Yoshioka, Kunihiro Kusudo, Kenichi Kanno and Yoshiyuki Watanabe
Processes 2021, 9(11), 1989; https://doi.org/10.3390/pr9111989 - 8 Nov 2021
Cited by 4 | Viewed by 2820
Abstract
Immature persimmons are unripe fruits that are cut off during the persimmon cultivation process and immediately discarded, amounting to an annual fruit loss of approximately 100 to 400 kg per 1000 m2. The purpose of this study was to make effective [...] Read more.
Immature persimmons are unripe fruits that are cut off during the persimmon cultivation process and immediately discarded, amounting to an annual fruit loss of approximately 100 to 400 kg per 1000 m2. The purpose of this study was to make effective use of unused resources, namely, immature persimmons, and attempt to use them as food additives. In this study, we studied the Tone Wase (fully astringent persimmon) and Fuyu (fully sweet persimmon) cultivars. As a result, we performed a component analysis of the immature persimmons, isolating 12 compounds, of which two were newly identified. Differences in the components and their contents were found between cultivars and between the peel and flesh. To effectively use immature persimmons as food for the elderly, we searched for active substances that inhibit AGE formation and found that extracts of immature persimmons and isolated compounds showed high activity. In particular, high activity was observed for catechin and its polymeric form, procyanidin. Regarding the inhibition of aroma deterioration, 5 mg/L of gallic acid in octadecane was found to be the optimal condition for the inhibition of citral deterioration. As for antimicrobial activity, we found that extracts at a concentration of 500 mg/L had no antimicrobial effect. Based on these findings, we made a microencapsulation process, and plan to advance to the clinical trial study in future. These findings confirmed the effectiveness of immature persimmons, which are an unused resource, and reveal their potential as a food for the elderly and as a food additive in other food products, which we hope will lead to new industrial innovations. Full article
(This article belongs to the Special Issue Plants as Functional Food Ingredients and Food Preservative)
Show Figures

Figure 1

13 pages, 4345 KiB  
Article
Asymmetric Flow Control in a Slab Mold through a New Type of Electromagnetic Field Arrangement
by Yanming Bao, Zhuang Li, Lintao Zhang, Junxia Wu, Danzhu Ma and Fengrui Jia
Processes 2021, 9(11), 1988; https://doi.org/10.3390/pr9111988 - 8 Nov 2021
Cited by 5 | Viewed by 1989
Abstract
This research aims to investigate the control effect of asymmetric flow in a slab mold using a novel magnetic field arrangement: freestanding adjustable combination electromagnetic brake (FAC-EMBr). Three scenarios (submerged entry nozzle moves to the narrow face, wide face of the slab mold, [...] Read more.
This research aims to investigate the control effect of asymmetric flow in a slab mold using a novel magnetic field arrangement: freestanding adjustable combination electromagnetic brake (FAC-EMBr). Three scenarios (submerged entry nozzle moves to the narrow face, wide face of the slab mold, and rotates 10°) were studied using three-dimensional numerical simulation. The results show that the magnetic field generated by the FAC-EMBr system can effectively cover three key zones in mold and that the magnetic flux density in the zone cover by a vertical magnetic pole can be adjusted according to the actual flow condition. The FAC-EMBr can effectively improve the asymmetric flow in a mold and near the narrow surface caused by the asymmetric arrangement of the nozzle and can effectively inhibit the occurrence of the flow deviation phenomenon and stabilize the steel/slag interface fluctuation. At the same time, FAC-EMBr has obvious inhibition effects on the surface velocity and can optimize the asymmetric distribution of the surface velocity and the upper reflux velocity caused by the asymmetric arrangement of the nozzle. This study can provide theoretical evidence for the development and utilization of a new electromagnetic brake technology. Full article
(This article belongs to the Section Process Control and Monitoring)
Show Figures

Figure 1

16 pages, 6892 KiB  
Article
Real-Time Dynamic Carbon Content Prediction Model for Second Blowing Stage in BOF Based on CBR and LSTM
by Maoqiang Gu, Anjun Xu, Hongbing Wang and Zhitong Wang
Processes 2021, 9(11), 1987; https://doi.org/10.3390/pr9111987 - 8 Nov 2021
Cited by 22 | Viewed by 2509
Abstract
The endpoint carbon content is an important target of converters. The precise prediction of carbon content is the key to endpoint control in converter steelmaking. In this study, a real-time dynamic prediction of the carbon content model for the second-blowing stage of the [...] Read more.
The endpoint carbon content is an important target of converters. The precise prediction of carbon content is the key to endpoint control in converter steelmaking. In this study, a real-time dynamic prediction of the carbon content model for the second-blowing stage of the converter steelmaking process was proposed. First, a case-based reasoning (CBR) algorithm was used to retrieve similar historical cases and their corresponding process parameters in the second blowing stage, based on the process parameters of the new case in the main blowing stage. Next, a long short-term memory (LSTM) model was trained by using process parameters of similar cases from the previous moment as the input and the carbon content for the next moment as the output. Finally, the process parameters of the new case were input into the trained LSTM model to produce a real-time dynamic prediction of the carbon content in the second blowing stage. Actual production data were used for the verification, and the results showed that the prediction errors of the proposed model within the ranges of (−0.005, 0.005), (−0.010, 0.010), (−0.015, 0.015) and (−0.020, 0.020) were 25%, 54%, 71%, and 91% respectively, which were higher than the prediction accuracies of the traditional carbon integral model, cubic model, and exponential model. Full article
(This article belongs to the Section AI-Enabled Process Engineering)
Show Figures

Figure 1

11 pages, 2176 KiB  
Article
Analysis on the Leakage of the Flange Connection of the Water-Containing Hydrofluoric Acid Pipeline
by Kun Lu, Junhua Dong, Aoqing Zhang and Bingjun Gao
Processes 2021, 9(11), 1986; https://doi.org/10.3390/pr9111986 - 8 Nov 2021
Cited by 2 | Viewed by 3122
Abstract
Leakages of bolted pipe flange connections of water-containing hydrofluoric acid pipelines were frequently reported by the extraction section in the fluorine chemical industry. Water-containing hydrofluoric acid can cause severe injuries to human beings due to its strong causticity. The water-containing hydrofluoric acid pipe [...] Read more.
Leakages of bolted pipe flange connections of water-containing hydrofluoric acid pipelines were frequently reported by the extraction section in the fluorine chemical industry. Water-containing hydrofluoric acid can cause severe injuries to human beings due to its strong causticity. The water-containing hydrofluoric acid pipe was a short lined pipe, so a lot of flange connections and supports were adopted in the pipeline. In this paper, the finite element models of the pipeline were established to analyze the internal force of the pipeline under conditions including internal pressure, temperature, self-weight, and so on. Based on this, the equivalent design pressure of the flange connections was determined. The results of the stress analyses of the pipeline showed that leakages were mainly caused by a large bending moment, due to the unreasonable layout of the piping supports under self-weight. When the pipeline was supported on the beam of the pipe gallery, which is not necessarily beneficial to reduce the bending moment of the pipeline, and the flange connection was close to the supporting beam at the same time, leakages frequently occurred in this flange connection. To support the pipeline reasonably, the flange connection should be placed at zero bending moment positions. Therefore, the positions with zero bending moments of the pipeline with equal and unequal spacing supports were obtained under gravity load, to provide a basis for the rational support of lining piping. Full article
(This article belongs to the Special Issue Recent Advances in Chemical Process Safety)
Show Figures

Figure 1

18 pages, 2785 KiB  
Article
Channel Structure Choice for Remanufacturing under Green Consumerism
by Hong Tan, Guohua Cao, Yu He and Yujia Lu
Processes 2021, 9(11), 1985; https://doi.org/10.3390/pr9111985 - 7 Nov 2021
Cited by 8 | Viewed by 2474
Abstract
In recent decades, more and more consumers—referred to as “green consumers”—are willing to incorporate environmentally responsible decisions into their purchasing behaviors. This tendency is particularly notable in the European Union, the USA, and China. From a research perspective, while recent studies on remanufacturing [...] Read more.
In recent decades, more and more consumers—referred to as “green consumers”—are willing to incorporate environmentally responsible decisions into their purchasing behaviors. This tendency is particularly notable in the European Union, the USA, and China. From a research perspective, while recent studies on remanufacturing have investigated optimal practices in regard to green consumerism, they have failed to address the flexibility manufacturers are afforded to outsource remanufacturing operations to third parties. In practice, some brand-name manufacturers—such as IBM, Land Rover, and Sun—do indeed outsource their remanufacturing operations. To further our understanding of the implications of differentiated structures for remanufacturing operations under green consumerism, we developed two models: one for a manufacturer undertaking remanufacturing themselves (Model M), and one for a manufacturer outsourcing it to a third-party remanufacturer (Model O). Our results indicate that, for markets with significant green consumerism, Model M tends to result in more remanufactured units and creates higher profitability for the manufacturer. However, under certain conditions, this model may also result in greater harm to the environment due to the comparative excess of manufacturers in the remanufacturing process. This implies that environmental groups and agencies should not only aim to encourage green consumerism, but should also focus their attention on the channel structures for remanufacturing. Full article
(This article belongs to the Special Issue Advances in Green Manufacturing and Optimization)
Show Figures

Figure 1

23 pages, 6839 KiB  
Article
Effects of Different Biodiesel-Diesel Blend Fuel on Combustion and Emission Characteristics of a Diesel Engine
by Yanhui Zhang, Yunhao Zhong, Jie Wang, Dongli Tan, Zhiqing Zhang and Dayong Yang
Processes 2021, 9(11), 1984; https://doi.org/10.3390/pr9111984 - 7 Nov 2021
Cited by 51 | Viewed by 6697
Abstract
In this paper, biodiesel was used as an alternative fuel to investigate the combustion and emission characteristics of a four-stroke diesel engine, in terms of cylinder pressure, heat release rate, cylinder temperature, brake thermal efficiency, brake specific fuel consumption, nitrogen oxide, soot, carbon [...] Read more.
In this paper, biodiesel was used as an alternative fuel to investigate the combustion and emission characteristics of a four-stroke diesel engine, in terms of cylinder pressure, heat release rate, cylinder temperature, brake thermal efficiency, brake specific fuel consumption, nitrogen oxide, soot, carbon monoxide, and hydrocarbon. Firstly, a diesel engine cylinder model was developed by AVL-Fire software coupled with CHEMKIN code to simulate the injection and combustion of biodiesel with a kinetic mechanism with 106 species and 263 reactions. Then, the simulation model was validated by experimental results under 100% and 50% load conditions and used to simulate the combustion process of a diesel engine fueled with pure diesel, biodiesel, and biodiesel–diesel blends with 10%, 20%, 30% biodiesel by volume, respectively. The results showed that the brake specific fuel consumption increased with the increase of mixed biodiesel ratio. The brake specific fuel consumptions of B10, B20 and B30 increased by 1.1%, 2.3% and 3.3%, respectively, compared with that of D100. The combustion and emission characteristics of the diesel engine are improved. Therefore, biodiesel can be used as an alternative fuel for the diesel engine. The diesel–biodiesel fuel can improve the combustion and emission characteristics of the diesel engine. Full article
(This article belongs to the Special Issue Clean Combustion and Emission in Vehicle Power System)
Show Figures

Figure 1

11 pages, 1693 KiB  
Article
In Silico Assessment and Molecular Docking Studies of Some Phyto-Triterpenoid for Potential Disruption of Mortalin-p53 Interaction
by Minh Quan Pham, Thuy Huong Le Thi, Quoc Long Pham, Le Thi Le, Huy Toan Dao, Thanh Le Thi Dang, Dung Thuy Nguyen Pham and Hai Ha Pham Thi
Processes 2021, 9(11), 1983; https://doi.org/10.3390/pr9111983 - 7 Nov 2021
Cited by 3 | Viewed by 3202
Abstract
Human hepatocellular carcinoma (HCC), the most common type of liver cancer, represents the second most common cause of death from cancer worldwide. The high toxicity and side effects of some cancer chemotherapy drugs increase the demand for new anti-cancer drugs from natural products. [...] Read more.
Human hepatocellular carcinoma (HCC), the most common type of liver cancer, represents the second most common cause of death from cancer worldwide. The high toxicity and side effects of some cancer chemotherapy drugs increase the demand for new anti-cancer drugs from natural products. Mortalin/mtHsp70, a stress response protein, has been reported to contribute to the process of carcinogenesis in several ways, including the inhibition of the transcriptional activation of p53. This study conducted a molecular docking study of 41 phyto triterpenes originated from Vietnamese plants for potential Mortalin inhibition activity. Nine compounds were considered as promising inhibitors based on the analysis of binding affinity and drug-like and pharmacokinetic properties. Full article
Show Figures

Figure 1

22 pages, 2628 KiB  
Review
Immunological Analytical Techniques for Cosmetics Quality Control and Process Monitoring
by Martina Zangheri, Maria Maddalena Calabretta, Donato Calabria, Jessica Fiori, Massimo Guardigli, Elisa Michelini, Sonia Melandri, Assimo Maris, Mara Mirasoli and Luca Evangelisti
Processes 2021, 9(11), 1982; https://doi.org/10.3390/pr9111982 - 6 Nov 2021
Cited by 8 | Viewed by 4151
Abstract
Cosmetics analysis represents a rapidly expanding field of analytical chemistry as new cosmetic formulations are increasingly in demand on the market and the ingredients required for their production are constantly evolving. Each country applies strict legislation regarding substances in the final product that [...] Read more.
Cosmetics analysis represents a rapidly expanding field of analytical chemistry as new cosmetic formulations are increasingly in demand on the market and the ingredients required for their production are constantly evolving. Each country applies strict legislation regarding substances in the final product that must be prohibited or regulated. To verify the compliance of cosmetics with current regulations, official analytical methods are available to reveal and quantitatively determine the analytes of interest. However, since ingredients, and the lists of regulated/prohibited substances, rapidly change, dedicated analytical methods must be developed ad hoc to fulfill the new requirements. Research focuses on finding innovative techniques that allow a rapid, inexpensive, and sensitive detection of the target analytes in cosmetics. Among the different methods proposed, immunological techniques are gaining interest, as they make it possible to carry out low-cost analyses on raw materials and finished products in a relatively short time. Indeed, immunoassays are based on the specific and selective antibody/antigen reaction, and they have been extensively applied for clinical diagnostic, alimentary quality control and environmental security purposes, and even for routine analysis. Since the complexity and variability of the matrices, as well as the great variety of compounds present in cosmetics, are analogous with those from food sources, immunological methods could also be applied successfully in this field. Indeed, this would provide a valid approach for the monitoring of industrial production chains even in developing countries, which are currently the greatest producers of cosmetics and the major exporters of raw materials. This review aims to highlight the immunological techniques proposed for cosmetics analysis, focusing on the detection of prohibited/regulated compounds, bacteria and toxins, and allergenic substances, and the identification of counterfeits. Full article
(This article belongs to the Special Issue Feature Review Papers in Advanced Process Systems Engineering)
Show Figures

Figure 1

19 pages, 1424 KiB  
Article
Wastewater Treatment Plants as Local Thermal Power Stations—Modifying Internal Heat Supply for Covering External Heat Demand
by Florian Kretschmer, Bernd Hrdy, Georg Neugebauer and Gernot Stoeglehner
Processes 2021, 9(11), 1981; https://doi.org/10.3390/pr9111981 - 6 Nov 2021
Cited by 10 | Viewed by 3925
Abstract
To counteract climate change, the application of renewable energy sources and their efficient use are of crucial importance. In this context, wastewater has also gained increased attention in recent years. For decades, wastewater treatment plants have applied the heat from digester gas combustion [...] Read more.
To counteract climate change, the application of renewable energy sources and their efficient use are of crucial importance. In this context, wastewater has also gained increased attention in recent years. For decades, wastewater treatment plants have applied the heat from digester gas combustion to supply internal demands. However, in the context of efficient energy use the question arises: can using high temperature heat for supplying low temperature demand still be considered the best option? This article presents an innovative approach to covering wastewater treatment plant (WWTP) internal demand with low temperature wastewater heat recovery, making thermal energy from digester gas combustion available for feed-in to a local high temperature district heating network. The presented feasibility study was carried out in an Austrian municipality and investigates the heat balance, the economic risk, climatic benefits and the social aspects of the suggested approach. The practical implementation of the novel approach was planned in two steps. First, the WWTP should be connected to the district heating network to enable the feed-in of excess heat. Second, the WWTP internal heat supply should be modified and based on wastewater heat recovery from the effluent. Due to the promising results of the feasibility study, the first step was realized in summer 2020. The second and final step was initiated in 2021. Full article
(This article belongs to the Special Issue Renewable Energy in Environmental Engineering)
Show Figures

Graphical abstract

20 pages, 2485 KiB  
Article
Parallel Implementation of the Deterministic Ensemble Kalman Filter for Reservoir History Matching
by Lihua Shen, Hui Liu and Zhangxin Chen
Processes 2021, 9(11), 1980; https://doi.org/10.3390/pr9111980 - 6 Nov 2021
Cited by 2 | Viewed by 2360
Abstract
In this paper, the deterministic ensemble Kalman filter is implemented with a parallel technique of the message passing interface based on our in-house black oil simulator. The implementation is separated into two cases: (1) the ensemble size is greater than the processor number [...] Read more.
In this paper, the deterministic ensemble Kalman filter is implemented with a parallel technique of the message passing interface based on our in-house black oil simulator. The implementation is separated into two cases: (1) the ensemble size is greater than the processor number and (2) the ensemble size is smaller than or equal to the processor number. Numerical experiments for estimations of three-phase relative permeabilities represented by power-law models with both known endpoints and unknown endpoints are presented. It is shown that with known endpoints, good estimations can be obtained. With unknown endpoints, good estimations can still be obtained using more observations and a larger ensemble size. Computational time is reported to show that the run time is greatly reduced with more CPU cores. The MPI speedup is over 70% for a small ensemble size and 77% for a large ensemble size with up to 640 CPU cores. Full article
(This article belongs to the Special Issue New Challenges in Advanced Process Control in Petroleum Engineering)
Show Figures

Figure 1

19 pages, 7520 KiB  
Article
Resonance Analysis and Vibration Reduction Optimization of Agricultural Machinery Frame—Taking Vegetable Precision Seeder as an Example
by Jinwu Wang, Changsu Xu, Yanan Xu, Jinfeng Wang, Wenqi Zhou, Qi Wang and Han Tang
Processes 2021, 9(11), 1979; https://doi.org/10.3390/pr9111979 - 5 Nov 2021
Cited by 9 | Viewed by 2834
Abstract
In order to solve the problem of vigorous vibration of agricultural machinery frames, taking a vegetable precision seeder as an example, the concept of vibration reduction was proposed. The modal analysis of the frame was carried out, and the accuracy of the finite [...] Read more.
In order to solve the problem of vigorous vibration of agricultural machinery frames, taking a vegetable precision seeder as an example, the concept of vibration reduction was proposed. The modal analysis of the frame was carried out, and the accuracy of the finite element model was verified by comparing the modal test of multipoint input and multipoint output (MIMO) and simulation results. Additionally, the main frequency of engine vibration was the main excitation source of frame resonance. According to the modal shapes, it was proposed to increase the fixed beam structure and to carry out simulation tests. The time-domain signal of the maximum deformation position in the first-order vibration mode was measured, and the vibration spectrum analysis maps before and after optimization were obtained by Fourier transform. A field experiment showed that the seeding quality of the whole machine was significantly improved after optimization. This study provides a reference for the analysis of vibration characteristics and the vibration reduction design of the agricultural machinery equipment. Full article
(This article belongs to the Special Issue Numerical Simulation of Nonlinear Dynamical Systems)
Show Figures

Figure 1

12 pages, 2936 KiB  
Article
The Biological Effects of Ozone Gas on Soft and Hard Dental Tissues and the Impact on Human Gingival Fibroblasts and Gingival Keratinocytes
by Alin Daniel Floare, Alexandra Denisa Scurtu, Octavia Iulia Balean, Doina Chioran, Roxana Buzatu, Ruxandra Sava Rosianu, Vlad Tiberiu Alexa, Daniela Jumanca, Laura-Cristina Rusu, Robert Cosmin Racea, Dorina Coricovac, Iulia Pinzaru, Cristina Adriana Dehelean and Atena Galuscan
Processes 2021, 9(11), 1978; https://doi.org/10.3390/pr9111978 - 5 Nov 2021
Cited by 7 | Viewed by 3372
Abstract
Ozone is an allotropic form of oxygen, so in the medical field ozone therapy has special effects. Starting from the premise that bio-oxidative ozone therapy reduces the number of bacteria, in the present study two approaches were proposed: to evaluate the biological effects [...] Read more.
Ozone is an allotropic form of oxygen, so in the medical field ozone therapy has special effects. Starting from the premise that bio-oxidative ozone therapy reduces the number of bacteria, in the present study two approaches were proposed: to evaluate the biological effects of ozone gas on the tooth enamel remineralization process and to demonstrate its impact on the morphology and confluence of human primary gingival cells, namely keratinocytes (PGK) and fibroblasts (HGF). The ozone produced by HealOzone was applied in vivo to 68 M1s (first permanent molars), both maxillary and mandibular, on the occlusal surfaces at pit and fissure. The molars included in the study recorded values between 13 and 24 according to the DIAGNOdent Pen 2190 scale, this being the main inclusion/exclusion criterion for the investigated molars. Because the gas can make contact with primary gingival cells during the ozonation process, both human gingival fibroblasts and keratinocytes were exposed to different doses of ozone (20 s, 40 s, 60 s), and its effects were observed with the Olympus IX73 inverted microscope. The contact of ozone with the human primary gingival cells demonstrates cell sensitivity to the action of ozone, this being higher in fibroblasts compared to keratinocytes, but it is not considered toxic because all the changes are reversible at 48 h after exposure. Full article
(This article belongs to the Special Issue Basic, Biological and Therapeutic Processes of Ozone Therapy)
Show Figures

Figure 1

19 pages, 5590 KiB  
Article
Experimental Research of High-Pressure Methane Pulse Jet and Premixed Ignition Combustion Performance of a Direct Injection Injector
by Shenggang Guo, Yan Lei, Xiaofeng Wang, Tao Qiu, Bin Pang, Lei Shi and Xuehui An
Processes 2021, 9(11), 1977; https://doi.org/10.3390/pr9111977 - 5 Nov 2021
Cited by 1 | Viewed by 2216
Abstract
Natural gas (NG) direct injection (DI) technology benefits the engine with high efficiency and clean emissions, and the high-pressure gas fuel injection process causes crucial effects on the combustion. This study presents an optical experimental investigation on the high-pressure methane single-hole direct injection [...] Read more.
Natural gas (NG) direct injection (DI) technology benefits the engine with high efficiency and clean emissions, and the high-pressure gas fuel injection process causes crucial effects on the combustion. This study presents an optical experimental investigation on the high-pressure methane single-hole direct injection and premixed ignition combustion based on a visualization cuboid constant volume bomb (CVB) test rig. The experimental results show that the methane jet process is divided into two stages. The methane gas jet travels at a faster speed during the unstable stage I than that during the stable stage II. The injection pressure causes more influence on both the jet penetration distance and the jet cone area during stage II. The methane jet premixed flame is a stable flame with a nearly spherical shape, and its equivalent radius linearly increases. The methane jet premixed flame area also increases while the flame stretch rate declines. The methane jet premixed flame velocity rises as both the standing time and equivalent ratio increase. The methane jet premixed flame is a partial premixed flame, and the peak of the methane jet premixed flame occurs at greater equivalence ratio ϕ, i.e., ϕ > 2. As the injection pressure rises, the jet premixed flame equivalent radius increases, and the flame velocity linearly increases. The higher the methane injection pressure, the faster the jet premixed flame velocity. Full article
(This article belongs to the Special Issue Combustion Process and Emission Control of Alternative Fuels)
Show Figures

Figure 1