Traditional Thermal Methods Research Articles

Comparative investigation of ultrafast thermal shock of Ti3AlC2 ceramic in water and air

AbstractIn this work, ultrafast thermal shock of Ti3AlC2 ceramic was evaluated in water and air by utilizing the induction heating method. First, the annealed samples were heated to the set temperature in tens of seconds and dropped into the cooling water within 0.1 s which is rather short not to degrade the sample temperature. Compared to the traditional thermal shock method when quenching in water, the abnormal thermal shock phenomenon did not occur, which is owing to that no dense oxide layers were formed on the samples’ surface to act as the thermal barrier. The continuous decrease in residual flexural strength when quenched in water is associated with water infiltration, chemical reaction, and large surface tensile stress. The residual strength has 27.25 MPa upon 1250°C. Second, at the same testing temperature, the residual flexural strength when quenched in air maintains a high value of 388 MPa up to 1400°C. Dense oxide scales existed on the quenched surface of Ti3AlC2 samples. The results exhibit that Ti3AlC2 ceramic possesses excellent thermal shock resistance in water and air, suitable to be applied in extreme environments.

The improved evaporation efficiency of a hot-bubble pilot plant (HBPP) caused by combustion gas for water treatment

HBPP uses hot dense bubbles as heat and mass carriers to evaporate the solution with improved evaporation efficiency, compared with the traditional thermal method. To develop an energy efficient water treatment process, we applied combustion gas as inlet gas within HBPP, for the first time to evaporate synthetic seawater. The advantage of using combustion gas is that the hot waste combustion gas from factories can be used at almost no energy cost, thereby reducing energy consumption. In this paper, the evaporation efficiency was determined by measuring the weight loss of column solution of HBPP in a 60 min run. Firstly, the ability of the HBPP to treat different types of wastewater, including 0.5 m NaCl solution or synthetic sewage, was tested by pumping air at the temperature of 80, 120 and 160 °C, respectively. The observed amount of evaporated water vapour was higher for the 0.5 m NaCl solution than for the synthetic sewage at inlet air temperatures of 80 °C and 120 °C but the same at a temperature of 160 °C. The HBPP shows the potential for water treatment regardless of wastewater type. Then, the evaporation efficiency was calculated for both combustion gas and air, at the inlet temperature of 120 °C to evaporate 0.5 m NaCl solution. The result showed an increment of 37% of evaporation efficiency achieved by sparging combustion gas. That is because the contained water vapour has a high capacity for efficient heat transfer to evaporate the solution. As a result, applying combustion gas within HBPP can provide an energy conservative method with improved evaporation efficiency for water treatment.

A novel direct method in one-step for catalytic heavy crude oil upgrading using iron oxide nanoparticles

We proposed a direct in situ synthesis method for iron oxide nanoparticles (NPs) along with catalytic erformance upgrading of heavy crude oil (HCO). Our method compares the upgrading of a HCO where other iron oxide nanoparticles were synthesized by a traditional thermal decomposition method of organometallic compounds in the presence of stabilizing agents and solvents of high boiling points. Furthermore, the in situ nanoparticles were extensively characterized by XRD, Mössbauer spectroscopy and TEM microscopy which confirmed the presence of magnetite and akaganeite phases, with an average diameter of 20−43 nm. Nanoparticles by thermal decomposition method were investigated by XRD, UHR-FE-SEM and HRTEM and showed the formation of magnetite nanoparticles with an average diameter of 6.7 ± 1.4 nm. Subsequently, the nanoparticles were evaluated in a batch reactor using HCO from the Golden Lane of Mexico at 44.1 bar (initial H2 pressure) and 380 °C, for 1 h at 500 rpm. It was observed that, even under hydrogen limited conditions, there are better physicochemical properties in terms of viscosity, API gravity and heavy fractions decrease, for example, the residue conversion was about 20 % and the kinetic model was adjusted to a five lump model. The formation of the iron sulfide phase (FeS) was detected during the analysis of the spent catalyst.

Application of Pulsed Electric Field for Inactivation of Yeast S. cerevisiae in Apple Juice

Pulsed electric filed (PEF) is a non-thermal food preservation method as alternative to traditional thermal method. The effect of pulsed electric field (PEF) on inactivation of yeast Saccharomyces cerevisiae (S.cerevisiae) in apple juice containing different sugar concentration was studied. The results of this study have shown that, using PEF, the yeast could be inactivated at room temperature (20°C). The inactivation effect of PEF was dependent on pulse number, field strength, and pulse width as well as sugar concentration. Pulse numbers less than 20 pulses (at 12.6kV/cm) had no or very less effect on yeast inactivation. Increasing the pulse number up to 400 pulses resulted about 3 logs yeast inactivation. The most important factor for yeast inactivation was the field strength (10 to 30 kV/cm). Whereas, at 10.2 kV/cm and 100 pulses, less than 2 logs yeast inactivation could be achieved, was the yeast inactivation at filed strength of 30kV/cm and 100 pulses about 5 logs. At given field strength and pulse number, longer pulse width (1 to 2.5 μF) affected positively the inactivation of microorganism. In contrast, increasing the sugar concentration in apple juice higher than 20% negatively affected the inactivation of yeast during PEF treatment at given treatment conditions.

Research on integrated CO2 absorption-mineralization and regeneration of absorbent process

The hot potassium-alkali method provides excellent performance for the absorption of CO2 from flue gas. However, the high energy consumption by absorbent regeneration poses a critical barrier to the widespread industrialization of the hot potassium-alkali method. In this study, an integrated CO2 absorption-mineralization and regeneration of absorbent (IAMR) process was proposed using K2CO3 solution as the absorbent and steel slag as the desorbent at normal temperature and pressure. This method greatly reduced the energy consumption and costs compared with the traditional thermal regeneration method. Under the optimal conditions, i.e. a K2CO3 concentration of 1.0 mol/L, reaction temperature of 60 °C and liquid-solid (K2CO3 solution-steel slag) ratio of 14 mL/g, the carbonation conversion of the steel slag reached 58.63% after 120min, corresponding to a CO2 storage capacity of 212 kg/t steel slag. The reaction process showed that the main component Ca2SiO4 in the steel slag had high solubility activity in K2CO3 solution which significantly enhanced the rate and efficiency of CO2 sequestration. Moreover, the performance stability of K2CO3 solution during CO2 absorption-desorption circulation was discussed. This research is of great significance for the simultaneous treatment of alkaline waste slags (steel slag, fly ash, etc.) and mitigation of greenhouse gases.

An effective thermal treatment of toluene-contaminated soil by uniform heating from microwave coupled infrared radiation (MCIR)

Thermal treatment technologies are generally very effective for the remediation of soils contaminated. For the traditional thermal treatment method of contaminated soil, the heating method from the outside to the inside will inevitably cause a waste of energy, and it may be expensive due to the energy costs. Therefore, it is necessary to find a new heating technology to improve the thermal treatment. In this study, a novel microwave coupled infrared radiation (MCIR) technology was used to achieve uniform heating treatment of contaminated soil. A mathematical model was established and applied to simulate the electric field and temperature induced by microwave radiation and MCIR. The model results showed that MCIR heating produces well uniformity of thermal field distribution. Then, the influence of infrared in the MCIR treatment of soil was investigated by the lab experiment. The lab experimental results indicated that infrared could efficiently improve the microwave treatment of soil. A toluene removal efficiency of 92.8% could be achieved at 500 W microwave coupled with 300 W infrared radiation for 300 s, retaining 9.2% soil moisture. In addition, it exhibited a high cost-benefit. Furthermore, MCIR did not destroy the structure of toluene by infrared spectrum analysis. The results show that this MCIR treatment has the advantages of uniform heating, high efficiency, and low damage, which indicates the application prospect of MCIR in soil remediation.

Ultraviolet Light-Densified Oxide-Organic Self-Assembled Dielectrics: Processing Thin-Film Transistors at Room Temperature.

Low-temperature, solution-processable, high-capacitance, and low-leakage gate dielectrics are of great interest for unconventional electronics. Here, we report a near room temperature ultraviolet densification (UVD) methodology for realizing high-performance organic-inorganic zirconia self-assembled nanodielectrics (UVD-ZrSANDs). These UVD-ZrSAND multilayers are grown from solution in ambient, densified by UV radiation, and characterized by X-ray reflectivity, atomic force microscopy, X-ray photoelectron spectroscopy, and capacitance measurements. The resulting UVD-ZrSAND films exhibit large capacitances of >700 nF/cm2 and low leakage current densities of <10-7 A/cm2, which rival or exceed those synthesized by traditional thermal methods. Both the p-type organic semiconductor pentacene and the n-type metal oxide semiconductor In2O3 were used to investigate UVD-ZrSANDs as the gate dielectric in thin-film transistors, affording mobilities of 0.58 and 26.21 cm2/(V s), respectively, at a low gate voltage of 2 V. These results represent a significant advance in fabricating ultra-thin high-performance dielectrics near room temperature and should facilitate their integration into diverse electronic technologies.

Modern methods of physiotherapy in Comprehensive Thermal Treatment Assessed by patients

Introduction: In rehabilitation, the symbol of the 21st century is the presence of new technologies related to the virtual world (VR), biofeedback, and rehabilitation robots. These trends are also observed in thermal treatment. The complexity of this form of treatment introduces therapies based on modern devices for balance exercises, body stability, gait re-education with biofeedback, and virtual reality. How do patients rate this new quality in the thermal station? Aim: The study aimed to collect the subjective opinions of patients undergoing treatment in a thermal and rehabilitation hospital on therapy using modern devices for balance exercises, stability with biofeedback, and virtual reality. Material and methods: The study included a group of 184 patients staying at the 21st Military Thermal and Rehabilitation Hospital in Busko-Zdrój as part of benef i ts reimbursed by the National Health Fund and as part of treatment and prophylactic stays with anti-stress training for soldiers returning from missions abroad fi nanced by the Minister of National Defense. Apart from traditional thermal treatment methods, the subjects performed an exercise program on stabilometric and dynamographic platforms and two types of treadmills during the treatment. Results: In the respondents’ opinion, therapy based on devices using modern technologies (virtual reality and biofeedback) was interesting, patient-friendly, and increased their motivation to exercise. The surveyed soldiers in all age groups and civilians aged 41-60 expressed their willingness to re-use the therapy on devices using modern technologies. The results were analyzed statistically. Conclusions: Thermal treatment in the 21st century is gaining a new quality, in which devices based on modern technologies of computer games, virtual reality, and biofeedback unquestionably participate in the therapy of patients. Patients, regardless of their age or type of stay, in a subjective opinion expressed a positive opinion about the therapy on devices using modern technologies.

Water holding capacity and microstructure of sturgeon (Acipenser gueldenstaedti) fillets as affected by low temperature vacuum heating

ABSTRACT This study was aimed to investigate the effect of low-temperature vacuum heating (LTVH; versus the traditional thermal method– TC - 100°C boiling water) on water content/distributions, microstructure, and tenderness of sturgeon fillets. Although all fillets were well done, those fillets heated at lower temperature/time showed higher moisture content (P< .05). Furthermore, microstructure by paraffin section and shear force results also indicated LTVH70-30 (LTVH method; 70°C, 30 min) shown the most similar to TC fillets, the less firm and less juicy. Oppositely, LTVH60-15/30 (LTVH method, 60°C, 15/30 min) showed the best tenderness/juiciness among all fillets. Therefore, the LTVH method is agood alternative to the TC for fish processing in the catering industry, with tenderness/juiciness gains.

Multiscale computational fluid dynamics modeling and reactor design of plasma-enhanced atomic layer deposition

Plasma-enhanced atomic layer deposition (PEALD) is one of the most widely adopted deposition methods in the semiconductor industry. It is chosen largely due to its superior ability to deliver ultra-conformal dielectric thin-films with high aspect-ratio surface structures, which are encountered more and more often in the novel design of metal-oxide-semiconductor field-effect transistors (MOSFETs) in the NAND (Not-And)-type flash memory devices. Compared with the traditional thermal ALD method, PEALD allows for lower operating temperature and speeds up the deposition process with the involvement of plasma species. Despite its popularity, the development of PEALD operation policies remains a complicated and expensive task, which motivates the construction of an accurate and comprehensive simulation model. While existing models have described the individual or partially coupled domains, none of these models has captured all three domains in the PEALD process: surface reaction, macroscopic gas transport, and plasma generation. In this work, a comprehensive multiscale computational fluid dynamics (CFD) model is developed for a remote PEALD reactor used in the deposition of HfO2 thin-films. First, a previously developed kinetic Monte-Carlo (kMC) model is adapted for the multiscale simulation to describe the surface reactions. Then, two macroscopic models, specifically tailored for the remote plasma reactor, are formulated to describe the dynamic behaviors of the plasma generation and bulk species transport domains, respectively. Additionally, an integrated message passing interface (MPI) scheme is built to couple and resolve the communication between different scales in the model. The model results are then validated with experimental data and an automated workflow is established for model calculations without human intervention. Finally, a set of baseline operating conditions derived from the model simulation results is proposed to guarantee the production of high-quality thin-films.

Effect of dielectric barrier discharge plasma excitation frequency on the enzymatic activity, antioxidant capacity and phenolic content of apple cubes and apple juice

Cold plasma is a potential alternative to traditional thermal conservation methods because of its high efficiency in the preservation and retention of quality parameters. The objective of this study was to evaluate the application of atmospheric cold plasma on some qualitative aspects of apple cubes and apple juice. The research used dielectric barrier discharge plasma and studied different excitation frequencies of plasma: 50, 200, 400, 600, and 900 Hz. The effects of plasma application were evaluated on enzymatic activity (PPO and POD), total phenolic compounds, antioxidant capacity, and colorimetry. Plasma treatment partially inactivated the polyphenol oxidase enzyme in apples cubes and juice. Inactivation of peroxidase occurred only in apple juice. Total phenolic content and antioxidant capacity presented no significant difference between the treated and control samples of apple cubes, while significant changes were observed in apple juice. The changes in color parameters were slight and did not compromise the product quality. Plasma application was able to partially inactivate the enzymes responsible for browning while maintaining the quality and sensory properties of apple cubes and juice.

Design calculation and thermal-hydraulic analysis of 290 MW intermediate heat exchanger for pool-type sodium-cooled fast reactor

The intermediate heat exchanger (IHX) is a type of shell-and-tube heat exchanger. It is assembled with thousands of straight or expansion bend tubes in concentric circles and extremely huge and complex in geometry which leads to the non-uniform flow in the shell-side. The motivation of this work is to design a 6 m long, 290 MW IHX and clarify the influence of the tube specification on its performance. Traditional thermal design method is employed here for the design process, while 2-D porous medium model with anisotropic properties is adopted for simulation to support the design process adjusting the tube specification. The results show that the tube specification mainly affects the flow uniformity in the inlet region but has little effects on outlet region flow distribution. Comparing the IHX thermal-hydraulic performance under different tube specifications, it is found that the specification with 19 mm outer diameter, 25 mm radial pitch and 0.8 mm wall thickness is the best choice.

Potential application of nano graphene oxide for saving energy in water thermal desalination system part I

Graphene derivatives revolutionize a lot of industries since its discovery. In this investigation nano graphene oxide (NGOCB) was synthesized via sulfuric acid dehydration by mixing of sugar (as source of carbon) with bentonite clay as substrate. NGOCB was characterized by using scaning electron microscope, transmission electron microscope, X-ray diffraction, Fourier transform infrared spectroscopy and scattered area electronic diffraction analysis. The experimental results showed that the particles of graphene oxide are spherical in shape and the diameter ranged from 6 to 33 nm. The data indicated the presence of graphene oxide mono-layers with hexagonal pattern over the bentonite substrate surfaces. On applying the obtained NGOCB in thermal desalination process, several findings were observed such as saving the energy required for reaching the boiling temperature from room temperature by 11% (NGOCB 4 g/l). While on using 10 g/l of NGOCB more than 50% of the energy consumption for evaporation was saved. Also the generated desalinated water quantity obtained using nano graphene oxide was more than double the quantity that obtained by the traditional thermal desalination method. The generated steam was applied for electricity generation by mini steam turbine, which leads to 22% energy saving.

Ultrasonics Sonochemistry Assisted Preparation of Polysiloxane Main‐Chain Liquid‐Crystalline Elastomers

AbstractFor the first time, an ultrasonics sonochemistry method is developed to promote the one‐pot hydrosilylation polyaddition polymerization and crosslinking reaction in the preparation of polysiloxane main‐chain liquid‐crystalline elastomers (MC‐LCEs). Due to the extraordinary effect of acoustic cavitation, the polyaddition polymerization and crosslinking reaction can be successfully carried out in an ordinary laboratory ultrasonic cleaner at room temperature, and generates the LCE matrix network in about 30 min. The prepared MC‐LCEs demonstrate good quality, good properties, and stimuli‐actuation performances. Compared to the traditional thermal processing methods for preparing polysiloxane MC‐LCEs, this method exhibits superior properties rapidly, with high convenience and efficiency, and can be a path for batch fabrication at low cost. The work also demonstrates that the ultrasonics sonochemistry method is effective in generating linear main‐chain liquid crystal polymers through hydrosilylation polyaddition and polysiloxane side‐chain LCE matrix through hydrosilylation crosslinking reaction, thus confirming the high availability of ultrasonics sonochemistry in the processes of hydrosilylation polymerization, crosslinking reactions, or synchronous polymerization and crosslinking reactions.

Study on the absorption-mineralisation for low-energy CO2 capture in BDA activated DEEA aqueous solution using calcium chloride

The large amount of energy in the thermal regeneration process of the absorbent is a challenge for the CO2 capture technology. The CO2 absorption-mineralization was investigated, which is different from the traditional thermal method. 1,4-Diaminobutane (BDA) promoted 2-diethylaminoethanol (DEEA) aqueous solutions were used to capture CO2. In the desorption process, adding anhydrous calcium chloride (CaCl2) in CO2 loaded amine solutions can rapidly removal CO2 from the rich amine solutions. In addition, we also analyzed the mineralized products by X-ray diffractometer, and discussed the stability of cyclic absorption-mineralization technology.

Comparison and analysis of the electromagnetic radiation, ionizing radiation and other physical technologies for disinfection and sterilization

Disinfection and sterilization technologies are of great significance in the food industry, medical field and water treatment, et al. Compared with traditional chemical and thermal methods, physical disinfection and sterilization approaches such as γ-rays, X-rays, electron beams, microwaves, low-temperature plasmas, ultraviolet rays and high-voltage pulsed electric fields have the advantages of no environmental pollution, low sterilization temperatures, no chemical residues, and so on. These physical disinfection and sterilization approaches are getting increasing concerns because of unique advantages. In this paper, the mechanisms of present physical disinfection and sterilization technics were summarized. The advantages and disadvantages of these physical means as well as their application areas are reviewed. Based on the superiorities and drawbacks of each method, different approaches should be adopted for the disinfection and sterilization of specific objects. Moreover, this paper highlights the trends on development of physical disinfection and sterilization approaches and proposes the extensive demands of the physical approaches on various aspects of our life.

Effect of Vacuum Steam Treatment of Hard Red Spring Wheat on Flour Quality and Reduction of Escherichia coli O121 and Salmonella Enteritidis PT 30

Recent outbreaks traced to contaminated flour have created a need in the milling industry for a process that reduces pathogens in wheat while maintaining its functional properties. Vacuum steam treatment is a promising technology for treatment of low-moisture foods. Traditional thermal treatment methods can compromise wheat functionality due to high temperatures; thus, maintaining the functional quality of the wheat protein was critical for this research. The objective of this study was to evaluate the effect of vacuum steam treatment of hard red spring (HRS) wheat kernels on final flour quality and the overall efficacy of vacuum stream treatment for reducing pathogens on HRS wheat kernels. HRS wheat samples were treated with steam under vacuum at 65, 70, 75, and 85°C for 4 and 8 min. Significant changes in dough and baked product functionality were observed for treatments at ≥70°C. Treatment time had no significant effect on the qualities evaluated. After determining that vacuum steam treatment at 65°C best preserved product quality, HRS wheat was inoculated with Escherichia coli O121 and Salmonella Enteritidis PT 30 and processed at 65°C for 0, 2, 4, 6, or 8 min. The treatments achieved a maximum average reduction of 3.57 ± 0.33 log CFU/g for E. coli O121 and 3.21 ± 0.27 log CFU/g for Salmonella. Vacuum steam treatment could be an effective pathogen inactivation method for the flour milling industry.

Performance enhancement of cabinet cooling system by utilizing cross-flow plate heat exchanger

Gas-gas plate heat exchanger is an important component to remove heat generated from electronic devices in the cabinet cooling system. The counter-flow plate heat exchanger is usually used due to its higher heat transfer performance than the cross-flow plate heat exchanger. However, in the cabinet cooling system, the overall dimensions for the heat exchanger is limited. Therefore, it is necessary to consider the overall dimensions of the system during heat exchanger design, but the traditional thermal design method of heat exchanger doesn’t consider the effect of system parameters. In this paper, a cross-flow plate heat exchanger is proposed to improve the cooling performance of cabinet cooling system, and is compared with the counter-flow plate heat exchanger. The ε-NTU method and effectiveness-thermal resistance method are applied to evaluate the performance. It is found that for large width of cabinet cooling system, the system with cross-flow plate heat exchanger has higher cooling performance and lower thermal resistance than the system with counter-flow plate heat exchanger. When the width is 700 mm, the cooling capacity of the two systems are 176.13 W/K and 138.95 W/K, respectively. The dimensionless thermal resistance can characterize the irreversibility of the heat transfer at constant mass flow rate.

Microwave processing of carbon fibre polymer composites: a review

Microwave processing of carbon fibre-reinforced polymer (CFRP) composites is gaining increasing attention as an alternative to conventional thermal processing techniques. It has the potential to reduce part processing times and alleviate the bottleneck that often exists in composite component production. The present study reviews the current research and the state-of-the-art of microwave processing of CFRP composites. The benefits and limitations of microwave processing compared with traditional thermal processing methods are examined. The mechanical properties of microwave-cured composites are compared against conventionally-cured counterparts with varying levels of success. Current industrial microwave heating technologies are also examined. It is evident that microwave processing of polymer composites is promising but has notable limiting factors which have stunted its uptake in industry. Due to their prevalence in literature, CFRP composites with thermosetting matrices are the focus of this review. However, potential applications to carbon fibre-reinforced thermoplastics are also briefly described.

EFFECT OF CEDAR (CEDRUS LIBANI A. RICH) TAR ON BACTERIAL GROWTH

The main objective of this study is to research the inhibitory effect of Cedar tar produced from cedarwoods collected from Gume village of Mut, Mersin, Turkey, against Escherichia coli and Staphylococcus haemolyticus using scanning electron microscopy. The inhibitory effect of cedar tar at varying concentrations (0.1-100%) was examined on bacterial growth (E. coli and S. haemolyticus) by using Kirby-Bauer agar diffusion method. Cedar tar showed a strong inhibitory activity in the range of 15-30 mm against all tested microorganisms. The MICs value of Cedar tar was 5% for E. coli and S. haemolyticus. The bacterial growth in liquid culture including 5% Cedar tar was observed by optical density and standard plate count method for 24 h. The optical density and viable cell counts in culture including Cedar tar (5%) reduced after 2 h of incubation period for all test strains. The bacterial colonies belonging to tested strains were not encountered on agar plates at the end of 10 h incubation. The cell images were not also determined in SEM micrographs of cultures with Cedar tar. Our data clearly indicated that cedar tar obtained by traditional thermal method had a strong inhibitory activity on bacterial cells.