Thermal Processing Technologies Research Articles

Research on gasification of low-grade fuels in a continuous layer

The technology of thermal processing of low-grade fuel into gaseous fuel is an essential problem whose solution will create clean energy as an alternative to natural gas and coal gasification. It also can solve the problems of the ecological utilization of industrial and household waste as well as of obtaining cheap energy and improving industrial effects for the environment. The analysis of the theoretical provisions and experimental tests has proved the possibility of processing wood during its gasification in a gas generator with a continuous layer; it is processed into gaseous fuel with the lower calorific value being 1.5 times higher in comparison with the calorific value of the gaseous fuel that is produced by other known gas generators of this type. The experimental results have specified the regression dependence of heat that is produced by burning the synthesis gas during the gasification of low-grade fuel on the fractional composition of the fuel, the amount of air, and the fuel layer height. The resulting regression equations can be the basis for implementing the studied process and its rational management. The equations of the input factors’ dependence on the original setting make it possible to determine every possible parameter of assessing the process under study at any value of the factors between the upper and lower levels. The tests have revealed the rational values of the input parameters for operating a gas generator with a continuous layer at which the lower heating value of burning the syngas reaches its maximum.

Heat transfer phenomena during thermal processing of liquid particulate mixtures—A review

ABSTRACTDuring the past few decades, food industry has explored various novel thermal and non-thermal processing technologies to minimize the associated high-quality loss involved in conventional thermal processing. Among these are the novel agitation systems that permit forced convention in canned particulate fluids to improve heat transfer, reduce process time, and minimize heat damage to processed products. These include traditional rotary agitation systems involving end-over-end, axial, or biaxial rotation of cans and the more recent reciprocating (lateral) agitation. The invention of thermal processing systems with induced container agitation has made heat transfer studies more difficult due to problems in tracking the particle temperatures due to their dynamic motion during processing and complexities resulting from the effects of forced convection currents within the container. This has prompted active research on modeling and characterization of heat transfer phenomena in such systems. This review brings to perspective, the current status on thermal processing of particulate foods, within the constraints of lethality requirements from safety view point, and discusses available techniques of data collection, heat transfer coefficient evaluation, and the critical processing parameters that affect these heat transfer coefficients, especially under agitation processing conditions.

Impact of the Pulsed Electric Field Treatment on Bioactive Food Compounds: Bioaccessibility and Bioavailability

Pulsed Electric Field (PEF) treatment is a non-thermal food processing technology that mostly applied to low viscosity high acidity food samples. Due to its non-thermal nature, it is preferred over thermal processing technologies since it has a superiority to preserve physical, chemical, biochemical and sensory properties of food with extended shelf life. Studies focused on preservation of bioactive and health-related compounds usually involve effect of PEF on water soluble vitamins, total antioxidant capacity, total phenolic compounds, phenolic substances, organic acids, and anthocyanins and are limited on how bioaccessibility and bioavailability of these compounds are changed by PEF processing. Thus, effects of PEF processing on bioaccessibility and bioavailability of food components with both in vivo and in vitro studies emphasizing on future needs are emphasized in this review.

A novel method to prepare microcellular poly(vinyl alcohol) foam based on thermal processing and supercritical fluid

Combining the thermal processing and supercritical fluid technology develops a novel preparation method of microcellular poly(vinyl alcohol) (PVA). Water, as the plasticizer in system, can form the hydrogen bonding with pendant hydroxyl of PVA and weaken its strong intermolecular and intramolecular forces to realize the thermal processing. Supercritical carbon dioxide (sc‐CO2) can easily dissolve into water‐plasticized PVA (WPVA) because of the destruction of crystal region caused by water, and the enhanced sc‐CO2 solubility can greatly improve the foamability of WPVA. The porous structure generates through the saturation of sc‐CO2 in WPVA sample and followed by pressure drop‐induced phase separation. The foaming behavior of WPVA was studied as a function of saturation pressure, foaming temperature, and saturation time. The cell density, cell size, and distribution of the obtained foam can be controlled by tuning processing conditions. The results revealed that the cell size decreased, and its distribution narrowed with saturation pressure increasing, or decrease of foaming temperature. But excessively increasing the saturation time generated a negative effect on the foaming behavior owing to the deteriorated plasticization effect resulted from the loss of water. Copyright © 2016 John Wiley & Sons, Ltd.

Structure and performance of Poly(vinyl alcohol)/wood powder composite prepared by thermal processing and solid state shear milling technology

Abstract In this study, the Poly(vinyl alcohol)(PVA)/wood powder composite was prepared through combining the novel technologies of solid-state shear milling (S 3 M) and thermal processing of PVA, which provided a large-scale and non-solvent way to efficiently utilize the abundant biomass materials. The results showed that S 3 M can significantly promote pulverization, dispersion, mechanical activation, and interfacial compatibility of the components, endowing the materials with better processability and mechanical performances. The XRD and FTIR results showed that with the increasing of milling cycles, the hydrogen bonds of PVA molecules were partially destroyed, leading to the formation of looser crystalline structure and lower crystalline degree, while the hydrogen bonding between PVA and wood powder was strengthened. Combining with thermal processing technology of PVA, the composite treated by S 3 M had a good processability and mechanical properties. DSC curves revealed that the melting temperature of PVA/wood powder (70 wt/30 wt) composite decreased to 123 °C, providing a quite wide thermal processing window for composite. High-pressure Capillary rheology analysis showed that the shear viscosity of the composite decreased with the increasing milling cycles. Finally, the composites exhibited significant improvements in mechanical properties. The tensile strength increased from 16.6 MPa to 22.5 MPa, and the elongation at break increased from 32.0% to 120.5%, respectively.

Microwave Annealing for NiSiGe Schottky Junction on SiGe P-Channel.

In this paper, we demonstrated the shallow NiSiGe Schottky junction on the SiGe P-channel by using low-temperature microwave annealing. The NiSiGe/n-Si Schottky junction was formed for the Si-capped/SiGe multi-layer structure on an n-Si substrate (Si/Si0.57Ge0.43/Si) through microwave annealing (MWA) ranging from 200 to 470 °C for 150 s in N2 ambient. MWA has the advantage of being diffusion-less during activation, having a low-temperature process, have a lower junction leakage current, and having low sheet resistance (Rs) and contact resistivity. In our study, a 20 nm NiSiGe Schottky junction was formed by TEM and XRD analysis at MWA 390 °C. The NiSiGe/n-Si Schottky junction exhibits the highest forward/reverse current (ION/IOFF) ratio of ~3 × 105. The low temperature MWA is a very promising thermal process technology for NiSiGe Schottky junction manufacturing.

Thermal Processing of PVP- and HPMC-Based Amorphous Solid Dispersions.

Thermal processing technologies continue to gain interest in pharmaceutical manufacturing. However, the types and grades of polymers that can be utilized in common thermal processing technologies, such as hot-melt extrusion (HME), are often limited by thermal or rheological factors. The objectives of the present study were to compare and contrast two thermal processing methods, HME and KinetiSol® Dispersing (KSD), and investigate the influence of polymer type, polymer molecular weight, and drug loading on the ability to produce amorphous solid dispersions (ASDs) containing the model compound griseofulvin (GRIS). Dispersions were analyzed by a variety of imaging, solid-state, thermal, and solution-state techniques. Dispersions were prepared by both HME and KSD using polyvinylpyrrolidone (PVP) K17 or hydroxypropyl methylcellulose (HPMC) E5. Dispersions were only prepared by KSD using higher molecular weight grades of HPMC and PVP, as these could not be extruded under the conditions selected. Powder X-ray diffraction (PXRD) analysis showed that dispersions prepared by HME were amorphous at 10% and 20% drug load; however, it showed significant crystallinity at 40% drug load. PXRD analysis of KSD samples showed all formulations and drug loads to be amorphous with the exception of trace crystallinity seen in PVP K17 and PVP K30 samples at 40% drug load. These results were further supported by other analytical techniques. KSD produced amorphous dispersions at higher drug loads than could be prepared by HME, as well as with higher molecular weight polymers that were not processable by HME, due to its higher rate of shear and torque output.

Microbiological Design and Validation of Thermal and High Pressure Processing of Acidified Carrots and Assessment of Product Quality

Modification of pH and combined use of novel processing methods may be a good strategy to improve the quality of canned vegetables. In this study, selected thermal (TP) and high pressure-assisted thermal (HP-T) processing methods were validated for citric acid-infused carrots (pH ≤ 4.5) using Bacillus licheniformis spores. Previously established thermal inactivation kinetics data were used to setup the target process times (to achieve 7-log kill of B. licheniformis). The microbial spores were inoculated at the center of simulated carrot alginate beads and subjected to different processing methods. Delivered process lethalities, evaluated by the microbial count/re-count method and measured time–temperature data, were equal to or higher than the targeted values. No survivors were found after the treatments, demonstrating the adequacy of the processes. Texture, color and β-carotene retention in processed carrots, evaluated and compared with those processed under conventional canning, showed higher texture retention (P < 0.05) in the modified processing methods. Residual hardness values of carrots were 86% with HP-T, 70% with ohmic heating and 8% with conventionally canned product. The same trend was observed with chewiness value. However, processing methods showed no differences (P > 0.05) with respect to color change. In terms of β-carotene, carrots subjected to a relatively more severe heat treatment (water immersion mode in static retort) showed better β-carotene extractability than samples from HP-T. Practical Applications Conventional thermal processing of “low acid” foods (pH > 4.6) experiences significant quality loss due to the long thermal processing times required to inactivate spores of the key pathogen Clostridium botulinum. Alternative thermal processing techniques have evolved to shorten the processing times by enhancing heating rate to the product through process modifications or using thin profile packages. Even though quality retention can be enhanced through these modifications, thermal damage to quality is still indispensable since the sensitively microbial destruction to heat remain unaltered. Product acidification moves the “low acid” foods to “acid” category, thereby shifting the process regulation from the high temperature sterilization to the lower temperature pasteurization conditions. Savings in energy and reduction in process time immediately become obvious. Novel acidification methods are necessary for making the process efficient. Bacillus licheniformis is important and a suitable microorganism for validating thermal processing of acidified foods. The combined use of acid infusion methods and alternative thermal processing technologies could play a significant role to improve quality of acidified foods as compared to current practices.

Comparative Effects of Ohmic and Conventional Heating for Inactivation of Escherichia coli O157:H7, Salmonella enterica Serovar Typhimurium, and Listeria monocytogenes in Skim Milk and Cream

Ohmic heating has proven advantages over conventional thermal processing and novel thermal alternative technologies. In this study, the effect of ohmic and conventional heating for pasteurizing skim milk and cream was examined. All treatment conditions for ohmic and conventional heating were identical except for composition of the heating chamber. In most cases, the reduction of three pathogens did not differ significantly between ohmic heating and conventional heating at fixed treatment temperatures and times. However, temperature can be increased more rapidly with ohmic than with conventional heating treatment, both in skim milk and in cream. Therefore, E. coli O157:H7, Salmonella Typhimurium, and L. monocytogenes were inactivated more effectively by ohmic heating treatment for the same treatment time intervals. Also, the time required for pathogen populations to decrease to below the detection limit was less for ohmic heating than conventional heating. Quality aspects (viscosity, pH, and color) of skim milk and cream suffered less degradation by ohmic than by conventional heating. Although there was little evidence of a nonthermal effect of ohmic heating, the results demonstrate significant advantages in the use of ohmic heating over conventional methods for pasteurizing skim milk and cream.

Chemical characterization of milk after treatment with thermal (HTST and UHT) and nonthermal (turbulent flow ultraviolet) processing technologies

As a result of growing interest to nonthermal processing of milk, the purpose of this study was to characterize the chemical changes in raw milk composition after exposure to a new nonthermal turbulent flow UV process, conventional thermal pasteurization process (high-temperature, short-time; HTST), and their combinations, and compare those changes with commercially UHT-treated milk. Raw milk was exposed to UV light in turbulent flow at a flow rate of 4,000L/h and applied doses of 1,045 and 2,090 J/L, HTST pasteurization, and HTST in combination with UV (before or after the UV). Unprocessed raw milk, HTST-treated milk, and UHT-treated milk were the control to the milk processed with the continuous turbulent flow UV treatment. The chemical characterization included component analysis and fatty acid composition (with emphasis on conjugated linoleic acid) and analysis for vitamin D and A and volatile components. Lipid oxidation, which is an indicator to oxidative rancidity, was evaluated by free fatty acid analysis, and the volatile components (extracted organic fraction) by gas chromatography-mass spectrometry to obtain mass spectral profile. These analyses were done over a 14-d period (initially after treatment and at 7 and 14 d) because of the extended shelf-life requirement for milk. The effect of UV light on proteins (i.e., casein or lactalbumin) was evaluated qualitatively by sodium dodecyl sulfate-PAGE. The milk or liquid soluble fraction was analyzed by sodium dodecyl sulfate-PAGE for changes in the protein profile. From this study, it appears that continuous turbulent flow UV processing, whether used as a single process or in combination with HTST did not cause any statistically significant chemical changes when compared with raw milk with regard to the proximate analysis (total fat, protein, moisture, or ash), the fatty acid profile, lipid oxidation with respect to volatile analysis, or protein profile. A 56% loss of vitamin D and a 95% loss of vitamin A content was noted after 7 d from the continuous turbulent flow UV processing, but this loss was equally comparable to that found with traditional thermal processing, such as HTST and UHT. Chemical characterization of milk showed that turbulent flow UV light technology can be considered as alternative nonthermal treatment of pasteurized milk and raw milk to extend shelf life.

Radio-Frequency Applications for Food Processing and Safety.

Radio-frequency (RF) heating, as a thermal-processing technology, has been extending its applications in the food industry. Although RF has shown some unique advantages over conventional methods in industrial drying and frozen food thawing, more research is needed to make it applicable for food safety applications because of its complex heating mechanism. This review provides comprehensive information regarding RF-heating history, mechanism, fundamentals, and applications that have already been fully developed or are still under research. The application of mathematical modeling as a useful tool in RF food processing is also reviewed in detail. At the end of the review, we summarize the active research groups in the RF food thermal-processing field, and address the current problems that still need to be overcome.

Partial gasification of lignite in a bed with a pulsed reverse blast

The aim of this work is to develop a technology of thermal processing of brown coal to produce carbonizate with increased strength. Here are presented the results of an experimental study of the process of partial gasification of brown coal (grade 3B) in the bed apparatus with pulsating reversed blow. In previous work, it was shown that satisfactory strength of a particle (no less than 8 MPa compression) is achieved by limiting the heating rate, as well as, the maximum temperature of the heating medium. To provide these conditions, it was proposed to use partial gasification of the coal in the fuel-bed apparatus using a pulsating supply mode of an oxidant. Parameters of blowing: flow rate 0.022 m3/(m2 s); blowing period 25 s; stop blowing period 150 s. Under these conditions, the producing lignite coke had a crush strength in the range of 8–10 MPa. The product yield was 56%.

Effect of Ohmic Heating on the Electrical Conductivity, Biochemical and Rheological Properties of Papaya Pulp

AbstractA laboratory scale static ohmic heating unit of 1 L capacity was designed and fabricated for conducting the study. The electrical conductivity of the pulp was measured over a temperature range of 35–95C. Ohmic heating was conducted at three voltage gradients (6.66, 13.33 and 20 V/cm) and holding times (1, 2 and 3 min). Voltage gradient of 13.33 V/cm with a holding time of 2 min was optimized statistically for the pasteurization of papaya pulp based on the microbial analysis. The ohmic heated pulp was compared with fresh pulp with respect to the biochemical and rheological properties. Ohmic heated pulp retained 86.44% lycopene, 87.13% β‐carotene and 85.23% ascorbic acid. Rheologically, papaya pulp exhibited a non‐Newtonian (n &lt; 1) and pseudoplastic behavior with yield stress following Herschel–Bulkley model (R2 0.99). The frequency sweep curve established the resemblance of ohmic heated pulp to that of the fresh pulp without any structural breakdown upon processing.Practical ApplicationsPapaya fruit possesses high nutritional and medicinal properties which are recommended for infants and adults. But owing to its faster rate of deterioration, about 50% of the fruit harvest suffers heavy postharvest losses. A thermal processing technology is required in order to prevent the postharvest losses and make the pulp suitable for infant formulations. Novel thermal processing technology, such as ohmic heating, could preserve the pulp for a long period without compromising on the microbial stability and quality of the product. Hence, this research was planned to concentrate on understanding the suitability of ohmic heating for the pasteurization of papaya pulp. The research finding would contribute toward the growth of pulp processing and infant formulating industries.

Research on the Development of Ultra High Pressure Fresh-Keeping Packaging Technology

&lt;b&gt; &lt;/b&gt;Ultra high pressure technology is a new type of non thermal processing technology; it is mainly through the structure of the cell wall and cell membrane and cell space destruction of microorganisms, the protein composition of degeneration, the enzyme activity decreased to achieve the purpose of sterilization. This article from the ultra high pressure technology in aquatic products industry, meat industry and fruit and vegetable and its products industry and other aspects of the application status and development direction of ultra high pressure sterilization technology, hope to be able to provide certain support theory in the study of ultra high pressure technology.

Interface characterization of nitrogen plasma‐treated gate oxide film formed by RTP technology

We described thin nitrogen plasma‐treated gate oxide film formed by rapid thermal process technology. This thin nitrogen plasma‐treated gate oxide film has been formed using remote plasma nitridation process onto in situ steam generated oxide layer. We investigated the nitrogen profile within the gate dielectric film formed by this technique using SIMS analysis. The result shows that nitrogen concentration profile is composed of high at top surface and low at SiO2/Si interface. The peak concentration of nitrogen is placed at near top place and goes rapidly down to SiO2/Si interface. This nitrogen profile results in excellent boron diffusion barrier characteristics and superior interface properties for p+PMOSFET. We also performed the electrical analysis such as capacitance–voltage (C–V), gate leakage current, dielectric breakdown voltage and time‐to‐breakdown (TBD) measurement. It has been found that this thin nitrogen plasma‐treated gate oxide film results in superior electrical reliability having significant lower leakage current, superior dielectric strength and outstanding TBD. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Малоэнергоемкая технология термообработки изделий из пенобетона на полигонах с помощью солнечной энергии

Малоэнергоемкая технология термообработки изделий из пенобетона на полигонах с помощью солнечной энергии

Safety of the Surrogate Microorganism Enterococcus faecium NRRL B-2354 for Use in Thermal Process Validation

Enterococcus faecium NRRL B-2354 is a surrogate microorganism used in place of pathogens for validation of thermal processing technologies and systems. We evaluated the safety of strain NRRL B-2354 based on its genomic and functional characteristics. The genome of E. faecium NRRL B-2354 was sequenced and found to comprise a 2,635,572-bp chromosome and a 214,319-bp megaplasmid. A total of 2,639 coding sequences were identified, including 45 genes unique to this strain. Hierarchical clustering of the NRRL B-2354 genome with 126 other E. faecium genomes as well as pbp5 locus comparisons and multilocus sequence typing (MLST) showed that the genotype of this strain is most similar to commensal, or community-associated, strains of this species. E. faecium NRRL B-2354 lacks antibiotic resistance genes, and both NRRL B-2354 and its clonal relative ATCC 8459 are sensitive to clinically relevant antibiotics. This organism also lacks, or contains nonfunctional copies of, enterococcal virulence genes including acm, cyl, the ebp operon, esp, gelE, hyl, IS16, and associated phenotypes. It does contain scm, sagA, efaA, and pilA, although either these genes were not expressed or their roles in enterococcal virulence are not well understood. Compared with the clinical strains TX0082 and 1,231,502, E. faecium NRRL B-2354 was more resistant to acidic conditions (pH 2.4) and high temperatures (60°C) and was able to grow in 8% ethanol. These findings support the continued use of E. faecium NRRL B-2354 in thermal process validation of food products.

Flash grafting of functional random copolymers for surface neutralization

Rapid Thermal Processing (RTP) technology was employed to perform flash grafting reactions of a hydroxyl terminated poly(styrene-r-methylmethacrylate) random copolymer to a silicon surface.

Impact of High Pressure Homogenization (HPH) Treatment on the Nutritional Quality of Egg/Yogurt, Vegetable and Fruit Based Creams

The food industry has made large investments in processing facilities relying mostly on conventional thermal processing technologies with well-established reliability and efficacy. These techniques have important disadvantages such as off flavors, destruction of nutrients, and other losses of product quality. Non thermal processing is a key factor for preserving or improving the nutritional value of food, and high pressure homogenization (HPH) processing is now a celebrated option experiencing worldwide commercial growth. Notwithstanding, little is known on the impact of HPH treatments on the nutritional value of food. In this study we have evaluated the possible modification induced by HPH treatment in egg-yogurt, mixed vegetable, and mixed fruit creams. Our results evidence that HPH does not affect the nutritional quality of lipids and does not cause lipolysis, lipid peroxidation and vitamin E loss. In plant food products, HPH preserved or improved the nutritional quality, suggesting its use as valid alternative to thermal pasteurization for obtaining high quality products with preserved nutritional characteristics. Although further investigations are needed, especially at extreme pressure and temperature combinations, our results open new perspectives for the production of ambient stable products with good nutritional value, and contribute to process optimization.

Study on feasibility of fusion process using microwave and high temperature heating element for purification of oil contaminated soil

This study aimed to examine the purification efficiency of fusion process using microwave and high temperature heating element on the effect of temperature, moisture content and removal rate of oil in oil polluted soil. The thermal processing technology was also developed based on the removal efficiency accompanied by carbon number in microwave process. Total petroleum hydrocarbon (TPH) (C18-50) and TPH (diesel, gasoline) were collected from junkyard as polluted soil in this experiment, and they did not meet TPH criterion <2000 mg kg−1 at maximum power of 4 kW in batch process. On the other hand, the oil with carbon number 18-50 in continuing process had <2000 mg kg−1 of TPH criterion at 6 kW, 700°C for 40 min. In addition, TPH density was found to be 566·62 mg kg−1 when the oil with low number of carbon was treated at 6 kW, 500°C for 20 min. It was finally observed that temperature more than critical temperature can remove oil by combining the high temperature heating element with microwave.