Hot Drying Research Articles

CONTENT MODIFICATION OF DIFFERENT TYPES OF NONMETALLIC INCLUSIONS DURING LOW-CARBON IF STEEL LADLE TREATMENT

Development of advanced materials for the automotive industry allows us to produce a lighter body without losing strength characteristics of the structure. It became possible by the creation and subsequent introduction into the production of such steel grades as IF (Interstitial Free) – steel with no interstitial solute atoms to strain the solid iron lattice and IF-BH (Bake Hardening) – steel with hardening during hot drying. The article provides a brief overview of the history of the emergence of IF steel and the current situation in the production of it in Russia. One of the quality criteria for steels of IF grades is purity of the metal by non-metallic inclusions (NMI), which negatively affect the plastic properties of the material, lead to the formation of surface defects of flat rolled products and reduce the manufacturability due to a decrease in the casting speed of steel, as they cause overgrowing of steel casting nozzles. The article presents investigation results of the content, composition, size and morphology of non-metallic inclusions (NMI) in the metal samples taken at all stages of ladle treatment and casting of IF steel grade production using quantitative metallographic analysis, electrochemical dissolution (ED) followed by X-ray microanalysis of isolated inclusions, Auger electron spectroscopy and fractional gas analysis (FGA). As a result of the analysis of inclusions in the studied samples using a scanning electron microscope, according to morphological features, five characteristic types of inclusions were identified, which reduce the performance properties and strength cha racteristics of the materials produced from them. Results of the analysis of nonmetallic inclusions in metal samples obtained by the ED method are in good agreement with the results of the determination of oxide nonmetallic inclusions by the FGA method. The method of fractional gas analysis shows the dynamics of changes in the content of various types of oxide nonmetallic inclusions during the secondary (ladle) treatment of steel. It is shown that application of the FGA method allows to make analysis of causes of the harmful NMI formation in the metal and to correct operations at ladle treatment.

Application of spore-forming probiotic Bacillus in the production of Nabat - A new functional sweetener

The basis of the present study was developing a novel type of functional sweet product with the additive probiotic spore forming bacteria that do not require cold chain or any specific storage condition. In this study, rock candy containing probiotic bacteria was produced in dry ambient condition. Spore-forming bacilli were selected as probiotics that are resistant to thermal processes and osmotic conditions. Rock candies were coated with an edible coating containing carboxymethyl cellulose, sucrose, glucose syrup, fructose syrup and a probiotic strain. After coating process, the parameters of turbidity (created by water dissolution of coated Nabat); effect of drying temperature on bacterial viability; moisture content, water activity, ash content of product; as well as product storage time were evaluated. Under thermal stress during both dissolution in hot liquid and drying, the survivability of the spores used in the coated rock candies did not fall significantly. Viability evaluation of the probiotic bacilli in the product after six months of storage at ambient temperature revealed 90.39 and 89.07% viability of Bacillus coagulans and Bacillus subtilis spores, respectively. Our results showed that spore-forming probiotics embedded in rock candy are highly stable during storage at ambient temperature and dry condition.

Rice Starch–Based Sponge for Use as Topical Hemostatic Agent

The topical hemostatic agents in surgery are biomaterials that very important for surgeons to stop bleeding in the complicated areas. Currently available hemostatic agents are often expensive, ineffective or raise safety concerns. Synthetic rice starch-based sponge was an inexpensive and promising alternative. In this study, we synthesized and characterized a new hemostatic agent from rice starch and investigated their use as a hemostatic material. The rice starch-based sponge having interconnected pore were synthesized via blending of the rice starch and additive of carboxymethylcellulose (CMC), polyvinyl alcohol (PVA), and glycerol in hot water, freezing and drying by vacuum sublimation with enlarged porosity and rapid swelling behavior. Characteristics of the final products were then investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM-EDS). In vivo studies using 4 rabbits with liver injury showed rice starch-based sponge blood aggregate formation as well as bulk blood coagulation inhibition. The biocompatibility tests showed that this sponge is safe and effective after follow-up for at least 6 months of animal and clinical trial.

Prediction of energy and exergy of mushroom slices drying in hot air impingement dryer by artificial neural network

In current work, the energy and exergy analysis of hot air impingement drying mushroom slices was conducted under different air temperature (55, 60, 65, 70, and 75 °C), air velocity (3, 6, 9, and 12 m/s), and sample thickness (6, 9, and 12 mm) by the first and second law of thermodynamics. The statistical analysis results indicated that the effect of air velocity and temperature on the energy and exergy was more important than the sample thickness on it. The energy utilization and energy utilization ratio were in the range of 0.067–0.859 kJ/s and 0.087–0.34, respectively. The exergy loss and exergy efficiency was varied from 0.045–0.571 kJ/s and 0.315–0.879, respectively. Besides, the artificial neural network (ANN) was employed to predict the energy and exergy parameters. The modeling results revealed that the ANN models with arranged training algorithms and transfer function could be utilized to predict the performance of hot air impingement drying system with satisfactory accuracy.

Role of Steam as a Medium for Droplet Crystallization

Mannitol and sodium chloride (NaCl) were spray dried using a counter current superheated spray dryer. Superheated steam was found to induce relatively high nucleation during the solidification of the sprayed droplets when compared to hot air. This allowed the production of spherical mannitol particles with very fine crystals at a lower temperature. In addition, superheated steam led to the formation of unique salt microspheres consisting of hollow hopperlike sodium chloride crystals. These unique particle morphologies were not observed in hot air spray drying. Further analysis revealed that higher droplet temperature during the constant rate drying period, under superheated steam conditions, led to the high nucleation phenomenon. Results from this work illustrate the potential of superheated steam as a useful medium for in situ crystallization control in spray dryers.

The Optimum Window-to-Wall Ratio in Office Buildings for Hot‒Humid, Hot‒Dry, and Cold Climates in Iran

About half of the energy loss in buildings is wasted through windows. Determining the optimum window-to-wall ratio (WWR) for different building facades would reduce such energy losses. The optimum WWR is the window area that minimizes the total annual energy of cooling, heating, and lighting. The purpose of this study is to investigate the optimum WWR of different facades of an office building. For this purpose, a sample building is simulated by means of DesignBuilder software in order to investigate the annual solar heat gain, cooling load, heating load, and lighting consumption for the three cities of Bushehr, Shiraz, and Tabriz, and optimum window areas of office buildings for the three cities are determined. Based on the results, the optimum window area for the north building facade for all climates is 20–30%. This amount for the southern facade of the building in Bushehr, Shiraz, and Tabriz is, respectively, 20–30%, 10–30%, and 20–50%. The optimum window area for the eastern and western building facades in Bushehr is 30–50%; in Tabriz it is 40–70%, and in Shiraz it is 20–60% and 40–70%, respectively. The difference between the maximum and minimum energy consumption with different window areas in Bushehr and Shiraz is 20–100% and in Tabriz it is 16–25%.

Perbandingan Aktivitas Antioksidan Ekstrak Apel Hijau (Malus Domestica) Segar Dan Kering Dengan Metode Spektrofotometri

Abstract: Green apples containing antioxidants substance that has beneficial effect in skin health. Green apples containing catechin, epicatechin, ploridzin, quercetin, ellergic acid and chlorogenic acid. One of food processing is hot drying, hot drying can influence bioactive substance in the food. The aim of this study is to measure antioxidant activity of fresh and dry green apple extract. Design of this study is experimental design, independent variable of this study is hot drying, and dependent variable of this study is antioxidant activity level. Extraction method using ultrasonic maseration, hot drying using oven. Antioxidant activity measuring using spectrophotometry method. IC50 level of fresh green apple extract is 31.26 ppm, IC50 of dry green apple extract is 52.36 ppm. IC50 level of fresh green apple extract are less than 50 ppm and IC50 level of dry green apple extract are more than 500 ppm. Conclusion of this study is fresh green apple extract has strong antioxidant activity and dry green apple extract has very strong antioxidant activity.

Cellulose porosity improves its dissolution by facilitating solvent diffusion

This paper reports on the effect of improved porous characteristics of cellulose on its solubility in DMAc/LiCl. The use of freeze-drying (FD) treatment led to higher surface area and void fraction of volume for high-molecular-weight (HMW) cotton cellulose (DP~5000). Improvement in porous characteristics of cellulose did not change the chemical and crystalline structures of cellulose, as compared to hot-drying (HD) treatment. However, significant improvement in the dissolution of FD-HMW cellulose in DMAc/LiCl was observed under relatively low temperature (80 °C). The relationship between the solubility and the porous characteristics of cellulose was discussed using Stokes-Einstein Equation and effective diffusion coefficient equation. It was concluded that the increase in the diffusion coefficient of the solvent and the improvement in the porous characteristics of cellulose played key roles to enhance the diffusion rate of the solvent through the cellulose molecular network.

Evaluation of quality properties and water mobility in vacuum microwave-dried carrot slices using pulse-spouted bed with hot air

Fried carrot slices feature high fat content to impair people healthy. To resolve this issue, microwave hot air-assisted pulse-spouted vacuum drying (MHAPSVD) has been designed using microwave vacuum dry on pulse-spouted bed with hot-air steam. Dying characteristics, moisture mobility and qualities of carrot slices had been confirmed after dying using 915 MHz microwave generator. Experiment was carried out at 3 W/g, 90 °C air stream, 0.08 MPa vacuum pressure and 2 s pulse interval for drying time of 10–80 min. The quality properties of color, odor, rehydration ratios, shrinkage ratios as well as tastes in 70 min drying are found to be suitable for a snack food. High moisture stability of carrot slices was achieved after 50 min. Free water decreased dramatically from start to 20 min and bound water declined sharply from 20 to 50 min. MHAPSVD could be a high efficient and quality drying technology for crisp product.

Investigating a Novel Hot Melt Extrusion-Based Drying Technique to Solidify an Amorphous Nanosuspension Using Design of Experiment Methodology.

The hot melt extrusion (HME) technology was explored and optimized to solidify an amorphous nanosuspension using Quality by Design (QbD) methodology. A design of experiments (DoE) approach was used to perform a set of 15 experiments, varying independent variables (feed rate, input temperature, and screw speed) within a design space. Redispersibility index (RDI), moisture content, and process yield constituted the critical quality attributes (CQAs) of the experimental design. Regression analysis and ANOVA were employed to identify and estimate significant main effects and two-way interactions, and model the process of HME drying for predictive purposes. The optimized HME-dried end product was characterized for physicochemical properties using differential scanning calorimetry (DSC), X-ray powder diffractions (XRPD), polarized light microscopy (PLM), Fourier transform infrared spectroscopy (FTIR), and in vitro dissolution studies. The statistical analysis reveals feed rate and input temperature as significant independent variables, critically influencing RDI and moisture content of solidified end product. The model developed for process yield was insignificant at a p-value of 0.05. The API retained its amorphous nature after the extrusion process which was confirmed using DSC and XRPD techniques. PLM was unsuitable to differentiate and determine crystallinity of drug moiety in the presence of a semi-crystalline bulking agent, microcrystalline cellulose (MCC). In vitro dissolution study depicted solubility and dissolution enhancement for HME-dried amorphous nanosuspension in both the dissolution media which can be attributed to amorphous nature of nanosized drug particles. A well-designed study implemented by DoE aided in developing a robust and novel HME technique to dry aqueous nanosuspension.

Effect of Low-temperature Induction on Heat Mining Performance of EGS in Hot Dry

Effect of Low-temperature Induction on Heat Mining Performance of EGS in Hot Dry

Joint opening or hydroshearing? Analyzing a fracture zone stimulation at Fenton Hill

In this study, we analyze a deep hydraulic stimulation of a fracture zone that was conducted as part of the classical Fenton Hill Hot Dry Rock Program in the 1970s. At the time, it was suggested that a pre-existing fracture or multiple fractures within the fracture zone were jacked open by injection-induced increase in pressure. In this study, we analyze the same stimulation experiment, but investigate the possibility of an alternative mechanism of shear reactivation of pre-existing fractures. We conduct modeling that accounts for both jacking (or elastic-fracture opening) and shear-slip dilation and demonstrate that injection-induced shear reactivation (or hydroshearing) could have occurred simultaneously with seismic events of magnitudes lower than what can be felt by humans. In fact, simulations considering shear reactivation seem to better match observed fluid recovery after multiple injection cycles. Shear reactivation and shear dilation results in locked-open fractures, especially near the injection well that provides permeability of higher flow recovery. We then investigate the sensitivity of the proposed model by varying some of the critical parameters such as maximum aperture, dilation angle, as well as fracture density. Interestingly, none of the simulated cases resulted in a large event that could have been felt by humans, but did result in a cumulative seismic magnitude of less than 1 for each given stimulation step. These results suggest that a permanent irreversible permeability increase of several orders of magnitude can be obtained by hydroshearing in a “seismically” safe manner.

Experimental Study on a Low-Temperature Heat Pump Sludge Drying System

The low-temperature sludge drying has become a kind of emerging hot drying technology. A small low-temperature heat pump sludge drying system is constructed in this paper. System operation characteristics are experimental studied. The results demonstrate that the set of an auxiliary fan is helpful to the system stable operation, but also leads temperature fluctuation of the main and auxiliary condenser. The inlet temperature and humidity of moist air in the drying closet and evaporator presents the opposite vibrate trend. The moisture contents in the above two devices both show a trend of increasing first and then decreasing, but the fluctuation range in drying closet is bigger. The wind resistances of the drying box and evaporator, which account for more than 90% of the whole system, both shows a certain extent fluctuation. The average specific power consumption of the system is 0.97 kWh/kg.

A comparative study of three drying methods on drying time and physicochemical properties of chicken powder

ABSTRACTChicken powder produced by hot air drying (HAD), hot air-assisted radio frequency drying (HA-RFD) and spray drying (SD) was obtained. Drying time along with flavor, taste, free amino acid (FAA) content and physico-chemical properties of products were compared. It was resulted that HA-RFD was the fastest means (90 min) with HAD was the slowest (240 min) to achieve target moisture content (under 5%). Concerning product quality, HA-RFD chicken powder exhibited the lowest hygroscopicity (1.80%), best rehydration (137.72%), and better flavor and taste as well as color, and HAD powder exerted best color, solubleness (45.68%) and better rehydration (130.27%). While for chicken powder produced by SD showed the most undesirable color and flavor and highest degree of hygroscopicity (8.40%). Besides, the total FAA content of HA-RFD was the most abundant (3.615 g/100 g), followed by HAD (3.551 g/100 g) and the SD powder had minimum content of total FAA (1.175 g/100 g), which suggested that HA-RFD can reduce thermal quality degradation and improve nutritional value with the lowest damage. Besides, HA-RFD chicken powder had the largest total content of Asp and Glu (3.615 g/100 g), which were the primary contributor to umami. Based on the results, it was concluded that HAD or HA-RFD appeared to be a promising way to prepare for chicken powder.

Optimization of Heat-Dried Silane Application for CAD/CAM Ceramic Resin Bonding

Purpose. Evaluate surface treatments and silane application methods and their effect on shear bond strength (SBS) before and after aging. Materials and methods. Slices of IPS e.max CAD and Vitablocs Mark II, were embedded in acrylic resin. The block was randomly assigned to 5 groups; E:etching with hydrofluoric acid (HF), rinsing, followed by cleaning in ultrasonic bath; E/S:HFetching and cleaned as group E followed by silane application for 20s, air drying and hot drying; E/S+:HFetching and cleaned as group E, followed by silane application for 60s, air drying and hot air drying, rinsing with boiling water and hot air drying; S:silane application for 20s followed by air drying and hot air drying; S+:silane application for 60s followed by air drying, air drying and hot air drying, rinsing in boiling water and hot drying. Cylinders of composite resin (n=12) were bonded with adhesive. SBS testing was carried out after 24h or after thermocycling for groups E; E/S and E/S+. Results. For 24h SBS showed significantly higher mean bond strength with E/S, for both ceramic, compared to E and E/S+. The use of silane alone showed significantly lower mean bond strength. No significant differences were found between E/S and E/S+ for VITA. The SBS was negatively affected by simulated aging in E/S group and positively in E/S+. Conclusions. The association of HFetching and a heat-dried silane showed to be significant to obtain a high SBS. Furthermore, the optimized silane application is not relevant to the immediate SBS while it enhances after aging.

Optimization of Heat-Dried Silane Application for CAD/CAM Ceramic Resin Bonding

Purpose. Evaluate surface treatments and silane application methods and their effect on shear bond strength (SBS) before and after aging. Materials and methods. Slices of IPS e.max CAD and Vitablocs Mark II, were embedded in acrylic resin. The block was randomly assigned to 5 groups; E:etching with hydrofluoric acid (HF), rinsing, followed by cleaning in ultrasonic bath; E/S:HFetching and cleaned as group E followed by silane application for 20s, air drying and hot drying; E/S+:HFetching and cleaned as group E, followed by silane application for 60s, air drying and hot air drying, rinsing with boiling water and hot air drying; S:silane application for 20s followed by air drying and hot air drying; S+:silane application for 60s followed by air drying, air drying and hot air drying, rinsing in boiling water and hot drying. Cylinders of composite resin (n=12) were bonded with adhesive. SBS testing was carried out after 24h or after thermocycling for groups E; E/S and E/S+. Results. For 24h SBS showed significantly higher mean bond strength with E/S, for both ceramic, compared to E and E/S+. The use of silane alone showed significantly lower mean bond strength. No significant differences were found between E/S and E/S+ for VITA. The SBS was negatively affected by simulated aging in E/S group and positively in E/S+. Conclusions. The association of HFetching and a heat-dried silane showed to be significant to obtain a high SBS. Furthermore, the optimized silane application is not relevant to the immediate SBS while it enhances after aging.

Effects of drying methods on quality attributes of peach (Prunus persica) leather

ABSTRACTIn this article, the effect of four drying techniques namely hot air drying (AD), infrared drying (IRD), hot air-assisted radio frequency drying (RFD), and microwave-assisted hot air drying (MWD) on quality attributes of dried peach (Prunus persica) leather (PL) was investigated. Drying tests were conducted at 70°C, air velocity of 1.0 m/s and at fixed power level of 4 W/g for RFD, IRD, and MWD. Moisture distribution, texture, rehydration ratio, color, and microstructure of PL were investigated. The results showed that the samples dried by MWD had the shortest drying time (180 min) followed by IRD (210 min), RFD (210 min) and AD (300 min). Study on microstructure and flavor analysis reveals that IRD gave the best results. Sensory tests using electronic tongue and electronic nose that evaluate the odor and taste profiles of dried PL indicates that IRD produced the best quality among the four drying techniques.

Chemical composition of apricots affected by fruit size and drying methods

ABSTRACTCombined practice of sulfuration and drying is widely applied for extending shelf life of fruits. The differences in fruit size are not taken into consideration during these applications and during fresh fruit consumption. In this study, effect of fruit size and drying methods (hot air-drying and sun drying) on the chemical composition of fresh and sulfurated apricot was investigated. Total drying times for sun drying and hot air-drying were 11 d and 51 h, respectively. A temperature gradient was applied during hot air-drying. The fruit size substantially affects the composition of both fresh and dried apricots. The results were subjected to principal component analysis. The small-sized fresh apricots discriminate themselves from large ones with higher amounts of phenolic compounds, whereas the large-sized fresh apricots contain more sugar and organic acids. Size classification and hot air-drying are advisable for high-quality dried apricot production.

Serial combination drying processes: A measure to improve quality of dried carrot disks and to reduce drying time

ABSTRACTConventional drying processes like hot air-drying (HAD), freeze-drying (FD) and microwave vacuum drying (MVD) have specific advantages and disadvantages concerning product quality and drying time. Recent studies have shown that serial combinations of these processes can lead to better product quality (water content, color, hardness, rehydration, volume, and ingredient retention) and favorable process parameters (shorter time, less energy consumption). However, little is known about the timing of the changeover point between the different processes. In this study, we investigated the development of quality parameters (volume retention, rehydration properties) during FD, HAD, and MVD either as a single or as a serial combination process with varying changeover point. Therefore, carrot disks were processed in a modular drying processor to different final relative moisture contents. On this basis, recommendations were derived for certain combinations of drying processes to achieve desired product quality parameters, partially with shorter drying times.

Seasonal variation in physiological responses, stress and metabolic-related hormones, and oxidative status of Murrah buffaloes

Harsh environmental conditions adversely affect the health and productivity of buffaloes. The present study was conducted to investigate the effect of seasonal thermal stress on the physiological responses, oxidative stress and some related hormones in Murrah buffaloes. A significant (p < 0.05) rise was observed in the rectal temperature, respiration rate, pulse rate and superoxide dismutase (SOD) during hot-humid (HH) and hot-dry (HD) seasons compared to thermoneutral (TN) season. Plasma cortisol and malondialdehyde (MDA) levels were low during TN season, intermediate in HD and highest during HH season. Although the levels of plasma triiodothyronine and thyroxine were high during TN season, their levels declined notably during HD and HH seasons. The temperature humidity index had a positive correlation (p < 0.01) with physiological responses, SOD, MDA and plasma cortisol levels. However, it was negatively correlated (p < 0.01) with the concentration of plasma thyroid hormones. The results reveal that buffaloes could cope efficiently with heat stress by reducing the levels of metabolic heat production-related hormones and releasing more antioxidant (SOD). However, they were still showing signs of stress which were reflected by higher levels of cortisol, lipid peroxidation (MDA) and physiological responses. Therefore, promoting health and productivity of buffaloes requires suitable management strategies to alleviate heat stress and provide comfort to them during extreme seasons.