Moist Materials Research Articles

Potential of Harum Manis Mango (Mangifera Indica L.) Seed Extract for Nosocomial Infections

Nosocomial infections occur in hospitals and attack patients who are in the recovery process and have low immunity. The emergence of nosocomial conditions in the hospital environment is caused by bacteria and moist objects or materials, especially in the operating room and even the treatment room for children and babies. One type of bacteria that causes the infection is Pseudomonas aeruginosa. P. aeruginosa has been recognized as an irreversible problem in hospitals due to resistance to 3 antibiotic classes. The content of sweet mango seeds has a high phytochemical content in the form of steroid compounds, terpenoids, flavonoids, alkaloids, phenolics, tannins and saponins. This study aimed to determine the potential of sweet mango seed extract against nosocomial infections. The research method is quantitative experimental, using ethanol extract of sweet fragrant mango seeds with well diffusion and dilution tests (MIC and MBC). The results of the antibacterial activity test measured the inhibition zone formed and tested MIC and MBC. MIC value of sweet fragrant mango seed extract showed at 1.56 mg/mL and 0.78, and at MBC value of 25 mg/mL and 50 mg/mL. The results of sweet fragrant mango seed extract have the potential to be developed as an antibacterial agent, especially against nosocomial infections.

Chicken litter: A waste or a source of chemicals? Fast pyrolysis and hydrothermal conversion as alternatives in the valorisation of poultry waste

Poultry production is one of the main and fastest developing branches of the agri-food industry in the world. Chicken litter (ChL) is the most abundant waste from this industry and requires alternative treatments to help mitigate the environmental impacts of improper disposal. Fast pyrolysis and hydrothermal conversion are two recognized thermochemical approaches for the transformation of different types of biomasses, including agro-industrial waste. Fast pyrolysis takes place at atmospheric pressure or under vacuum at moderate to high temperatures (400–800 °C) in the absence of oxygen and requires drying of the feedstock, whereas hydrothermal conversion is a low temperature (180–300 °C) and high pressure (up to 30 MPa) process that takes place in liquid water and particularly suited for moist materials. In this work, we present experimental results that provide a comparison of bio-oils produced by fast pyrolysis and hydrothermal conversion of ChL. In addition, the composition of the pyrolytic oils from ChL is compared with the data obtained from rice husk (the main component of ChL), studied previously. Fast pyrolysis experiments were carried out in a bed reactor at temperatures ranging from 400° to 700°C and at two reaction times of 20- and 40-min. Phenols and other oxygenated compounds were the main families of chemicals present in the bio-oils. Among oxygenated derivatives, fatty acids were predominant. Hydrothermal conversion experiments were performed between 220 and 240 °C for 20- and 40- min and the oil fraction was obtained by evaporation of water from the reaction mixture followed by freeze-drying. These bioliquids were found to be concentrated in fatty acids, especially palmitic acid.

Impact of reattachment surface characteristics on the flow field generated by slot jet reattachment nozzle – A numerical study

Slot jet reattachment (SJR) nozzle is a novel nozzle design that overperforms the regular impingement nozzles or perforated plates for heat transfer and drying, heating or cooling applications of moist materials. The SJR nozzle is a viable design to dry fragile products such as food and paper. Mesh-type conveyor belts are commonly used in the food industry. There is a need for understanding how the SJR nozzle performs with mesh-type conveyor belts because prior studies have solely considered solid surfaces. Therefore, an extensive numerical study is performed to solve the flow field of the SJR nozzle with an exit angle of +45° on top of a mesh-type belt with and without products using COMSOL Multiphysics® without including heat transfer. Turbulent fluid flow is theoretically modeled using the k-ɛ turbulence model for the SJR nozzle. The numerical predictions are validated with experimental data for stationary surface. Six different cases are studied to capture the effects of the presence of products on the belt and the conveyor belt speed. Additionally, the presence of an SJR nozzle on the bottom of the belt with and without a lateral offset is studied. The mass flow rate escaping underneath the belt is compared to the total mass flow rate at the nozzle exit, shear stresses are compared at three different surface velocities, and maximum force magnitudes as product travels are reported. The results show that the flow can reattach to the product surface regardless of surface motion, but reattachment characteristics depend on product orientation with respect to the SJR nozzle. Although significant mass flow escapes through the belt, the presence of products mitigates this loss. In addition, doubling the belt speed increases the shear stresses applied by the surface and decreases the average mass flow loss. Also, an additional SJR nozzle on the bottom of the belt almost cancels this mass flow loss even when there is a lateral offset between the nozzles.

Investigation of the drying process of moist materials under convective heat input conditions

One of the most important tasks of agricultural production is to obtain food products of plant origin, which include grain legumes, vegetables, fruits, etc. Long-term storage of many kinds of plants in their natural form under normal conditions is not possible and requires the use of processing, such as drying. A special niche is occupied by medicinal plants, on the basis of which medicinal preparations, biologically active additives (BAAs), as well as spices for food are produced. Nowadays, out of 100 thousand medicines used in the world medical practice, medicinal preparations made of plants make up more than 30%. In our country the share of such remedies and preparations is about 40%. In addition to natural methods of drying, artificial methods are widely used with the help of special drying units. This requires large amounts of electrical or thermal energy from fuel combustion, as more than 65,000 tonnes of medicinal raw materials are harvested in our country each year. It is not always possible to achieve the required product performance. The use of electric energy seems to be the most preferable, since it eliminates the costs of delivery, storage of solid or liquid fuel, reduces environmental damage, and obtains the necessary properties through “fine” control of the drying technology. Currently, farms and individual farms specialise in growing medicinal plants and supplying medicinal raw materials for homeopathic pharmacies and pharmacological industries. In this regard, improving drying methods and creating small capacity electric drying plants that ensure an efficient technological process and reduce the energy intensity of drying is an urgent task.

Study on Designing and Manufacturing the Freeze Drying System with the Process of Freezing Moist Materials inside the Freeze Drying Chamber to Preserve Valuable Products

Freeze drying is one of the most advanced drying technologies for food processing and preserving using temperature under 0oC or under the freezing point, and pressure of drying chamber environment under 4.58mmHg to process foods. This method helps to maintain the initial quality of proteins, lipids, carbohydrates, vitamins, bioactive substances and sensory activities… In this study, the calculation and design were carried out to find suitable technology parameters to make the freeze drying system in which the freezing process occurred inside the freeze drying chamber. Heat was transferred by short wavelength thermal radiation, l = 50´10-3 m. As a result, time of freeze drying had been shortened to 13.33h/batch. The system was successfully manufactured, showed the steadily working, producing the high quality products, and reduced products price. In the conditions of Vietnam, the freeze drying system replacing that of other countries is the indispensable factor to apply for processing and preserving foods.

Equations for Calculating the Thermal Conductivity of Capillary-Porous Materials with over Sorption Moisture Content

This article is the result of the authors’ work on the method of calculating the effective thermal conductivity of moist capillary-porous materials used in wall partitions. The proposed methodology was developed based on the theory of generalized conductivity and geometric modeling of the structure. Materials are considered as heterogeneous ternary systems consisting of a solid skeleton, gas and liquid, and all components are simultaneously taken into account in the calculation. In this work, additional equations are constructed that allow calculation of the effective thermal conductivity of capillary-porous materials with over sorption moisture, thus extending the scope of application of the method to the entire possible range of changes in moisture content. The details of calculating the thermal conductivity of moist capillary-porous materials are demonstrated using experimental data for wall ceramics samples. It is shown that the proposed equations are capable of predicting the thermal conductivity of moist capillary-porous materials with sufficient accuracy. Knowledge of the thermal conductivity of materials in conditions of their actual moisture is fundamental in the sustainable design of new buildings as well as thermo-renovation and dump protection of historic ones.

INVESTIGATION OF SOYBEAN PROCESSING BY FORCING – EXTRACTION METHOD

The study of the influence of physicochemical parameters of different sorts of soybean on the extraction of oil in soybean processing, as were as determining the quality of soybean products – petal, meal and oil. Soybean seed samples of three sorts were selected for the study: Mriya, Skelya and Ukrainka, of different humidity and degree of contamination. The Perten DA 7250 infrared analyzer and physicochemical methods in accordance with DSTU were used to determine the quality indicators of soybean seeds. Skelya sort was noted as more oily (20.36%), and Ukrainka sort as more protein (38.49%), the mass fraction of fiber in the samples is from 5.9 to 6.5%. The scheme of soybean processing by the method of forcing – extraction with hexane at the enterprise of «Tavria Agroinvest» was used. Soybean oil is extracted according to the technological regime of the enterprise. After the process of extraction and distillation of the solvent in the evaporator tank, unrefined soybean oil and soybean meal are obtained. According to the scheme of the extraction process, the quality of the final product will depend on the degree of grinding of raw materials and the quality of the petal. Organoleptic and physicochemical parameters of unrefined soybean oil and soybean meal obtained at «Tavria Agroinvest» from three sorts of soybean seeds were determined. It is shown that from moist materials (18.5%) is obtained oil with higher acid and peroxide numbers. The iodine number and cloud point of soybean oil of this sample are also higher than those obtained for dry seeds. The quality indicators of soybean meal for the studied soybean seed sorts were obtained. Mass fraction of crude protein in terms of absolute dry matter is the largest for the Skelya sort and is 46.2%. Soybean meal sort Mriya is less purified from moisture and crude fat, and its high acid number can shorten the shelf life.

Optimization of the thermal conductivity test for building insulation materials under multifactor impact

The thermal conductivity of building materials is an important parameter in building thermal engineering and energy conservation. When building thermal insulation materials are placed in the real environment, they are affected by dynamic temperature and humidity conditions, and most materials have certain moisture content. However, moist materials have a different thermal conductivity than dry materials, and an inaccurate estimation of thermal conductivity will cause errors in the energy conservation calculation of the building envelope. To accurately measure the thermal conductivity under a controllable environment and reduce energy conservation calculation errors, the effects of the measuring apparatuses, drying temperature, specimen size, specimen moisture content, ambient temperature and humidity on the thermal conductivity of the building thermal insulation materials are studied. The sensitivity of thermal conductivity to various influencing factors is analyzed, and the thermal conductivity value of moist building thermal insulation materials is determined as the basis to select or design products for building envelopes. In addition, the test method of thermal conductivity for building thermal insulation materials is optimized.

Mechanism of strengthening looseness and overcoming plugging during rigid-flexible coupled ultra-high elastic screening and parameter optimization

In this paper, a novel rigid-flexible coupled ultra-high elastic screen surface was proposed. Then vibration test was conducted to investigate kinematic characteristics of the screen surface. Moreover, a high-speed camera device was utilized to study deformations of the screen surface and the mechanism of strengthening looseness and overcoming plugging. Furthermore, the screening performance of screen surface was investigated. The obtained results show that the maximum acceleration and the displacement of the proposed screen surface can be as high as 27 g and 21.37 mm, which are 8.82 times and 7.32 times of the side plate area, respectively. Accordingly, the screen surface can produce strong impact on the sticky and moist materials, so as to make materials loosen and overcome the plugging problem of the screen surface. After optimizing the parameters, the screening efficiency can reach the maximum value of 85.41% and the content of the total misplaced material is 7.07%.

Isothermal drying characteristics and kinetics of human faecal sludges.

Background: Drying is an important step for the thermochemical conversion of solid fuels, but it is energy-intensive for treating highly moist materials. Methods: To inform the thermal treatment of faecal sludge (FS), this study investigated the drying characteristics and kinetics of various faecal wastes using thermogravimetric analysis and isothermal heating conditions. Results: The findings show that FS from the anaerobic baffled reactor (ABR) and ventilated improved pit latrines (VIP) exhibit similar drying characteristics, with maximum drying rates at 0.04 mg/min during a constant rate period that is followed by a distinct falling rate period. On the contrary, fresh human faeces (HF) and FS from urine diversion dry toilets (UDDT) exhibited a falling rate period regime with no prior or intermittent constant rate periods. The absence of a constant rate period in these samples suggested limited amounts of unbound water that can be removed by dewatering and vice versa for VIP and ABR faecal sludges. The activation energies and effective moisture diffusivity for the sludges varied from 28 to 36 kJ/mol and 1.7·10 -7 to 10·10 -7 m 2/s at 55°C and sludge thickness of 3mm. The Page model was consistent in modelling the different sludges across all temperatures. Conclusions: These results presented in this study can inform the design and development of innovative drying methods for FS treatment.

Stereospecific Response of E/Z-isomers of N-Nitrososarcosine in LC-ESI-MS/MS.

The carcinogenic compound N-nitrososarcosine (NSAR) is found in foods and tobacco products, and its quantification is of great interest. Although the presence of two stereoisomers, E- and Z-NSAR, is well-known, individual investigation of the isomers has not been reported so far. The present study by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) reveals that (i) the mass spectrometric responses of the isomers differ by a factor of approximately two and (ii) the isomer ratio is unstable in freshly prepared standard solutions. As a consequence, NSAR concentrations determined by LC-ESI-MS/MS are biased if those facts are not taken into account. The method described here overcomes the difficulty of stereospecific response by adjusting the isomer ratio and was applied to 100 tobacco products and fully validated for moist and dry snuff reference materials showing expanded measurement uncertainties of ~20% and limits of quantification of ~20ng/g.

Determining Soil Moisture Content and Material Properties with Dynamic Cone Penetrometer

This study utilised static triaxial and dynamic cone penetration tests to examine the identification of changes in strength in soil materials as a result of an increase in moisture content. The applicability of a light dynamic cone penetrometer device in railway environments was also studied. On a broader scale, the aim was to find an investigation method suited to field locations that identify low-quality or persistently moist materials directly from the structure. The triaxial tests found an apparent increase in shear strength when the water content dropped below 7%. Based on the series of laboratory tests, the dynamic cone penetrometer reacted strongly to material density, but the impact of moisture content was also evident. Furthermore, the results showed that dynamic cone resistance is a reasonably unfeasible metric for assessing the structural quality of materials consisting primarily of sand, due to the number of factors affecting the resistance. In the laboratory tests, the lowest dynamic cone resistances were measured in the material with the highest structural quality.

Research on Static and Dynamic Characteristics of Shear Spring of the Vibrating Flip-Flow Screen

The vibrating flip-flow screen (VFFS) is a high-efficiency device currently used for deep screening of moist fine-grained materials. During VFFS operation, the normal operation of the screen is affected by fatigue damage to the shear springs arranged symmetrically on both sides of the screen, leading to equipment failures and disruption production. In this paper, the shear spring’s static and dynamic characteristics in different operation conditions were studied using the INSTRON 8801 fatigue test system and Dynacell dynamic sensors. Using an experimental test of shear spring stiffness and damping coefficients, the effects of some factors, i.e., temperature, hardness, amplitude and frequency, were studied. The results show that the temperature of the shear spring on the left side of the flip-flow screen was higher than that of the right side (driving side). With an increase in temperature, the stiffness of the shear spring decreased. With the increase in amplitude, the dynamic stiffness decreased and the damping coefficients did not change; with the increase in frequency, the dynamic stiffness increased and the damping coefficient decreased. At the same amplitude, with the increase in hardness of the shear spring, the dynamic stiffness increased. Finally, the stiffness and damping coefficients of the shear spring before and after tearing were obviously reduced. These research results reveal the relationship of the characteristics of a shear spring with operational conditions, and could provide a theoretical reference for the design of the VFFS and the selection of the shear spring.

Isothermal drying characteristics and kinetics of human faecal sludges

Background: Drying is an important step for the thermochemical conversion of solid fuels, but it is energy-intensive for treating highly moist materials. Methods: To inform the thermal treatment of faecal sludge (FS), this study investigated the drying characteristics and kinetics of various faecal wastes using thermogravimetric analysis and isothermal heating conditions. Results: The findings show that FS from the anaerobic baffled reactor (ABR) and ventilated improved pit latrines (VIP) exhibit similar drying characteristics, with maximum drying rates at 0.04 mg/min during a constant rate period that is followed by a distinct falling rate period. On the contrary, fresh human faeces (HF) and FS from urine diversion dry toilets (UDDT) exhibited a falling rate period regime with no prior or intermittent constant rate periods. The absence of a constant rate period in these samples suggested limited amounts of unbound water that can be removed by dewatering and vice versa for VIP and ABR faecal sludges. The activation energies and effective moisture diffusivity for the sludges varied from 28 to 36 kJ/mol and 1.7·10 -7 to 10·10 -7 m 2/s at 55°C and sludge thickness of 3mm. The Page model was consistent in modelling the different sludges across all temperatures. Conclusions: These results presented in this study can inform the design and development of innovative drying methods for FS treatment.

Impact of the Drying Temperature and Grinding Technique on Biomass Grindability

The process of biomass compaction depends on many factors, related to material and process. One of the most important is the proper fragmentation of the raw material. In most cases, more fragmented raw material makes it easier to achieve the desired quality parameters of pellets or briquettes. While the chipping of biomass prefers moist materials, for grinding, the material needs to be dried. As drying temperature changes the properties of the material, these may affect the grinding process. The aim of this work was to determine the influence of the drying temperature of biomass raw material in the range of 60–140 °C on the biomass grindability. To only determine this effect, without the influence of moisture, grinding was carried out on the material in a dry state. The research was carried out on a mill with a knife and hammer grinding system, which is the most popular in the fragmentation of biomass. The analysis of particle size distribution and bulk density of the obtained material was carried out. The energy demand for the grinding process was determined and it was shown that drying temperature, grinding system, and mainly type of biomass affects the grindability.

Development of an apparatus with induced heat-and-mass transfer for drying and hydrothermal processing of moist materials

The need to solve the problems of efficient use of energy resources in processes of heat-and-mass transfer which are widely used in the food and processing industries and are very power-intensive was substantiated. The prospects of application of the induced processes such as the effect of induced heat-and-mass transfer characterized by high energy efficiency and environmental friendliness were noted. Drying and hydrothermal treatment of moist raw materials with gas-tight inserts in horizontal and vertical orientations were modeled. It was established that the nature of this effect in the presence of gas-tight inserts in the solid phase inside the thermostat does not differ from the nature of the effect of induced heat-and-mass transfer in absence of such inserts. It was proved that during the induced heat-and-mass transfer, features of the flow of any volume of internal thermostat medium affect the nature of this flow for other allocated volumes. It was noted that the feature of «artificiality» and controllability of this effect makes it possible to perform certain manufacturing operations in processing different raw materials in one device without their mixing. A technical solution of an apparatus using the effect of induced heat-and-mass transfer for drying and hydrothermal treatment of moist raw materials was proposed based on the obtained experimental results and established theoretical conclusions. The productivity of the developed apparatus in hydrothermal processing of cereals makes 18 kg/h and the energy consumption is 8.1·10 6 J/kg of dried product. The final product is a quick-recoverable porridge that does not require cooking. It was noted that the economic attractiveness of the developed device with the effect of induced heat-and-mass transfer for drying and hydrothermal treatment consists in the ability to reduce energy consumption for these manufacturing operations by 30 %

Isothermal drying characteristics and kinetics of human faecal sludges

Background: Drying is an important step for the thermochemical conversion of solid fuels, but it is energy-intensive for treating highly moist materials. Methods: To inform the thermal treatment of faecal sludge (FS), this study investigated the drying characteristics and kinetics of various faecal wastes using thermogravimetric analysis and isothermal heating conditions. Results: The findings show that FS from anaerobic baffled reactor (ABR) and ventilated improved pit (VIP) latrines exhibit similar drying characteristics, with maximum drying rates at 0.04 mg/min during a constant rate period that is followed by a distinct falling rate period. On the contrary, fresh human faeces (HF) and FS from urine-diverting dry toilets (UDDT) exhibited a falling rate period regime with no prior or intermittent constant rate periods. The absence of constant rate period in these samples suggested limited amounts of unbound water that can be removed by dewatering and vice versa for VIP and ABR faecal sludges. The activation energies and effective moisture diffusivity for the sludges varied from 20 to 30 kJ/mol and 3∙10-7 to 1∙10-5 m2/s at 55°C and sludge thickness of 3mm. The Page model was consistent in modelling the different sludges across all temperatures. Conclusions: These results presented in this study can inform the design and development of innovative drying methods for FS treatment.

Dependencies for Determining the Thermal Conductivity of Moist Capillary-Porous Materials

A method of determining the effective thermal conductivity of moist capillary-porous materials has been proposed, in which calculations are carried out while taking into account all components of the system (solid, liquid and gas) at once. The method makes it easy to take into account the way water is distributed in the pore space of the material, either as isolated inclusions (drops) or as a continuous component, depending on the moisture content of the material. In the analysis of heat transport in moist capillary-porous materials, the theory of generalized conductivity is used and the structure of moist material is modeled using an ordered geometric structure consisting of identical unit cells in the form of a cube. An equation is obtained for calculating the effective conductivity of capillary-porous materials with isolated and continuous liquid inclusions, with adiabatic and isothermal division of the unit cell. The proposed method is compared to the previously proposed method of determining the effective thermal conductivity of moist materials, in which the three-component system is gradually reduced to a binary system, showing disadvantages of this method compared to the currently proposed. It has been shown that the proposed formulas grant the possibility of a sufficiently accurate prediction of experimental results using the experimental results of the thermal conductivity of moist aerated concrete.

Convective drying of food materials: An overview with fundamental aspect, recent developments, and summary

AbstractConvective drying is an ancient technique to dry moist materials. Many experimental and numerical studies on convective drying enriched the knowledge of researchers and industrialists for further research and developments. In this study, a thorough review is made on convective drying of food materials. A brief history of convective drying, its importance, methods, applications, and statistical data are clearly reviewed. The impact of important drying parameters such as shrinkage and influence of pretreatment during convective drying have been critically appraised. Instruments used, experimental setup developed, and properties measured and estimated have been listed and analyzed. A novel technology of taking snapshots during drying using the thermal camera is discussed. Different mathematical models such as analytical and numerical methods and its present challenges are extensively reviewed and discussed. An advanced level solution for convective drying at present is explained. Gaps in numerical methods to solve convective drying problems have been discussed and effective summaries are drawn.

Terms and constructive measures of transition from laboratory installations to industrial design of vortex dryers

Vortex and cyclone apparatuses are increasingly used for intensive flow of combined technological processes of pro-cessing (fine grinding, classification, drying, mixing, hydrophobization, etc.) dispersed materials. One of the types of equipment of this class with an active hydrodynamic regime is an apparatus with an upward (or downward) spiral-swirling gas-dispersed flow. The studies conducted by A.F. Frolov, V.I. Mushtaev, V.M., Ulyanov and B.S. Sazhin con-firm the high drying efficiency of highly moist dispersed materials. One of the tasks of a large-scale transition from laboratory facilities to industrial designs is the development of design features that determine the similarity of the hy-drodynamic regimes of heat and mass transfer processes. To determine the hydrodynamic characteristics of the gas-dispersed flow, methods based on the measurement of flow rates, velocities and hydraulic resistances were used. To establish the drying curves and the temperature curves of the polydisperse material (TPP hydraulic ash removal) of different fractions under various conditions of convective heat input, the kinetic method was applied. This method was based on measuring the moisture (mass) and temperature of the dried particles by selecting along their movement. The developed conditions and design measures allow for a large-scale transition from laboratory facilities to industrial de-signs without intermediate costly research on pilot plants. The generalized analytical and experimental data on the de-termination of the external heat and mass transfer characteristics of the drying process of dispersed material (hydraulic ash removal) in a vortex dryer depending on the hydrodynamic and structural parameters of the gas-dispersed flow have been presented. The presented experimental data allow suggesting the limiting effect of hydrodynamic phenomena that determine the efficiency of the drying process of dispersed materials in a gas stream.