A Note on Development of Industrial Drying Technology in China

Industrial drying technology in Chinese industry has been developing rapidly since the early 1980s. In the past 30 years, many products on both a small and a large scale have been initiated. The number of dryer varieties made in China has expanded from 10 to 60. About 20,000–30,000 dryers are made in China each year. Review of this development indicates that the tremendous progress in drying technology is due to a series of policy decisions and measures that were carried out, such as imported technology assimilation and further improvement of advanced overseas technology combining production and research and development. Drying technology development has benefited from the rapid economic development in China as well as market pull and market competition. Some suggestions are also put forward for future trends in this industry.     

Drying of Fish Press-Cake with Superheated Steam in a Pilot Plant Impingement System

Drying tests for pine sawdust and mackerel press-cake with hot air and with superheated steam were carried out in a pilot impingement cylindrical dryer. Wet particles move axially along the dryer, adjusting the inclination of the equipment, whereas hot gases circulate in cross-flow against the particles, forming a corotational impingement front. Feed rate and residence time of solids were studied experimentally as a function of dryer inclination for hot air and superheated steam as drying media. Drying rates and heat and mass transfer coefficients were found to increase at shorter residence times and higher gas temperatures. Dried mackerel press-cake with superheated steam resulted in a product with high moisture removal and very low losses of the valuable omega-3 fatty acids.     

Drying of Fish Press-Cake with Superheated Steam in a Pilot Plant Impingement System

Drying tests for pine sawdust and mackerel press-cake with hot air and with superheated steam were carried out in a pilot impingement cylindrical dryer. Wet particles move axially along the dryer, adjusting the inclination of the equipment, whereas hot gases circulate in cross-flow against the particles, forming a corotational impingement front. Feed rate and residence time of solids were studied experimentally as a function of dryer inclination for hot air and superheated steam as drying media. Drying rates and heat and mass transfer coefficients were found to increase at shorter residence times and higher gas temperatures. Dried mackerel press-cake with superheated steam resulted in a product with high moisture removal and very low losses of the valuable omega-3 fatty acids.     

Energy Analysis on Use of Air and Superheated Steam as Drying Media

ABSTRACT

The physical properties of air and superheated steam were analysed in a range of temperature applied in paper and paperboard drying processes. On the basis of tests carried out on a pilot stand the values of energy indices for air and steam drying processes are compared. With the drying media temperature as T_m = 300°C, nozzle velocity v= 60m/s and using the Huang and Mujumdar model as well as relationships given by Chance a compartive analysis of the results has been carried out Variation of several indices in the range of temperatures 100-600°C and various nozzle velocities was studied.     

Study of Intermittent Low-Pressure Superheated Steam and Vacuum Drying of a Heat-Sensitive Material

Low-pressure superheated steam drying (LPSSD) has recently been applied to drying of various heat-sensitive foods and bioproducts with success. Several studies have shown that the quality of LPSSD-dried products is superior to that obtained using conventional hot air or vacuum drying. However, drying time and energy consumption for LPSSD is generally greater than that for vacuum drying. Therefore, it is necessary to examine different methodologies to improve the energy efficiency of LPSSD. An intermittent drying scheme is one possible method to reduce the energy consumption of the process while maintaining the desired product quality. In this study, the effect of intermittent supply of energy (through an electric heater and steam injection to the dryer) and vacuum (through the use of a vacuum pump) at various intermittency values or on:off periods (10:5, 10:10 and 10:20 min in the case of intermittent supply of energy and 5:0, 5:5, and 5:10 min in the case of intermittent supply of vacuum) at the on-period setting temperatures of 70, 80, and 90°C on the drying kinetics and heat transfer behavior of the drying samples (banana chips) was studied. The effects of these intermittent drying schemes and conditions on the quality parameters of dried banana chips; i.e., color, shrinkage, texture, and ascorbic acid retention, were also studied. Finally, the energy consumption values for intermittent LPSSD and vacuum drying were monitored through the effective (or net) drying time at various intermittent drying conditions and compared with those using continuous LPSSD and vacuum drying.     

Superheated Steam Drying of Single Wood Particles: Modeling and Comparative Study with Hot Air Drying

A deterministic model is developed to describe the superheated steam drying process of single wood particles. A comparison between calculated data and experimental observations infers that the moisture‐dependent effective diffusivity is suitable to be used for beechwood material drying. To reduce the computational cost of the deterministic drying model, a semi‐empirical model is proposed within the framework of a reaction engineering approach (REA). The validity of the proposed model is checked by comparing against experimental data from literature. The experimental drying behavior may fairly be reflected by the reduced model. Due to the simplicity and predictive ability of the REA model, this semi‐empirical model can be implemented to describe heat and mass transfer between a population of single particles and a drying agent in dryer models.     

高水分玉米真空低温干燥工艺生产性试验研究

东北是我国玉米的主产区，产量占全国的30％～40％。受自然条件的影响，玉米收获水分常达22％～30％；成熟度及含水率都不均匀。根据玉米热敏性物料干燥的热特性及市场要求，考虑到它的热稳定性及破碎敏感性的特点，采用真空低温干燥技术进行了生产性试验，设计了300t／d高水分玉米真空低温连续干燥工业自动化生产线，对生产性试验关键技术进行了分析和研究。依据试验结果，分析玉米含水率、干燥介质温度、真空度、玉米温度、干燥时间、汽化蒸发温度等参数之间的联系与相互作用。生产试验表明：玉米含水率在24％时，维持干燥塔内真空度，采用高温水加热，汽化蒸发温度40～43℃，一次降水幅度达到10％～15％，保证了玉米品质的色、香、味、形及营养成分，具有干燥品质好、降水速度快、产量高、能耗低、操作方便、经济性价比高等优点。     

Intracellular Ca2+ Signaling in Protozoan Parasites: An Overview with a Focus on Mitochondria

Ca²⁺ signaling has been involved in controling critical cellular functions such as activation of proteases, cell death, and cell cycle control. The endoplasmatic reticulum plays a significant role in Ca²⁺ storage inside the cell, but mitochondria have long been recognized as a fundamental Ca²⁺ pool. Protozoan parasites such as Plasmodium falciparum, Toxoplasma gondii, and Trypanosoma cruzi display a Ca²⁺ signaling toolkit with similarities to higher eukaryotes, including the participation of mitochondria in Ca²⁺-dependent signaling events. This review summarizes the most recent knowledge in mitochondrial Ca²⁺ signaling in protozoan parasites, focusing on the mechanism involved in mitochondrial Ca²⁺ uptake by pathogenic protists.     

Thermodynamic Analysis on a Lignite-Fired Power System Integrated with a Steam Dryer: Investigation on Energy Supply System of the Dryer

Lignite is becoming a competitive fuel for power generation with high security of supply and a low price. But a power plant firing lignite directly always has some weaknesses, including low thermal efficiency and high construction investment. Predrying lignite before feeding it to the boiler is a potential method to tackle these weaknesses, and low-pressure steam extracted from steam turbines is considered a competitive heat source for the drying process. In a lignite-fired power system integrated with a steam dryer, the steam extraction is led to the dryer via a connection pipe and depressurization valve. To obtain a stable drying temperature at a variable load of power, steam extraction is often used by the dryer after depressurization, which indeed causes exergy loss. To reduce the exergy loss, the steam extraction was proposed to be supplied to the dryer via a compressor or ejector. Thermodynamic models were developed to calculate the net efficiency of a power system with different energy supply systems. The energy saving boundary—that is, the net efficiency of power system could be increased in some ranges of drying temperature by some energy supply system of dryer—was obtained. Furthermore, the exergy efficiencies were calculated.     

Effect of a Topical Collagen Tripeptide on Antiaging and Inhibition of Glycation of the Skin: A Pilot Study

The glycation process has been recognized as one of the critical parameters that accelerate signs of skin aging, especially in skin exposed to environment factors, such as ultraviolet radiation. Although previous studies showed the anti-inflammatory and antiaging properties of the hydrolyzed collagen tripeptide (CTP), its exact mechanism is not fully understood. Therefore, in this study, we sought to investigate the effect of a topical CTP on facial skin. Our group designed a 4 week prospective, single-arm study of 22 Asian women who applied topical CTP. We observed significant improvements in skin wrinkles, elasticity, and density with a reduction in skin accumulation of advanced glycated end products (AGEs) at week 4 without any adverse effects. The in vitro study revealed a preventive effect of the topical CTP on the accumulation of AGEs, denatured collagen production, and reactive oxygen species in dermal fibroblasts. Moreover, treatment with the CTP decreased induction of matrix metalloproteinases while increasing the collagen 1 level. These results suggest that the application of a topical CTP might improve clinical aging phenotypes via the inhibition of glycation and oxidative stress, leading to a delay in cellular aging.     

Design of microalgal biomass production in a continuous photobioreactor: An integrated experimental and modeling approach

The industrial production of microalgae in continuous photobioreactors (PBRs) was investigated using an integrated experimental-modeling approach.     

An Overview of Systematic Reviews of the Role of Vitamin D on Inflammation in Patients with Diabetes and the Potentiality of Its Application on Diabetic Patients with COVID-19

Almost two years have passed since the outbreak reported for the first time in Wuhan of coronavirus disease 2019 (COVID-19), due to severe acute respiratory syndrome (SARS)-CoV-2 coronavirus, rapidly evolved into a pandemic. This infectious disease has stressed global health care systems. The mortality rate is higher, particularly in elderly population and in patients with comorbidities such as hypertension, diabetes mellitus, cardiovascular disease, chronic lung disease, chronic renal disease, and malignancy. Among them, subjects with diabetes have a high risk of developing severe form of COVID-19 and show increased mortality. How diabetes contributes to COVID-19 severity remains unclear. It has been hypothesized that it may be correlated with the effects of hyperglycemia on systemic inflammatory responses and immune system dysfunction. Vitamin D (VD) is a modulator of immune-response. Data from literature showed that vitamin D deficiency in COVID-19 patients increases COVID-19 severity, likely because of its negative impact on immune and inflammatory responses. Therefore, the use of vitamin D might play a role in some aspects of the infection, particularly the inflammatory state and the immune system function of patients. Moreover, a piece of evidence highlighted a link among vitamin D deficiency, obesity and diabetes, all factors associated with COVID-19 severity. Given this background, we performed an overview of the systematic reviews to assess the association between vitamin D supplementation and inflammatory markers in patients with diabetes; furthermore, vitamin D’s possible role in COVID-19 patients was assessed as well. Three databases, namely MEDLINE, PubMed Central and the Cochrane Library of Systematic Reviews, were reviewed to retrieve the pertinent data. The aim of this review is to provide insight into the recent advances about the molecular basis of the relationship between vitamin D, immune response, inflammation, diabetes and COVID-19.     

Foaming of polypropylene with supercritical carbon dioxide: An experimental and theoretical study on a new process

A new process was used to foam polypropylene (PP) with batch foaming technique with supercritical carbon dioxide (scCO₂) as the blowing agent. Comparing with the conventional process, the new one takes less time to foam and the foaming temperature range is much broader, which is about 2.5 h and 55°C, respectively. An activation model was established on the basis of mass equilibrium, this model was combined with classical nucleation theory and S‐L EOS model to explain foaming behaviors of PP and simulate the cell nucleation and cell diameter. A satisfactory agreement between calculated and experimental values was obtained. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2877–2885, 2013