EXPERIMENTAL STUDY OF CASSAVA SUN DRYING

ABSTRACT

Experiments were carried out in Davis, California, USA to compare sun drying of a bed of cassava chips placed in wire mesh trays with those placed in trays made of sheet metal. The wire mesh permitted wind to blow easily through the bed of chips, while the sheet metal constrained the wind to flow across the top of the bed, Drying was faster in the wire mesh trays; the chips reached a moisture content for safe storage after 27 hours of drying, while those in the sheet metal trays took 35 hours. The uniformity of drying was also markedly better in the wire mesh trays. Higher temperatures were attained in the chips contained in the sheet metal trays due to contact heat transfer between the trays and the chips. However the restricted air flow around the chips in the sheet metal trays led them to dry slower than those in the wire mesh trays.     

提高涤纶膨体变形长丝断裂强度初探

采用常规聚酯(PET)切片为原料,在进口专用纺丝机上生产PET膨体变形长丝(BCF)。选择合适的聚酯切片,优选预结晶和干燥工艺,合理设计纺丝温度,改进牵伸装置,优化牵伸工艺,生产出断裂强度大于2.5 cN/dtex的PET BCF。     

Effect of Homogenization Pressure and Oil Load on the Emulsion Properties and the Oil Retention of Microencapsulated Basil Essential Oil (Ocimum basilicum L.)

The objective of this work was to evaluate the influence of oil concentration and homogenization pressure on the emulsion and particle properties during the microencapsulation of basil essential oil by spray drying, using gum arabic as the wall material. Experiments were planned according a 2² rotational central composite design. The independent variables were oil concentration with respect to total solids (10–25%) and homogenization pressure (0–100 MPa). Emulsions were analyzed for droplet mean diameter, stability, and viscosity, and particles were analyzed for oil retention, moisture content, particle size, and morphology. Emulsion viscosity was not affected by any of the independent variables. The increase in the homogenization pressure from 0 to 100 MPa resulted in smaller emulsion droplet size (down to 0.40 µm) and, consequently, higher oil retention (up to 95%). On the other hand, higher oil loads (25%) resulted in poorer oil retention (51.22%). Microencapsulation of basil essential oil using gum arabic as the wall material proved to be a suitable process to obtain powdered basil essential oil, presenting great oil retention with the use of lower oil concentration and higher homogenization pressure.     

INTERMITTENT THIN LAYER CORN DRYING

ABSTRACT

In this study a block oriented modelling technique was introduced in order to simulate the intermittent drying technology process. First, the relevant blocks of the parameters concerning to drying air and the properties of material to be dried were developed. These blocks were then used to set up the full modell of a fix bed dryer including the temperature and moisture distribution of drying air and The material along the depth of the dryer. The simulation results were compared to Bakker-Arkema model with a good agreement. Finally, several measurements were performed for the case of thin layer of com to prove the advantage of the intermittent drying technology. It has been founded that in both energy saving and quality of dried product the intermittent technology has a significant contribution.     

DRYING KINETICS OF A MULTICOMPONENT MIXTURE OF ORGANIC SOLVENTS

ABSTRACT

Drying kinetics of volatile organic solvents have been examined during the drying process of a pharmaceutical coating containing a multicomponent mixture of ethyl acetate, n-heptane, propanol-2, and toluene. A complete set of experiments was performed in two drying apparatuses, a laboratory air-dryer and an oven dryer, for a wide range of drying temperature, air velocity, initial coating thickness and drying time. An empirical kinetic model is used to predict the concentration of each organic solvent in the mixture during the drying process. The results show that both drying conditions and sample characteristics affect significantly the drying rate of solvents.     

混凝土长墙收缩裂缝分析

对 5 6m混凝土长墙出现的贯穿性裂缝进行了计算及成因分析。通过对 2天拆模时的裂缝间距及宽度的计算 ,证明裂缝是由温度骤降引起的 ,而拆模过早和水平浇筑距离过长是事故的主要原因。为避免类似的混凝土长墙工程出现相似的情况 ,提出了施工措施建议。     

Studies on shrinkage,depth of cure,and cytotoxic behavior of novel organically modified ceramic based dental restorative resins

Polymerization shrinkage, depth of cure, and in vitro cytotoxic behavior of dental restorative composite based on inorganic–organic hybrid (organically modified ceramic) resins, containing alkoxides of silicone, calcium, and titanium with various polymeric methacrylate groups were evaluated in this study. Comparison was made between dimethacrylate and tetra methacrylate resins. Statistical evaluation using analysis of variance (single factor) showed that tetramethacrylate organically modified ceramic resin‐based composites showed better shrinkage properties. P < 0.05 was considered as statistically significant. Compared to dimethacrylates, tetramethacrylates based composites showed lower depth of cure value. Cytotoxicity characteristics of these composites were mainly depending on the nature of inorganic material incorporated rather than difference in dimethacrylate or tetramethacrylate structure. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Model‐Based Energy Efficiency Optimization of a Low‐Temperature Adsorption Dryer

Low‐temperature drying is important for heat‐sensitive products, but at these temperatures conventional convective dryers have low energy efficiencies. To overcome this challenge, an energy efficiency optimization procedure is applied to a zeolite adsorption dryer subject to product quality. The procedure finds a trade‐off between the improved drying capacity due to dehumidification and energy expenditure due to regeneration while incorporating product drying properties. By optimizing the regeneration air inlet temperature, drying air, adsorbent, and regeneration air flow rates as well as sensible and latent heat recovery from the regenerator exhausts, the energy efficiency is improved by up to 45 % compared to the state‐of‐the‐art. The high mass transfer effect of high temperatures is utilized in the regenerator to boost dehumidification while isolating the heat‐sensitive dried product from the quality‐degrading effect.     

骨汤粉末香精的生产工艺论述

随着食品市场多样化的发展,咸味香精不仅仅局限于液态和膏状,利用美拉德反应配合人工调配的氧化油脂和微乳化工艺,再经离心喷雾干燥而成的粉末香精,既保留了通过美拉德反应的逼真肉香,又能通过乳化包埋、喷雾干燥得到风味浓郁、使用方便的食品香精。     

Microencapsulation of β‐carotene using native pinhão starch,modified pinhão starch and gelatin by freeze‐drying

Beta‐carotene was microencapsulated by freeze‐drying using native pinhão starch, hydrolysed pinhão starch 6 dextrose equivalent (DE), hydrolysed pinhão starch 12 DE and the mixture of these materials with gelatin as coating material. The purpose of this research was to produce and characterize these microcapsules. The capsules’ efficiency, surface content, moisture, morphology, solubility, particle size and glass transition temperature were analysed. The hydrolysed pinhão starch 12 DE showed the highest total β‐carotene content and the lowest surface β‐carotene content, unlike the native starch. Using scanning electron microscopy, it was observed that all microcapsules presented undefined shapes. The samples with gelatin had wider particle size distribution, higher diameters, lower solubility and higher glass transition temperature when compared with other the samples. Results obtained suggest that the modified pinhão starch can be considered as potential wall material for encapsulation of β‐carotene.