BULK DENSITY, POROSITY AND RESISTANCE TO AIRFLOW OF GARLIC SLICES

The bulk density of garlic slices at different moisture levels (ranging from approximately 3 to 65% MC wet basis) was determined by weighing the contents of a container of known volume. The porosity was calculated using its relationship with bulk and apparent densities. An analysis of variance (ANOVA) revealed that bulk density and porosity were affected significantly by moisture and slice thickness as well as the interaction of these variables. Bulk density varied in a positive linear fashion with moisture and thickness while a negative linear correlation was found for the calculated bulk porosity. The linear model met me adequacy criterion for characterising the behaviour of garlic. Using a laboratory unit, the vertical resistance to airflow through the product and die effect of moisture and slice thickness were investigated for an airflow rates of 0.09 to 1.2 m³/s-m². A higher resistance to airflow was noted for the wet product with the experimental data fitting to Shedd's model when the airflow range was divided into two sub-flow rates and to a modified Ergun's equation for the full range.     

AIRFLOW RESISTANCE OF OAT SEEDS: EFFECT OF AIRFLOW DIRECTION,MOISTURE CONTENT AND FOREIGN MATERIAL

ABSTRACT

Pressure drops through oat (Oat Sp.) beds were evaluated in the range of airflow rate from 0·0097 to 0·459 m³/s-m² using two airflow directions to determine the effect of grain moisture and foreign material on the resistance to airflow. Horizontal airflow resistance was lesser than vertical airflow resistance (e.g., for oat with 9·0% moisture content the pressure drop in horizontal direction was 4–17% of corresponding in vertical direction). The resistance decreased with the increase of moisture content and increased when the fraction of foreign material. An increase in the moisture content from 9·0 to 24·9% produced a decrease on the bulk density from 583 to 513 kg/m³. Mattel's model (1969) fitted adequately the experimental data. The Haque et al.'s equation (1982) have an adequate representation of the data for both airflow directions. The Paterson et al. (1971) and Bern-Charity (1975)equations resulted applicable only for vertical airflow direction. A simplification planed of this model in function of the bulk density conduced to a good relation DP-Q.     

固体返料气流-流化组合干燥器的湿含量分布

分析了固体返料气流 -流化组合式干燥器出口粒子湿含量分布特性 ,建立了湿含量分布密度函数 ,并就硫酸亚铁的干燥过程进行了模拟计算 结果表明 ,具有降速段的流化床干燥器的优化设计 ,除了应满足干燥过程的热量供求平衡并由此确定流化床底面积外 .还应满足 :①保证湿分传质汽化所需的停留干燥时间 ,应根据干燥所需的平均停留时间来确定流化床容积 ;②控制湿含量的分散程度 ,应由干燥产品的均匀性指标来确定流化床室数 .     

A THIN LAYER METHOD FOR THE INVESTIGATION OF BULK DENSITY AND AIR FLOW RESISTANCE DISTRIBUTIONS DURING DEEP BED DRYING

A thin layer experimental method is presented for the investigation of the effect of compression and drying on bulk density and air flow resistance. A thin layer was subjected to a compressive load and ventilated with drying air to simulate the conditions within a deep bed. The technique is analogous to thin layer drying work and in the same way produces thin layer equations which can be incorporated in deep bed simulation programs. It was found that for a bed of germinated barley (malt) the volume change could be considered in terms of three components: initial compaction, transient settling and drying shrinkage. These were correlated with bed pressure, time and moisture content reduction. The effect of initial compression and settling was shown to produce bulk density variations of the order 20% in 1.5 metre beds. Drying shrinkage was found to produce a height reduction of the order 15%. The pressure gradient due to air flow resistance was increased by as much as a factor of six as a result of compression. Moisture content did not have a great effect on air flow resistance.     

A THIN LAYER METHOD FOR THE INVESTIGATION OF BULK DENSITY AND AIR FLOW RESISTANCE DISTRIBUTIONS DURING DEEP BED DRYING

A thin layer experimental method is presented for the investigation of the effect of compression and drying on bulk density and air flow resistance. A thin layer was subjected to a compressive load and ventilated with drying air to simulate the conditions within a deep bed. The technique is analogous to thin layer drying work and in the same way produces thin layer equations which can be incorporated in deep bed simulation programs. It was found that for a bed of germinated barley (malt) the volume change could be considered in terms of three components: initial compaction, transient settling and drying shrinkage. These were correlated with bed pressure, time and moisture content reduction. The effect of initial compression and settling was shown to produce bulk density variations of the order 20% in 1.5 metre beds. Drying shrinkage was found to produce a height reduction of the order 15%. The pressure gradient due to air flow resistance was increased by as much as a factor of six as a result of compression. Moisture content did not have a great effect on air flow resistance.     

计算蒸发潜热的通用公式

著者综合前人计算蒸发潜热的经验公式,诱导出一个新的计算公式如下:λ/T_c=-6.7logP_r(T_r/(1-T_r)~(0.62))任何物质在任何温度T与压力P状态下的蒸发潜热λ,只要有了该物质临界温度与临界压力的数据,就可以根据这个公式计算.式中T_r为绝对温度与临界绝对温度之比,P_r为压力与临界压力之比.此公式的错误小于百分之五.     

CORRELATIONS FOR THE EQUILIBRIUM MOISTURE CONTENT OF SOI.IDS

Water adsorption and desorption isotherms at various temperatures have been generated for a variety of particulate materials (ion exchange resin, silica gel, wheat and cellulose materials). Most of thc data were obraincd with the SPS Equilibrium Moisture Content rig, using a dynamic equilibration method. Equilibration over saturated salt solutions at 2°C (static method) was also used for some of the data. Seven semi-empitical correlations, available in the literature, and one developed by SPS have been used to relate the equilibrium moisture content of the material to the relative humidity and temperature of the air. These equations enable the equilibrium moisture content to be predicted under various conditions of relative humidity and temperature from a small number of tests. For each of the six materials tested at least one of the correlations gave a good fit. However, there was no correlation which predicted the equilibrium moisnrre content well for every one of the six materials.     

室外用超薄膨胀型钢结构防火涂料的耐湿热性能研究

采用三聚氰胺、季戊四醇和聚合度为20的聚磷酸铵作为超薄膨胀型钢结构防火涂料的防火助剂时,在湿热环境下使用,涂层表面有白色晶体析出,防火性能显著降低,采用红外光谱分析确认此白色晶体为聚磷酸铵。采用聚合度大于60的聚磷酸铵和聚磷酸三聚氰胺代替聚合度为20的聚磷酸铵,试验结果表明,在保持防火性能的同时,能显著提高涂料的耐湿热性能。     

中国神府-东胜煤降水提质的可能途径

根据神府—东胜煤的特性提出了降水提质的可能途径。可为扩大神府—东胜煤的利用和销路提供参考。     

AN IMPROVED GENERALIZED WATSON EQUATION FOR PREDICTION OF LATENT HEAT OF VAPORIZATION

In this paper, an improved generalized Watson equation for the prediction of latent heats of vaporization at any temperature in the two-phase region for any substance has been proposed. Generalized relations for exponents n₁, and n_2, have also been established, respectively.

In the current work, the latent heats of vaporization calculated with the proposed equation are compared with corresponding experimental values presented in the literature for 108 substances involving a total of 3361 points. These comparisons are further examined using the results of the original Watson equation and three other well-known equations available in the literature. The results of these comparisons indicate that the proposed equation is more accurate than the other four equations.     

硬质聚氨酯泡沫塑料力学性能与密度、增强剂含量的关系

探讨了硬质聚氨酯泡沫塑料的力学性能与密度、增强剂含量的特别是在较宽的密度和增强剂含量范围内对硬质聚氨酯泡沫塑料进行了应用研究,为其作为结构材料提供了依据。     

AN IMPROVED GENERALIZED WATSON EQUATION FOR PREDICTION OF LATENT HEAT OF VAPORIZATION

In this paper, an improved generalized Watson equation for the prediction of latent heats of vaporization at any temperature in the two-phase region for any substance has been proposed. Generalized relations for exponents n ₁, and n _2, have also been established, respectively.

In the current work, the latent heats of vaporization calculated with the proposed equation are compared with corresponding experimental values presented in the literature for 108 substances involving a total of 3361 points. These comparisons are further examined using the results of the original Watson equation and three other well-known equations available in the literature. The results of these comparisons indicate that the proposed equation is more accurate than the other four equations.     

A GENERALIZED EQUATION OF STATE FOR POLAR AND NON-POLAR FLUIDS BASED ON FOUR-PARAMETER CORRESPONDING STATES THEOREM

A new generalized equation of state for polar and non-polar fluids based on the corresponding states theorem is developed, f n addition to two critical parameters, four parameters are required; two for the calculation of volumetric properties and two for the calculation of pressure and departure functions. Parameteres for more than 100 polar and non-polar fluids are given. Comparison with the existing generalized state equations showed that the new method, in general, shows a better agreement with the experimental data. The absolute average deviation is 0.48% for the vapor pressure and 0.32% for the saturated liquid volume.     

高强高密石墨材料的制备研究现状

讨论了高强高密石墨材料的性能和应用,从原料选择和工艺强化两个方面进行了分析。重点讨论了超细石墨粉、生焦粉、中间相炭微球、"二次焦"、COPNA树脂等原料制备高强高密石墨材料的优点和实际应用中的不足,对现行的高压成型、加压焙烧、加压成型焙烧、多次浸渍再焙烧进行了分析总结。     

TSY-32型物料水份快速检测仪水分指数定标法探讨

本文介绍了ＴＳＹ－３２型物料水份快速检测仪的结构和定标原理,并且在非标原理和相对值原理的基础上提出和探讨了一种新的定标方法———水份指数定标法。     

GENERALIZED SEMI-EMPIRICAL NON CUBIC EQUATION OF STATE FOR THE REPRESENTATION OF PROPERTIES OF PURE SUBSTANCES

The analytical equation of state first introduced by Ponce and Renon was modified. At a given temperature, the addition of a corrective term in virial form yields an equation with four parameters. All parameters are assumed temperature dependent and properties of pure substances can be represented with 11 parameters. A corresponding state form using the characteristic parameters T_c, P_c, ω was developed. It yields an improvement in representation of molar volumes compared with the generalized cubic (Soave, Peng-Robinson) and non cubic (Simonet) equations. Enthalpy can also be calculated.     

水分对吡虫啉缩合反应的影响及对策

探讨了水分对吡虫啉缩合反应的影响,并找出一种脱水新工艺。过程总收率为６３．３９％（以－２氯－５－氯甲基吡啶计）,产品质量分数大于９０％。     

AN APPROXIMATION METHOD FOR THE DETERMINATION OF THE DISTRIBUTION OF TEMPERATURE AND OF MOISTURE CONTENT IN THE FALLING RATE PERIOD OF DRYING

The present paper deals with the periods of dif- ferent drying mechanism. A calculation method is pre- sented for the temperature distribution of the material during these periods and for distribution of moisture content in the falling rate period. The test material was a 100 x 100 x 30 mm gypsum plate.     

AN APPROXIMATION METHOD FOR THE DETERMINATION OF THE DISTRIBUTION OF TEMPERATURE AND OF MOISTURE CONTENT IN THE FALLING RATE PERIOD OF DRYING

The present paper deals with the periods of dif- ferent drying mechanism. A calculation method is pre- sented for the temperature distribution of the material during these periods and for distribution of moisture content in the falling rate period. The test material was a 100 x 100 x 30 mm gypsum plate.     

合成气压缩机气流激振原因分析和处理

合成气压缩机在投用以后,因振动原因达不到满负荷生产,通过对故障现象分析,确定振动由气流激振引发,通过对气封和轴承进行改进,达到了设备稳定运行的目的。