湿度标准及湿度计量之进展

Determination of the wet-bulb temperature at the surface of a material is the basis of one class of humidity measuring instruments, and is important in industrial applications such as dryer modelling and simulation. The psychrometer equation is a frequently used method of estimating wet-bulb temperature, and contains a psychrometer “constant”. Analysis shows that this is in fact a variable coefficient affected by temperature, pressure,radiation and conduction effects, and the identity of the gas and vapour. Radiation and conduction affect the difference between adiabatic saturation temperature and indicated wet-bulb temperature. Inconsistencies in currently recommended values for the psychrometer coefficient, including published international standards, are identified and explained. Particular problems arise when the enhancement factor is applied to vapour pressure to account for non-ideality of gases. Special considerations are also needed for wet-bulb temperatures approaching the boiling point, where the psychrometer coefficient tends to zero. Self-consistent recommendations recently published in the new British Standard BS1339 are given, which cover both the air-water system and a general vapour-gas system.     

空气湿度对干燥过程的影响

以脉冲气流干燥过程为研究对象,利用数值模拟方法,分析了空气湿度对干燥过程的影响。     

卫生陶瓷干燥制度中临界湿度的确定

以实验为依据分析了影响临界湿度的主要因素,并在此基础上得出了临界湿度确定的原则.     

流化床干燥器中临界湿含量测定

介绍用气相法和固相法测定流化状态下物料临界湿含量的方法，并将实验结果与洞道式干燥器中测得的数据做了比较。结果表明，用气相法测定流化状态下物料临界湿含量具有操作简便、快速和省料的优点。     

石化企业仪表风空气干燥装置的优化设计

仪表风又被称作仪用空气,是针对石化企业的化工装置提供工厂仪表用空气专门设计的。作为企业正常运行中最关键和最基本的装置,空气干燥装置的设计情况直接关系到该企业的运作状况,本文通过对石化企业仪表风空气干燥装置设置过程中的管道材料、设备选型、以及设备布置等影响因素的具体分析,试图为企业的具体设计过程中提供有益参考。     

氯气透平机保护气用干燥空气的制备

介绍了取代氮气作氯气透平机保护气的空气的干燥工艺,采用空气降低了生产成本。     

带自控系统的PVC干燥空气加热装置的研究

针对PVC干燥工序,设计了一种带自动控制系统的空气加热装置。该装置主要由送风机装置、空气加热器装置、干燥装置、冷凝水疏水装置构成,具有加热效率高、节约能耗、使用范围广、通用性强、自动控温等优点。     

相反转乳化—液中干燥法制备线型氯甲基化聚苯乙烯微球

采用相反转乳化—液中干燥法成功制备出在2~40μm粒径可控且分散性较好的线型氯甲基聚苯乙烯(PCM S)微球,考察了搅拌速度、油相/水相比例、乳化分散体系的组成及加入量等因素对微球粒径及粒径分散度的影响;用扫描电子显微镜观察了微球的形貌。研究结果表明,采用相反转乳化—液中干燥法可制备出球形度极好的PCM S微球;搅拌速度、乳化分散体系的组成与加入量对PCM S微球的粒径都有很大的影响,而影响微球粒径分散系数的主要因素是搅拌速度与油相/水相的比例,分散剂的量对分散系数也有很大的影响。     

强制干燥空气温度对木质家具用单组分水性封闭底漆的水分挥发规律的影响

在湿度恒定、温度变化的强制干燥条件下,为了探讨在重涂间隔时间内温度对水分挥发速度和挥发量的影响,本研究以枫木薄木贴面家具板件为基材,以单组分水性封闭底漆为涂料,在相对湿度恒定为50%、温度为15～35℃范围内强制干燥涂层,研究涂层的水分挥发规律。结果表明:随时间的推移,同一温度条件下,水性封闭底漆的水分挥发率不断增加,水分挥发速度逐渐降低;不同温度条件下,水分挥发率和挥发速度差异不明显;相同的时间段内,在15～25℃温度范围内水分挥发率的差异程度要小于25～35℃的干燥条件;随着时间的推移,水分挥发速度的差距越来越不明显。     

MEASUREMENT OF HUMIDITY ABOVE TEMPERATURE OF 100°C WITH A DOUBLE-WICK WET BULB PSYCHROMETER

A need exists for a simple device to measure the psychrometric properties of high temperature and high humidity air. To meet this need, a small laboratory double-wick psychrometer was developed and tested which showed good results to 175°C dry bulb temperature and 100°C wet bulb temperature. Based on the results of the laboratory unit, a portable prototype psychrometric system was designed and built. The overall design provided quick measurement and indication of wet bulb temperature, dry bulb temperature, humidity, and enthalpy of a high temperature air stream.     

NATURAL ZEOLITES IN AIR DRYING

The local clinoptilolite from Bigadis region in Turkiye, was used for air drying in packed column. The effective diffusion coefficient of water in natural zeolite was found as 5×10^-10 m² s^-1 from isothermal uptake measurements. Effects of packing height and airvelocity on breakthrough curves were studied.     

Cu/TiO2催化湿式氧化甲醛废水

甲醛废水排放入水体后,破坏生态系统,影响人们的身体健康。考察了以自制的Cu/TiO2为催化剂,用催化湿式氧化的方法降解甲醛废水的情况。通过优化反应条件,在180℃、pH=5、0.5 MPa、催化剂量为6 g/L时反应2 h,TOC的去除率高达85%,且Cu2+和Ti4+基本没有流失。此外还检测了甲醛溶液中甲醇变化情况和经处理后甲醛废水的降解产物甲酸。结果表明,以Cu/TiO2为催化剂的催化湿式氧化能有效地降解甲醛废水。     

NATURAL ZEOLITES IN AIR DRYING

ABSTRACT

The local clinoptilolite from Bigadis region in Turkiye, was used for air drying in packed column. The effective diffusion coefficient of water in natural zeolite was found as 5×10^?10 m² s^?1 from isothermal uptake measurements. Effects of packing height and airvelocity on breakthrough curves were studied.     

SHRINKAGE OF APPLE DISKS DURING DRYING BY WARM AIR CONVECTION AND FREEZE DRYING

Volumetric and thickness shrinkage evaluated by direct measurement and n-heptane displacement were determined during convective and freeze drying of Golden delicious apples. For convective drying, the influence of blanching and diameter/thickness ratio of the apple disks used were analysed at different levels of moisture content under constant conditions. It was found that shrinkage of dried samples, both by convection and by freeze-drying, is anisotropic to a level which depends on sample geometry (ratio diameter/thickness) used. Blanching did not affect shrinkage results.

Based on results obtained a new model to predict bulk density of materials during drying is proposed, showing a better fit to experimental data than previous models reported in the literature. This model was further used to predict changes in apple porosity during drying.     

WATER TRANSFER IN POTATO DURING AIR DRYING

ABSTRACT

Drying data (moisture vs time) were obtained on slabs of potato in an air dryer operated at 70°C and an air velocity of 1.6 m/s. The considerable differences between the experimental data and the receeding front: and Fickian diffusion models for moisture profiles were found. The temperature in the potato sample increased with increasing drying time. This increase which results in starch gelation might be the main reason in the formation of moisture profile peaks.     

污泥湿式空气氧化处理研究的进展

本文综述了湿式空气氧化的发展过程，技术要点和催化氧化的研究领域以及该技术的发展动向和前景。     

WATER TRANSFER IN POTATO DURING AIR DRYING

Drying data (moisture vs time) were obtained on slabs of potato in an air dryer operated at 70°C and an air velocity of 1.6 m/s. The considerable differences between the experimental data and the receeding front: and Fickian diffusion models for moisture profiles were found. The temperature in the potato sample increased with increasing drying time. This increase which results in starch gelation might be the main reason in the formation of moisture profile peaks.     

SHRINKAGE OF APPLE DISKS DURING DRYING BY WARM AIR CONVECTION AND FREEZE DRYING

ABSTRACT

Volumetric and thickness shrinkage evaluated by direct measurement and n-heptane displacement were determined during convective and freeze drying of Golden delicious apples. For convective drying, the influence of blanching and diameter/thickness ratio of the apple disks used were analysed at different levels of moisture content under constant conditions. It was found that shrinkage of dried samples, both by convection and by freeze-drying, is anisotropic to a level which depends on sample geometry (ratio diameter/thickness) used. Blanching did not affect shrinkage results.

Based on results obtained a new model to predict bulk density of materials during drying is proposed, showing a better fit to experimental data than previous models reported in the literature. This model was further used to predict changes in apple porosity during drying.     

DRYING OF AIR IN SILICA GEL PACKED COLUMNS

Silica gels that were made humidity indicating by impregnation of CoCl₂ were used for air drying in isothermal packed column. The effects of type of silica gel, packing height, particle size and air flow rate on breakthrough curves were studied. The breakthrough curves predicted by Rasmuson and Neretniek's analytical solution were in good agreement with experimental data.