PORCELAIN ENAMEL AS A PROTECTIVE COATING FOR HOT-WATER TANKS*

The suitability of zinc and porcelain enamel as protective surfaces for water-storage tanks is discussed. The test methods are given in detail as well as the results of the simulated service tests.     

羰基的三甲基硅腈保护基脱除新方法

报道了用氟化钾－硝酸银在四氢呋喃－水（体积之比为６０：１）体系中脱除羰基的三甲基硅腈保护基的新方法,该法反应条件温和,反应体系为中性,产率较高,特别适合于对酸、碱敏感的底物。     

大化肥煤代油CO耐硫变换工艺流程的设计

分析石脑油制氨装置改扩建为水煤浆制氨装置ＣＯ耐硫变换工艺的特点，具体阐述其工艺流程优化设计中需考虑的主要技术问题。     

ADAPTIVE CONTROL OF A HEAT EXCHANGER USING FUNCTION BLOCKS

Many adaptive control strategies require on-line identification, which implies that a digital computer is needed for implementation. The objective of the work presented in this paper is to demonstrate that adaptive process control can be accomplished by combining relatively simple digital control algorithms called function blocks. These function blocks are easily implemented in low-level microprocessor-based digital controllers without requiring a computer. The feasibility of these methods is illustrated through an industrial heat exchanger control example, and the performance benefits of this adaptive approach are illustrated by means of simulation results.     

ADAPTIVE CONTROL OF A HEAT EXCHANGER USING FUNCTION BLOCKS

Many adaptive control strategies require on-line identification, which implies that a digital computer is needed for implementation. The objective of the work presented in this paper is to demonstrate that adaptive process control can be accomplished by combining relatively simple digital control algorithms called function blocks. These function blocks are easily implemented in low-level microprocessor-based digital controllers without requiring a computer. The feasibility of these methods is illustrated through an industrial heat exchanger control example, and the performance benefits of this adaptive approach are illustrated by means of simulation results.     

用H_2-CH_4气制备碳化铁的反应过程

用Ｈ２－ＣＨ４混合气制备碳化铁实验结果表明：铁矿粉还原生成碳化铁的过程由氧化铁的还原、甲烷的裂解和金属铁的碳化三个步骤组成为建立铁矿粉还原制备碳化铁的动力学模型提供了实验依据     

PROPERTIES OF KAOLINITE AS A FUNCTION OF ITS PARTICLE SIZE*

This investigation was undertaken to ascertain whether or not certain properties of kaolinite are definite functions of particle size. The studies were carried out on carefully fractionated, single-base kaolinite. The following properties of these fractions were measured: (a) base-exchange capacity, (b) permeability, (c) heat of wetting, (d) thermal conduct, and (e) drying shrinkage. Base-exchange capacity, heat of wetting, and drying shrinkage are not simple functions of the measured particle size of kaolinite because of the unpredictable physical characteristics and habits of the crystalline aggregates. The first three properties named are each linear functions of the other. These properties are independent of the physical groupings of the kaolinite crystals and therefore cannot be predicted from measured particle size except in the case of the finest fractions. Permeability is dependent both on apparent surface and true surface. Thermal-analysis curves may be useful as a rough guide to clay properties.     

采用布模板合成生物形态纳米MgO

以棉布为模板,通过浸渍和低温煅烧,在常压空气气氛中800℃成功地制备出棉纤维形态、纳米氧化镁.X射线衍射、扫描电镜、差热-热重及Fourier红外光谱分析表明:获得纤维状MgO为中空管状结构,煅烧后仍然保有生物模板的原始形状,管径约5μm,管壁厚约1～2μm.由Scherrer公式计算得出晶粒尺寸约14～19nm.     

A DRYING HEAT PUMP USING CARBON DIOXIDE AS WORKING FLUID

ABSTRACT

The application of carbon dioxide as working fluid in refrigeration and heat pump systems is regaining increasingly importance in view of the chlorofluorocarbon (CFC) substitution problem. It is both under ecological and economical aspects an attractive alternative to the hydrofluorocarbon (HFC) working fluids being in practical use. The thermophysical properties and characteristics of carbon dioxide are quite different from those of refrigerants used in conventional vapour compression cycles. Its application in conventional vapour compression refrigerating systems is limited by its critical parameters (t _c = 31.1°C and p _c = 73.8 bar). The possibility to use carbon dioxide also beyond these limits in high temperature processes, e.g., heat pumps, is given by the application of a trans-critical process. The design and construction of a commercial drying heat pump system (batch type cabinet dryer with 12 kW heating capacity and closed air circuit) using the natural working fluid carbon dioxide is shown and experimental results of investigations carried out are presented. Possible energy savings calculated theoretically are given for comparison.