Belgian Experiences in the Ozonization of Water

After reviewing the uses of ozone in the preparation of drinking water, high purity water for Pharmaceuticals industries, and swimming pools throughout Belgium, a discussion of technological developments made at the Tailfer plant (serving Brussels) concerning the uses of ozone is presented. These subjects include analytical and monitoring techniques developed for ozone, procedures for ozone contacting employed at this plant, treatment of ozone contactor off–gases, and the use of oxygen–enriched process gas to produce supplemental amounts of ozone required periodically. Capital and operating cost data are presented.     

基于MVC模式的Struts框架研究

Struts框架是当前Web应用开发中最流行的开发框架之一。在介绍了MVC模式的基础上对Struts框架的体系结构和工作流程作了介绍,并结合数据库连接池实现了一个电子商务网站的客户登录系统。     

MBR膜处理控制系统的实现

该文围绕MBR膜处理系统工艺,主要介绍了该控制系统的结构、组成、硬件配置和软、硬件设计。该系统以西门子S7—300系列PLC为控制核心,通过以太网与上位机通信,实现命令输入以及图形显示,通过PROFIBUS—DP现场总线与8个PLC功能子站进行数据通信,从而实现对整个系统的控制。PLC编程软件采用SIMATICSTEP7V5．4＋SP4,上位机软件采HMISCADAIFIX4．0组态软件。     

Effect of bulk lubricant concentration on the excess surface density during R134a pool boiling

This paper investigates the effect that the bulk lubricant concentration has on the non-adiabatic lubricant excess surface density on a roughened, horizontal flat pool-boiling surface. Both pool boiling heat transfer data and lubricant excess surface density data are given for pure R134a and three different mixtures of R134a and a polyolester lubricant (POE). A spectrofluorometer was used to measure the lubricant excess density that was established by the boiling of an R134a/POE lubricant mixture on a test surface. The lubricant is preferentially drawn out of the bulk refrigerant/lubricant mixture by the boiling process and accumulates on the surface in excess of the bulk concentration. The excess lubricant resides in an approximately 40 μm layer on the surface and influences the boiling performance. The lubricant excess surface density measurements were used to modify an existing dimensionless excess surface density parameter so that it is valid for different reduced pressures. The dimensionless parameter is a key component for a refrigerant/lubricant pool-boiling model given in the literature. In support of improving the boiling model, both the excess measurements and heat transfer data are provided for pure R134a and three R134a/lubricant mixtures at 277.6 K. The heat transfer data show that the lubricant excess layer causes an average enhancement of the heat flux of approximately 24% for the 0.5% lubricant mass fraction mixture relative to pure R134a heat fluxes between 5 and 20 kW/m². Conversely, both 1 and 2% lubricant mass fraction mixtures experienced an average degradation of approximately 60% in the heat flux relative to pure R134a heat fluxes between approximately 4 and 20 kW/m². This study is an effort toward generating data to support a boiling model to predict whether lubricants degrade or improve boiling performance.     

JSP数据库连接池的设计

探讨了JSP数据库连接池的设计思想和实现方法，在连接池的调度管理下，连接池动态地保持一定量的，并且保持不大于一定使用次数的空闲连接，使Web访问数据库的性能达到最佳。     

Numerical investigation on the heat transfer characteristics of a liquid-metal pool subjected to a partial solidification process

The main purpose of this paper is to investigate numerically the effects of solidification on the heat transfer characteristics of the liquid metal layer, for use in accident analyses. The situation is very similar to an overlying liquid melt pool that could be fooned in the reactor lower head during the late phase of a severe nuclear accident. Based on a computational model, MPCOOL, the numerical predictions were then assessed through a comparison with the experimental data that was obtained with various boundary temperature conditions and geometrical aspect ratios, especially for the Ra-Nu relationship. For the cases with solidification, the results of the comparison show that(a) the computational model does show a good agreement with heat transter rates inferred from the experimental data, with a few exceptions at the Ra numbers which suggest a turbulent transport; and also (b) the computational model underpredicts the heat transfer rates by about 6% than that inferred from the experimental data when it is integrally evaluated with the Ra-Nu correlation. The foregoing results are mainly due to the currently limited applicability of the computational model up to the laminar-to-turbulence transition flows and its application to the turbulence flows because it is always subjected to a model uncertainty between the laminar and turbulence. Next, an additional comparison for the cases with and without solidification was made to examine the effects of the solidification on the energy partition within the liquid metal layer and its effects on the directional heat transfer rates. The results of the comparison show that the computational model for the case without solidification predicts higher heat transfer rates by about 15% than when solidification is included, but there isn't any experimental data that directly supports this trend.     

Heat release characteristics of ethanol-water mixtures: Small-scale experiments

Small-scale pool fire tests of ethanol-water mixtures are described in this paper. The main goal of the tests was to obtain data on the heat release rate per unit area, the total heat release per unit area, and the effective heat of combustion of such mixtures with ethanol percentage of 20 vol% or more. The results can be utilised in the interpolation and extrapolation of these quantities for different ethanol percentages and irradiance levels. In addition, the results give information on the heat release of possible pool fires of alcoholic beverages in a retail store in the case of a fully developed fire. It was concluded that significant fire load is not formed until the ethanol percentage of the alcoholic beverage is ca. 20 vol% or more. The data reported can also be used as an input to simulations of ethanol-water mixture pool fires in the performance-based fire safety design.     

Fouling Resistance on Chemically Etched Hydrophobic Surfaces in Nucleate Pool Boiling

Chemical etching, liquid phase deposition, and dipping techniques were utilized to fabricate highly hydrophobic micro‐ and nanoscale coating surfaces on stainless‐steel substrates. Heat transfer and fouling characteristics on these surfaces in pool boiling of deionized water and CaSO₄ solution were studied. High roughness and hydrophobicity of coated surfaces were obtained on chemically etched substrates. Compared to the polished stainless‐steel surface, the chemically etched coating surface provided a three times enhanced nucleate boiling coefficient at high heat flux. Obvious decrease of CaSO₄ fouling resistance was obtained on chemically etched surfaces due to the higher roughness and hydrophobicity before the fouling resistance reaches the asymptotic value. Slightly high asymptotic fouling resistance was observed compared with coating surfaces without chemical etching of substrates.     

Total radiative heat loss and radiation distribution of liquid pool fire flames

The radiative characteristics of laboratory-scale pool fire flames have been studied in detail. Experiments were conducted in the ASTM E2058/ISO 12136 Fire Propagation Apparatus (FPA). Eleven liquid fuels with different sooting propensities, including alcohols and alkanes, burning in a 9.5 cm diameter quartz dish were considered. Radiative power distribution (along the flame axis) and global radiant emission were measured for all the fuels by using slit and wide-view-angle radiometers, respectively. The effects of measurement location and fuel type on the measured data were investigated. Radiation distribution profiles for a given fuel, when adequately normalized, show little sensitivity to the horizontal separation distance of the slit radiometer. Fuels with similar chemical structures exhibit similar distributions, consistent with flame image analyses. The radiative power distributions along with the wide-view-angle radiometer data were used to derive radiant fractions for the pool fires studied by applying a multiple-point source (MPS) radiation model. To examine the sensitivity of the calculated radiant fractions to the measurement location, the position of the wide-view-angle radiometer was considerably varied both vertically and horizontally. The results show that the radiant fractions derived based on the measured radiative power distribution are independent of the location of the wide-view-angle radiometer and consistent with literature values. Therefore, the approach developed in this study presents a flexible methodology apt for the accurate determination of radiation properties of diffusion flames in a laboratory setting.