采煤工作面局部风流雾化降温效果分析

为分析低温雾化喷淋对高温采煤工作面局部风流的降温效果,采用Eulerian-Lagrangian二相流描述方法,通过液滴与湿空气的双向耦合作用,对高温风流的降温效果进行了数值计算,计算结果表明：1次降温后,风流温度约有4℃的急剧降低,1排喷嘴的有效作用距离为10 m,10 m后,风流温度又逐渐升高1.5℃,总体上,回采面风流的温度呈现出阶跃性的上升趋势;拟合得到的风流降温效果随喷嘴流量呈负指数变化;液滴喷射角在70°~90°范围时,降温效果较明显,而细水雾的高压雾化喷嘴能明显提高降温效果。     

Coupled effects of flow field geometry and diffusion media material structure on evaporative water removal from polymer electrolyte fuel cells

In this work, the coupled effects of flow field geometry and diffusion media (DM) material structure on evaporative water removal during gas purge are investigated with the ex-situ test methods developed in previous works 31 and 32. Three different flow field structures with various land to channel width ratios (L/C) were utilized with paper and cloth-type DM to understand the impact of L/C and DM properties on evaporative water removal rate, water distribution in DM, purge efficiency, and irreducible saturation. In the capillary flow dominant regime, it was determined that evaporative water removal is not significantly affected by L/C or DM properties, and can be semi-empirically correlated with critical purge time. The cloth-type DM was found to be superior to paper-type to mitigate the in-plane impedance of the land on water removal. In addition to the ex-situ evaporative tests, neutron radiography was utilized to visualize the in-situ water removal behavior. Results validate a novel purge protocol suggested by the authors in a previous study to achieve a more efficient and durable gas purge that preserves membrane durability.     

AN EXPERIMENTAL EVALUATION OF THE GOVERNING MOISTURE MOVEMENT PHENOMENA IN THE PAPER COATING PROCESS. I. THEORETICAL ASPECTS

The most important issue when coating paper is the modelling of the moisture movement in the coating process, since the water movement pattern is strongly connected to binder movement and the final structure of fibres and coating colour, which in turn affects the final printing properties of the paper. Therefore, we are now studying a novel laboratory method to determine the dynamic water movement in a hygroscopic porous media, i.e. the liquid movement in the paper coating process. The experimentally determined physical properties yield information relevant to the mass and energy balances of a real paper coating process. We have also studied the widely used Lucas-Washburn capillary suction theory in combination with the build-up of a filter-cake in the coating colour. The study shows, that the water loss from the coating colour into a hygroscopic material can be well explained by applying vapour diffusion into the base paper as the governing mass transfer mechanism.     

Research on new method of electron beam candle melting used for removal of P from molten Si

Abstract

A new method, electron beam candle melting (EBCM), is proposed for the removal of P in molten Si, to produce high quality material such as solar grade silicon for photovoltaic applications. EBCM is designed to overcome the shortcomings of electron beam melting while utilising the high saturated pressure of P in molten Si to effect refining. The experimental result showed that it could remove P from Si effectively; in addition, the energy utilisation ratio was experimentally proved to be high. The evaporation coefficient of P removal is in a reasonable region and comparable with the theoretical value, which indicates that EBCM is a feasible method for the removal of P in molten Si in low power.     

Comparison of Simplified Pan-Based Equations for Estimating Reference Evapotranspiration

Accurate estimation of reference evapotranspiration (ET0) is essential for irrigation practice. Conversion from pan evaporation data to reference evapotranspiration is commonly practiced. The objective of this study was to evaluate the reliability of simplified pan-based approaches for estimating ET0 directly that do not require the data of relative humidity and wind speed. In this study, three pan-based (FAO-24 pan, Snyder ET0, and Ghare ET0) equations were compared against lysimeter measurements of grass evapotranspiration using daily data from Policoro, Italy. Based on summary statistics, the Snyder ET0 equation ranked first with the lowest RMSE value (0.449?mm?day?1). The pan-based equations were additional tested using mean daily data collected in Novi Sad, Serbia. The Snyder ET0 equation best matched ET0 estimates by Penman-Monteith equation at Novi Sad with lowest root mean square error value of 0.288?mm?day?1. The obtained results demonstrate that simplified pan-based equations can be successful alternative to FAO-56 Penman-Monteith equation for estimating reference evapotranspiration. The overall results recommended Snyder ET0 equation for pan evaporation to evapotranspiration conversions. The Snyder ET0 equation consistently provides better results compared to FAO-24 pan equation, although required measurements of only one weather parameter pan evaporation.     

A novel ice slurry producing system: Producing ice by utilizing inner waste heat

Ice storage is a potential energy saving method for air conditioning systems. An ice slurry is an ideal material for ice storage. The conventional ice slurry producing method using supercooled water suffers from the instability of ice block and depends heavily on electric power. A novel ice slurry producing system utilizing inner waste heat was proposed to improve this situation. This system consists of two major processes: an evaporative supercooling process and a liquid dehumidification process. Both theoretical and experimental works are presented about these two processes. Simulation analysis has been made on the evaporative supercooling process and the performance of the whole system. Experiments were performed about the two processes. The theoretical conclusion agrees well with the experimental results. Compared with the conventional system, this new system can alleviate the burden on electric power and raise the efficiency. Those improvements are essentially attributed to the reutilization of the inner waste heat generated from the system itself.     

Mechanism of droplet generation in silver thin films for organic light-emitting diode displays

Thin silver film is widely used as the cathode in organic light-emitting diode displays and it is generally fabricated using the thermal evaporation method. But during the evaporation process, there is an inevitable outgassing problem and this creates high viscosity bubbles in melted silver. When the bubbles break, the high energy released scatters silver droplets which damage the silver surface. In this study, we were able to decrease the number of droplets from 6,171 to 278 with a degassing process of 400 °C for 6 h before proceeding with a thermal evaporation process.     

烧碱液蒸发过程的有效能分析

利用有效能概念对烧碱液蒸发系统进行有效能的分析.在分析时,充分考虑了物质的物理和化学有效能,为蒸发系统的节能提供了依据.     

船用直喷式柴油机燃油蒸发、燃烧模型

为了更好地预测船用柴油机的性能，改进了包括燃油蒸发和燃烧过程的准维多区燃烧模型，该模型采用数值模拟计算方法，考虑了缸内工质的对流辐射换热，用正十六烷和α－甲基萘按适当比例混合来模拟燃油，在空气卷吸计算中考虑了燃油碰壁和着火对空气卷吸的影响，经实验验证，本模型理论计算与实测结果吻合良好，表明本模型对柴油机工作过程的模拟是正确的，应用本模型可以方便地预测发动机的性能。