Optimisation of fluid application in grinding

This paper addresses the quantity of fluid required for grinding and the method of application. Results from this research suggest that supply flowrate needs to be 4 times the achievable ‘useful’ flowrate. Extra flowrate is wasted. It is shown that jet velocity and jet flowrate can be separately specified. Improved system design allows ‘actual’ useful flowrate to approach ‘achievable’ useful flowrate. Achievable useful flowrate depends on wheel porosity and wheel speed whereas actual useful flowrate depends on nozzle position, design, flowrate and velocity. Experimental methods are complemented by computational fluid dynamics (CFD) simulations.     

反应堆冷却剂沸腾中子噪声物理模型研究

中子噪声用于反应堆冷却剂沸腾监测有独特的作用。本文使用Ｗａｃｈ－Ｋｏｓａｌｙ的理论模型,比较成功地解释了堆芯中冷却剂的沸腾引起中子噪声,通过对压水堆局部沸腾零功率堆模拟实验的计算与分析,得出了判断汽泡上升速度的物理量。     

Study of the characteristics of temperature rise and coolant flow rate control during malfunction of PEM fuel cells

In actual PEM fuel cell systems, the coolant flow rate is generally controlled to maintain a preset temperature at the coolant outlet. This implies that a change in coolant supply flow rate is a good early indicator of a malfunctioning PEM fuel cell stack and system components. In this study, various fuel cell malfunctions are simulated based on the practical coolant flow control strategy by using a three-dimensional, two-phase, multiscale PEM fuel cell model developed in our previous studies. The focus is on analysis of the characteristics of coolant flow rate change along with voltage degradation in various fuel cell malfunction cases. The model predictions show that in general, the coolant flow rate tends to increase proportionally with the degree of voltage degradation, but the increase in temperature inside the membrane electrode assembly (MEA) is not always related to the voltage drop and is influenced more directly by local current density distribution. Although the present numerical comparison between the normal and malfunctioning cases is conducted at the low current density of 0.3 A cm^?2, the general cell behavior will not be altered at higher current densities due to inverse relationship between cell performance and waste heat generation. The present work elucidates the complex interplay among increase in coolant flow rate, increase in MEA temperature, voltage drop, and change in local current density distribution when a PEM fuel cell malfunctions.     

An investigation on solid lubricant moulded grinding wheels

The conventional flood coolants employed in grinding suffer many limitations in performing their functions. They cannot be recommended in the light of ecological and economic manufacture. Application of solid lubricant in grinding has proved to be a feasible alternative to the fluid coolants, if it could be applied in a proper way. Towards finding out an improved method of application of solid lubricant, attempts on development of solid lubricant moulded grinding wheels with various bonding and lubricants have been reported here. Such wheels with resin bonding were successfully made and improved process results were obtained. But the wheel wear depended on the type of the lubricant used.     

Evaluation of coolant power losses in a thermal plasma arc reactor

Coolant power losses, associated with the operation of a research prototype plasma arc reactor, have been studied experimentally and are described herein. These power losses were measured in four separate fluid-cooled plasma arc reactor zones while plasma power input levels were increased from 4.8 to 13.7 k W. During this increase, all other controllable variables, such as plasma gas flow rate and coolant fluid flow rate were held constant. As operating power levels were increased, the coolant power losses in all four fluid-cooled zones of the plasma arc reactor also increased. However, the relative distribution of power losses changed significantly as the plasma power input levels were increased.     

发动机冷却水三维流动数值模拟基础研究

本文在作者已完成的不可压缩流体三维流动数值模拟研究的基础上，对发动机冷却水三维流动的数值模拟方法进行了基础性研究。文章对具有发动机冷却水腹复杂形状的箱体内的水进行了三维流动模拟计算，介绍了数值模拟的基本方法，并对计算结果进行了分析，说明了该方法的有效性。该文介绍的内容是深入研究实际发动机冷却水三维流动数值模拟的基础。     

重型汽车柴油机冷却系统的化学保护

水冷式柴油机冷却系统与润滑系统、燃烧系统一样，对柴油机的可靠性、耐久性、经济性、动力性有着重要的影响，因此必须解决好其穴蚀、腐蚀和积垢等方面的问题，以确保柴油机冷却系统始终处于良好的工作状态．本文着重阐述重型汽车柴油机冷却系统的化学保护．     

热气溶胶的冷却技术

为解决热气溶胶释放时高温所带来的二次火灾问题，对其原因进行了分析，提出将冷却剂匹配使用，并合理设计装药结构的方法。     

国内外内燃机冷却水添加剂标准之比较

冷却水添加剂已广泛应用于内燃机，有关冷却水添加剂有许多国家和行业标准，本在综述国内外标准基础上，着重比较了中国和美国的有关标准。对有关冷却水添加剂标准下一步的制订提出了作的观点。