LIU Gu
,
WANG Liu-ying
,
CHEN Gui-ming
,
HUA Shao-chun
钢铁研究学报(英文版)
Plasma surface hardening process was performed to improve the performance of the AISI 1045 carbon steel. Experiments were carried out to characterize the hardening qualities. A predicting and optimizing model using genetic algorithm-back propagation neural network (GA-BP) was developed based on the experimental results. The non-linear relationship between properties of hardening layers and process parameters was established. The results show that the GA-BP predicting model is reliable since prediction results are in rather good agreement with measured results. The optimal properties of the hardened layer were deduced from GA. And through multi optimizations, the optimum comprehensive performances of the hardened layer were as follows: plasma arc current is 90 A, hardening speed is 22 m/min, plasma gas flow rate is 60 L/min and hardening distance is 43 mm. It concludes that GA-BP mode developed in this study provides a promising method for plasma hardening parameters prediction and optimization.
关键词:
plasma transferred arc
,
surface hardening
,
optimization
,
neural network
,
genetic algorithm
WANG Hui-tao
,
WANG Hua
,
ZHANG Zhu-ming
钢铁研究学报(英文版)
Low temperature exhaust gases carrying large amount of waste heat are released by steel-making process and many other industries, Organic Rankine Cycles (ORCs) are proven to be the most promising technology to recover the low-temperature waste heat, thereby to get more financial benefits for these industries. The exergy analysis of ORC units driven by low-temperature exhaust gas waste heat and charged with dry and isentropic fluid was performed, and an intuitive approach with simple impressions was developed to calculate the performances of the ORC unit. Parameter optimization was conducted with turbine inlet temperature simplified as the variable and exergy efficiency or power output as the objective function by means of Penalty Function and Golden Section Searching algorithm based on the formulation of the optimization problem. The power generated by the optimized ORC unit can be nearly as twice as that generated by a non-optimized ORC unit. In addition, cycle parametric analysis was performed to examine the effects of thermodynamic parameters on the cycle performances such as thermal efficiency and exergy efficiency. It is proven that performance of ORC unit is mainly affected by the thermodynamic property of working fluid, the waste heat temperature, the pinch point temperature of the evaporator, the specific heat capacity of the heat carrier and the turbine inlet temperature under a given environment temperature.
关键词:
waste heat recovery
,
organic Rankine cycle
,
optimization
,
working fluid
,
exergy
,
pinch point
邓小旋
,
王强强
,
钱龙，王新华
,
黄福祥
钢铁
采用1∶1的水模型研究了5种不同底孔直径(16～28mm)的三孔水口下漏斗型薄板坯结晶器内的流场、液面特征和卷渣行为。结果表明：在常规工艺参数下，5种三孔水口下结晶器内钢液的流场都是典型的“双辊流”，且流场稳定；在5种三孔水口下结晶器液面波动都较平稳，且波动范围都在±(3～5)mm之间。5种不同水口下结晶器液面主要发生剪切卷渣，漩涡卷渣很少发生。试验得知：在水口浸入深度280mm，拉速为5m/min时，剪切卷渣发生的钢液临界表面速度是0.32m/s，与文献报道的模型计算值较吻合。在水口浸入深度280mm、拉速为5m/min的条件下，适合薄板坯连铸的最佳的三孔水口的底孔直径为22mm。
关键词:
三孔水口
,
thin slab
,
continuous casting
,
optimization
,
mold
,
slag entrapping
