In the design of the CAT 3408 engine, the Low Temperature (BT) circuits used to cool the engine lubricating oil and the charge air and the High Temperature (HT) circuits for cooling the cylinder liners, cylinder heads...In the design of the CAT 3408 engine, the Low Temperature (BT) circuits used to cool the engine lubricating oil and the charge air and the High Temperature (HT) circuits for cooling the cylinder liners, cylinder heads and body of turbofans are mainly used to cool the engine, so that it works properly. This work, based on the analysis carried out, to determine the lubrication compliance of the Yacco VX 100 - SAE 15 W-40 oil and that of the Camwater water used in the engine of the Boat Yang 1 by carrying out a series of conventional tests such as that: the density, the viscosity, the viscosity index, the flash point, the density, the sulphate center content, the water content, the total acidity index (TAN), total basic number (TBN) and pour point for the oil case and pH, hardness, sodium chloride content [NaCl], sodium sulphate content [NaSO<sub>4</sub>] for the water case which will be compared to the specified requirements to determine whether compliance is achieved for each of these characteristics. The results of the oil and water samples taken from the engine after use show that the used oil gives a specific gravity of 0.8822, a viscosity (at 40°C) of 92.29 mm<sup>2</sup>/s, a viscosity (at 100°C) of 13.99 mm<sup>2</sup>/s, a viscosity index (VI) of 155.39, a pour point -21°C, a Flash Point (VO) 215°C, a Sulfated ash content of 18%, a density 881.5 kg/m<sup>3</sup>, a total basic number (TBN) of 12.60 mgKOH/g, a Total Acid Index (TAN) of 3.096 mgKOH/g, a Water Content of 1.8 % and the water used gives a pH of 6.00, a hardness of 3.2 french degrees, a sodium chloride content [NaCl] of 0.468 mg/L, and a calcium sulphate content [CaSO<sub>4</sub>] of 2.38345 mg/L. the results of the water content and content of sulfated centers justify the thermal overload and power losses in the marine diesel engine CAT 3408 of the boat Yang 1 because of their values which are not in conformity with the standards.展开更多
Thermal overload relays are economic electromechanical protection devices which offers reliable protection for electric motors in the event of overload or phase failure. Presently there are two types of overload relay...Thermal overload relays are economic electromechanical protection devices which offers reliable protection for electric motors in the event of overload or phase failure. Presently there are two types of overload relays which depend on the temperature characteristics of metals to provide protection by tripping the circuit. These relays lack accuracy as they do not activate the trip circuit at any exact specified temperature. In this paper we introduce a new form of thermal over-load relay actuated by ferrofluid. The ferrofluid has a very accurate transition temperature known as curie temperature. It acts as a ferromagnetic material below the curie temperature and loses the property of ferromagnetism above this temperature. By using this property of the fluid we propose an alternative method for more accurate op-eration under overload condition. This relay finds application in the protection system of electrical machines. Thus, in this paper we present a novel and simple technique for protection against thermal overloading using ferrofluid.展开更多
电力需求的增长和系统容量的提升对输配电电缆的传输容量和运行可靠性提出了更高的要求,有效利用高压直流(high voltage direct current,HVDC)电缆线路的动态增容潜力对于实现电力资源优化配置具有重要意义。通过有限元分析(finite elem...电力需求的增长和系统容量的提升对输配电电缆的传输容量和运行可靠性提出了更高的要求,有效利用高压直流(high voltage direct current,HVDC)电缆线路的动态增容潜力对于实现电力资源优化配置具有重要意义。通过有限元分析(finite element analysis,FEA)方法建立了不同敷设环境中高压直流电缆线路的暂态热场及电场模型,仿真分析了电缆在多种典型动态负荷下的温度分布及绝缘电场特性,研究发现:相比于架空及土壤直埋敷设,隧道敷设的HVDC电缆系统热响应时间常数达到数百小时,因此具有更好的动态增容能力。论文以隧道中敷设为例,通过相应FEA模型反演计算了不同初始负荷与应急时长下直流电缆的允许最大过负荷电流,给出了针对HVDC电缆线路短时动态增容能力的评估方法,并对直流电缆线路动态增容过程中的暂态电热特性进行了分析。结果表明:初始负荷率高,应急持续时间长,绝缘电导率温度敏感性强的高压XLPE直流电缆在动态增容过程中场强变化幅度大,应予以特别关注;初始负荷率不超过50%的隧道敷设双极直流电缆线路,单级可在1.5倍额定电流下安全运行2 h。该结果可为工程中HVDC电缆线路动态增容与优化调度提供理论指导。展开更多
为更准确预测输电线路未来允许的输送容量,提出利用动态提高输电线路输送容量(dynamic line rating,DLR)系统及混沌理论预测线路的输送容量。利用改进的C-C算法可靠性高、计算速度快的特点对容量时间序列进行相空间重构,并证实了线路允...为更准确预测输电线路未来允许的输送容量,提出利用动态提高输电线路输送容量(dynamic line rating,DLR)系统及混沌理论预测线路的输送容量。利用改进的C-C算法可靠性高、计算速度快的特点对容量时间序列进行相空间重构,并证实了线路允许输送容量具有混沌特性,可运用混沌理论预测线路输送的容量。然后采用基于奇异值分解的混沌时间序列Volterra方法对一条安装有DLR系统的110kV线路可输送的容量及线路可能发生的热过载故障进行预测。预测结果显示该方法能够反映容量序列未来变化的趋势及线路发生热过载故障的风险性,提高了预测的精度,是有效、可行的。展开更多
文摘In the design of the CAT 3408 engine, the Low Temperature (BT) circuits used to cool the engine lubricating oil and the charge air and the High Temperature (HT) circuits for cooling the cylinder liners, cylinder heads and body of turbofans are mainly used to cool the engine, so that it works properly. This work, based on the analysis carried out, to determine the lubrication compliance of the Yacco VX 100 - SAE 15 W-40 oil and that of the Camwater water used in the engine of the Boat Yang 1 by carrying out a series of conventional tests such as that: the density, the viscosity, the viscosity index, the flash point, the density, the sulphate center content, the water content, the total acidity index (TAN), total basic number (TBN) and pour point for the oil case and pH, hardness, sodium chloride content [NaCl], sodium sulphate content [NaSO<sub>4</sub>] for the water case which will be compared to the specified requirements to determine whether compliance is achieved for each of these characteristics. The results of the oil and water samples taken from the engine after use show that the used oil gives a specific gravity of 0.8822, a viscosity (at 40°C) of 92.29 mm<sup>2</sup>/s, a viscosity (at 100°C) of 13.99 mm<sup>2</sup>/s, a viscosity index (VI) of 155.39, a pour point -21°C, a Flash Point (VO) 215°C, a Sulfated ash content of 18%, a density 881.5 kg/m<sup>3</sup>, a total basic number (TBN) of 12.60 mgKOH/g, a Total Acid Index (TAN) of 3.096 mgKOH/g, a Water Content of 1.8 % and the water used gives a pH of 6.00, a hardness of 3.2 french degrees, a sodium chloride content [NaCl] of 0.468 mg/L, and a calcium sulphate content [CaSO<sub>4</sub>] of 2.38345 mg/L. the results of the water content and content of sulfated centers justify the thermal overload and power losses in the marine diesel engine CAT 3408 of the boat Yang 1 because of their values which are not in conformity with the standards.
文摘Thermal overload relays are economic electromechanical protection devices which offers reliable protection for electric motors in the event of overload or phase failure. Presently there are two types of overload relays which depend on the temperature characteristics of metals to provide protection by tripping the circuit. These relays lack accuracy as they do not activate the trip circuit at any exact specified temperature. In this paper we introduce a new form of thermal over-load relay actuated by ferrofluid. The ferrofluid has a very accurate transition temperature known as curie temperature. It acts as a ferromagnetic material below the curie temperature and loses the property of ferromagnetism above this temperature. By using this property of the fluid we propose an alternative method for more accurate op-eration under overload condition. This relay finds application in the protection system of electrical machines. Thus, in this paper we present a novel and simple technique for protection against thermal overloading using ferrofluid.
文摘电力需求的增长和系统容量的提升对输配电电缆的传输容量和运行可靠性提出了更高的要求,有效利用高压直流(high voltage direct current,HVDC)电缆线路的动态增容潜力对于实现电力资源优化配置具有重要意义。通过有限元分析(finite element analysis,FEA)方法建立了不同敷设环境中高压直流电缆线路的暂态热场及电场模型,仿真分析了电缆在多种典型动态负荷下的温度分布及绝缘电场特性,研究发现:相比于架空及土壤直埋敷设,隧道敷设的HVDC电缆系统热响应时间常数达到数百小时,因此具有更好的动态增容能力。论文以隧道中敷设为例,通过相应FEA模型反演计算了不同初始负荷与应急时长下直流电缆的允许最大过负荷电流,给出了针对HVDC电缆线路短时动态增容能力的评估方法,并对直流电缆线路动态增容过程中的暂态电热特性进行了分析。结果表明:初始负荷率高,应急持续时间长,绝缘电导率温度敏感性强的高压XLPE直流电缆在动态增容过程中场强变化幅度大,应予以特别关注;初始负荷率不超过50%的隧道敷设双极直流电缆线路,单级可在1.5倍额定电流下安全运行2 h。该结果可为工程中HVDC电缆线路动态增容与优化调度提供理论指导。
文摘为更准确预测输电线路未来允许的输送容量,提出利用动态提高输电线路输送容量(dynamic line rating,DLR)系统及混沌理论预测线路的输送容量。利用改进的C-C算法可靠性高、计算速度快的特点对容量时间序列进行相空间重构,并证实了线路允许输送容量具有混沌特性,可运用混沌理论预测线路输送的容量。然后采用基于奇异值分解的混沌时间序列Volterra方法对一条安装有DLR系统的110kV线路可输送的容量及线路可能发生的热过载故障进行预测。预测结果显示该方法能够反映容量序列未来变化的趋势及线路发生热过载故障的风险性,提高了预测的精度,是有效、可行的。
