船舶行业余热利用技术研究

本文对船舶行业余热资源的回收技术进行了较为详细的分析总结。首先简要分析介绍了船舶主机余热回收技术,其次对船舶制造企业余热利用现状进行了分析,并以船厂空压站为例,提出一套空压机余热综合利用方案,并进行了经济性分析。分析结果表明,船舶企业空压站具有较大的余热回收潜力,这部分余热如能得到充分利用,将会取得较好的节能效果及经济效益。     

A numerical study of the effects of the longitudinal baffle on nickel ore slurry sloshing in a prismatic cargo hold

The nickel ore slurry sloshing in a rolling partially loaded prismatic cargo hold with a longitudinal baffle is investigated. A numerical model based on the volume of fluid (VOF) method and the non-Newtonian Herschel-Bulkley and Bingham equations is proposed to study the dynamic behavior of nickel ore slurry sloshing. The numerical model is solved by using the finite volume approximations and the dynamic mesh technique is utilized to handle the cargo hold's motion. After taking grid and time step independence study, the numerical results are compared with experimental data. Comparisons show good agreement in the cases investigated. Further, the relationship between the moment amplitude induced on the hold boundary and the excitation frequency is checked numerically. The ratio of baffle height to the initial cargo depth has been changed in the range of 0.0 ≤ h_B/d ≤ 1.2. The variation of the sloshing-induced moment and the deformation of the free surface under different baffle heights have been obtained and discussed. To clearly understand the sloshing behavior of nickel ore slurry, the sloshing of liquid water has also been carried out. Meanwhile, the dynamic viscosity of the nickel ore slurry is monitored. The critical baffle height with regard to the sloshing-induced moment and the elevation difference of the free surface at two sides of the cargo hold has also been presented and discussed.     

多轴车辆轮荷计算方法研究

针对以往多轴车辆设计中只计算轴荷的情况,提出了计算多轴车辆轮荷的计算方法。通过分析多轴车辆空间受力情况并作适当假设,建立了多轴车辆轮荷计算模型,利用二维变形协调方程推导了轮荷计算公式。将由该公式计算的某多轴车辆轮荷与实际称重结果进行了对比,结果表明,所建立的轮荷计算公式能够较好地反映每个车轮实际的承载情况,可用于多轴车辆的整车设计、校核和优化。     

管换热器中插入螺旋纽带的研究现状(英文)

Heat transfer enhancement is used in many applications including heat exchangers, air conditioning, and refrigeration systems; hence many researchers have conducted experimental and numerical researches on heat transfer enhancement and have developed various techniques and methods. As a passive heat transfer technique, twisted tapes are widely used in various industries for their cost savings, lower maintenance requirements and the fact that they are easily set up. This paper introduces the principle of heat transfer enhancement of twisted tapes and reviews some of the experimental works done by researchers on this technique in recent years. The variously modified twisted tape inserts are widely researched and used to enhance heat transfer efficiency for heat exchangers. Twisted tapes perform better in low Re conditions and in square tubes. However, they could also cause higher pressure drops. Twisted tapes have great potential and profound implications if they can be used in traditional heat exchangers. Besides this, some correlations between the Nusselt number and friction factors are presented in this paper.     

船舶节能环保技术综述

根据船舶节能环保要求,通过采用新技术实现船舶工业低消耗、低污染、低排放,促进我国经济和社会的持续发展。本文从余热回收技术、节能泵技术、节能空调技术、新能源应用技术4个领域出发,探讨其对于船舶低碳环保的指导意义。     

The Current Situation of the Study on Twisted Tape Inserts in Pipe Exchangers

Heat transfer enhancement is used in many applications including heat exchangers, air conditioning, and refrigeration systems; hence many researchers have conducted experimental and numerical researches on heat transfer enhancement and have developed various techniques and methods. As a passive heat transfer technique, twisted tapes are widely used in various industries for their cost savings, lower maintenance requirements and the fact that they are easily set up. This paper introduces the principle of heat transfer enhancement of twisted tapes and reviews some of the experimental works done by researchers on this technique in recent years. The variously modified twisted tape inserts are widely researched and used to enhance heat transfer efficiency for heat exchangers. Twisted tapes perform better in low Re conditions and in square tubes. However, they could also cause higher pressure drops. Twisted tapes have great potential and profound implications if they can be used in traditional heat exchangers. Besides this, some correlations between the Nusselt number and friction factors are presented in this paper.     

流体扰动对不同排列方式下翅片套管换热器换热性能的影响

翅片排列方式影响换热器的换热系数．以翅片排列顺序不同的错列式和直列式翅片换热器作为研究对象,采用数值分析手段,分析并比较不同翅片排列方式的套管换热器与光管换热器的换热系数．研究结果表明,翅片换热器换热系数比光管套管换热器换热系数分别提高了87.8％与98.2％,同时压降分别增加了35.1％和37.6％．错列式翅片换热器比直列式翅片换热器换热系数提高了5.2％．     

波高对桩柱最大水平波浪力新算法精确性影响

对Morison方程进行适当变形、推演,得到了一种可直接计算近海平台支撑物所受最大水平波浪力的计算方法。将此计算方法与经典计算法进行对比。对比发现,当阻力相对于惯性力起主要作用时,新算法与经典算法所得结论完全一致。当惯性力相对于阻力起主要作用时,新算法存在一定偏差,在该情况下,使用Matlab辅助计算,得到了波高对桩柱最大水平波浪力新算法精确性的影响曲线。     

一类定态薄膜方程解的存在性

为研究四阶退化抛物方程解的存在性问题,需构建相应的半离散问题.研究与其相关的Dirichlet边界条件下,定态薄膜方程解的存在性,方法上,需将原有问题转化成二阶椭圆型方程组,利用Lax-Mil-gram定理,获得构造的不动点算子的可行性.再以紧嵌入定理为基础,应用Leray-Schauder不动点定理证得解的存在性.     

燃烧室形状对大功率机车柴油机工作性能的影响

针对大功率铁路机车柴油机的工作过程进行仿真计算,仿真计算得到的数据与实际试验数据相符合,将整个缸内工作过程按放热率规律分为三个阶段并分别进行研究分析.设计两种不同的燃烧室方案与原机型进行比较,讨论燃烧室喉口直径和燃烧室深度对于柴油机放热量、污染物排放量和缸内微观流场的影响.对比结果显示,当喉口直径为198 mm、燃烧室深度18.16 mm时,碳烟排放量和氮氧化物排量比喉口直径为188 mm、深度20 mm时分别下降了84.2％和43.4％;当喉口直径增加到208 mm时,缸内温度整体有所升高,氮氧化物排放量有所下降但是碳烟排放量增大.