不同压力下具有内热源的包装箱内传热特性

目的研究具有内热源的某产品包装箱在不同压力下的传热特性。方法搭建具有内热源的某产品包装箱传热特性实验系统,对不同压力下内部具有热源的某产品包装箱内的温度场进行测量,讨论产品各部件的传热特性,并基于计算结果,拟合各部件的传热关联式。结果常压状态下各测点温度较低压状态更易达到平衡,箱体内温度场的分布符合被加热物四周热边界层厚度分布规律。包装箱内对流传热能力随着压强的增大而增强,且箱内压强处于较小范围时,压强的增加对于箱内各部的冷却效果更加显著。结论正常工作的温度范围内,该产品包装箱内传热能力的强弱主要受对流传热影响,对流传热能力随着压强的增大而增强;得到了各部件壁面传热关联式,误差在5%以内。     

金属相变储能与技术的研究与发展

相变储能是有效的储热方式.其中,金属相变储热因吸放热过程中,储能密度大,过冷度小,导热率高,反复相变后长期性能稳定,过程易控制,因而在高温储热方面具有广泛的用途.从金属相变储热材料、传热分析、金属相变材料与容器材料的相容性和应用4个方面,回顾了金属固液相变储热的发展.     

跌落系统的冲击振动试验及动态特性

本文介绍了某核燃料运输容器跌落试验时有关的冲击振动测量技术,以及该运输容器和靶基础的冲击响应特性及试验研究方法。为了预估与分析试验结果,研制了运输容器撞击分析程序。对撞击过程中不锈钢-铅-不锈钢复合结构容器的弹塑性大变形情况进行了电算;并对跌落试验中冲击试验台的动力特性进行了有限元计算。将试验与理论计算结果进行了对照比较。     

军械应急备件箱的设计

目的为满足当前军械应急维修保障需要,提升部队战斗力,研制一种新型的军械应急备件箱。方法通过部队调研得出军械应急备件箱的基本设计要求,运用机械原理和电子技术,重点从结构、功能和材料方面考虑,设计军械应急备件箱的技术方案。结果针对新研制的军械应急备件箱,分别进行了携运行能力、备件取用测试,测试结果表明军械应急备件箱携运行能力和备件取用便捷性均优于现有的备件箱。军械应急备件箱全箱采用了全封闭式结构,并分别在5,7,9,11 mm/min的降雨强度下进行了防水测试,均能保证备件盒内不渗水,说明该箱完全适用于在全天候条件下使用。结论经过试用认为,军械应急备件箱的研制弥补了现行部队军械维修时备件供应不精准且不便携行的缺陷,构建了合理的军械维修体系。     

Quay crane scheduling in container terminals

The problem of scheduling identical quay cranes moving along a common linear rail to handle containers for a ship is studied. The ship has a number of container-stacking compartments called bays, and only one quay crane can work on a bay at the same time. The objective of the scheduling problem is to find the work schedule for each quay crane which minimizes the ship’s stay time in port. Finding the optimal solution of the scheduling problem is computationally intractable and a heuristic is proposed to solve it. The heuristic first decomposes the difficult multi-crane scheduling problem into easier subproblems by partitioning the ship into a set of non-overlapping zones. The resulting subproblems for each possible partition are solved optimally by a simple rule. An effective algorithm for finding tight lower bounds is developed by modifying and enhancing an effective lower-bounding procedure proposed in the literature. Computational experiments were carried out to evaluate the performance of the heuristic on a set of test problems randomly generated based on typical terminal operations data. The computational results show that the heuristic can indeed find effective solutions for the scheduling problem, with the heuristic solutions on average 4.8% above their lower bounds.     

Thermal analysis of airflow inside a refrigerated container

A numerical study of conjugated heat transfer in ceiling-slot refrigerated containers is carried out to analyze the temperature distribution effectiveness and to determine the ventilation characteristics. The effect of slot size on thermal characteristics is studied by considering half-span and full-span injection. The container walls are defined as conductive opaque and are interacting with outside environment. The outer surface heat transfer coefficients of conductive walls are computed by studying the flow around the refrigerated truck. The Reynolds number at the slot exit varied between 2 × 10⁴ ≤ Re ≤ 2 × 10⁵. The gravity effect is taken into account, and the coupled mass, momentum, and energy equations are discretized in finite volumes. The heat transfer coefficients of inner flow are presented as plots of the mean Nusselt number versus the modified Reynolds number. The maximum dispersion in the numerical data being at 14.54-percent, the mean Nusselt number, the modified Reynolds number, and the aspect ratio of the container are correlated.     

水平管外R404A降膜蒸发传热的实验研究

搭建了降膜蒸发实验台,研究了水平单管外的降膜蒸发传热特性。测试管为外径19mm、有效实验长度为2500mm的光滑管和强化管。实验采用R404A作为管外降膜蒸发工质,与管内热水进行换热。布液采用喷嘴喷淋的方式,通过21个喷口当量直径为2mm的喷嘴完成。分别在变饱和温度(0、5、10、15℃)、变热流密度(从8到30kW/m2)和变喷淋量(从0.07到0.11kg/(m·s)时进行实验,研究了降膜蒸发换热性能相应的变化情况,得到R404A的管外降膜蒸发换热的一些规律,这对降膜蒸发器的设计及应用具有一定的参考作用。     

舰船尾流气泡声学测试系统研究

针对舰船尾流气泡的声学特性测试需求,开展了系统工程样机试制及实际航行(简称“实航”)试验测试研究。针对声学探测反演舰船尾流几何尺寸、气泡分布密度等基本原理进行说明。综合分析国内相关研究现状,采用基于(Remote Operated Vehicle,ROV)平台的移动式一体化测试方案,解决不同水深的试验测试问题;利用比对分析方法,降低水声环境对尾流气泡声学测试系统的影响。研制相应试验测试系统装置,并开展湖上实航试验。试验测量结果与当前相关研究及试验测试结论基本一致,证明该测试系统具备舰船尾流气泡声学探测能力,具备广泛的军事和民用价值。     

化学镀镍在舰船冷却器防护中的应用

通过正交试验法优选出一种具有高磷含量的快速化学镀镍工艺配方。用扫描电子显微镜和能谱法分析了镀层结构和磷元素的含量。对镀层进行中性盐雾试验、腐蚀介质浸泡试验并测定极化曲线 ,结果表明 ,化学镀层具有优良的耐蚀性能、较高的硬度和耐磨性能 ,可在钢铁、铜、不锈钢等材料的表面上施镀 ,是舰船冷却器防护的有效方法     

地震载荷下岸桥跳轨相似模型研究

为了提高地震载荷下岸桥跳轨研究结果的准确率问题,基于简化的岸桥跳轨运动方程推导了岸桥原型与模型之间的相似关系,建立了岸桥的动力学相似模型,制作并开展了1∶20岸桥比例模型的振动台试验,研究了不同地震波载荷条件下的试验模型监测点的响应值,分析了不同工况条件下岸桥轮轨压力随时间变化的规律,测试了岸桥比例模型在振动试验中的跳轨响应结果,最后结合有限元方法将试验结果与仿真结果进行了对比。结果表明:振动台试验中模型跳轨响应结果与有限元仿真中出现的跳轨的情况吻合,基于跳轨运动方程建立的相似关系是准确可靠的。该研究为大型结构相似模型设计提供了一种理论参考。     

Estimation of the atmospheric corrosion on metal containers in industrial waste disposal

Solid industrial waste are often stored in metal containers filled with concrete, and placed in well-aerated warehouses. Depending on meteorological conditions, atmospheric corrosion can induce severe material damages to the metal casing, and this damage has to be predicted to achieve safe storage. This work provides a first estimation of the corrosivity of the local atmosphere adjacent to the walls of the container through a realistic modeling of heat transfer phenomena which was developed for this purpose. Subsequent simulations of condensation/evaporation of the water vapor in the atmosphere were carried out. Atmospheric corrosion rates and material losses are easily deduced. For handling realistic data and comparison, two different meteorological contexts were chosen: (1) an oceanic and damp atmosphere and (2) a drier storage location. Some conclusions were also made for the storage configuration in order to reduce the extent of corrosion phenomena.     

Note on sway, roll and yaw motions of a ship with forward speed: analytical study

Summary The paper deals with the prediction of coupled sway-roll-yaw motions of a ship with constant forward speed, subject to regular wave force. The governing equations derived in time domain after balancing the hydrodynamic and exciting forces are solved analytically while considering the motion variables, wave frequency and external force are complex quantities. Numerical experiments were carried out for a Panamax container ship under the action of a sinusoidal wave of periodicity 11.2 sec with the variations of speed and wave height. The effect of various parameters on motion responses and system stability is investigated.     

Determination of heat transfer coefficients during solidification of a casting in a jet crystallizer

The problem of determining heat transfer coefficients in thermal processes described by nonlinear initial boundary-value problems for heat conduction equations in a cylindrical coordinate system is considered subject to axial symmetry. An algorithm is suggested and program means are created for identifying heat transfer coefficients. A computational experiment on determining heat transfer coefficients for the AK12 alloy is carried out, and recommendations for selecting numerical calculation parameters have been developed.     

Design of a hybrid glass composite anchor for LNG cargo containment systems

Large cryogenic container for liquefied natural gas (LNG) should be joined to the inner hull of a ship. The minimum heat inflow, due to the large temperature difference between the LNG cargo container and inner hull, can induce considerable heat flux through the joined area.In this work, a hybrid composite anchor composed of two stainless steel caps and a glass fiber composite body was developed and optimized for strength, thermal stress and heat loss of the anchor. The stainless steel caps were adhesively bonded to the top and bottom areas of the glass composite body. The top stainless cap was then welded to the two stainless steel membranes, and the flange of the bottom stainless steel cap was bolt-fastened to the inner hull of a ship.The static adhesive strength and impact characteristics between the stainless steel caps and glass composite body of the hybrid glass composite anchor at the cryogenic temperature were investigated with respect to adhesive thickness. Finally, the optimal design for the hybrid glass composite anchor for the cryogenic containment systems of a LNG ship was suggested.     

Convective heat transfer at a stretching sheet

Summary Analysis of convection flow and heat transfer of a viscous heat-generating fluid near an infinite vertical stretching surface is carried out. The effects of free convection and the presence of heat generation/absorption on the flow and heat transfer characteristics are considered. The equations of conservation of momentum, mass, and energy, which govern the flow and heat transfer problem, are solved numerically by using a variable order, variable step size finite-difference method. The numerical results obtained for the flow and heat transfer characteristics reveal many interesting behaviors. These behaviors warrant further study of the effects of free convection on the flow and heat transfer characteristics.     

Heat and moisture insulation by means of air curtains: Application to refrigerated chambers

The present study is devoted to the determination of the efficiency of air curtain units (ACUs) applied to heat and moisture insulation of refrigerated chambers. A detailed study of the fluid dynamics and heat and mass transfer of the ACU in the refrigerated space and the external ambient is carried out by means of large eddy simulations (LES). The heat and moisture entrainment through the doorway and their transport inside the inner space are fully described. Three different configurations are studied: non-recirculating, recirculating and twin-jet air curtains. The condensation produced in the cool walls of the refrigerated space is evaluated considering the warm humid air from the ambient which penetrates inside the chamber through the doorway. The influence of both the discharge velocities and the discharge angles on the sealing capabilities of the three different tested ACU configurations is determined.     

Hybrid genetic algorithm for test bed scheduling problems

In this paper, we address the scheduling problem for a heavy industry company which provides ship engines for shipbuilding companies. Before being delivered to customers, ship engines are assembled, tested and disassembled on the test beds. Because of limited test bed facilities, it is impossible for the ship engine company to satisfy all customers’ orders. Therefore, they must select the orders that can be feasibly scheduled to maximise profit. An integer programming model is developed for order selection and test bed scheduling but it cannot handle large problems in a reasonable amount of time. Consequently, a hybrid genetic algorithm (GA) is suggested to solve the developed model. Several experiments have been carried out to demonstrate the performance of the proposed hybrid GA in scheduling test beds. The results show that the hybrid GA performs with an outstanding run-time and small errors in comparison with the integer programming model.     

A Novel Primal-mixed Finite Element Approach for Heat Transfer in Solids

A new reliable primal–mixed finite element approach for the heat transfer analysis in solids, is examined in detail. The essential contribution is that both variables of interest, temperature and heat flux, are calculated simultaneously from the same system of finite element equations. In addition, as a novelty, continuity of the trial and test heat flux functions is enforced, to avoid the need for some a posteriori heat flux smoothing technique. In order to minimize the accuracy error and enable introduction of the flux constraints, tensorial character of the present finite element equations is fully respected. The proposed finite element is subjected to low and high order convergence and efficiency tests in steady state and transient heat transfer analysis, which enlighten its solvability, stability, accuracy and effectiveness, i.e. its reliability.     

空气冷却器传热性能试验研究

对空气冷却器在结霜工况下的传热性能进行了试验研究，简述了结霜工况下传热系数测试的原理、方法和主要过程。根据实验结果对影响空气冷却器传热性能的主要因素进行了分析，并得出了一些有益的结论。     

Orts- und temperaturabh?ngige W?rme��bergangskoeffizienten bei der Spr��hk��hlung von AlSi10Mg-Gussplatten

The purpose of the current investigations is the measurement and modelling of the heat transfer coefficients?? spatial and temperature dependency, which are determined for the spraying properties of circular and flat fan nozzles. Thermographically measured cooling curves from spray-cooled discs of an AlSi10Mg aluminium cast-alloy serve as data for calculating the heat transfer coefficients. The computation is carried out by means of a model which uses the series solution for a semi-infinite plate. The heat transfer coefficients could be determined and modelled as a function of both the location of an impinging spray on a plate??s surface as well as the surface temperature. The influence of the spraying parameters air pressure and water pressure as well as the test piece temperature on the heat transfer coefficients, which were observed in other research, is confirmed.