船舶低温冷库融霜对比试验研究

船舶伙食冷库的低温库风机盘管结霜会恶化蒸发器换热性能,影响冷藏食品品质,因此对低温库蒸发盘管必须定期融霜。船舶伙食冷库低温库一般采用热气融霜和电热融霜2种方式,经相同试验工况对比,热气融霜耗时短,效率高,库房内温度波动小,节能效果明显;低温库温度越低,热气融霜的节能效果也就越突出。对船舶冷库设计及融霜控制方式的选择具有重要借鉴意义。     

强制性EEDI要求对LNG船适用性分析

通过对世界范围内近10年间建造的LNG船的评估分析,证明目前IMO在MEPC62届会议以MEPC.203(62)决议通过的MARPOL附则VI框架下的船舶能效条款中关于气体运输船的参考线对LNG船而言是不适合的,并提出LNG船的参考线设定建议,对国内LNG船的设计建造有借鉴意义。     

船用柴油机双燃料系统设计及其特性

随着排放法规的日趋严苛和运输市场竞争日益激烈，为降低航运业运营成本、保护环境，船舶发动机燃油系统不断被改进，双燃料发动机以其污染更少、燃料价格较低， 成为研究热点。本文介绍了一种新的船用柴油天然气双燃料系统，并为系统设计了性能可靠控气精准的组合喷射阀。为了提高系统适应性，设计了通过T-S模糊控制算法处理油耗和转速信息得出系统的天然气喷入量的控制系统，不安装限油装置，最大限度地利用了原柴油机的控制系统，通过发动机自身调节机构对引燃柴油量调节，安装简单方便。在台架实验中，双燃料发动机的替代率随着转速的升高逐渐增大，在额定转速（负荷）点工作时，替代率达到了73%，费用节省率达到了31%，运行可靠稳定。     

天然气发动机曲轴箱爆炸模拟及分析

为了验证船用天然气发动机曲轴箱的设计强度能否承受最恶劣爆炸工况下的超压,利用CFD计算软件对曲轴箱内燃料-空气混合气体爆炸后果进行了数值模拟。现有的CFD计算方法普遍采用等效气体云模型,其中最新的Q9模型能够综合考虑气体膨胀率和层流燃烧速率对爆炸后果的影响,应用广泛。然而在曲轴箱等高拥塞度受限空间内发生的气体爆炸,火焰传播猛烈且燃烧状态复杂,对于这种情况采用Q9模型来进行模拟会造成结果的不准确,为此基于荷兰应用科学院(TNO)多能法在现有模型的基础上推导了适合曲轴箱内爆炸模拟的等效气体云模型。通过与试验数据的验证对比发现,新模型在高拥塞度较小容积受限空间中的计算结果精度较高,误差在20%以内,且混合气体越接近理想状态(化学计量浓度),该模型的计算精度越高。以某典型船用天然气发动机曲轴箱为例,采用新的等效气体云模型计算了最恶劣爆炸工况下曲轴箱内的超压分布,并导入有限元软件进行了强度评估。评估结果表明：曲轴箱内最大应力的位置发生在结构强度较弱的油底壳处,应力峰值为361.257MPa,油底壳采用Q235材料,该应力已超过其许用应力,该部分结构无法承受最恶劣爆炸工况下的超压,因此如不安装防爆阀,需在设计时对曲轴箱油底壳结构进行适当加强。     

一种舰船气体泄漏的声发射检测方法

目前舰船对气体泄漏检测的方法还存在较大局限性,迫切需要一种新的检测手段。本文论证了目前常用检测方法的利弊,提出采用气体泄漏产生的声发射现象进行检测的方法。采用便携装置完成了模拟泄漏装置和实际管路试验,结果表明：该方法针对不同漏孔大小、泄漏压力、距离均可检测气体泄漏,不依赖经验,可满足舰船实际使用的需求。     

考虑转捩的某高速船用汽油机排气管流固热耦合分析

针对某高速船用汽油机原排气管在热冲击试验中的开裂问题,在增加排气管冷却水套的基础上,采用流固热耦合分析方法对排气管进行换热和热应力分析,并在此基础上,研究不同湍流模式和转捩对复杂流场流动与换热的影响。结果表明,不同湍流模型的温度计算结果和试验数据的吻合度均较好,证实了计算模型的准确性,而排气管的开裂系热应力过高所致,通过增加冷却水套可以解决排气管开裂问题;选用合适的湍流模型并考虑转捩影响,可以更加准确地判断分离点位置,提高复杂流场的数值模拟精度。     

A bi-level model for GHG emission charge based on a continuous distribution of travelers’ value of time (VOT)

Transportation is an important source of greenhouse gas (GHG) emissions. In this paper, we develop a bi-level model for GHG emission charge based on continuous distribution of the value of time (VOT) for travelers. In the bi-level model framework, a policy maker (as the leader) seeks an optimal emission charge scheme, with tolls differentiated across travel modes (e.g., bus, motorcycles, and cars), to achieve a given GHG reduction target by shifting the proportions of travelers taking different modes. In response, travelers (as followers) will adjust their travel modes to minimize their total travel cost. The resulting mode shift, hence the outcome of the emission charge policy, depends on travelers’ VOT distribution. For the solution of the bi-level model, we integrate a differential evolution algorithm for the upper level and the “all or nothing” traffic assignment for the lower level. Numerical results from our analysis suggest important policy implications: (1) in setting the optimal GHG emission charge scheme for the design of transportation GHG emission reduction targets, policy makers need to be equipped with rigorous understanding of travelers’ VOT distribution and the tradeoffs between emission reduction and system efficiency; and (2) the optimal emission charge scheme in a city depends significantly on the average value of travelers’ VOT distribution—the optimal emission charge can be designed and implemented in consistency with rational travel flows. Further sensitivity analysis considering various GHG reduction targets and different VOT distributions indicate that plausible emission toll schemes that encourage travelers to choose greener transportation modes can be explored as an efficient policy instrument for both transportation network performance improvement and GHG reduction.     

镇江市天然气汽车推广应用分析研究

本文以镇江市天然气汽车的推广应用情况和配套设施情况为基础，分析天然气汽车推广应用存在的问题，有针对性地提出推广应用天然气汽车的政策建议。     

Incremental costs for reduction of air pollution from ships: a case study on North European emission control area

In addition to sulphur oxides control, the North and the Baltic Seas have recently been designated as nitrogen oxides control area. Amidst ongoing developments in energy markets and international trade, shipowners have to develop cost-efficient strategies to comply with the new regulation. This study creates and tests a model calculating the incremental costs of abating NO_x and SO_x emissions under MARPOL Annex VI regulations for the following methods: SCR, HAM and internal engine modifications, marine gas oil, wet scrubbers, and liquefied natural gas propulsion. The model is tested empirically on a broad sample of 244 ships from the Swedish Commercial Fleet database for different operating contexts and fuel prices. Individual ship emission reductions and incremental abatement costs are calculated and the results are presented for the entire studied sample and per ship type class.

The study also explores the sensitivity of the chosen abatement methods to cost determinants and to main engine time operation under the light of economic performance and cost-efficiency. The results of the study aim to contribute to company abatement strategy.     

Design of a novel drilled-and-grouted pile in sand for offshore oil&gas structures

New offshore oil and gas exploration has placed renewed emphasis on developing structures in relatively complex geological conditions. Due to the damaging nature of impact driving, traditional steel piles used to support jacket structures, are not ideally suited to specific soil types, such as carbonate sands. Drilled and grouted piles are commonly used to support structures in these soil conditions. This paper describes a novel drilled pile, which has been developed specifically to provide a cost effective installation process while maintaining the benefits of grouted piles. The installation process negates the need for temporary casing in weak soils and minimizes the number of offshore operations. In this paper, the installation methodology and post-installation performance of a large scale onshore field trial is described. The installation process was successfully demonstrated with a 1.9 m diameter test pile installed in fine sand to 17.7 m depth in under 3 h. The performance of the pile, as measured in a tension static load test, was shown to compare favorably with existing pile design methods.