Refrigeration Performance Analysis and Its Applicability of a New Metal Hydride Couple in Auto Air-conditioning

With COP and dynamic characteristics in refrigeration cycle as criteria,a new metal hydride couple--LaNi4.61Mn0.26Al0. 13/La0.6Y0.4Ni4.8Mn0.2 was selected by establishing calculation procedure and metal hydride selection model. The experimental results show that the refigeration cycle of the selected couple is good in the performance. The recovered waste heat and refrigeration power from exhaust gas of several kinds of automobile are calculated by waste-heat formula ,coefficient RQ and COP. Refrigeration cycle of the new couple can satisfy the air-conditioning requirement of truck and car and is not enough in passenger car,according to the respective cooling load.     

Predicting auto-ignition characteristics of RCCI combustion using a multi-zone model

The objective of new combustion concepts is to meet emission standards by improving fuel air mixing prior to ignition. Since there is no overlap between injection and ignition, combustion is governed mainly by chemical kinetics and it is challenging to control the phasing of ignition. Reactivity Controlled Compression Ignition (RCCI) combustion aims to control combustion phasing by altering the fuel ratios of the high- and low octane fuel and injection timings. In this study the dual fuel blend is prepared with gasoline and diesel fuels. The applied injection timings of the diesel are very early (90 to 60° CA bTDC). In the detailed reaction mechanism, n-heptane and iso-octane represent diesel and gasoline fuel, respectively. A multi-zone model approach is implemented to perform RCCI combustion simulation. Ignition characteristics are analyzed by using CA50 as the main parameter. In the experiments for the early direct injection (DI) timing advancing the injection time results in a later ignition. Qualitatively, the trend effect of the diesel injection timing and the effect of the ratio gasoline/diesel are captured accurately by the multi-zone model.     

Estimation of TKE dissipation rates in dense bottom plumes using a Pulse Coherent Acoustic Doppler Profiler (PC-ADP) — Structure function approach

During a hydrographic survey in January 2006 the spreading of inflowing saline water was observed in the Arkona Basin (Western Baltic Sea). Two bottom mounted ‘pulse coherent’ acoustic Doppler profilers (PC-ADP) were used to measure the near-bottom current field of the dense plume with a high temporal (1 s) and spatial resolution (5 cm). In order to estimate the dissipation rate of turbulent kinetic energy () a structure function approach was applied to the beam velocity data. Simultaneous measurements with a microstructure shear profiler (MSS) and an acoustic Doppler velocimeter (ADV) supplied independent data for the verification of the structure function method. Additional measurements with standard CTD, near-bottom towed and vessel mounted acoustic Doppler current profilers (ADCP) completed the data set.The estimated dissipation rates from the structure function approach fit well with the values derived from the ADV and the MSS probe. It is shown that the structure function approach is a reliable and easily applicable method to derive estimates of TKE dissipation rates from PC-ADP beam velocities. The observed dissipation rates ranged between 5 · 10^− 6 and 1 · 10^− 8 W kg^− 1 depending on the hydrographic conditions. Inside the plume the dissipation rates exceeded that of the overlaying brackish water by two orders of magnitude. Since the noise level of velocity data in pulse coherent mode is considerably lower than in the Doppler mode the PC-ADP can also be used for estimates in marine environments with low turbulence level. Reynolds stresses estimated from the PC-ADP and the ADV agreed well at the same depth level. TKE production derived from PC-ADP measurements compared reasonably well with the dissipation rate of TKE in a varying environment.     

Individual versus mass transportation: feasibility of substitution

This paper is addressed to the question of social costs and social benefits (primarily environmental) which might derive from a large‐scale substitution of so‐called mass‐transit for the present, largely private, system of automotive transportation. Energy consumption and emissions are compared for the two basic alternatives and several variants. Varying degrees of physiological tolerance to pollutants are taken into account, in an attempt to develop comparable weight‐factors for different types of emissions. It is suggested that if automobiles succeed in meeting the 1975/76 emission standards set by the Clean Air Act of 1970, rail rapid transit will probably offer no advantage (in environmental terms) unless electric power is available from virtually non‐polluting sources (e.g., natural gas or nuclear plants). Economic implications of large‐scale substitution are examined, and it is noted that such substitution would involve major restructuring of our society as a whole. However, more intensive use of mass transit in central cities, possibly in conjunction with various measures to discourage the use of private automobiles in very congested areas is feasible and likely.     

Approach to assess a fast welding simulation in an industrial environment — Application for an automotive welded part

Fusion welding processes are widely used for joining metal structures, such as pipes, ships, and cars. In general, these joining processes offer a very good compromise between reliability, safety, cost and maintenance which are important issues in the current economical context. The negative heat effects of welding, i.e. distortions and residual stresses of the welded parts, are well known and many researches in this field have already been done in the last decades in order to minimize them. On the experimental side, many sophisticated procedures have become state of the art to deal with this problem. On the computational side, the improvement of the simulation algorithms and the computing power enables the simulations of many physical phenomena occurring during the welding process. The implementation of welding simulation techniques is nevertheless not an easy task and often associated with expert knowledge which hinders their global application in an industrial environment. This paper is focused on the industrial requirements of a welding simulation software with special respect to the needs of the automotive industry. The necessary information to run a welding simulation and the expectations of a weld specialist without deep knowledge in numerical methods are investigated. These expectations are tested on an automotive welded assembly with a commercially available welding simulation software designed especially for the needs of the automotive industry. A welding experiment is done and the measured temperature distributions and distortions serve as reference to validate the simulation results. The result quality of the simulations of temperature fields and distortions is in best agreement with experimental data. The workflow is well adapted for the considered industrial requirements and the time-tosolution as well as the computational costs are acceptable, whereas the efficient calibration of the heat input model is still a point which will be further investigated in current and future research works.     

Large-eddy simulation of air entrainment during diesel spray combustion with multi-dimensional CFD

Large-Eddy Simulation (LES) was used to perform computations of air entrainment and mixing during diesel spray combustion. The results of this simulation were compared with those of Reynolds Averaged Navier Stokes (RANS) simulations and an experiment. The effect of LES on non-vaporizing and vaporizing sprays was evaluated. The validity of the grid size used for the LES analysis was confirmed by determining the subgrid-scale (SGS) filter threshold on the turbulent energy spectrum plot, which separates a resolved range from a modeled one. The results showed that more air was entrained into the jet with decreasing ambient gas temperatures. The mass of the evaporated fuel increased with increasing ambient gas temperatures, as did the mixture fraction variance, showing a greater spread in the profile at an ambient gas temperature of 920 K than at 820 K. Flame lift-off length sensitivity was analyzed based on the location of the flame temperature iso-line. The results showed that for the flame temperature iso-line of 2000oC, the computed lift-off length values in RANS matched the experimental values well, whereas in LES, the computed lift-off length was slightly underpredicted. The apparent heat release rate (AHRR) computed by the LES approach showed good agreement with the experiment, and it provided an accurate prediction of the ignition delay; however, the ignition delay computed by the RANS was underpredicted. Finally, the relationships between the entrained air quantity and mixture fraction distribution as well as soot formation in the jet were observed. As more air was entrained into the jet, the amount of air-fuel premixing that occurred prior to the initial combustion zone increased, upstream of the lift-off length, and therefore, the soot formation downstream of the flame decreased.     

Fracture properties of aluminum foam crash box

This study investigates the compression property experiment to examine impact absorption when aluminum foam is applied to crash box in order to absorb impact energy in car crash with low speed. The result of compression property experiment shows that case 6, which involves the buckling that collapses into 5-layer structure, is the best model with regard to impact absorption. This study analyzes impact characteristics according to the structure of crash box which influences such factors as damage and safety of vehicles. As the simulation result can be agreed with experimental graph, all experimental data at this study are verified. These experimental results can be applied into real field effectively. It also proposes the effective design to improve impact performance by analyzing the property of crash box through its compressive test.     

基于分形技术的铁路选线虚拟环境三维动态建模方法

运用分形技术实现虚拟选线环境中的三维动态建模。所建模型能在铁路选线虚拟环境仿真系统中模拟地面、背景天空、树木等的三维图像。与传统的静态建模方法相比,这种建模方式不仅具有较高的真实性和多样性,而且对整个三维场景的运动速度影响非常小。运用分形技术进行动态建模的方法能够取得很好的视觉效果,所建模型不但能够满足铁路三维动态建模的要求,还可以应用到其它三维场景中。     

出口澳大利亚5单元关节式集装箱平车

阐述了5单元关节式集装箱平车的技术参数、结构、性能特点，并介绍了该车的试验和运用情况。