High efficient configuration design and simulation of platelet heat exchanger in solar thermal thruster

Solar thermal propulsion system includes solar thermal propulsion and nuclear thermal propulsion, and it is a sig- nificant issue to improve the heat transfer efficiency of the solar thermal thruster. This paper proposes a platelet configuration to be used in the heat exchanger core, which is the most important component of solar thermal sys- tem. The platelet passage can enhance the heat transfer between the propellant and the hot core heated by the concentrated sunlight. Based on fluid-solid coupled heat transfer, the paper utilized the platelet heat transfer characteristic to simulate the heat transfer and flow field of the platelet passage. A coupled system includes the coupled flow and heat transfer between the fluid region and solid region. The simulation result shows that the propellant can be heated to the design temperature of 2300K in platelet passage of the thermal propulsion system, and the fluid-solid coupled method can solve the heat transfer in the platelet structure more precisely.     

Performance Analysis of Plug-in Hybrid Passenger Vehicles

PHEVs （passenger plug-in hybrid electric vehicles） have shown significant fuel reduction potential. Furthermore, PHEVs can also improve longitudinal vehicle dynamics with respect to acceleration and engine elasticity. The objective of this study is to investigate potential of concurrent optimization of fuel efficiency and driving performance. For the studies, a backward vehicle model for a parallel PHEV was designed, where the power flow is calculated from the wheels to the propulsion units, the conventional ICE （internal combustion engine） and the EMG （electric motor/generator） unit. The hybrid drive train is according to a P2 layout, consequently the EMG is situated between the shifting clutch and the ICE. The implemented operation strategy distributes the power to both propulsion units depending on the vehicle speed, requested driving torque, the battery＇s SOC （state of charge） and SOP （state of power）. Additional information, such as the slope of the road, can be taken into account by the operation strategy. In the paper, the fuel saving potential as well as the longitudinal dynamics change of different PHEV configurations is presented as a function of battery capacity and EMG power. Consequently, applicable hybrid components can be defined. By using additional information of the environment like various sensor data, road slope amongst others, the fuel saving potential can be improved even more. By studying the dynamic model, the overall results of the backward model are confirmed. In conclusion, this study shows that it is possible to concurrently reduce fuel consumption and increase driving performance in PHEVs. The potential depends strongly on the configuration of the electric components and the implemented operation strategy. Consequently, the hybrid system configuration has to be chosen carefully and aligned to the vehicle performance.     

Study of Space Reactors for Exploration Missions

Nuclear propulsion has been studied for many decades. The power density of nuclear fission is much higher than chemical process, and for missions to outer solar system requiring several hundred of kilowatts, or for flexible manned missions to Mars requiring several megawatts, nuclear electric propulsion might be the only option offering a reasonable mass in low earth orbit. Despite the existence of low power experiences--SNAP10 in the 60＇s or Buk/Topaz in the 60-80＇s--no high power reactor has been developed： investment cost, long term timeframe, high technological challenges and radioactive hazards are the main challenges we must overtake. However, it seems reasonable to look at the technical challenges that have to be overcome for a next generation of nuclear electric systems for space exploration. This paper will present some recent studies going on in France, on space reactors for exploration. Three classes of power have been considered： 10 kWe, 100 kWe, and several megawatts. Available data from previous studies and developments performed in Russia, USA, and Europe have been collected and gave us a large overview of potential technical solutions. This was the starting point of a trade-off analysis aiming at the selection of the best options, with regards to the technological readiness level in France and Europe. The resulting preliminary designs will be presented and critical technologies needing maturation activities will be highlighted.     

Numerical investigation on effectiveness of flow separation control in two-dimensional high-load compressor cascade by synthetic jet

The effectiveness of flow separation control in two-dimensional high load cascade by synthetic jet is investigated through numerical simulation of the effect of excitation frequency and amplitude together with the adaptability of synthetic jet to off-design conditions. Test results indicate that synthetic jet can be used to effectively control the large-scale two-dimensional flow separation in compressor cascade. Preferable results can be obtained when excitation frequency is close to or times of the characteristic frequency of original flow field. Excitation amplitude has a more important effect on the effectiveness of flow separation control, and the increase in excitation amplitude can bring about a dramatic decrease in the loss of total pressure. Synthetic jet has also a very good adaptability to off-design conditions. It can therefore be concluded that the incidence sensitivity of compressor cascade can be effectively reduced by synthetic jet.     

Numerical prediction of indoor airborne particle concentration in a test chamber with drift-flux model

The time-dependent variation of airborne particle concentration for different sizes in a test chamber was numerically predicted with drift-flux model. The performance of the drift-flux model for particle transport in different kinds of airflow fields was analyzed. The results show the drift-flux model can predict the transport of indoor fine particles reasonably well. When the air flow field varies slowly, the model can predict both the time-dependent variation ratio of the particle concentration and final stable concentration very well, and the difference for particles with different sizes can be also well predicted. When the air flow varies drastically, the accuracy of the model is decreased due to the neglect of the particles’ independent convective terms in the air flow.     

The design and performance of a high temperature rise combustor for wind tunnel

A high-temperature-rise combustor that can be used in high-temperature wind tunnel is introduced in this study.Aviation kerosene is used in this type of combustor,with division combustion scheme and evaporator fuel-supply device adopted.In the performance test under atmospheric pressure,when the inlet temperature is 500K and air flow is within the range of 1.5-3.0 kg/s,the outlet temperature can be precisely regulated within the range of 1050K-2100K.Moreover,higher uniformity of outlet temperature distribution and higher combustion efficiency can be achieved.After the long-time working in the wind tunnel,various components of the combustor,especially the combustor liners are checked without finding any anomaly such as thermal deformation.     

3D Computation of Hydrogen-Fueled Combustion around Turbine Blade-Effect of Arrangement of Injector Holes

Recently,a number of environmental problems caused from fossil fuel combustion have been focused on.Inaddition,with the eventual depletion of fossil energy resources,hydrogen gas is expected to be an alternativeenergy resource in the near future.It is characterized by high energy per unit weight,high reaction rate,widerange of flammability and the low emission property.On the other hand,many researches have been underway inseveral countries to improve a propulsion system for an advanced aircraft.The system is required to have higherpower,lighter weight and lower emissions than existing ones.In such a future propulsion system,hydrogen gaswould be one of the promising fuels for realizing the requirements.Considering these backgrounds,our group hasproposed a new cycle concept for hydrogen-fueled aircraft propulsion system.In the present study,we perform 3dimensional computations of turbulent flow fields with hydrogen-fueled combustion around a turbine blade.Themain objective is to clarify the influence of arrangement of hydrogen injector holes.Changing the chordwise andspanwise spacings of the holes,the 3 dimensional nature of the flow and thermal fields is numerically studied.     

Hydrogen Fuel Cell Electric Vehicle

正There are many great hopes with electrically powered vehicles,like fewer pollutants and less noise. For this electromobility,we may quickly think of vehicles with a large battery that can be charged from a wall outlet,but actually there is another propulsion technology,hydrogen engine,also known as the fuel cell electric vehicle (FCEV).A fuel cell vehicle is a type of electric vehicle that uses a fuel cell,instead of a battery,to power its on-board electric motor. Fuel cells in vehicles generate electricity to power the motor,generally using oxygen from the ambient     

Design and Analysis of a Single-Stage Transonic Centrifugal Turbine for organic Rankine cycle(ORC)

The recovery of low temperature heat sources is a hot topic in the world.The ORC system can effectively use the low temperature heat source.As its main output device,the performance of the turbine is very important.The single stage transonic turbine has the characteristics of small size and large output power.In this paper,the complete design process of a transonic centrifugal turbine with R245fa in low working temperature condition is introduced.At the design conditions,the shaft power and the wheel efficiency of the centrifugal turbine can reach 1.12 MW and 83.61%,respectively.In addition,a thermodynamic ORC cycle is presented and the off-design conditions of the turbine and its influence on the system are studied in detail.The results obtained in the present work show that the single-stage transonic centrifugal turbine can be regarded as a potential choice to be applied in small scale ORC systems.     

基于模型的航天器推进系统故障诊断

设计了基于模型的推进系统的故障诊断系统,根据推进系统的结构和行为模型,分析出各组件可处的工作状态及组件之间的连接关系,利用JMPL建模语言建立了推进系统各组件的定性模型。把推进系统模型和系统场景文件输入给诊断推理引擎,可实现推进系统的实时诊断。诊断结果表明,建立的推进系统模型是准确可靠的,开发的诊断系统能有效地找出故障组件并确定故障组件的状态。     

Design and evaluation of hybrid propulsion ship powered by fuel cell and bottoming cycle

Fuel cells are a promising power source in the electric propulsion systems for zero-emission vessels. The electric efficiency of fuel cells can be increased to 55% practically, but significant amounts of remaining energy from the electrochemical reaction are wasted as heat. This article proposes a hybrid propulsion system for ships that utilizes both the electric energy and thermal energy generated by fuel cells. The electric power capacity of fuel cells and the steam generation capacity of recovered heat from fuel cell systems are calculated, and then the propulsion power of the hybrid system is simulated by MATLAB Simulink. The overall energy efficiency of the proposed ship propulsion system is compared with that of conventional systems by comparing fuel consumption rate. Simulation results indicate that the proposed hybrid propulsion system can increase energy efficiency by 22.5% by additional utilization of the recovered heat from fuel cells.     

船舶综合电力推进系统综述

从电力推进与柴油机推进的比较、电力推进的优点、电力推进系统的组成等方面综述了船舶综合电力推进系统,并较为全面地阐述了电力推进系统的关键设备:大功率变频器、推进电动机、吊舱式推进装置、电站管理及监控系统等。指出随着技术进步,电力推进优越性日益凸显,21世纪将是船舶电力推进系统发展的黄金时代。     

交流变频电力推进系统仿真建模

舰船的推进方式正由传统的原动机-齿轮箱-艉轴-螺旋桨方式向综合电力推进的方向发展。本文对电力推进中各个环节进行分析,建立相应的数学模型,并提出在MATLAB中的实现算法。     

Molten carbonate fuel cell (MCFC)-based hybrid propulsion systems for a liquefied hydrogen tanker

This study proposes a molten carbonate fuel cell (MCFC)-based hybrid propulsion system for a liquefied hydrogen tanker. This system consists of a molten carbonate fuel cell and a bottoming cycle. Gas turbine and steam turbine systems are considered for recovering heat from fuel cell exhaust gases. The MCFC generates a considerable propulsion power, and the turbomachinery generates the remainder of the power. The hybrid systems are evaluated regarding system efficiency, economic feasibility, and exhaust emissions. The MCFC with a gas turbine has higher system efficiency than that with a steam turbine. The air compressor consumes substantial power and should be mechanically connected to the gas turbine. Although fuel cell-based systems are less economical than other propulsion systems, they may satisfy the environmental regulations. When the ship is at berth, the MCFC systems can be utilized as distributed generation that is connected to the onshore-power grid.     

Introducing and evaluation of a new propulsion system composed of solid oxide fuel cell and downstream cycles; usage in Unmanned Aerial Vehicles

Recently, Unmanned Aerial Vehicles (UAVs) with propulsion systems based on fuel cells have led to increased flight endurance and fuel economy. However, due to the limited operation of propulsion systems designed with alone fuel cells, the integration of fuel cells with other power generators can be used. This article attempts to provide a conceptual model of a new solid oxide fuel cell based-propulsion system that is cascaded with thermionic and thermoelectric generators. The fuel cell produces power and heat by receiving hydrogen fuel and oxidant. The required heat of thermionic and thermoelectric generators is supplied by the dissipative heat of the fuel cell and the dissipated heat of thermionic, respectively. The objective of this article is to determine the necessary electricity of a small UAV under mission profile. The conceptual design and structure of the proposed propulsion system (for use in a small drone) is new. In addition, the results presented do not correspond to the same literature. Results showed that the proposed propulsion system is capable of producing 481.3 W of power with an overall efficiency of 46.7%. In addition, UAV needs 1110.3 W of electricity under the desired mission profile. Five various sizing of the propulsion system to provide the necessary electricity of an UAV are discussed.     

大气呼吸模式激光推进的理想动力循环模型

大气呼吸模式激光推进的比冲和冲量耦合系数受制于其能量转换效率,对能量转换效率进行分析具有重要意义。建立了大气呼吸模式激光推进的理想动力循环模型,分析了激光推进过程中的能量转换效率,并探讨了提高能量转换效率的可行途径。研究结果表明,增大冲压比或定容增压比是提高能量转换效率的有效途径,其中增大飞行速度能有效增大冲压比,提高激光功率密度和改变工质掺杂特性能有效增大定容增压比。掺入水滴杂质形成的气液两相工质在激光推进领域具有较好的发展前景。     

7500DWT化学品船主推进动力系统设计简介

介绍了7500DWT化学品船主推进动力系统的组成和设计特点,应用Hydrocomp PropExpert软件对几种设计方案作了比较,最终选用双机双浆双齿轮箱带双轴带发电机的推进方案,保证了该化学品船的稳定性和经济性。     

船舶综合全电力推进系统

船舶综合全电力推进系统综合现行船舶平台的电力和推进两大系统,实现电能综合利用和推进供电一体化,是20世纪90年代推出的一种全新的电力推进系统,文中论述并分析了全电力推进系统的结构、模块、吊舱式推进器和监控分系统,提出大力发展现场总线的全电力推进局域网和电能管理技术。