Modeling a Combined Heat and Power Cogeneration System in Vietnam with a Fluidized Bed Combustor Burning Biomass

Agricultural biomass, suitable for the generation of electrical power using a combined heat and power (CHP) plant, is abundantly available in Vietnam. This study used a fluidized bed combustor (FBC) plant with the biomass fuel mixtures hemp residue and rapeseed residue. A theoretical model for the technical parameters of the combustion process and drying system is proposed. The results determine the optimal ratio of each kind of residue to decrease emissions and increase thermal efficiency of the system. The presented model is suitable for experimental investigations, and/or may be applied for the design of a small scale rural power station

Present State, Potential and the Future of electrical Power Generation from Biomass Residues in Vietnam

Process heat and electrical power for the countryside in Vietnam is in the state of widely absence. Actual this place has high potential to produce renewable energy by biomass and especially agricultural residues but does not have enough power to use. The source of wasted biomass from the agricultural residues is very large. Currently only a low amount of the available biomasses are used as fuels. Beside food for cattle or manure, the most is disposed of into lakes, ponds and rivers, polluting the environment and wasting the source of fuels. This article describes the present state, biomass potential in Vietnam and introduces state-of-the-art of combustion technology in the world. Especially focused is the Fluidized Bed Combustion (FBC) technique which is mostly favourable for Vietnam to create power generation from biomass residues in the future

Wind tunnel studies of pressure distribution around a 5:1 rectangular cylinder

In this paper, a wind tunnel study is described focusing on analysing the pressure distribution and correlation around both static and dynamic 5:1 rectangular cylinders in smooth and turbulent flow. Results from the static tests highlighted the significant influences of the turbulence on the surface pressure distribution. For the dynamic section, the VIV was triggered by the motion-induced leading edge vortex; a strongly correlated flow feature close to the trailing edge was found to be responsible for an increase in the amplitude of the vortex-induced vibration. An increase in the turbulence effectively weakened the motion-induced leading edge vortex or removed the flow feature close to the trailing edge, which led to a large reduction in the VIV response

Computational studies of pressure distribution around a 5:1 rectangular section in turbulent flow

This paper presents a numerical method based on a LES approach to modelling the unsteady flow around and the vortex-induced vibration (VIV) of a 5:1 rectangular cylinder in the smooth and turbulent flow. A fluid-structure interaction algorithm was also developed to model the aerodynamic behaviour of a half of the bridge deck in the bending and torsional modes. Results from the static and heaving simulations have validated the accuracy of the proposed computational method and revealed the important role of the motion-induced vortex during the lock-in and its interaction with the von Karman vortex. By introducing the bending motion on the bridge deck, some preliminary results of the bending simulation have indicated some distinct features including the variation of the surface pressure and the separation bubble in the spanwise direction which could promote the spanwise flow. The relative strength between the motion-induced vortex and the von Karman vortex was observed to vary across the spanwise length of the bridge deck, largely influencing the response of the bridge deck in the lock-in. The project will go on to investigate these features together with the surface pressure distribution and the pressure coherence and correlation structure in order to offer a quantitative explanation on the turbulence-induced effect on the VIV and torsional flutter of a 5:1 rectangular cylinder

Computational studies on pressure distribution around a bending 5:1 rectangular cylinder

This paper describes the development and testing of a numerical model, based around the Large Eddy Simulation model, of a flexible 5:1 rectangular cylinder. We report on the vortex-induced vibration (VIV) of the bending cylinder, which is an analogue for a flexible bridge deck. Compared with a 3D heaving sectional model, distinct differences in surface pressure distributions and Strouhal number in the span-wise direction were found. In addition, certain span-wise flow features were thought to trigger the lock-in when the flexible model underwent the bending VIV response

A Framework for Task-Based Flipped Classroom in EFL Education in Vietnam

When it comes to language teaching in general education in Vietnam, there are many challenges for teachers to overcome. Such as time constraints, examination wash-back effects, students’ demotivation and students’ individualization causes of learning. Various innovative teaching methods and approaches have been applied to address these concerns, such as task-based language learning and flipped classrooms (FCs). However, each mode of teaching has its advantages and disadvantages. Due to this, it is essential to carefully examine the combination of TBLT and the flipped classroom (FC). This paper reviews the effects of the implementation of task-based language learning in the clipped classroom, discusses the integration of both teaching approaches, and suggests the applied model for English as a Foreign Language (EFL) education in Vietnam

Positioning precision of GPS/Galileo integration in Vietnam

The design of Galileo has been conceived so as to facilitate its possible joint use with GPS thus contributing to a favorable multi-GNSS environment. Evaluating the performances of such multi-GNSS combination is crucial for end users to assess the quality of obtainable PVT and the easiness of interoperability of the two systems. In this paper, we evaluate the GPS/Galileo integration performances in terms of estimated precision in position determination and in terms of availability of the service. Results obtained from real data are presented and show that there is an improvement of both these criteria when the two systems are jointly used