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  • Study on Buildings CCHP System Based on SOFC
  • Abstract The relationship among the working temperature, pressure and current density of a Solid oxide fuel cell (SOFC) and its output power and efficiency are analyzed in the framework of a theoretical model able to provide, among other things, the volt ampere characteristic curve. In particular, following the principle of temperature matching and cascade utilization, we consider a gas turbine (GT) and a LiBr absorption chiller to recycle the high-grade exhaust heat produced by the considered SOFC. This distributed total energy system is set up with the intent to meet typical needs of buildings for cooling, heating and power (CCHP). The…
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  • Convection-Diffusion Model for Radon Migration in a Three-Dimensional Confined Space in Turbulent Conditions
  • Abstract Convection and diffusion are the main factors affecting radon migration. In this paper, a coupled diffusion-convection radon migration model is presented taking into account turbulence effects. In particular, the migration of radon is simulated in the framework of the k-ε turbulence model. The model equations are solved in a complex 3D domain by the finite element method (FEM). Special attention is paid to the case study about radon migration in an abandoned air defense shelter (AADS). The results show that air convection in a confined space has a great influence on the radon migration and the radon concentration is inversely…
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  • Numerical Investigations on the Impact of Turbulent Prandtl Number and Schmidt Number on Supersonic Combustion
  • Abstract The flow field inside the combustor of a scramjet is highly complicated and the related turbulent Prandtl and Schmidt numbers have a significant impact on the effective numerical prediction of such dynamics. As in many cases researchers set these parameters on the basis of purely empirical laws, assessing their impact (via parametric numerical simulations) is a subject of great importance. In the present work, in particular, two test cases with different characteristics are selected for further evaluation of the role played by these non-dimensional numbers: Burrows-Kurkov case and DLR case. The numerical results indicate that these parameters influence ignition location.…
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  • CFD-Based Optimization of Hot Primary-Air Pipe Networks in Power Plant Milling Systems
  • Abstract A hot primary-air pipe system is the bridge connecting an air-preheater with a coal mill in power generation stations. The effective geometrical configuration of the pipe network greatly affects the air flow distribution and consequently influences the safe and economic operation of milling systems in power stations. In order to improve the properties of the air flow, in the present work the SIMPLEC method is used to simulate numerically the flow field for the original layout of the system. As a result, the internal mechanisms influencing the uneven pressure drop in each branch are explored and three optimization schemes are…
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  • Influence of Steam and Sulfide on High Temperature Selective Catalytic Reduction
  • Abstract The influences of steam and sulfide on the efficiency of NOx reduction using ammonia (NH3) over the nanometer-class V-W/Ti catalyst in conditions of high temperature is experimentally investigated using a steady-flow reactor. The results showed that selective catalytic reduction (SCR) is inhibited by H2O at low temperature, but higher NO conversion efficiency is achieved at high temperature since the reaction of NH3 oxidized by O2 to NOx is inhibited by H2O. The activity of SCR is promoted by SO2 in the temperature range of 200~500° C, the NO conversion efficiency was improved to 98% from 94% by adding SO2. SCR…
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  • Numerical Study of High-Temperature Nonequilibrium Flow around Reentry Vehicle Coupled with Thermal Radiation
  • Abstract Accurate aerodynamic heating prediction is of great significance to current manned space flight and deep space exploration missions. The temperature in the shock layer surrounding the reentry vehicle can reach up to 10,000 K and result in remarkable thermochemical nonequilibrium, as well as considerable radiative heat transfer. In general, high-temperature flow simulations coupled with thermal radiation require appropriate numerical schemes and physical models. In this paper, the equations governing hypersonic nonequilibrium flow, based on a three-temperature model combined with a thermal radiation solving approach, are used to investigate the radiation effects in the reentry shock layer. An axisymmetric spherical case…
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  • Numerical Simulation of Axial Inflow Characteristics and Aerodynamic Noise in a Large-Scale Adjustable-Blade Fan
  • Abstract Numerical simulation are conducted to explore the characteristics of the axial inflow and related aerodynamic noise for a large-scale adjustable fan with the installation angle changing from −12° to 12°. In such a range the maximum static (gauge) pressure at the inlet changes from −2280 Pa to 382 Pa, and the minimum static pressure decreases from −3389 Pa to −8000 Pa. As for the axial intermediate flow surface, one low pressure zone is located at the junction of the suction surface and the hub, another is located at the suction surface close to the casing position. At the outlet boundary,…
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  • Influence of Diesel Engine Intake Throttle and Late Post Injection Process on the Rise of Temperature in the Diesel Oxidation Catalyst
  • Abstract In order to effectively implement DPF (Diesel Particulate Filters) regeneration control, thermal management of exhaust products before and inside Diesel Oxidation Catalyst (DOC) is necessary. In the present study, the Influence of the intake throttle valve and late post injection process on temperature rise inside DOC is analyzed through engine bench tests. The steady experiment results show that adjustment of the intake throttle valve can effectively increase exhaust temperature before DOC; in particular, with intake throttle valve opening at 20%, temperature before DOC can be increased by about 170°C with respect to the full opening. An increase in the late…
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  • RANS Simulation for the Maneuvering and Control of a Suboff Submarine Model
  • Abstract Submarine maneuverability has been analyzed by means of computational fluid dynamics (CFD). This approach provides an alternative, accurate, and cost-effective method for simulating actual flow. The numerical results show that the numerical simulation of the viscous flow related to a moving submarine based on the RANS equation with a relevant turbulence model can not only provide rich flow field details such as flow separation, but also accurately predict its hydrodynamic performance. The present study indicates that CFD can be used to forecast the submarine’s maneuverability in the initial design stage. The present results will be used in the future as…
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  • Simulation of the Thermal Environment and Velocity Distribution in a Lecture Hall
  • Abstract The rational design of heating ventilation and air conditioning systems is an important means to achieve energy conservation and sustainable development. The simulation of air-conditioning systems with finite element methods has gradually become an important auxiliary means of complex airspace design. In this paper, a k-ε turbulence model is used to conduct 3D simulations and optimize the summer air conditioning system of a lecture hall. Various conditions are considered in terms of fresh air temperature and flow rate towards the end to improve comfort. The approach used in this paper could also be used in the future as an auxiliary…
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  •   Views:328       Downloads:199        Download PDF
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