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Fuel cells are still undergoing intense development, and the combination of new and optimized materials, improved product development, novel architectures, more efficient transport processes, and design optimization and integration are expected to lead to major gains in performance, efficiency, reliability, manufacturability and cost-effectiveness. Computational fuel cell engineering (CFCE) tools...
The present work provides three case studies featuring applications of computational fluid dynamics (CFD) in the area of thermal waste treatment (TWT). The purpose of the paper is to demonstrate the benefits offered by simulations in TWT technology in the design, optimisation and troubleshooting of those systems. The case studies deal with practical problems, namely a performance evaluation of a fabric...
The object of the present paper is a review of issues related to the testing of gas and liquid fuel burners which are amongst the most important items of equipment in materials processing and energy producing industries. The text gives basic information about fuels, types of burners and their testing and also about modelling of combustion and formation of pollutants, mainly nitrogen oxides. The first...
As the interest for energy recovery from waste incineration has increased over the years, concern for the impact such processes have on the environment has also grown. To reduce such an impact, the legislation enforced in Italy and Europe imposes important restrictions on the temperature of the exhausts in the combustion chamber, which must be kept above certain values depending on the type of waste...
Pressure-wave supercharger (PWS) is a technical way to raise engine intake pressure. In this research, a compression-ignition (CI) engine is boosted by COMPREX PWS and the performance of the engine was tested. In order to improve the power of the PWS diesel engine, the Grey Relational Analysis was completed. The analysis results show that two factors, the intake air flow and the exhaust gas temperature,...
The performance of the fuel cell is affected by many parameters. One of these parameters is assembly pressure that changes the mechanical properties and dimensions of the fuel cell components. Its first duty, however, is to prevent gas or liquid leakage from the cell and it is important for the contact behaviors of fuel cell components. Some leakage and contact problems can occur on the low assembly...
Thermo vapor compressor (TVC) is simply a steam ejector employed in multi-effect desalination (MED) system. A greater understanding of flow phenomena inside an ejector is important for improving ejector performance. We conducted a computational fluid dynamics (CFD) investigation into the flow structure inside a steam ejector. The study focused on the effects of operating pressure and ejector geometry...
Cavity formation is an important phenomenon in the underground coal gasification (UCG) process. In the early stages of cavity formation, only the combustion reaction is performed in order to stabilize the temperature field. In the present work, we study the formation of the combustion cavity and the effect of various design and operating parameters such as the distance between the wells, feed flow...
Diesel engines, especially for trucks and buses, cause many economical and ecological problems. Diesel exhaust emissions are a major source of pollution in most urban centers around the world. Furthermore, the price of crude oil continues to increase rapidly. The use of alternative fuels (liquified petroleum gas, LPG and compressed natural gas, CNG) and the optimization of combustion present effective...
The aim of this paper is to study the hydrodynamic behavior induced by a three different turbines: the FBT6 (six flat blades turbine), the RT6 (Rushton turbine), the PBT6 (pitched blades turbine). The turbulent flow generated in stirred tanks is numerically predicted by the resolution of the Navier–Stokes equation in conjunction with the RNG (Renormalization Group) of the k-ε turbulent model. These...
Grate-firing is one of the main technologies currently used for biomass combustion for heat and power production. However, grate-firing is yet to be further developed, towards a better technology for biomass combustion, particularly towards higher efficiency, lower emissions, and better reliability and availability. To better understand grate-firing of biomass and to establish a reliable but relatively...
Oxy-fuel combustion is considered as one of promising options for carbon dioxide capture in future coal power plants. Currently models available in CFD codes fail to predict accurately the radiative heat transfer in oxy-fuel cases due to higher pressure of carbon dioxide and water vapor. This paper concerns numerical investigation applying three band formulations aiming an accurate prediction of radiative...
The impact of local depth-wise velocity profiles on tidal turbine performance is important. Although the use of standard power laws for predicting velocity profiles is common, these laws may underestimate the magnitude of the depth-wise velocity shear and power attenuation. Predicting the performance of a tidal turbine in a high velocity shear is crucial in terms of power extraction. This paper discusses...
The present paper describes the application of computational fluid-dynamics (CFD) to the design and characterization of a medium scale energy storage unit for district heating systems. The shell-and-tube LHTES unit contains a technical grade paraffin (RT100) as phase change material (PCM) and uses water as heat transfer fluid (HTF). The system has been designed to transfer heat from the district to...
Since millenaries humans have attempted to harness the wind energy through diverse means. Vertical axis wind turbines (VAWTs) were originally considered as very promising, before being superseded by the present, horizontal axis turbines. For various reasons, there is now a resurgence of interests for VAWTs, in particular Darrieus turbines. Using modern design tools and computational approaches, it...
Kathmandu University (KU) is one of the leading educational institutes in Nepal with a decade long experience with R&D of micro-hydro turbines. With a technical collaboration with Norwegian University of Science and Technology (NTNU), KU has also conducted several studies related to sediment erosion in hydro turbine.In the presented study a new program has been developed to create and optimize...
The aim of this work is to investigate design improvements of a shell-and-tube latent heat thermal energy storage unit using an approach based on the analysis of entropy generation. The study is conducted by means of a computational fluid-dynamic (CFD) model which takes into account phase change phenomenon by means of the enthalpy method. Thermal-fluid dynamic problem is solved both for the phase...
Numerical simulations using the computational fluid dynamics (CFD) software ANSYS Fluent were undertaken to characterize the airflow and temperature distribution in a natural convection thermal energy storage refrigerator. The model compared the household refrigerator temperature stability with different phase change materials (PCM) incorporated into the storage compartment. Scenarios investigated...
This article presents the study of heat transfer and fluid flow processes in an artificially roughened solar air heater by using computational fluid dynamics (CFD). The effects of small diameter of transverse wire rib roughness on heat transfer and fluid flow have been investigated. The Reynolds number, relative roughness pitch (P/e) and relative roughness height (e/D) are chosen as design variables...
Wells turbine is a part of OWC (Oscillating Water Column) which is one of the most practical wave energy converters. However, they suffer low aerodynamic efficiency and consequently low power produced. It is proposed to improve the aerodynamic efficiency of Wells turbines by optimizing the blade pitch angle. A fully automated optimization algorithm is implemented in the present work. Two different...
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