Showing 4 results for Nitrogen Oxide
Mehran Rajabi Zargarabadi, Moosa Zaki,
Volume 14, Issue 10 (1-2015)
Abstract
The nitrogen oxide emission is known as a potentially hazardous pollutant in reacting flows. To improve this process, it is of fundamental importance to take into consideration environment protection through reduction of fuel consumption in addition to increasing combustion efficiency. The control of NO emission from the combustion process is an important design criterion in modern gas turbine technology. In the present work a two-dimensional combustion simulation is developed for a model gas turbine combustion chamber. The k−ε turbulence model and the eddy dissipation concept model are applied for flow predictions and reaction rate simulation respectively. The flow field pressure linked equations are solved using the SIMPLE algorithm. In the present work, the thermal and prompt NO formations are estimated and calculated for three different methane, propane and pentane fuels. Also the effects of equivalence ratio and primary aeration on nitrogen oxide emission are considered. Results of numerical simulation show that the nitrogen oxide emission significantly affected by the equivalence ratio for all three type of fuels. Also by applying primary aeration the averaged nitrogen oxide production can be significantly reduced.
Fathollah Ommi, Zoheir Saboohi,
Volume 16, Issue 10 (1-2017)
Abstract
The design of combustor has long been the most challenging portion in the design process of a gas turbine. This paper focused on the conceptual design methodology for aircraft combustors. The necessity of this work arose from an urgent need for a comprehensive model that can quickly provide data in the initial phases (conceptual design and preliminary design) of the design process. The proposed methodology integrated the performance and the design of combustors. To accomplish this, a computer code has been developed based on the design procedures. The design model could provide the combustor geometry and the combustor performance. Based on the available inputs data in the initial phases of the design process, a chemical reactor network (CRN) approach is selected to model the combustion with a detailed chemistry. In this way, three different chemical mechanisms are studied for Jet-A aviation fuel. Furthermore, the droplet evaporation for liquid fuel and the non-uniformity in the fuel-air mixture are modelled. The results of a developed design tool are compared with data of an annular engine’s combustor. The results have good agreement with the actual geometry and outputs of engine test rig emissions.
Mohammad Saeedan, Mohammad Hassan Saeedi, Hamid Reza Fajri,
Volume 17, Issue 4 (6-2017)
Abstract
In this study, a numerical investigation of using Rapeseed Oil in National Diesel Engine has been developed and validated against the experimental data. By using validated model, the effect of injection timing, exhaust gas recirculation and initial pressure on performance and emissions of this engine with three different range of using diesel and biodiesel fuels have been investigated. Biodiesel fuel has two significant characteristics, existing Oxygen Atom in its structure and low lower heating value comparing diesel fuel. The results show by increasing biodiesel fuel, better combustion process has been achieved and consequently, increasing in thermal efficiency and reducing carbon monoxide emission have been observed. Because of different characteristics of biodiesel fuel, increasing and decreasing in the amount of this fuel can effect differently on engine power and producing nitrogen oxide emission.
M. Zhaleh Rafati, A. Javadi , M. Taherinezhad, S.f. Chini,
Volume 19, Issue 2 (2-2019)
Abstract
Controlling the gas turbine emissions has led the manufacturers to use new technologies. Nitrogen oxides (NOx) are one of the major pollutants of gas turbines with natural gas as fuel. Thermal NOx is the main cause of NOx formation in gas turbines at high temperatures. So, water injection can be useful in reducing the NOx emission. In addition to NOx reduction, water injection causes an increase in carbon monoxide emission and damage to combustion chamber. Therefore, it is desirable to find the optimum amount of water injected to the combustion chamber to meet the regulations. To find the optimal water mass flow rate, we numerically investigated the combustion inside the chamber for full load and part load before and after water injection. Then, the effect of water injection at different flow rates was studied to obtain optimal water flow rate. The results showed that for the full load, the optimal water flow rate was 100% of the fuel flow rate and the upstream pressure of the feed water system was 24.45 bar. For the part load (fuel flow rate equals to 75% of the full load), the optimum water injection rate is 80% of the fuel flow rate. In this case, the pressure required for water injection is about 16.5 bar. Results also show that the change in water temperature in the range of 10-80˚C has no significant effect on NOx formation and water can be injected at the ambient temperature.
