scispace - formally typeset
Search or ask a question
Topic

NOx

About: NOx is a research topic. Over the lifetime, 26367 publications have been published within this topic receiving 496555 citations.


Papers
More filters
Proceedings ArticleDOI
23 Feb 1998
TL;DR: In this paper, the effects of exhaust gas recirculation on diesel engine exhaust emissions were isolated and studied in earlier investigations (1,2,3,4,5,6).
Abstract: The effects of Exhaust Gas Recirculation (EGR) on diesel engine exhaust emissions were isolated and studied in earlier investigations (1,2,3,4,5). This paper analyses the heat release patterns during the combustion process and co-relates the results with the exhaust emissions. The EGR effects considered include the dilution of the inlet charge with CO2 or water vapour, the increase in the inlet charge temperature, and the thermal throttling arising from the use of hot EGR. The use of diluents (CO2 and H 2O), which are the principal constituents of EGR, caused an increase in ignition delay and a shift in the location of start of combustion. As a consequence of this shift, the whole combustion process was also shifted further towards the expansion stroke. This resulted in the products of combustion spending shorter periods at high temperatures which lowered the NOx formation rate. In addition, the longer ignition delay period provided more time for the fuel top penetrate which could have led to larger amounts of gases in the flame envelop, thereby lowering the combustion temperature and resulting in lower NOx formation. Although the increased ignition delay period is expected to cause increasing amount of fuel being burned during the pre-mixed burning period, however, the reduction in oxygen availability associated with the application of EGR diluents reduced the rate at which the fuel burnt in the pre-mixed phase. Moreover, the shift of the combustion process towards the expansion stroke resulted in earlier quenching of the combustion process, that is, shorter combustion duration, which yielded higher levels of products of incomplete combustion in the exhaust. The different effects of inlet charge thermal throttling (associated with the use of hot EGR) were simulated and the heat release patterns were analysed. The reduction in the inlet charge oxygen, resulting from throttling the inlet charge, caused an increase in the ignition delay; however, this increase was largely offset by reductions in ignition delay due to increased inlet charge temperature and decreased inlet charge mass. Copyright © 1998 Society of Automotive Engineers, Inc.

115 citations

Journal ArticleDOI
TL;DR: In this paper, the potential of partial ammonia substitution to improve the safety of hydrogen use and the effects on the performance of internal combustion engines, the propagation, development of surface cellular instability and nitrogen oxide (NOx) and nitrous oxide (N2O) emissions of spark-ignited spherical laminar premixed ammonia/hydrogen/air flames were studied experimentally and computationally.

115 citations

Journal ArticleDOI
TL;DR: In this article, the reduction of nitrogen oxide with ammonia using carbon catalysts with chemically modified surfaces was studied using carbon samples with different surface chemistry obtained from commercial activated carbon D43/1 (CarboTech, Essen, Germany).

115 citations

Journal ArticleDOI
01 Jan 2009
TL;DR: In this article, an investigation of NO x -emissions under Ar/O 2 as well as CO 2 /O 2 atmospheres was carried out in order to quantify the ratio of fuel- to thermal-NO.
Abstract: Flameless or ‘mild’ combustion is a well known measure to reduce NO x -emissions. This work aims at the application of the technique to coal combustors. Experiments have been carried out with lignite as well as bituminous coals showing an overall NO x -reduction capability with the current burner design of about 20–50% depending on fuel type and the stoichiometry at the burner. The most important design feature is a high momentum of the combustion air inducing a strong recirculation which reduces the temperature variations and temperature peaks in the combustion chamber and thus prevents thermal NO formation. An investigation of NO x -emissions under Ar/O 2 as well as CO 2 /O 2 atmospheres was carried out in order to quantify the ratio of fuel- to thermal-NO. This investigation showed a high reduction of thermal NO in the flameless combustion mode. It also showed an increase of fuel-NO which was primarily related to the decrease of the peak flame temperature in flameless combustion. The intensive mixing in flameless combustion also allows a reduction of the oxidiser oxygen concentration under oxyfuel conditions to 15 vol % as compared to 17 vol % with a standard swirl burner.

115 citations

Journal ArticleDOI
01 Nov 2005-Fuel
TL;DR: In this paper, a 20kW vertical combustor equipped with a single pf-burner was used for coal combustion in air and O2/CO2 mixtures with NOx recycle.

115 citations


Network Information
Related Topics (5)
Combustion
172.3K papers, 1.9M citations
88% related
Biomass
57.2K papers, 1.4M citations
78% related
Adsorption
226.4K papers, 5.9M citations
76% related
Carbon
129.8K papers, 2.7M citations
76% related
Particle size
69.8K papers, 1.7M citations
76% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20241
20231,699
20223,249
20211,405
20201,353
20191,367