NOx

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

Methane and Nitrogen Oxide Fluxes in Tropical Agricultural Soils: Sources, Sinks and Mechanisms

Abstract: Tropical soils are important sources and sinks of atmospheric methane (CH4) and major sources of oxides of nitrogen gases, nitrous oxide (N2O) and NOx (NO+NO2). These gases are present in the atmosphere in trace amounts and are important to atmospheric chemistry and earth’s radiative balance. Although nitric oxide (NO) does not directly contribute to the greenhouse effect by absorbing infrared radiation, it contributes to climate forcing through its role in photochemistry of hydroxyl radicals and ozone (O3) and plays a key role in air quality issues. Agricultural soils are a primary source of anthropogenic trace gas emissions, and the tropics and subtropics contribute greatly, particularly since 51% of world soils are in these climate zones.

High-temperature potentiometric/amperometric nox sensors combining stabilized zirconia with mixed-metal oxide electrode

Abstract: Electrochemical sensors using stabilized zirconia and oxide electrodes were tested for detecting NO or NO2 potentiometrically and amperometrically at high temperature. For a mixed-potential-type NOx sensor of two-electrode structure, CdCr2O4 was found to give fairly excellent NOx sensing characteristics among the perovskite-type and spinel-type oxides tested. The CdCr2O4-attached device gave a linear correlation between EMF and the logarithm of NO or NO2 concentration at 500–600°C. The mixed potential sensing mechanism was also verified. In order to improve the sensitivity and selectivity to NO, the above device was modified to three-electrode structure. With a fixed bias voltage being applied between the sensing (oxide) and counter (Pt) electrodes, the voltage between the sensing and reference (Pt) electrodes was measured as a sensing signal. The responses to NO and NO2 were found to be enhanced and suppressed with a positive bias, respectively. The tubular device with two-electrode structure was tested for amperometric detection of NOx. A CdCr2O4-attached tubular device was found to show quick and selective response to NO over NO2 at 500 and 550°C, if the oxide sensing electrode was polarized at +100 mV versus the reference Pt electrode. The NOx sensing mechanisms of the three-electrode device were proposed and discussed on the basis of the sensing characteristics obtained.

Impact of biodiesel on NOx emissions in a common rail direct injection diesel engine

Abstract: The impact of biodiesel on NOx emissions was investigated in a 2.5 L common rail direct injection diesel engine under both low load and high load conditions with different fuel injection strategies. Three fuels were used in this study, an ultralow sulfur diesel fuel (BP15), a blend of 20 vol % biodiesel in BP15 (B20), and a blend of 40 vol % biodiesel in BP15 (B40). Fuel injection timings were held the same for the biodiesel blends and the baseline diesel fuel to eliminate the potential injection timing differences due to the different fuel heating values. According to the needle lift profiles obtained from the needle lift sensor, no measurable injection timing differences were observed between the biodiesel blends and the baseline diesel fuel. Biodiesel blends were found to generally produce slightly lower NOx emissions than the baseline diesel fuel at the low load condition. Under the high load condition, evidently higher NOx emissions for biodiesel blends were observed under both single and double inje...