An experimental investigation of ammonia/landfill/air mixtures' pollutant emissions and temperature distribution under non-preheated moderate or intense low-oxygen dilution combustion.

This paper investigates the non-preheated MILD combustion behavior of landfill/ammonia mixtures. The experiments were carried out in a laboratory-scale furnace. The effects of equivalence ratio variation, CO2 dilution, and ammonia on the furnace temperature distribution and exhaust gas emissions were analyzed attentively. The experiment results indicate that a non-preheated MILD combustion establishment can provide a uniform temperature distribution and lower pollutant emissions while maintaining the same thermal efficiency. According to the results, equivalence ratio changes affect the MILD temperature structure sensibly. Variation of equivalence ratio is also effective on the pollutant emissions. Moreover, the rich burn condition increases the CO emissions by bringing the HCN and H radicals into the related reactions. Whereas in lean-burn states, little amounts of CO are generated, while the NO concentrations are higher due to the NH2 pathways. The results also indicate that CO2 dilution reduces the furnace's peak temperature. However, CO2 dilution may also increase the O and OH radicals, allowing HCN molecules to react and generate NO. Regarding the ammonia addition experiments, it was figured out that ammonia increases NOx emissions, while decreasing CO2 concentrations affect the flame temperature profile.

Effect of surfactant concentration on the evaporation-driven deposition of carbon nanotubes: from coffee-ring effect to strain sensing.

Carbon nanotubes (CNTs) as electrically conductive materials are of great importance in the fabrication of flexible electronic devices and wearable sensors. In this regard, the evaporation-driven self-assembly of CNTs has attracted increasing attention. CNT-based applications are mostly concerned with the alignment of CNTs and the density of CNT films. In the present work, we focus on the latter by trying to achieve an optimal evaporation-driven deposition with the densest CNT ring. Although surfactants are used for effective dispersion and colloidal stabilization of CNTs in the aqueous phase, their excessive usage induces Marangoni eddies in the evaporating sessile droplets, leading to poor ring depositions. Thus, there is an optimum surfactant concentration that contributes to CNTs deagglomeration and results in the densest ring-like deposition with relatively high thickness. We report that this optimum concentration for sodium dodecyl sulfate (SDS) as a surfactant can be approximately considered as much as the concentration of multi-walled carbon nanotubes (MWCNTs) as the colloidal nanoparticles. Optimal depositions show the lowest electrical resistances for each CNT concentration, making them suitable for electronic applications. We also propose the multiple depositions method in which a new droplet is printed after the complete evaporation of the previous droplet. This method can lead to denser rings with a higher conductivity using lower concentrations of CNTs. Lastly, we fabricate strain sensors based on the optimal evaporation-driven deposition of CNTs which show higher gauge factors than the commercial strain gauges, corroborating the applicability of our method.