Abstract: The present invention discloses methods and devices for controlling a heated mixer, situated downstream of a Urea-Water Solution (UWS) injector, to reduce NOx emission in an exhaust system from combustion engines, wherein the exhaust system has a Selective Catalytic Reduction (SCR) catalyst situated downstream of the UWS injector and the heated mixer, Methods include: determining a NOx reduction efficiency of the SCR catalyst; evaluating at least one reductant Uniformity Index (UI) based on operating parameters of the exhaust system and a mixer power calculation map; and modifying a mixer temperature of the heated mixer by regulating power to the heated mixer based on at least one reductant UI in order to improve at least one reductant UI and/or improve the NOx reduction efficiency. Alternatively, the method further includes: detecting at least one potential improvement of at least one UI and/or the NOx reduction efficiency based on an increased ammonia mass.

Abstract: A spray visualization apparatus and method are disclosed. Unlike laser or Doppler techniques requiring costly instrumentation, the herein disclosed technique is much simpler. The apparatus comprises a hollow flow tube, an injector device coupled to the hollow flow tube, and at least one membrane surface material substantially positioned cross-flow in the hollow flow tube. The method relies on a fluorescent dye marking the spray droplets impinging on the membrane surface material. The image of spray droplets on the membrane reveals the distribution pattern of droplets in the oncoming flow as the droplets impinge on the membrane. A digital scan of the membrane is acquired. The scanned image is quantitatively analyzed for droplet size, amount and uniformity index. The disclosed technique is a low-cost alternative for study and testing spray patterns generated by automobile emissions.